Boost-Commit mailing page: [Boost-commit] svn:boost r43674

Date view	Thread view	Subject view	Author view

From: anthony_at_[hidden]
Date: 2008-03-17 09:59:22

Next message: eric_at_[hidden]: "[Boost-commit] svn:boost r43675 - in branches/release: . libs/xpressive/doc"
Previous message: anthony_at_[hidden]: "[Boost-commit] svn:boost r43673 - in branches/release: boost/thread/pthread boost/thread/win32 libs/thread/test"

Author: anthonyw
Date: 2008-03-17 09:59:17 EDT (Mon, 17 Mar 2008)
New Revision: 43674
URL: http://svn.boost.org/trac/boost/changeset/43674

Log:
New documentation for thread library imported from trunk revision 43671
Added:
   branches/release/libs/thread/doc/acknowledgements.qbk
      - copied unchanged from r43671, /trunk/libs/thread/doc/acknowledgements.qbk
   branches/release/libs/thread/doc/barrier.qbk
      - copied unchanged from r43671, /trunk/libs/thread/doc/barrier.qbk
   branches/release/libs/thread/doc/changes.qbk
      - copied unchanged from r43671, /trunk/libs/thread/doc/changes.qbk
   branches/release/libs/thread/doc/condition_variables.qbk
      - copied unchanged from r43671, /trunk/libs/thread/doc/condition_variables.qbk
   branches/release/libs/thread/doc/mutex_concepts.qbk
      - copied unchanged from r43671, /trunk/libs/thread/doc/mutex_concepts.qbk
   branches/release/libs/thread/doc/mutexes.qbk
      - copied unchanged from r43671, /trunk/libs/thread/doc/mutexes.qbk
   branches/release/libs/thread/doc/once.qbk
      - copied unchanged from r43671, /trunk/libs/thread/doc/once.qbk
   branches/release/libs/thread/doc/overview.qbk
      - copied unchanged from r43671, /trunk/libs/thread/doc/overview.qbk
   branches/release/libs/thread/doc/shared_mutex_ref.qbk
      - copied unchanged from r43671, /trunk/libs/thread/doc/shared_mutex_ref.qbk
   branches/release/libs/thread/doc/thread.qbk
      - copied unchanged from r43671, /trunk/libs/thread/doc/thread.qbk
   branches/release/libs/thread/doc/thread_ref.qbk
      - copied unchanged from r43671, /trunk/libs/thread/doc/thread_ref.qbk
   branches/release/libs/thread/doc/tss.qbk
      - copied unchanged from r43671, /trunk/libs/thread/doc/tss.qbk
Removed:
   branches/release/libs/thread/doc/acknowledgements.xml
   branches/release/libs/thread/doc/barrier-ref.xml
   branches/release/libs/thread/doc/bibliography.xml
   branches/release/libs/thread/doc/build.xml
   branches/release/libs/thread/doc/concepts.xml
   branches/release/libs/thread/doc/condition-ref.xml
   branches/release/libs/thread/doc/configuration.xml
   branches/release/libs/thread/doc/design.xml
   branches/release/libs/thread/doc/entities.xml
   branches/release/libs/thread/doc/exceptions-ref.xml
   branches/release/libs/thread/doc/faq.xml
   branches/release/libs/thread/doc/glossary.xml
   branches/release/libs/thread/doc/implementation_notes.xml
   branches/release/libs/thread/doc/mutex-ref.xml
   branches/release/libs/thread/doc/once-ref.xml
   branches/release/libs/thread/doc/overview.xml
   branches/release/libs/thread/doc/rationale.xml
   branches/release/libs/thread/doc/read_write_mutex-ref.xml
   branches/release/libs/thread/doc/recursive_mutex-ref.xml
   branches/release/libs/thread/doc/reference.xml
   branches/release/libs/thread/doc/release_notes.xml
   branches/release/libs/thread/doc/thread-ref.xml
   branches/release/libs/thread/doc/thread.xml
   branches/release/libs/thread/doc/tss-ref.xml
   branches/release/libs/thread/doc/xtime-ref.xml
Text files modified:
   branches/release/libs/thread/doc/Jamfile.v2 | 80 ++++++++++++++++++++++++---------------
   1 files changed, 49 insertions(+), 31 deletions(-)

Modified: branches/release/libs/thread/doc/Jamfile.v2
==============================================================================
--- branches/release/libs/thread/doc/Jamfile.v2 (original)
+++ branches/release/libs/thread/doc/Jamfile.v2 2008-03-17 09:59:17 EDT (Mon, 17 Mar 2008)
@@ -1,11 +1,55 @@
-# Copyright (C) 2001-2003
-# William E. Kempf
+# (C) Copyright 2008 Anthony Williams
#
# Distributed under the Boost Software License, Version 1.0. (See accompanying
# file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)

-import toolset ;
-toolset.using doxygen ;
+path-constant boost-images : ../../../doc/src/images ;

-boostbook thread : thread.xml ;
+xml thread : thread.qbk ;
+
+boostbook standalone
+ :
+ thread
+ :
+ # HTML options first:
+ # Use graphics not text for navigation:
+ <xsl:param>navig.graphics=1
+ # How far down we chunk nested sections, basically all of them:
+ <xsl:param>chunk.section.depth=3
+ # Don't put the first section on the same page as the TOC:
+ <xsl:param>chunk.first.sections=1
+ # How far down sections get TOC's
+ <xsl:param>toc.section.depth=10
+ # Max depth in each TOC:
+ <xsl:param>toc.max.depth=3
+ # How far down we go with TOC's
+ <xsl:param>generate.section.toc.level=10
+ # Path for links to Boost:
+ <xsl:param>boost.root=../../../..
+ # Path for libraries index:
+ <xsl:param>boost.libraries=../../../../libs/libraries.htm
+ # Use the main Boost stylesheet:
+ <xsl:param>html.stylesheet=../../../../doc/html/boostbook.css
+
+ # PDF Options:
+ # TOC Generation: this is needed for FOP-0.9 and later:
+ #<xsl:param>fop1.extensions=1
+ # Or enable this if you're using XEP:
+ <xsl:param>xep.extensions=1
+ # TOC generation: this is needed for FOP 0.2, but must not be set to zero for FOP-0.9!
+ <xsl:param>fop.extensions=0
+ # No indent on body text:
+ <xsl:param>body.start.indent=0pt
+ # Margin size:
+ <xsl:param>page.margin.inner=0.5in
+ # Margin size:
+ <xsl:param>page.margin.outer=0.5in
+ # Yes, we want graphics for admonishments:
+ <xsl:param>admon.graphics=1
+ # Set this one for PDF generation *only*:
+ # default pnd graphics are awful in PDF form,
+ # better use SVG's instead:
+ <format>pdf:<xsl:param>admon.graphics.extension=".svg"
+ <format>pdf:<xsl:param>admon.graphics.path=$(boost-images)/
+ ;

Deleted: branches/release/libs/thread/doc/acknowledgements.xml
==============================================================================
--- branches/release/libs/thread/doc/acknowledgements.xml 2008-03-17 09:59:17 EDT (Mon, 17 Mar 2008)
+++ (empty file)
@@ -1,73 +0,0 @@
-<?xml version="1.0" encoding="utf-8"?>
-<!DOCTYPE library PUBLIC "-//Boost//DTD BoostBook XML V1.0//EN"
- "http://www.boost.org/tools/boostbook/dtd/boostbook.dtd" [
- <!ENTITY % thread.entities SYSTEM "entities.xml">
- %thread.entities;
-]>
-
-<section id="thread.acknowledgements"
-last-revision="$Date$">
- <title>Acknowledgements</title>
- <para>William E. Kempf was the architect, designer, and implementor of
- &Boost.Thread;.</para>
- <para>Mac OS Carbon implementation written by Mac Murrett.</para>
- <para>Dave Moore provided initial submissions and further comments on the
- <code>barrier</code>
- ,
- <code>thread_pool</code>
- ,
- <code>read_write_mutex</code>
- ,
- <code>read_write_try_mutex</code>
- and
- <code>read_write_timed_mutex</code>
- classes.</para>
- <para>Important contributions were also made by Jeremy Siek (lots of input
- on the design and on the implementation), Alexander Terekhov (lots of input
- on the Win32 implementation, especially in regards to boost::condition, as
- well as a lot of explanation of POSIX behavior), Greg Colvin (lots of input
- on the design), Paul Mclachlan, Thomas Matelich and Iain Hanson (for help
- in trying to get the build to work on other platforms), and Kevin S. Van
- Horn (for several updates/corrections to the documentation).</para>
- <para>Mike Glassford finished changes to &Boost.Thread; that were begun
- by William Kempf and moved them into the main CVS branch.
- He also addressed a number of issues that were brought up on the Boost
- developer's mailing list and provided some additions and changes to the
- read_write_mutex and related classes.</para>
- <para>The documentation was written by William E. Kempf. Beman Dawes
- provided additional documentation material and editing.
- Mike Glassford finished William Kempf's conversion of the documentation to
- BoostBook format and added a number of new sections.</para>
- <para>Discussions on the boost.org mailing list were essential in the
- development of &Boost.Thread;
- . As of August 1, 2001, participants included Alan Griffiths, Albrecht
- Fritzsche, Aleksey Gurtovoy, Alexander Terekhov, Andrew Green, Andy Sawyer,
- Asger Alstrup Nielsen, Beman Dawes, Bill Klein, Bill Rutiser, Bill Wade,
- Branko èibej, Brent Verner, Craig Henderson, Csaba Szepesvari,
- Dale Peakall, Damian Dixon, Dan Nuffer, Darryl Green, Daryle Walker, David
- Abrahams, David Allan Finch, Dejan Jelovic, Dietmar Kuehl, Douglas Gregor,
- Duncan Harris, Ed Brey, Eric Swanson, Eugene Karpachov, Fabrice Truillot,
- Frank Gerlach, Gary Powell, Gernot Neppert, Geurt Vos, Ghazi Ramadan, Greg
- Colvin, Gregory Seidman, HYS, Iain Hanson, Ian Bruntlett, J Panzer, Jeff
- Garland, Jeff Paquette, Jens Maurer, Jeremy Siek, Jesse Jones, Joe Gottman,
- John (EBo) David, John Bandela, John Maddock, John Max Skaller, John
- Panzer, Jon Jagger , Karl Nelson, Kevlin Henney, KG Chandrasekhar, Levente
- Farkas, Lie-Quan Lee, Lois Goldthwaite, Luis Pedro Coelho, Marc Girod, Mark
- A. Borgerding, Mark Rodgers, Marshall Clow, Matthew Austern, Matthew Hurd,
- Michael D. Crawford, Michael H. Cox , Mike Haller, Miki Jovanovic, Nathan
- Myers, Paul Moore, Pavel Cisler, Peter Dimov, Petr Kocmid, Philip Nash,
- Rainer Deyke, Reid Sweatman, Ross Smith, Scott McCaskill, Shalom Reich,
- Steve Cleary, Steven Kirk, Thomas Holenstein, Thomas Matelich, Trevor
- Perrin, Valentin Bonnard, Vesa Karvonen, Wayne Miller, and William
- Kempf.</para>
- <para>
- As of February 2006 Anthony Williams and Roland Schwarz took over maintainance
- and further development of the library after it has been in an orphaned state
- for a rather long period of time.
- </para>
- <para>Apologies for anyone inadvertently missed.</para>
-</section>
-

Deleted: branches/release/libs/thread/doc/barrier-ref.xml
==============================================================================
--- branches/release/libs/thread/doc/barrier-ref.xml 2008-03-17 09:59:17 EDT (Mon, 17 Mar 2008)
+++ (empty file)
@@ -1,82 +0,0 @@
-<?xml version="1.0" encoding="utf-8"?>
-<!DOCTYPE library PUBLIC "-//Boost//DTD BoostBook XML V1.0//EN"
- "http://www.boost.org/tools/boostbook/dtd/boostbook.dtd" [
- <!ENTITY % thread.entities SYSTEM "entities.xml">
- %thread.entities;
-]>
-
-<header name="boost/thread/barrier.hpp"
- last-revision="$Date$">
- <namespace name="boost">
- <class name="barrier">
- <inherit access="private">
- <type><classname>boost::noncopyable</classname></type>
- <purpose>Exposition only</purpose>
- </inherit>
-
- <purpose>
- <para>An object of class <classname>barrier</classname> is a synchronization
- primitive used to cause a set of threads to wait until they each perform a
- certain function or each reach a particular point in their execution.</para>
- </purpose>
-
- <description>
- <para>When a barrier is created, it is initialized with a thread count N.
- The first N-1 calls to <code>wait()</code> will all cause their threads to be blocked.
- The Nth call to <code>wait()</code> will allow all of the waiting threads, including
- the Nth thread, to be placed in a ready state. The Nth call will also "reset"
- the barrier such that, if an additional N+1th call is made to <code>wait()</code>,
- it will be as though this were the first call to <code>wait()</code>; in other
- words, the N+1th to 2N-1th calls to <code>wait()</code> will cause their
- threads to be blocked, and the 2Nth call to <code>wait()</code> will allow all of
- the waiting threads, including the 2Nth thread, to be placed in a ready state
- and reset the barrier. This functionality allows the same set of N threads to re-use
- a barrier object to synchronize their execution at multiple points during their
- execution.</para>
- <para>See <xref linkend="thread.glossary"/> for definitions of thread
- states <link linkend="thread.glossary.thread-state">blocked</link>
- and <link linkend="thread.glossary.thread-state">ready</link>.
- Note that "waiting" is a synonym for blocked.</para>
- </description>
-
- <constructor>
- <parameter name="count">
- <paramtype>size_t</paramtype>
- </parameter>
-
- <effects><simpara>Constructs a <classname>barrier</classname> object that
- will cause <code>count</code> threads to block on a call to <code>wait()</code>.
- </simpara></effects>
- </constructor>
-
- <destructor>
- <effects><simpara>Destroys <code>*this</code>. If threads are still executing
- their <code>wait()</code> operations, the behavior for these threads is undefined.
- </simpara></effects>
- </destructor>
-
- <method-group name="waiting">
- <method name="wait">
- <type>bool</type>
-
- <effects><simpara>Wait until N threads call <code>wait()</code>, where
- N equals the <code>count</code> provided to the constructor for the
- barrier object.</simpara>
- <simpara><emphasis role="bold">Note</emphasis> that if the barrier is
- destroyed before <code>wait()</code> can return, the behavior is
- undefined.</simpara></effects>
-
- <returns>Exactly one of the N threads will receive a return value
- of <code>true</code>, the others will receive a value of <code>false</code>.
- Precisely which thread receives the return value of <code>true</code> will
- be implementation-defined. Applications can use this value to designate one
- thread as a leader that will take a certain action, and the other threads
- emerging from the barrier can wait for that action to take place.</returns>
- </method>
- </method-group>
- </class>
- </namespace>
-</header>

Deleted: branches/release/libs/thread/doc/bibliography.xml
==============================================================================
--- branches/release/libs/thread/doc/bibliography.xml 2008-03-17 09:59:17 EDT (Mon, 17 Mar 2008)
+++ (empty file)
@@ -1,234 +0,0 @@
-<?xml version="1.0" encoding="utf-8"?>
-<!DOCTYPE library PUBLIC "-//Boost//DTD BoostBook XML V1.0//EN"
- "http://www.boost.org/tools/boostbook/dtd/boostbook.dtd" [
- <!ENTITY % thread.entities SYSTEM "entities.xml">
- %thread.entities;
-]>
-
-<bibliography id="thread.bibliography"
-last-revision="$Date$">
- <title>Bibliography</title>
- <biblioentry id="thread.bib.AndrewsSchneider83">
- <abbrev id="thread.bib.AndrewsSchneider83.abbrev">AndrewsSchnieder83</abbrev>
- <biblioset relation="journal">
- <title>ACM Computing Surveys</title>
- <volumenum>Vol. 15</volumenum>
- <issuenum>No. 1</issuenum>
- <date>March, 1983</date>
- </biblioset>
- <biblioset relation="article">
- <authorgroup>
- <author>
- <firstname>Gregory</firstname>
- <othername>R.</othername>
- <surname>Andrews</surname>
- </author>
- <author>
- <firstname>Fred</firstname>
- <othername>B.</othername>
- <surname>Schneider</surname>
- </author>
- </authorgroup>
- <title>
- <ulink
- url="http://www.acm.org/pubs/citations/journals/surveys/1983-15-1/p3-andrews/"
- >Concepts and Notations for Concurrent Programming</ulink>
- </title>
- </biblioset>
- <para>Good general background reading. Includes descriptions of Path
- Expressions, Message Passing, and Remote Procedure Call in addition to the
- basics</para>
- </biblioentry>
- <biblioentry id="thread.bib.Boost">
- <abbrev id="thread.bib.Boost.abbrev">Boost</abbrev>
- <bibliomisc>The <emphasis>Boost</emphasis> world wide web site.
- <ulink url="http:/www.boost.org">http://www.boost.org></bibliomisc>
- <para>&Boost.Thread; is one of many Boost libraries. The Boost web
- site includes a great deal of documentation and general information which
- applies to all Boost libraries. Current copies of the libraries including
- documentation and test programs may be downloaded from the web
- site.</para>
- </biblioentry>
- <biblioentry id="thread.bib.Hansen73">
- <abbrev id="thread.bib.Hansen73.abbrev">Hansen73</abbrev>
- <biblioset relation="journal">
- <title>ACM Computing Surveys</title>
- <volumenum>Vol. 5</volumenum>
- <issuenum>No. 4</issuenum>
- <date>December, 1973</date>
- </biblioset>
- <biblioset relation="article">
- <author>0-201-63392-2
- <firstname>Per Brinch</firstname>
- <lastname>Hansen</lastname>
- </author>
- <title>
- <ulink
- url="http://www.acm.org/pubs/articles/journals/surveys/1973-5-4/p223-hansen/"
- >Concurrent Programming Concepts</ulink>
- </title>
- </biblioset>
- <para>"This paper describes the evolution of language features for
- multiprogramming from event queues and semaphores to critical regions and
- monitors." Includes analysis of why events are considered error-prone. Also
- noteworthy because of an introductory quotation from Christopher Alexander;
- Brinch Hansen was years ahead of others in recognizing pattern concepts
- applied to software, too.</para>
- </biblioentry>
- <biblioentry id="thread.bib.Butenhof97">
- <abbrev id="thread.bib.Butenhof97.abbrev">Butenhof97</abbrev>
- <title>
- <ulink url="http://cseng.aw.com/book/0,3828,0201633922,00.html"
- >Programming with POSIX Threads </ulink>
- </title>
- <author>
- <firstname>David</firstname>
- <othername>R.</othername>
- <surname>Butenhof</surname>
- </author>
- <publisher>Addison-Wesley</publisher>
- <copyright><year>1997</year></copyright>
- <isbn>ISNB: 0-201-63392-2</isbn>
- <para>This is a very readable explanation of threads and how to use
- them. Many of the insights given apply to all multithreaded programming, not
- just POSIX Threads</para>
- </biblioentry>
- <biblioentry id="thread.bib.Hoare74">
- <abbrev id="thread.bib.Hoare74.abbrev">Hoare74</abbrev>
- <biblioset relation="journal">
- <title>Communications of the ACM</title>
- <volumenum>Vol. 17</volumenum>
- <issuenum>No. 10</issuenum>
- <date>October, 1974</date>
- </biblioset>
- <biblioset relation="article">
- <title>
- <ulink url=" http://www.acm.org/classics/feb96/"
- >Monitors: An Operating System Structuring Concept</ulink>
- </title>
- <author>
- <firstname>C.A.R.</firstname>
- <surname>Hoare</surname>
- </author>
- <pagenums>549-557</pagenums>
- </biblioset>
- <para>Hoare and Brinch Hansen's work on Monitors is the basis for reliable
- multithreading patterns. This is one of the most often referenced papers in
- all of computer science, and with good reason.</para>
- </biblioentry>
- <biblioentry id="thread.bib.ISO98">
- <abbrev id="thread.bib.ISO98.abbrev">ISO98</abbrev>
- <title>
- <ulink url="http://www.ansi.org">Programming Language C++</ulink>
- </title>
- <orgname>ISO/IEC</orgname>
- <releaseinfo>14882:1998(E)</releaseinfo>
- <para>This is the official C++ Standards document. Available from the ANSI
- (American National Standards Institute) Electronic Standards Store.</para>
- </biblioentry>
- <biblioentry id="thread.bib.McDowellHelmbold89">
- <abbrev id="thread.bib.McDowellHelmbold89.abbrev">McDowellHelmbold89</abbrev>
- <biblioset relation="journal">
- <title>Communications of the ACM</title>
- <volumenum>Vol. 21</volumenum>
- <issuenum>No. 2</issuenum>
- <date>December, 1989</date>
- </biblioset>
- <biblioset>
- <author>
- <firstname>Charles</firstname>
- <othername>E.</othername>
- <surname>McDowell</surname>
- </author>
- <author>
- <firstname>David</firstname>
- <othername>P.</othername>
- <surname>Helmbold</surname>
- </author>
- <title>
- <ulink
- url="http://www.acm.org/pubs/citations/journals/surveys/1989-21-4/p593-mcdowell/"
- >Debugging Concurrent Programs</ulink>
- </title>
- </biblioset>
- <para>Identifies many of the unique failure modes and debugging difficulties
- associated with concurrent programs.</para>
- </biblioentry>
- <biblioentry id="thread.bib.SchmidtPyarali">
- <abbrev id="thread.bib.SchmidtPyarali.abbrev">SchmidtPyarali</abbrev>
- <title>
- <ulink url="http://www.cs.wustl.edu/~schmidt/win32-cv-1.html8"
- >Strategies for Implementing POSIX Condition Variables on Win32</ulink>
- </title>
- <authorgroup>
- <author>
- <firstname>Douglas</firstname>
- <othername>C.</othername>
- <surname>Schmidt</surname>
- </author>
- <author>
- <firstname>Irfan</firstname>
- <surname>Pyarali</surname>
- </author>
- </authorgroup>
- <orgname>Department of Computer Science, Washington University, St. Louis,
- Missouri</orgname>
- <para>Rationale for understanding &Boost.Thread; condition
- variables. Note that Alexander Terekhov found some bugs in the
- implementation given in this article, so pthreads-win32 and &Boost.Thread;
- are even more complicated yet.</para>
- </biblioentry>
- <biblioentry id="thread.bib.SchmidtStalRohnertBuschmann">
- <abbrev
- id="thread.bib.SchmidtStalRohnertBuschmann.abbrev">SchmidtStalRohnertBuschmann</abbrev>
- <title>
- <ulink
- url="http://www.wiley.com/Corporate/Website/Objects/Products/0,9049,104671,00.html"
- >Pattern-Oriented Architecture Volume 2</ulink>
- </title>
- <subtitle>Patterns for Concurrent and Networked Objects</subtitle>
- <titleabbrev>POSA2</titleabbrev>
- <authorgroup>
- <author>
- <firstname>Douglas</firstname>
- <othername>C.</othername>
- <surname>Schmidt</surname>
- </author>
- <author>
- <firstname>Michael</firstname>
- <lastname>Stal</lastname>
- </author>
- <author>
- <firstname>Hans</firstname>
- <surname>Rohnert</surname>
- </author>
- <author>
- <firstname>Frank</firstname>
- <surname>Buschmann</surname>
- </author>
- </authorgroup>
- <publisher>Wiley</publisher>
- <copyright><year>2000</year></copyright>
- <para>This is a very good explanation of how to apply several patterns
- useful for concurrent programming. Among the patterns documented is the
- Monitor Pattern mentioned frequently in the &Boost.Thread;
- documentation.</para>
- </biblioentry>
- <biblioentry id="thread.bib.Stroustrup">
- <abbrev id="thread.bib.Stroustrup.abbrev">Stroustrup</abbrev>
- <title>
- <ulink url="http://cseng.aw.com/book/0,3828,0201700735,00.html"
- >The C++ Programming Language</ulink>
- </title>
- <edition>Special Edition</edition>
- <publisher>Addison-Wesley</publisher>
- <copyright><year>2000</year></copyright>
- <isbn>ISBN: 0-201-70073-5</isbn>
- <para>The first book a C++ programmer should own. Note that the 3rd edition
- (and subsequent editions like the Special Edition) has been rewritten to
- cover the ISO standard language and library.</para>
- </biblioentry>
-</bibliography>

Deleted: branches/release/libs/thread/doc/build.xml
==============================================================================
--- branches/release/libs/thread/doc/build.xml 2008-03-17 09:59:17 EDT (Mon, 17 Mar 2008)
+++ (empty file)
@@ -1,137 +0,0 @@
-<?xml version="1.0" encoding="utf-8" ?>
-<!DOCTYPE library PUBLIC "-//Boost//DTD BoostBook XML V1.0//EN"
- "http://www.boost.org/tools/boostbook/dtd/boostbook.dtd" [
- <!ENTITY % thread.entities SYSTEM "entities.xml">
- %thread.entities;
-]>
-
-<section id="thread.build" last-revision="$Date$">
- <title>Build</title>
- <para>
- How you build the &Boost.Thread; libraries, and how you build your own applications
- that use those libraries, are some of the most frequently asked questions. Build
- processes are difficult to deal with in a portable manner. That's one reason
- why &Boost.Thread; makes use of &Boost.Build;.
- In general you should refer to the documentation for &Boost.Build;.
- This document will only supply you with some simple usage examples for how to
- use <emphasis>bjam</emphasis> to build and test &Boost.Thread;. In addition, this document
- will try to explain the build requirements so that users may create their own
- build processes (for instance, create an IDE specific project), both for building
- and testing &Boost.Thread;, as well as for building their own projects using
- &Boost.Thread;.
- </para>
- <section id="thread.build.building">
- <title>Building the &Boost.Thread; Libraries</title>
- <para>
- Building the &Boost.Thread; Library depends on how you intend to use it. You have several options:
- <itemizedlist>
- <listitem>
- Using as a <link linkend="thread.build.precompiled">precompiled</link> library, possibly
- with auto-linking, or for use from within an IDE.
- </listitem>
- <listitem>
- Use from a <link linkend="thread.build.bjam">&Boost.Build;</link> project.
- </listitem>
- <listitem>
- Using in <link linkend="thread.build.source">source</link> form.
- </listitem>
- </itemizedlist>
- </para>
- <section id="thread.build.precompiled">
- <title>Precompiled</title>
- <para>
- Using the &Boost.Thread; library in precompiled form is the way to go if you want to
- install the library to a standard place, from where your linker is able to resolve code
- in binary form. You also will want this option if compile time is a concern. Multiple
- variants are available, for different toolsets and build variants (debug/release).
- The library files are named <emphasis>{lead}boost_thread{build-specific-tags}.{extension}</emphasis>,
- where the build-specific-tags indicate the toolset used to build the library, whether it's
- a debug or release build, what version of &Boost; was used, etc.; and the lead and extension
- are the appropriate extensions for a dynamic link library or static library for the platform
- for which &Boost.Thread; is being built.
- For instance, a debug build of the dynamic library built for Win32 with VC++ 7.1 using Boost 1.34 would
- be named <emphasis>boost_thread-vc71-mt-gd-1_34.dll</emphasis>.
- More information on this should be available from the &Boost.Build; documentation.
- </para>
- <para>
- Building should be possible with the default configuration. If you are running into problems,
- it might be wise to adjust your local settings of &Boost.Build; though. Typically you will
- need to get your user-config.jam file to reflect your environment, i.e. used toolsets. Please
- refer to the &Boost.Build; documentation to learn how to do this.
- </para>
- <para>
- To create the libraries you need to open a command shell and change to the
- <emphasis>boost_root</emphasis> directory. From there you give the command
- <programlisting>bjam --toolset=<emphasis>mytoolset</emphasis> stage --with-thread</programlisting>
- Replace <emphasis>mytoolset</emphasis> with the name of your toolset, e.g. msvc-7.1 .
- This will compile and put the libraries into the <emphasis>stage</emphasis> directory which is just below the
- <emphasis>boost_root</emphasis> directory. &Boost.Build; by default will generate static and
- dynamic variants for debug and release.
- </para>
- <note>
- Invoking the above command without the --with-thread switch &Boost.Build; will build all of
- the Boost distribution, including &Boost.Thread;.
- </note>
- <para>
- The next step is to copy your libraries to a place where your linker is able to pick them up.
- It is also quite possible to leave them in the stage directory and instruct your IDE to take them
- from there.
- </para>
- <para>
- In your IDE you then need to add <emphasis>boost_root</emphasis>/boost to the paths where the compiler
- expects to find files to be included. For toolsets that support <emphasis>auto-linking</emphasis>
- it is not necessary to explicitly specify the name of the library to link against, it is sufficient
- to specify the path of the stage directory. Typically this is true on Windows. For gcc you need
- to specify the exact library name (including all the tags). Please don't forget that threading
- support must be turned on to be able to use the library. You should be able now to build your
- project from the IDE.
- </para>
- </section>
- <section id="thread.build.bjam">
- <title>&Boost.Build; Project</title>
- <para>
- If you have decided to use &Boost.Build; as a build environment for your application, you simply
- need to add a single line to your <emphasis>Jamroot</emphasis> file:
- <programlisting>use-project /boost : {path-to-boost-root} ;</programlisting>
- where <emphasis>{path-to-boost-root}</emphasis> needs to be replaced with the location of
- your copy of the boost tree.
- Later when you specify a component that needs to link against &Boost.Thread; you specify this
- as e.g.:
- <programlisting>exe myapp : {myappsources} /boost//thread ;</programlisting>
- and you are done.
- </para>
- </section>
- <section id="thread.build.source">
- <title>Source Form</title>
- <para>
- Of course it is also possible to use the &Boost.Thread; library in source form.
- First you need to specify the <emphasis>boost_root</emphasis>/boost directory as
- a path where your compiler expects to find files to include. It is not easy
- to isolate the &Boost.Thread; include files from the rest of the boost
- library though. You would also need to isolate every include file that the thread
- library depends on. Next you need to copy the files from
- <emphasis>boost_root</emphasis>/libs/thread/src to your project and instruct your
- build system to compile them together with your project. Please look into the
- <emphasis>Jamfile</emphasis> in <emphasis>boost_root</emphasis>/libs/thread/build
- to find out which compiler options and defines you will need to get a clean compile.
- Using the boost library in this way is the least recommended, and should only be
- considered if avoiding dependency on &Boost.Build; is a requirement. Even if so
- it might be a better option to use the library in it's precompiled form.
- Precompiled downloads are available from the boost consulting web site, or as
- part of most linux distributions.
- </para>
- </section>
- </section>
- <section id="thread.build.testing">
- <title>Testing the &Boost.Thread; Libraries</title>
- <para>
- To test the &Boost.Thread; libraries using &Boost.Build;, simply change to the
- directory <emphasis>boost_root</emphasis>/libs/thread/test and execute the command:
- <programlisting>bjam --toolset=<emphasis>mytoolset</emphasis> test</programlisting>
- </para>
- </section>
-</section>

Deleted: branches/release/libs/thread/doc/concepts.xml
==============================================================================
--- branches/release/libs/thread/doc/concepts.xml 2008-03-17 09:59:17 EDT (Mon, 17 Mar 2008)
+++ (empty file)
@@ -1,2305 +0,0 @@
-<?xml version="1.0" encoding="utf-8"?>
-<!DOCTYPE library PUBLIC "-//Boost//DTD BoostBook XML V1.0//EN"
- "http://www.boost.org/tools/boostbook/dtd/boostbook.dtd" [
- <!ENTITY % thread.entities SYSTEM "entities.xml">
- %thread.entities;
-]>
-
-<section id="thread.concepts" last-revision="$Date$">
- <title>Concepts</title>
-
- <para>&Boost.Thread; currently supports two types of mutex concepts:
- ordinary <link linkend="thread.concepts.mutexes">Mutexes</link>,
- which allow only one thread at a time to access a resource, and
- <link linkend="thread.concepts.read-write-mutexes">Read/Write Mutexes</link>,
- which allow only one thread at a time to access a resource when it is
- being modified (the "Write" part of Read/Write), but allows multiple threads
- to access a resource when it is only being referenced (the "Read" part of
- Read/Write).</para>
- <note> Unfortunately it turned out that the current implementation of Read/Write Mutex has
- some serious problems. So it was decided not to put this implementation into
- release grade code. Also discussions on the mailing list led to the
- conclusion that the current concepts need to be rethought. In particular
- the schedulings <link linkend="thread.concepts.read-write-scheduling-policies.inter-class">
- Inter-Class Scheduling Policies</link> are deemed unnecessary.
- There seems to be common belief that a fair scheme suffices.
- The following documentation has been retained however, to give
- readers of this document the opportunity to study the original design.
- </note>
-
- <section id="thread.concepts.mutexes">
- <title>Mutexes</title>
-
- <note>Certain changes to the mutexes and lock concepts are
- currently under discussion. In particular, the combination of
- the multiple lock concepts into a single lock concept
- is likely, and the combination of the multiple mutex
- concepts into a single mutex concept is also possible.</note>
-
- <para>A mutex (short for mutual-exclusion) object is used to serialize
- access to a resource shared between multiple threads. The
- <link linkend="thread.concepts.Mutex">Mutex</link> concept, with
- <link linkend="thread.concepts.TryMutex">TryMutex</link> and
- <link linkend="thread.concepts.TimedMutex">TimedMutex</link> refinements,
- formalize the requirements. A model that implements Mutex and its
- refinements has two states: <emphasis role="bold">locked</emphasis> and
- <emphasis role="bold">unlocked</emphasis>. Before using a shared resource, a
- thread locks a &Boost.Thread; mutex object
- (an object whose type is a model of
- <link linkend="thread.concepts.Mutex">Mutex</link> or one of it's
- refinements), ensuring
- <link linkend="thread.glossary.thread-safe">thread-safe</link> access to
- the shared resource. When use of the shared resource is complete, the thread
- unlocks the mutex object, allowing another thread to acquire the lock and
- use the shared resource.</para>
- <para>Traditional C thread APIs, like POSIX threads or the Windows thread
- APIs, expose functions to lock and unlock a mutex object. This is dangerous
- since it's easy to forget to unlock a locked mutex. When the flow of control
- is complex, with multiple return points, the likelihood of forgetting to
- unlock a mutex object becomes even greater. When exceptions are thrown,
- it becomes nearly impossible to ensure that the mutex object is unlocked
- properly when using these traditional API's. The result is
- <link linkend="thread.glossary.deadlock">deadlock</link>.</para>
- <para>Many C++ threading libraries use a pattern known as <emphasis>Scoped
- Locking</emphasis> &cite.SchmidtStalRohnertBuschmann; to free the programmer from
- the need to explicitly lock and unlock mutex objects. With this pattern, a
- <link linkend="thread.concepts.lock-concepts">Lock</link> concept is employed where
- the lock object's constructor locks the associated mutex object and the
- destructor automatically does the unlocking. The
- &Boost.Thread; library takes this pattern to
- the extreme in that Lock concepts are the only way to lock and unlock a
- mutex object: lock and unlock functions are not exposed by any
- &Boost.Thread; mutex objects. This helps to
- ensure safe usage patterns, especially when code throws exceptions.</para>
-
- <section id="thread.concepts.locking-strategies">
- <title>Locking Strategies</title>
-
- <para>Every mutex object follows one of several locking strategies. These
- strategies define the semantics for the locking operation when the calling
- thread already owns a lock on the mutex object.</para>
-
- <section id="thread.concepts.recursive-locking-strategy">
- <title>Recursive Locking Strategy</title>
-
- <para>With a recursive locking strategy, when a thread attempts to acquire
- a lock on the mutex object for which it already owns a lock, the operation
- is successful. Note the distinction between a thread, which may have
- multiple locks outstanding on a recursive mutex object, and a lock object,
- which even for a recursive mutex object cannot have any of its lock
- functions called multiple times without first calling unlock.</para>
-
- <para>Internally a lock count is maintained and the owning thread must
- unlock the mutex object the same number of times that it locked it before
- the mutex object's state returns to unlocked. Since mutex objects in
- &Boost.Thread; expose locking
- functionality only through lock concepts, a thread will always unlock a
- mutex object the same number of times that it locked it. This helps to
- eliminate a whole set of errors typically found in traditional C style
- thread APIs.</para>
-
- <para>Classes <classname>boost::recursive_mutex</classname>,
- <classname>boost::recursive_try_mutex</classname> and
- <classname>boost::recursive_timed_mutex</classname> use this locking
- strategy.</para>
- </section>
-
- <section id="thread.concepts.checked-locking-strategy">
- <title>Checked Locking Strategy</title>
-
- <para>With a checked locking strategy, when a thread attempts to acquire a
- lock on the mutex object for which the thread already owns a lock, the
- operation will fail with some sort of error indication. Further, attempts
- by a thread to unlock a mutex object that was not locked by the thread
- will also return some sort of error indication. In
- &Boost.Thread;, an exception of type
- <classname>boost::lock_error</classname>
- would be thrown in these cases.</para>
-
- <para>&Boost.Thread; does not currently
- provide any mutex objects that use this strategy.</para>
- </section>
-
- <section id="thread.concepts.unchecked-locking-strategy">
- <title>Unchecked Locking Strategy</title>
-
- <para>With an unchecked locking strategy, when a thread attempts to acquire
- a lock on a mutex object for which the thread already owns a lock the
- operation will
- <link linkend="thread.glossary.deadlock">deadlock</link>. In general
- this locking strategy is less safe than a checked or recursive strategy,
- but it's also a faster strategy and so is employed by many libraries.</para>
-
- <para>&Boost.Thread; does not currently
- provide any mutex objects that use this strategy.</para>
- </section>
-
- <section id="thread.concepts.unspecified-locking-strategy">
- <title>Unspecified Locking Strategy</title>
-
- <para>With an unspecified locking strategy, when a thread attempts to
- acquire a lock on a mutex object for which the thread already owns a lock
- the operation results in
- <link linkend="thread.glossary.undefined-behavior">undefined behavior</link>.
- </para>
-
- <para>In general a mutex object with an unspecified locking strategy is
- unsafe, and it requires programmer discipline to use the mutex object
- properly. However, this strategy allows an implementation to be as fast as
- possible with no restrictions on its implementation. This is especially
- true for portable implementations that wrap the native threading support
- of a platform. For this reason, the classes
- <classname>boost::mutex</classname>,
- <classname>boost::try_mutex</classname> and
- <classname>boost::timed_mutex</classname> use this locking strategy
- despite the lack of safety.</para>
- </section>
- </section>
-
- <section id="thread.concepts.sheduling-policies">
- <title>Scheduling Policies</title>
-
- <para>Every mutex object follows one of several scheduling policies. These
- policies define the semantics when the mutex object is unlocked and there is
- more than one thread waiting to acquire a lock. In other words, the policy
- defines which waiting thread shall acquire the lock.</para>
-
- <section id="thread.concepts.FIFO-scheduling-policy">
- <title>FIFO Scheduling Policy</title>
-
- <para>With a FIFO ("First In First Out") scheduling policy, threads waiting
- for the lock will acquire it in a first-come-first-served order.
- This can help prevent a high priority thread from starving lower priority
- threads that are also waiting on the mutex object's lock.</para>
- </section>
-
- <section id="thread.concepts.priority-driven-scheduling-policy">
- <title>Priority Driven Policy</title>
-
- <para>With a Priority Driven scheduling policy, the thread with the
- highest priority acquires the lock. Note that this means that low-priority
- threads may never acquire the lock if the mutex object has high contention
- and there is always at least one high-priority thread waiting. This is
- known as thread starvation. When multiple threads of the same priority are
- waiting on the mutex object's lock one of the other scheduling priorities
- will determine which thread shall acquire the lock.</para>
- </section>
-
- <section id="thread.concepts.unspecified-scheduling-policy">
- <title>Unspecified Policy</title>
-
- <para>The mutex object does not specify a scheduling policy. In order to
- ensure portability, all &Boost.Thread;
- mutex objects use an unspecified scheduling policy.</para>
- </section>
- </section>
-
- <section id="thread.concepts.mutex-concepts">
- <title>Mutex Concepts</title>
-
- <section id="thread.concepts.Mutex">
- <title>Mutex Concept</title>
-
- <para>A Mutex object has two states: locked and unlocked. Mutex object
- state can only be determined by a lock object meeting the
- appropriate lock concept requirements
- and constructed for the Mutex object.</para>
-
- <para>A Mutex is
- <ulink url="../../libs/utility/utility.htm#Class%20noncopyable">
- NonCopyable</ulink>.</para>
- <para>For a Mutex type <code>M</code>
- and an object <code>m</code> of that type,
- the following expressions must be well-formed
- and have the indicated effects.</para>
-
- <table>
- <title>Mutex Expressions</title>
-
- <tgroup cols="2">
- <thead>
- <row>
- <entry>Expression</entry>
- <entry>Effects</entry>
- </row>
- </thead>
-
- <tbody>
- <row>
- <entry>M m;</entry>
- <entry><para>Constructs a mutex object m.</para>
- <para>Postcondition: m is unlocked.</para></entry>
- </row>
- <row>
- <entry>(&m)->~M();</entry>
- <entry>Precondition: m is unlocked. Destroys a mutex object
- m.</entry>
- </row>
- <row>
- <entry>M::scoped_lock</entry>
- <entry>A model of
- <link linkend="thread.concepts.ScopedLock">ScopedLock</link>
- </entry>
- </row>
- </tbody>
- </tgroup>
- </table>
- </section>
-
- <section id="thread.concepts.TryMutex">
- <title>TryMutex Concept</title>
-
- <para>A TryMutex is a refinement of
- <link linkend="thread.concepts.Mutex">Mutex</link>.
- For a TryMutex type <code>M</code>
- and an object <code>m</code> of that type,
- the following expressions must be well-formed
- and have the indicated effects.</para>
-
- <table>
- <title>TryMutex Expressions</title>
-
- <tgroup cols="2">
- <thead>
- <row>
- <entry>Expression</entry>
- <entry>Effects</entry>
- </row>
- </thead>
-
- <tbody>
- <row>
- <entry>M::scoped_try_lock</entry>
- <entry>A model of
- <link linkend="thread.concepts.ScopedTryLock">ScopedTryLock</link>
- </entry>
- </row>
- </tbody>
- </tgroup>
- </table>
- </section>
-
- <section id="thread.concepts.TimedMutex">
- <title>TimedMutex Concept</title>
-
- <para>A TimedMutex is a refinement of
- <link linkend="thread.concepts.TryMutex">TryMutex</link>.
- For a TimedMutex type <code>M</code>
- and an object <code>m</code> of that type,
- the following expressions must be well-formed
- and have the indicated effects.</para>
-
- <table>
- <title>TimedMutex Expressions</title>
-
- <tgroup cols="2">
- <thead>
- <row>
- <entry>Expression</entry>
- <entry>Effects</entry>
- </row>
- </thead>
-
- <tbody>
- <row>
- <entry>M::scoped_timed_lock</entry>
- <entry>A model of
- <link
- linkend="thread.concepts.ScopedTimedLock">ScopedTimedLock</link>
- </entry>
- </row>
- </tbody>
- </tgroup>
- </table>
- </section>
- </section>
-
- <section id="thread.concepts.mutex-models">
- <title>Mutex Models</title>
-
- <para>&Boost.Thread; currently supplies six models of
- <link linkend="thread.concepts.Mutex">Mutex</link>
- and its refinements.</para>
-
- <table>
- <title>Mutex Models</title>
-
- <tgroup cols="3">
- <thead>
- <row>
- <entry>Concept</entry>
- <entry>Refines</entry>
- <entry>Models</entry>
- </row>
- </thead>
-
- <tbody>
- <row>
- <entry><link linkend="thread.concepts.Mutex">Mutex</link></entry>
- <entry></entry>
- <entry>
- <para><classname>boost::mutex</classname></para>
- <para><classname>boost::recursive_mutex</classname></para>
- </entry>
- </row>
- <row>
- <entry><link linkend="thread.concepts.TryMutex">TryMutex</link></entry>
- <entry><link linkend="thread.concepts.Mutex">Mutex</link></entry>
- <entry>
- <para><classname>boost::try_mutex</classname></para>
- <para><classname>boost::recursive_try_mutex</classname></para>
- </entry>
- </row>
- <row>
- <entry><link linkend="thread.concepts.TimedMutex">TimedMutex</link></entry>
- <entry><link linkend="thread.concepts.TryMutex">TryMutex</link></entry>
- <entry>
- <para><classname>boost::timed_mutex</classname></para>
- <para><classname>boost::recursive_timed_mutex</classname></para>
- </entry>
- </row>
- </tbody>
- </tgroup>
- </table>
- </section>
-
- <section id="thread.concepts.lock-concepts">
- <title>Lock Concepts</title>
-
- <para>A lock object provides a safe means for locking and unlocking a mutex
- object (an object whose type is a model of <link
- linkend="thread.concepts.Mutex">Mutex</link> or one of its refinements). In
- other words they are an implementation of the <emphasis>Scoped
- Locking</emphasis> &cite.SchmidtStalRohnertBuschmann; pattern. The <link
- linkend="thread.concepts.ScopedLock">ScopedLock</link>,
- <link linkend="thread.concepts.ScopedTryLock">ScopedTryLock</link>, and
- <link linkend="thread.concepts.ScopedTimedLock">ScopedTimedLock</link>
- concepts formalize the requirements.</para>
- <para>Lock objects are constructed with a reference to a mutex object and
- typically acquire ownership of the mutex object by setting its state to
- locked. They also ensure ownership is relinquished in the destructor. Lock
- objects also expose functions to query the lock status and to manually lock
- and unlock the mutex object.</para>
- <para>Lock objects are meant to be short lived, expected to be used at block
- scope only. The lock objects are not <link
- linkend="thread.glossary.thread-safe">thread-safe</link>. Lock objects must
- maintain state to indicate whether or not they've been locked and this state
- is not protected by any synchronization concepts. For this reason a lock
- object should never be shared between multiple threads.</para>
-
- <section id="thread.concepts.Lock">
- <title>Lock Concept</title>
-
- <para>For a Lock type <code>L</code>
- and an object <code>lk</code>
- and const object <code>clk</code> of that type,
- the following expressions must be well-formed
- and have the indicated effects.</para>
-
- <table>
- <title>Lock Expressions</title>
-
- <tgroup cols="2">
- <thead>
- <row>
- <entry>Expression</entry>
- <entry>Effects</entry>
- </row>
- </thead>
-
- <tbody>
- <row>
- <entry><code>(&lk)->~L();</code></entry>
- <entry><code>if (locked()) unlock();</code></entry>
- </row>
- <row>
- <entry><code>(&clk)->operator const void*()</code></entry>
- <entry>Returns type void*, non-zero if the associated mutex
- object has been locked by <code>clk</code>, otherwise 0.</entry>
- </row>
- <row>
- <entry><code>clk.locked()</code></entry>
- <entry>Returns a <code>bool</code>, <code>(&clk)->operator
- const void*() != 0</code></entry>
- </row>
- <row>
- <entry><code>lk.lock()</code></entry>
- <entry>
- <para>Throws <classname>boost::lock_error</classname>
- if <code>locked()</code>.</para>
-
- <para>If the associated mutex object is
- already locked by some other thread, places the current thread in the
- <link linkend="thread.glossary.thread-state">Blocked</link> state until
- the associated mutex is unlocked, after which the current thread
- is placed in the <link
- linkend="thread.glossary.thread-state">Ready</link> state,
- eventually to be returned to the <link
- linkend="thread.glossary.thread-state">Running</link> state. If
- the associated mutex object is already locked by the same thread
- the behavior is dependent on the <link
- linkend="thread.concepts.locking-strategies">locking
- strategy</link> of the associated mutex object.</para>
-
- <para>Postcondition: <code>locked() == true</code></para>
- </entry>
- </row>
- <row>
- <entry><code>lk.unlock()</code></entry>
- <entry>
- <para>Throws <classname>boost::lock_error</classname>
- if <code>!locked()</code>.</para>
-
- <para>Unlocks the associated mutex.</para>
-
- <para>Postcondition: <code>!locked()</code></para></entry>
- </row>
- </tbody>
- </tgroup>
- </table>
- </section>
-
- <section id="thread.concepts.ScopedLock">
- <title>ScopedLock Concept</title>
-
- <para>A ScopedLock is a refinement of <link
- linkend="thread.concepts.Lock">Lock</link>.
- For a ScopedLock type <code>L</code>
- and an object <code>lk</code> of that type,
- and an object <code>m</code> of a type meeting the
- <link linkend="thread.concepts.Mutex">Mutex</link> requirements,
- and an object <code>b</code> of type <code>bool</code>,
- the following expressions must be well-formed
- and have the indicated effects.</para>
-
- <table>
- <title>ScopedLock Expressions</title>
-
- <tgroup cols="2">
- <thead>
- <row>
- <entry>Expression</entry>
- <entry>Effects</entry>
- </row>
- </thead>
-
- <tbody>
- <row>
- <entry><code>L lk(m);</code></entry>
- <entry>Constructs an object <code>lk</code>, and associates mutex
- object <code>m</code> with it, then calls
- <code>lock()</code></entry>
- </row>
- <row>
- <entry><code>L lk(m,b);</code></entry>
- <entry>Constructs an object <code>lk</code>, and associates mutex
- object <code>m</code> with it, then if <code>b</code>, calls
- <code>lock()</code></entry>
- </row>
- </tbody>
- </tgroup>
- </table>
- </section>
-
- <section id="thread.concepts.TryLock">
- <title>TryLock Concept</title>
-
- <para>A TryLock is a refinement of <link
- linkend="thread.concepts.Lock">Lock</link>.
- For a TryLock type <code>L</code>
- and an object <code>lk</code> of that type,
- the following expressions must be well-formed
- and have the indicated effects.</para>
-
- <table>
- <title>TryLock Expressions</title>
-
- <tgroup cols="2">
- <thead>
- <row>
- <entry>Expression</entry>
- <entry>Effects</entry>
- </row>
- </thead>
-
- <tbody>
- <row>
- <entry><code>lk.try_lock()</code></entry>
- <entry>
- <para>Throws <classname>boost::lock_error</classname>
- if locked().</para>
-
- <para>Makes a
- non-blocking attempt to lock the associated mutex object,
- returning <code>true</code> if the lock attempt is successful,
- otherwise <code>false</code>. If the associated mutex object is
- already locked by the same thread the behavior is dependent on the
- <link linkend="thread.concepts.locking-strategies">locking
- strategy</link> of the associated mutex object.</para>
- </entry>
- </row>
- </tbody>
- </tgroup>
- </table>
- </section>
-
- <section id="thread.concepts.ScopedTryLock">
- <title>ScopedTryLock Concept</title>
-
- <para>A ScopedTryLock is a refinement of <link
- linkend="thread.concepts.TryLock">TryLock</link>.
- For a ScopedTryLock type <code>L</code>
- and an object <code>lk</code> of that type,
- and an object <code>m</code> of a type meeting the
- <link linkend="thread.concepts.TryMutex">TryMutex</link> requirements,
- and an object <code>b</code> of type <code>bool</code>,
- the following expressions must be well-formed
- and have the indicated effects.</para>
-
- <table>
- <title>ScopedTryLock Expressions</title>
-
- <tgroup cols="2">
- <thead>
- <row>
- <entry>Expression</entry>
- <entry>Effects</entry>
- </row>
- </thead>
-
- <tbody>
- <row>
- <entry><code>L lk(m);</code></entry>
- <entry>Constructs an object <code>lk</code>, and associates mutex
- object <code>m</code> with it, then calls
- <code>try_lock()</code></entry>
- </row>
- <row>
- <entry><code>L lk(m,b);</code></entry>
- <entry>Constructs an object <code>lk</code>, and associates mutex
- object <code>m</code> with it, then if <code>b</code>, calls
- <code>lock()</code></entry>
- </row>
- </tbody>
- </tgroup>
- </table>
- </section>
-
- <section id="thread.concepts.TimedLock">
- <title>TimedLock Concept</title>
-
- <para>A TimedLock is a refinement of <link
- linkend="thread.concepts.TryLock">TryLock</link>.
- For a TimedLock type <code>L</code>
- and an object <code>lk</code> of that type,
- and an object <code>t</code> of type <classname>boost::xtime</classname>,
- the following expressions must be well-formed
- and have the indicated effects.</para>
-
- <table>
- <title>TimedLock Expressions</title>
- <tgroup cols="2">
- <thead>
- <row>
- <entry>Expression</entry>
- <entry>Effects</entry>
- </row>
- </thead>
-
- <tbody>
- <row>
- <entry><code>lk.timed_lock(t)</code></entry>
- <entry>
- <para>Throws <classname>boost::lock_error</classname>
- if locked().</para>
-
- <para>Makes a blocking attempt
- to lock the associated mutex object, and returns <code>true</code>
- if successful within the specified time <code>t</code>, otherwise
- <code>false</code>. If the associated mutex object is already
- locked by the same thread the behavior is dependent on the <link
- linkend="thread.concepts.locking-strategies">locking
- strategy</link> of the associated mutex object.</para>
- </entry>
- </row>
- </tbody>
- </tgroup>
- </table>
- </section>
-
- <section id="thread.concepts.ScopedTimedLock">
- <title>ScopedTimedLock Concept</title>
-
- <para>A ScopedTimedLock is a refinement of <link
- linkend="thread.concepts.TimedLock">TimedLock</link>.
- For a ScopedTimedLock type <code>L</code>
- and an object <code>lk</code> of that type,
- and an object <code>m</code> of a type meeting the
- <link linkend="thread.concepts.TimedMutex">TimedMutex</link> requirements,
- and an object <code>b</code> of type <code>bool</code>,
- and an object <code>t</code> of type <classname>boost::xtime</classname>,
- the following expressions must be well-formed
- and have the indicated effects.</para>
-
- <table>
- <title>ScopedTimedLock Expressions</title>
- <tgroup cols="2">
- <thead>
- <row>
- <entry>Expression</entry>
- <entry>Effects</entry>
- </row>
- </thead>
-
- <tbody>
- <row>
- <entry><code>L lk(m,t);</code></entry>
- <entry>Constructs an object <code>lk</code>, and associates mutex
- object <code>m</code> with it, then calls
- <code>timed_lock(t)</code></entry>
- </row>
- <row>
- <entry><code>L lk(m,b);</code></entry>
- <entry>Constructs an object <code>lk</code>, and associates mutex
- object <code>m</code> with it, then if <code>b</code>, calls
- <code>lock()</code></entry>
- </row>
- </tbody>
- </tgroup>
- </table>
- </section>
- </section>
-
- <section id="thread.concepts.lock-models">
- <title>Lock Models</title>
-
- <para>&Boost.Thread; currently supplies twelve models of
- <link linkend="thread.concepts.Lock">Lock</link>
- and its refinements.</para>
-
- <table>
- <title>Lock Models</title>
-
- <tgroup cols="3">
- <thead>
- <row>
- <entry>Concept</entry>
- <entry>Refines</entry>
- <entry>Models</entry>
- </row>
- </thead>
-
- <tbody>
- <row>
- <entry><link linkend="thread.concepts.Lock">Lock</link></entry>
- <entry></entry>
- <entry></entry>
- </row>
- <row>
- <entry><link linkend="thread.concepts.ScopedLock">ScopedLock</link></entry>
- <entry><link linkend="thread.concepts.Lock">Lock</link></entry>
- <entry>
- <para><classname>boost::mutex::scoped_lock</classname></para>
- <para><classname>boost::recursive_mutex::scoped_lock</classname></para>
-
- <para><classname>boost::try_mutex::scoped_lock</classname></para>
- <para><classname>boost::recursive_try_mutex::scoped_lock</classname></para>
-
- <para><classname>boost::timed_mutex::scoped_lock</classname></para>
- <para><classname>boost::recursive_timed_mutex::scoped_lock</classname></para>
- </entry>
- </row>
- <row>
- <entry><link linkend="thread.concepts.TryLock">TryLock</link></entry>
- <entry><link linkend="thread.concepts.Lock">Lock</link></entry>
- <entry></entry>
- </row>
- <row>
- <entry><link linkend="thread.concepts.ScopedTryLock">ScopedTryLock</link></entry>
- <entry><link linkend="thread.concepts.TryLock">TryLock</link></entry>
- <entry>
- <para><classname>boost::try_mutex::scoped_try_lock</classname></para>
- <para><classname>boost::recursive_try_mutex::scoped_try_lock</classname></para>
-
- <para><classname>boost::timed_mutex::scoped_try_lock</classname></para>
- <para><classname>boost::recursive_timed_mutex::scoped_try_lock</classname></para>
- </entry>
- </row>
- <row>
- <entry><link linkend="thread.concepts.TimedLock">TimedLock</link></entry>
- <entry><link linkend="thread.concepts.TryLock">TryLock</link></entry>
- <entry></entry>
- </row>
- <row>
- <entry><link linkend="thread.concepts.ScopedTimedLock">ScopedTimedLock</link></entry>
- <entry><link linkend="thread.concepts.TimedLock">TimedLock</link></entry>
- <entry>
- <para><classname>boost::timed_mutex::scoped_timed_lock</classname></para>
- <para><classname>boost::recursive_timed_mutex::scoped_timed_lock</classname></para>
- </entry>
- </row>
- </tbody>
- </tgroup>
- </table>
- </section>
- </section>
-
- <section id="thread.concepts.read-write-mutexes">
- <title>Read/Write Mutexes</title>
- <note> Unfortunately it turned out that the current implementation has
- some serious problems. So it was decided not to put this implementation into
- release grade code. Also discussions on the mailing list led to the
- conclusion that the current concepts need to be rethought. In particular
- the schedulings <link linkend="thread.concepts.read-write-scheduling-policies.inter-class">
- Inter-Class Scheduling Policies</link> are deemed unnecessary.
- There seems to be common belief that a fair scheme suffices.
- The following documentation has been retained however, to give
- readers of this document the opportunity to study the original design.
- </note>
-
- <para>A read/write mutex (short for reader/writer mutual-exclusion) object
- is used to serialize access to a resource shared between multiple
- threads, where multiple "readers" can share simultaneous access, but
- "writers" require exclusive access. The
- <link linkend="thread.concepts.ReadWriteMutex">ReadWriteMutex</link> concept, with
- <link linkend="thread.concepts.TryReadWriteMutex">TryReadWriteMutex</link> and
- <link linkend="thread.concepts.TimedReadWriteMutex"> TimedReadWriteMutex</link>
- refinements formalize the requirements. A model that implements
- ReadWriteMutex and its refinements has three states:
- <emphasis role="bold">read-locked</emphasis>,
- <emphasis role="bold">write-locked</emphasis>, and
- <emphasis role="bold">unlocked</emphasis>.
- Before reading from a shared resource, a thread
- <emphasis role="bold">read-locks</emphasis>
- a &Boost.Thread; read/write mutex object
- (an object whose type is a model of
- <link linkend="thread.concepts.ReadWriteMutex">ReadWriteMutex</link>
- or one of it's refinements), ensuring
- <link linkend="thread.glossary.thread-safe">thread-safe</link>
- access for reading from the shared resource. Before writing
- to a shared resource, a thread
- <emphasis role="bold">write-locks</emphasis> a &Boost.Thread;
- read/write mutex object
- (an object whose type is a model of
- <link linkend="thread.concepts.ReadWriteMutex">ReadWriteMutex</link>
- or one of it's refinements), ensuring
- <link linkend="thread.glossary.thread-safe">thread-safe</link>
- access for altering the shared resource. When use of the shared
- resource is complete, the thread unlocks the mutex object,
- allowing another thread to acquire the lock and use the shared
- resource.</para>
-
- <para>Traditional C thread APIs that provide read/write mutex
- primitives (like POSIX threads) expose functions to lock and unlock a
- mutex object. This is dangerous since it's easy to forget to unlock a
- locked mutex. When the flow of control is complex, with multiple
- return points, the likelihood of forgetting to unlock a mutex object
- becomes even greater. When exceptions are thrown, it becomes nearly
- impossible to ensure that the mutex object is unlocked
- properly when using these traditional API's. The result is
- <link linkend="thread.glossary.deadlock">deadlock</link>.</para>
-
- <para>Many C++ threading libraries use a pattern known as <emphasis>Scoped
- Locking</emphasis> &cite.SchmidtStalRohnertBuschmann; to free the
- programmer from the need to explicitly lock and unlock
- read/write mutex objects. With this pattern, a
- <link linkend="thread.concepts.read-write-lock-concepts">Read/Write Lock</link>
- concept is employed where the lock object's constructor locks
- the associated read/write mutex object
- and the destructor automatically does the unlocking. The
- &Boost.Thread; library takes this pattern to
- the extreme in that
- <link linkend="thread.concepts.read-write-lock-concepts">Read/Write Lock</link>
- concepts are the only way to lock and unlock a read/write mutex
- object: lock and unlock functions are not exposed by any
- &Boost.Thread; read/write mutex objects. This helps to
- ensure safe usage patterns, especially when code throws exceptions.</para>
-
- <section id="thread.concepts.read-write-locking-strategies">
- <title>Locking Strategies</title>
-
- <para>Every read/write mutex object follows one of several locking
- strategies. These strategies define the semantics for the locking
- operation when the calling thread already owns a lock on the
- read/write mutex object.</para>
-
- <section id="thread.concepts.read-write-locking-strategies.recursive">
- <title>Recursive Locking Strategy</title>
-
- <para>With a recursive locking strategy, when a thread attempts
- to acquire a lock on a read/write mutex object
- for which it already owns a lock, the operation is successful,
- except in the case where a thread holding a read-lock
- attempts to obtain a write lock, in which case a
- <classname>boost::lock_error</classname> exception will
- be thrown. Note the distinction between a thread, which may have
- multiple locks outstanding on a recursive read/write mutex object,
- and a lock object, which even for a recursive read/write mutex
- object cannot have any of its lock functions called multiple
- times without first calling unlock.</para>
-
- <informaltable>
- <tgroup cols="3">
- <thead>
- <row>
- <entry>Lock Type Held</entry>
- <entry>Lock Type Requested</entry>
- <entry>Action</entry>
- </row>
- </thead>
-
- <tbody>
- <row>
- <entry>read-lock</entry>
- <entry>read-lock</entry>
- <entry>Grant the read-lock immediately</entry>
- </row>
- <row>
- <entry>read-lock</entry>
- <entry>write-lock</entry>
- <entry>If this thread is the only holder of the read-lock,
- grants the write lock immediately. Otherwise throws a
- <classname>boost::lock_error</classname> exception.</entry>
- </row>
- <row>
- <entry>write-locked</entry>
- <entry>read-lock</entry>
- <entry>Grants the (additional) read-lock immediately.</entry>
- </row>
- <row>
- <entry>write-locked</entry>
- <entry>write-lock</entry>
- <entry> Grant the write-lock immediately</entry>
- </row>
- </tbody>
- </tgroup>
- </informaltable>
-
- <para>Internally a lock count is maintained and the owning
- thread must unlock the mutex object the same number of times
- that it locked it before the mutex object's state returns
- to unlocked. Since mutex objects in &Boost.Thread; expose
- locking functionality only through lock concepts, a thread
- will always unlock a mutex object the same number of times
- that it locked it. This helps to eliminate a whole set of
- errors typically found in traditional C style thread APIs.
- </para>
-
- <para>&Boost.Thread; does not currently provide any read/write mutex objects
- that use this strategy. A successful implementation of this locking strategy
- may require
- <link linkend="thread.concepts.read-write-locking-strategies.thread-identification">thread identification</link>.
- </para>
- </section>
-
- <section id="thread.concepts.read-write-locking-strategies.checked">
- <title>Checked Locking Strategy</title>
-
- <para>With a checked locking strategy, when a thread attempts
- to acquire a lock on the mutex object for which the thread
- already owns a lock, the operation will fail with some sort of
- error indication, except in the case of multiple read-lock
- acquisition which is a normal operation for ANY ReadWriteMutex.
- Further, attempts by a thread to unlock a mutex that was not
- locked by the thread will also return some sort of error
- indication. In &Boost.Thread;, an exception of type
- <classname>boost::lock_error</classname> would be thrown in
- these cases.</para>
-
- <informaltable>
- <tgroup cols="3">
- <thead>
- <row>
- <entry>Lock Type Held</entry>
- <entry>Lock Type Requested</entry>
- <entry>Action</entry>
- </row>
- </thead>
-
- <tbody>
- <row>
- <entry>read-lock</entry>
- <entry>read-lock</entry>
- <entry>Grant the read-lock immediately</entry>
- </row>
- <row>
- <entry>read-lock</entry>
- <entry>write-lock</entry>
- <entry>Throw <classname>boost::lock_error</classname></entry>
- </row>
- <row>
- <entry>write-locked</entry>
- <entry>read-lock</entry>
- <entry>Throw <classname>boost::lock_error</classname></entry>
- </row>
- <row>
- <entry>write-locked</entry>
- <entry>write-lock</entry>
- <entry> Throw <classname>boost::lock_error</classname></entry>
- </row>
- </tbody>
- </tgroup>
- </informaltable>
-
- <para>&Boost.Thread; does not currently provide any read/write mutex objects
- that use this strategy. A successful implementation of this locking strategy
- may require
- <link linkend="thread.concepts.read-write-locking-strategies.thread-identification">thread identification</link>.
- </para>
- </section>
-
- <section id="thread.concepts.read-write-locking-strategies.unchecked">
- <title>Unchecked Locking Strategy</title>
-
- <para>With an unchecked locking strategy, when a thread
- attempts to acquire a lock on the read/write mutex object
- for which the thread already owns a lock, the operation
- will <link linkend="thread.glossary.deadlock">deadlock</link>.
- In general this locking strategy is less safe than a checked
- or recursive strategy, but it can be a faster strategy and so
- is employed by many libraries.</para>
-
- <informaltable>
- <tgroup cols="3">
- <thead>
- <row>
- <entry>Lock Type Held</entry>
- <entry>Lock Type Requested</entry>
- <entry>Action</entry>
- </row>
- </thead>
-
- <tbody>
- <row>
- <entry>read-lock</entry>
- <entry>read-lock</entry>
- <entry>Grant the read-lock immediately</entry>
- </row>
- <row>
- <entry>read-lock</entry>
- <entry>write-lock</entry>
- <entry><link linkend="thread.glossary.deadlock">Deadlock</link></entry>
- </row>
- <row>
- <entry>write-locked</entry>
- <entry>read-lock</entry>
- <entry><link linkend="thread.glossary.deadlock">Deadlock</link></entry>
- </row>
- <row>
- <entry>write-locked</entry>
- <entry>write-lock</entry>
- <entry><link linkend="thread.glossary.deadlock">Deadlock</link></entry>
- </row>
- </tbody>
- </tgroup>
- </informaltable>
-
- <para>&Boost.Thread; does not currently provide any mutex
- objects that use this strategy. For ReadWriteMutexes on
- platforms that contain natively recursive synchronization
- primitives, implementing a guaranteed-deadlock can actually
- involve extra work, and would likely require
- <link linkend="thread.concepts.read-write-locking-strategies.thread-identification">thread identification</link>.
- </para>
- </section>
-
- <section id="thread.concepts.read-write-locking-strategies.unspecified">
- <title>Unspecified Locking Strategy</title>
-
- <para>With an unspecified locking strategy, when a thread
- attempts to acquire a lock on a read/write mutex object for
- which the thread already owns a lock, the operation results
- in <link linkend="thread.glossary.undefined-behavior">undefined behavior</link>.
- When a read/write mutex object has an unspecified locking
- strategy the programmer must assume that the read/write mutex
- object instead uses an unchecked strategy as the worse case,
- although some platforms may exhibit a mix of unchecked and
- recursive behavior.</para>
-
- <informaltable>
- <tgroup cols="3">
- <thead>
- <row>
- <entry>Lock Type Held</entry>
- <entry>Lock Type Requested</entry>
- <entry>Action</entry>
- </row>
- </thead>
-
- <tbody>
- <row>
- <entry>read-lock</entry>
- <entry>read-lock</entry>
- <entry>Grant the read-lock immediately</entry>
- </row>
- <row>
- <entry>read-lock</entry>
- <entry>write-lock</entry>
- <entry>
- <link linkend="thread.glossary.undefined-behavior">Undefined</link>, but generally <link linkend="thread.glossary.deadlock">deadlock</link>
- </entry>
- </row>
- <row>
- <entry>write-locked</entry>
- <entry>read-lock</entry>
- <entry><link linkend="thread.glossary.undefined-behavior">Undefined</link>, but generally <link linkend="thread.glossary.deadlock">deadlock</link></entry>
- </row>
- <row>
- <entry>write-locked</entry>
- <entry>write-lock</entry>
- <entry><link linkend="thread.glossary.undefined-behavior">Undefined</link>, but generally <link linkend="thread.glossary.deadlock">deadlock</link></entry>
- </row>
- </tbody>
- </tgroup>
- </informaltable>
-
- <para>In general a read/write mutex object with an unspecified
- locking strategy is unsafe, and it requires programmer discipline
- to use the read/write mutex object properly. However, this strategy
- allows an implementation to be as fast as possible with no restrictions
- on its implementation. This is especially true for portable implementations
- that wrap the native threading support of a platform. For this reason, the
- classes
- <classname>read_write_mutex</classname>,
- <classname>try_read_write_mutex</classname>, and
- <classname>timed_read_write_mutex</classname>
- use this locking strategy despite the lack of safety.</para>
- </section>
-
- <section id="thread.concepts.read-write-locking-strategies.thread-identification">
- <title>Thread Identification</title>
-
- <para>ReadWriteMutexes can support specific Locking Strategies
- (recursive and checked) which help to detect and protect against
- self-deadlock. Self-deadlock can occur when a holder of a locked
- ReadWriteMutex attempts to obtain another lock. Given an
- implemention <emphasis>I</emphasis> which is susceptible to
- self-deadlock but otherwise correct and efficient, a recursive or
- checked implementation <emphasis>Ir</emphasis> or
- <emphasis>Ic</emphasis> can use the same basic implementation,
- but make special checks against self-deadlock by tracking the
- identities of thread(s) currently holding locks. This approach
- makes deadlock detection othrogonal to the basic ReadWriteMutex
- implementaion.</para>
-
- <para>Alternatively, a different basic implementation for
- ReadWriteMutex concepts,
- <emphasis>I'</emphasis> (I-Prime) may exist which uses recursive
- or checked versions of synchronization primitives to produce
- a recursive or checked ReadWriteMutex while still providing
- flexibility in terms of Scheduling Policies. </para>
-
- <para>Please refer to the &Boost.Thread;
- <link linkend="thread.concepts.read-write-mutex-concepts">read/write mutex concept</link>
- documentation for a discussion of locking strategies.
- The read/write mutex supports only the
- <link linkend="thread.concepts.read-write-locking-strategies.unspecified">unspecified</link>
- locking strategy. ReadWriteMutexes are parameterized on a
- Mutex type which they use to control write-locking
- and access to internal state.</para>
- </section>
-
- <section id="thread.concepts.read-write-locking-strategies.promotion">
- <title>Lock Promotion</title>
-
- <para>ReadWriteMutexes can support lock promotion, where a
- mutex which is in the read-locked state transitions to a
- write-locked state without releasing the lock. Lock
- promotion can be tricky to implement; for instance,
- extra care must be taken to ensure that only one thread holding a
- read-lock can block awaiting promotion at any given time. If
- more than one read-lock holder is allowed to enter a blocked
- state while waiting to be promoted, deadlock will result since
- both threads will be waiting for the other to release their read-lock.
- </para>
-
- <para>Currently, &Boost.Thread; supports lock promotion
- through <code>promote()</code>, <code>try_promote()</code>,
- and <code>timed_promote()</code> operations.</para>
- </section>
-
- <section id="thread.concepts.read-write-locking-strategies.demotion">
- <title>Lock Demotion</title>
-
- <para>ReadWriteMutexes can support lock demotion, where a
- mutex which is in the write-locked state transitions to a
- read-locked state without releasing the lock.
- Since by definition only one thread at a time may hold
- a write-lock, the problem with deadlock that can occur
- during lock promotion is not a problem for lock
- demotion.</para>
-
- <para>Currently, &Boost.Thread; supports lock demotion
- through <code>demote()</code>, <code>try_demote()</code>,
- and <code>timed_demote()</code> operations.</para>
- </section>
- </section>
-
- <section id="thread.concepts.read-write-scheduling-policies">
- <title>Scheduling Policies</title>
-
- <para>Every read/write mutex object follows one of several scheduling
- policies. These policies define the semantics when the mutex object
- is unlocked and there is more than one thread waiting to acquire a
- lock. In other words, the policy defines which waiting thread shall
- acquire the lock. For a read/write mutex, it is particularly important
- to define the behavior when threads are requesting both read and
- write access simultaneously. This will be referred to as "inter-class
- scheduling" because it describes the scheduling between two
- classes of threads (those waiting for a read lock and those
- waiting for a write lock).</para>
-
- <para>For some types of inter-class scheduling, an "intra-class"
- scheduling policy can also be defined that will describe the order
- in which waiting threads of the same class (i.e., those
- waiting for the same type of lock) will acquire the thread.
- </para>
-
- <section id="thread.concepts.read-write-scheduling-policies.inter-class">
- <title>Inter-Class Scheduling Policies</title>
-
- <section id="thread.concepts.read-write-scheduling-policies.reader-priority">
- <title>ReaderPriority</title>
-
- <para>With ReaderPriority scheduling, any pending request for
- a read-lock will have priority over a pending request for a
- write-lock, irrespective of the current lock state of the
- read/write mutex, and irrespective of the relative order
- that the pending requests arrive.</para>
-
- <informaltable>
- <tgroup cols="3">
- <thead>
- <row>
- <entry>Current mutex state</entry>
- <entry>Request Type</entry>
- <entry>Action</entry>
- </row>
- </thead>
-
- <tbody>
- <row>
- <entry>unlocked</entry>
- <entry>read-lock</entry>
- <entry>Grant the read-lock immediately</entry>
- </row>
- <row>
- <entry>read-locked</entry>
- <entry>read-lock</entry>
- <entry>Grant the additional read-lock immediately.</entry>
- </row>
- <row>
- <entry>write-locked</entry>
- <entry>read-lock</entry>
- <entry>Wait to acquire the lock until the thread
- holding the write-lock releases its lock (or until
- the specified time, if any). A
- read-lock will be granted to all pending readers
- before any other thread can acquire a write-lock.
- <para>TODO: try-lock, timed-lock.</para>
- </entry>
- </row>
- <row>
- <entry>unlocked</entry>
- <entry>write-lock</entry>
- <entry>Grant the write-lock immediately, if and
- only if there are no pending read-lock requests.
- <para>TODO: try-lock, timed-lock.</para>
- </entry>
- </row>
- <row>
- <entry>read-locked</entry>
- <entry>write-lock</entry>
- <entry> Wait to acquire the lock until all
- threads holding read-locks release their locks
- <emphasis role="bold">AND</emphasis> no requests
- for read-locks exist. If other write-lock
- requests exist, the lock is granted in accordance
- with the intra-class scheduling policy.
- <para>TODO: try-lock, timed-lock.</para>
- </entry>
- </row>
- <row>
- <entry>write-locked</entry>
- <entry>write-lock</entry>
- <entry>Wait to acquire the lock until the thread
- holding the write-lock releases its lock
- <emphasis role="bold">AND</emphasis> no requests
- for read-locks exist. If other write-lock
- requests exist, the lock is granted in accordance
- with the intra-class scheduling policy.
- <para>TODO: try-lock, timed-lock.</para>
- </entry>
- </row>
- <row>
- <entry>read-locked</entry>
- <entry>promote</entry>
- <entry><para>TODO</para></entry>
- </row>
- <row>
- <entry>write-locked</entry>
- <entry>demote</entry>
- <entry><para>TODO</para></entry>
- </row>
- </tbody>
- </tgroup>
- </informaltable>
- </section>
-
- <section id="thread.concepts.read-write-scheduling-policies.writer-priority">
- <title>WriterPriority</title>
-
- <para>With WriterPriority scheduling, any pending request
- for a write-lock will have priority over a pending request
- for a read-lock, irrespective of the current lock state
- of the read/write mutex, and irrespective of the relative
- order that the pending requests arrive.</para>
-
- <informaltable>
- <tgroup cols="3">
- <thead>
- <row>
- <entry>Current mutex state</entry>
- <entry>Request Type</entry>
- <entry>Action</entry>
- </row>
- </thead>
-
- <tbody>
- <row>
- <entry>unlocked</entry>
- <entry>read-lock</entry>
- <entry>Grant the read-lock immediately.</entry>
- </row>
- <row>
- <entry>read-locked</entry>
- <entry>read-lock</entry>
- <entry>Grant the additional read-lock immediately,
- <emphasis role="bold">IF</emphasis> no outstanding
- requests for a write-lock exist; otherwise TODO.
- <para>TODO: try-lock, timed-lock.</para>
- </entry>
- </row>
- <row>
- <entry>write-locked</entry>
- <entry>read-lock</entry>
- <entry> Wait to acquire the lock until the
- thread holding the write-lock
- releases its lock. The read lock will be granted
- once no other outstanding write-lock requests
- exist.
- <para>TODO: try-lock, timed-lock.</para>
- </entry>
- </row>
- <row>
- <entry>unlocked</entry>
- <entry>write-lock</entry>
- <entry>Grant the write-lock immediately.</entry>
- </row>
- <row>
- <entry>read-locked</entry>
- <entry>write-lock</entry>
- <entry>Wait to acquire the lock until all
- threads holding read-locks release their locks.
- If other write-lock requests exist, the lock
- is granted in accordance with the intra-class
- scheduling policy. This request will be granted
- before any new read-lock requests are granted.
- <para>TODO: try-lock, timed-lock.</para>
- </entry>
- </row>
- <row>
- <entry>write-locked</entry>
- <entry>write-lock</entry>
- <entry>Wait to acquire the lock until the thread
- holding the write-lock releases its lock. If
- other write-lock requests exist, the lock is
- granted in accordance with the intra-class
- scheduling policy. This request will be granted
- before any new read-lock requests are granted.
- <para>TODO: try-lock, timed-lock.</para>
- </entry>
- </row>
- <row>
- <entry>read-locked</entry>
- <entry>promote</entry>
- <entry><para>TODO</para></entry>
- </row>
- <row>
- <entry>write-locked</entry>
- <entry>demote</entry>
- <entry><para>TODO</para></entry>
- </row>
- </tbody>
- </tgroup>
- </informaltable>
- </section>
-
- <section id="thread.concepts.read-write-scheduling-policies.alternating-many-reads">
- <title>AlternatingPriority/ManyReads</title>
-
- <para>With AlternatingPriority/ManyReads scheduling, reader
- or writer starvation is avoided by alternatively granting read
- or write access when pending requests exist for both types of
- locks. Outstanding read-lock requests are treated as a group
- when it is the "readers' turn"</para>
-
- <informaltable>
- <tgroup cols="3">
- <thead>
- <row>
- <entry>Current mutex state</entry>
- <entry>Request Type</entry>
- <entry>Action</entry>
- </row>
- </thead>
-
- <tbody>
- <row>
- <entry>unlocked</entry>
- <entry>read-lock</entry>
- <entry>Grant the read-lock immediately.</entry>
- </row>
- <row>
- <entry>read-locked</entry>
- <entry>read-lock</entry>
- <entry>Grant the additional read-lock immediately,
- <emphasis role="bold">IF</emphasis> no outstanding
- requests for a write-lock exist. If outstanding
- write-lock requests exist, this lock will not
- be granted until at least one of the
- write-locks is granted and released. If other
- read-lock requests exist, all read-locks will be
- granted as a group.
- <para>TODO: try-lock, timed-lock.</para>
- </entry>
- </row>
- <row>
- <entry>write-locked</entry>
- <entry>read-lock</entry>
- <entry> Wait to acquire the lock until the thread
- holding the write-lock releases its lock. If other
- outstanding write-lock requests exist, they will
- have to wait until all current read-lock requests
- are serviced.
- <para>TODO: try-lock, timed-lock.</para>
- </entry>
- </row>
- <row>
- <entry>unlocked</entry>
- <entry>write-lock</entry>
- <entry>Grant the write-lock immediately.</entry>
- </row>
- <row>
- <entry>read-locked</entry>
- <entry>write-lock</entry>
- <entry>
- <para>Wait to acquire the lock until all threads
- holding read-locks release their locks.</para>
-
- <para>If other write-lock requests exist, this
- lock will be granted to one of them in accordance
- with the intra-class scheduling policy.</para>
-
- <para>TODO: try-lock, timed-lock.</para>
- </entry>
- </row>
- <row>
- <entry>write-locked</entry>
- <entry>write-lock</entry>
- <entry>Wait to acquire the lock until the thread
- holding the write-lock releases its lock. If
- other outstanding read-lock requests exist, this
- lock will not be granted until all of the
- currently waiting read-locks are granted and
- released. If other write-lock requests exist,
- this lock will be granted in accordance with the
- intra-class scheduling policy.
- <para>TODO: try-lock, timed-lock.</para>
- </entry>
- </row>
- <row>
- <entry>read-locked</entry>
- <entry>promote</entry>
- <entry><para>TODO</para></entry>
- </row>
- <row>
- <entry>write-locked</entry>
- <entry>demote</entry>
- <entry><para>TODO</para></entry>
- </row>
- </tbody>
- </tgroup>
- </informaltable>
- </section>
-
- <section id="thread.concepts.read-write-scheduling-policies.alternating-single-read">
- <title>AlternatingPriority/SingleRead</title>
-
- <para>With AlternatingPriority/SingleRead scheduling, reader
- or writer starvation is avoided by alternatively granting read
- or write access when pending requests exist for both types of
- locks. Outstanding read-lock requests are services one at a
- time when it is the "readers' turn"</para>
-
- <informaltable>
- <tgroup cols="3">
- <thead>
- <row>
- <entry>Current mutex state</entry>
- <entry>Request Type</entry>
- <entry>Action</entry>
- </row>
- </thead>
-
- <tbody>
- <row>
- <entry>unlocked</entry>
- <entry>read-lock</entry>
- <entry>Grant the read-lock immediately.</entry>
- </row>
- <row>
- <entry>read-locked</entry>
- <entry>read-lock</entry>
- <entry>Grant the additional read-lock immediately,
- <emphasis role="bold">IF</emphasis> no outstanding
- requests for a write-lock exist. If outstanding
- write-lock requests exist, this lock will not
- be granted until at least one of the write-locks
- is granted and released.
- <para>TODO: try-lock, timed-lock.</para>
- </entry>
- </row>
- <row>
- <entry>write-locked</entry>
- <entry>read-lock</entry>
- <entry>
- <para>Wait to acquire the lock until the thread
- holding the write-lock releases its lock.</para>
- <para>If other outstanding write-lock requests
- exist, exactly one read-lock request will be
- granted before the next write-lock is granted.
- </para>
- <para>TODO: try-lock, timed-lock.</para>
- </entry>
- </row>
- <row>
- <entry>unlocked</entry>
- <entry>write-lock</entry>
- <entry>Grant the write-lock immediately.</entry>
- </row>
- <row>
- <entry>read-locked</entry>
- <entry>write-lock</entry>
- <entry>
- <para>Wait to acquire the lock until all
- threads holding read-locks release their
- locks.</para>
-
- <para>If other write-lock requests exist,
- this lock will be granted to one of them
- in accordance with the intra-class
- scheduling policy.</para></entry>
-
- <para>TODO: try-lock, timed-lock.</para>
- </row>
- <row>
- <entry>write-locked</entry>
- <entry>write-lock</entry>
- <entry>Wait to acquire the lock until the
- thread holding the write-lock releases its
- lock. If other outstanding read-lock requests
- exist, this lock can not be granted until
- exactly one read-lock request is granted and
- released. If other write-lock requests exist,
- this lock will be granted in accordance with
- the intra-class scheduling policy.
- <para>TODO: try-lock, timed-lock.</para>
- </entry>
- </row>
- <row>
- <entry>read-locked</entry>
- <entry>promote</entry>
- <entry><para>TODO</para></entry>
- </row>
- <row>
- <entry>write-locked</entry>
- <entry>demote</entry>
- <entry><para>TODO</para></entry>
- </row>
- </tbody>
- </tgroup>
- </informaltable>
- </section>
- </section>
-
- <section id="thread.concepts.read-write-scheduling-policies.intra-class">
- <title>Intra-Class Scheduling Policies</title>
-
- <para>Please refer to
- <xref linkend="thread.concepts.sheduling-policies" />
- for a discussion of mutex scheduling policies, which are identical to
- read/write mutex intra-class scheduling policies.</para>
-
- <para>For threads waiting to obtain write-locks, the read/write mutex
- supports only the
- <link linkend="thread.concepts.unspecified-scheduling-policy">Unspecified</link>
- intra-class scheduling policy. That is, given a set of threads
- waiting for write-locks, the order, relative to one another, in
- which they receive the write-lock is unspecified.</para>
-
- <para>For threads waiting to obtain read-locks, the read/write mutex
- supports only the
- <link linkend="thread.concepts.unspecified-scheduling-policy">Unspecified</link>
- intra-class scheduling policy. That is, given a set of threads
- waiting for read-locks, the order, relative to one another, in
- which they receive the read-lock is unspecified.</para>
- </section>
- </section>
-
- <section id="thread.concepts.read-write-mutex-concepts">
- <title>Mutex Concepts</title>
-
- <section id="thread.concepts.ReadWriteMutex">
- <title>ReadWriteMutex Concept</title>
-
- <para>A ReadWriteMutex object has three states: read-locked,
- write-locked, and unlocked. ReadWriteMutex object state can
- only be determined by a lock object meeting the appropriate lock concept
- requirements and constructed for the ReadWriteMutex object.</para>
-
- <para>A ReadWriteMutex is
- <ulink url="../../libs/utility/utility.htm#Class%20noncopyable">NonCopyable</ulink>.
- </para>
-
- <para>For a ReadWriteMutex type <code>M</code>,
- and an object <code>m</code> of that type,
- the following expressions must be well-formed
- and have the indicated effects.</para>
-
- <table>
- <title>ReadWriteMutex Expressions</title>
-
- <tgroup cols="2">
- <thead>
- <row>
- <entry>Expression</entry>
- <entry>Effects</entry>
- </row>
- </thead>
-
- <tbody>
- <row>
- <entry><code>M m;</code></entry>
- <entry>Constructs a read/write mutex object <code>m</code>.
- Post-condition: <code>m</code> is unlocked.</entry>
- </row>
- <row>
- <entry><code>(&m)->~M();</code></entry>
- <entry>Precondition: <code>m</code> is unlocked.
- Destroys a read/write mutex object <code>m</code>.
- </entry>
- </row>
- <row>
- <entry><code>M::scoped_read_write_lock</code></entry>
- <entry>A type meeting the
- <link linkend="thread.concepts.ScopedReadWriteLock">ScopedReadWriteLock</link>
- requirements. </entry>
- </row>
- <row>
- <entry><code>M::scoped_read_lock</code></entry>
- <entry>A type meeting the
- <link linkend="thread.concepts.ScopedLock">ScopedLock</link>
- requirements. </entry>
- </row>
- <row>
- <entry><code>M::scoped_write_lock</code></entry>
- <entry>A type meeting the
- <link linkend="thread.concepts.ScopedLock">ScopedLock</link>
- requirements. </entry>
- </row>
- </tbody>
- </tgroup>
- </table>
- </section>
-
- <section id="thread.concepts.TryReadWriteMutex">
- <title>TryReadWriteMutex Concept</title>
-
- <para>A TryReadWriteMutex is a refinement of
- <link linkend="thread.concepts.ReadWriteMutex">ReadWriteMutex</link>.
- For a TryReadWriteMutex type <code>M</code>
- and an object <code>m</code> of that type,
- the following expressions must be well-formed
- and have the indicated effects.</para>
-
- <table>
- <title>TryReadWriteMutex Expressions</title>
-
- <tgroup cols="2">
- <thead>
- <row>
- <entry>Expression</entry>
- <entry>Effects</entry>
- </row>
- </thead>
-
- <tbody>
- <row>
- <entry><code>M::scoped_try_read_write_lock</code></entry>
- <entry>A type meeting the
- <link linkend="thread.concepts.ScopedTryReadWriteLock">ScopedTryReadWriteLock</link>
- requirements.</entry>
- </row>
- <row>
- <entry><code>M::scoped_try_read_lock</code></entry>
- <entry>A type meeting the
- <link linkend="thread.concepts.ScopedTryLock">ScopedTryLock</link>
- requirements.</entry>
- </row>
- <row>
- <entry><code>M::scoped_try_write_lock</code></entry>
- <entry>A type meeting the
- <link linkend="thread.concepts.ScopedTryLock">ScopedTryLock</link>
- requirements.</entry>
- </row>
- </tbody>
- </tgroup>
- </table>
- </section>
-
- <section id="thread.concepts.TimedReadWriteMutex">
- <title>TimedReadWriteMutex Concept</title>
-
- <para>A TimedReadWriteMutex is a refinement of
- <link linkend="thread.concepts.TryReadWriteMutex">TryReadWriteMutex</link>.
- For a TimedReadWriteMutex type <code>M</code>
- and an object <code>m</code> of that type
- the following expressions must be well-formed
- and have the indicated effects.</para>
-
- <table>
- <title>TimedReadWriteMutex Expressions</title>
-
- <tgroup cols="2">
- <thead>
- <row>
- <entry>Expression</entry>
- <entry>Effects</entry>
- </row>
- </thead>
-
- <tbody>
- <row>
- <entry><code>M::scoped_timed_read_write_lock</code></entry>
- <entry>A type meeting the
- <link linkend="thread.concepts.ScopedTimedReadWriteLock">ScopedTimedReadWriteLock</link>
- requirements.</entry>
- </row>
- <row>
- <entry><code>M::scoped_timed_read_lock</code></entry>
- <entry>A type meeting the
- <link linkend="thread.concepts.ScopedTimedLock">ScopedTimedLock</link>
- requirements.</entry>
- </row>
- <row>
- <entry><code>M::scoped_timed_write_lock</code></entry>
- <entry>A type meeting the
- <link linkend="thread.concepts.ScopedTimedLock">ScopedTimedLock</link>
- requirements.</entry>
- </row>
- </tbody>
- </tgroup>
- </table>
- </section>
- </section>
-
- <section id="thread.concepts.read-write-mutex-models">
- <title>Mutex Models</title>
-
- <para>&Boost.Thread; currently supplies three models of
- <link linkend="thread.concepts.ReadWriteMutex">ReadWriteMutex</link>
- and its refinements.</para>
-
- <table>
- <title>Mutex Models</title>
-
- <tgroup cols="3">
- <thead>
- <row>
- <entry>Concept</entry>
- <entry>Refines</entry>
- <entry>Models</entry>
- </row>
- </thead>
-
- <tbody>
- <row>
- <entry><link linkend="thread.concepts.ReadWriteMutex">ReadWriteMutex</link></entry>
- <entry></entry>
- <entry><classname>boost::read_write_mutex</classname></entry>
- </row>
- <row>
- <entry><link linkend="thread.concepts.TryReadWriteMutex">TryReadWriteMutex</link></entry>
- <entry><link linkend="thread.concepts.ReadWriteMutex">ReadWriteMutex</link></entry>
- <entry><classname>boost::try_read_write_mutex</classname></entry>
- </row>
- <row>
- <entry><link linkend="thread.concepts.TimedReadWriteMutex">TimedReadWriteMutex</link></entry>
- <entry><link linkend="thread.concepts.TryReadWriteMutex">TryReadWriteMutex</link></entry>
- <entry><classname>boost::timed_read_write_mutex</classname></entry>
- </row>
- </tbody>
- </tgroup>
- </table>
- </section>
-
- <section id="thread.concepts.read-write-lock-concepts">
- <title>Lock Concepts</title>
-
- <para>A read/write lock object provides a safe means for locking
- and unlocking a read/write mutex object (an object whose type is
- a model of
- <link linkend="thread.concepts.ReadWriteMutex">ReadWriteMutex</link>
- or one of its refinements). In other words they are an
- implementation of the <emphasis>Scoped Locking</emphasis>
- &cite.SchmidtStalRohnertBuschmann; pattern. The
- <link linkend="thread.concepts.ScopedReadWriteLock">ScopedReadWriteLock</link>,
- <link linkend="thread.concepts.ScopedTryReadWriteLock">ScopedTryReadWriteLock</link>, and
- <link linkend="thread.concepts.ScopedTimedReadWriteLock">ScopedTimedReadWriteLock</link>
- concepts formalize the requirements.</para>
-
- <para>Read/write lock objects are constructed with a reference to a
- read/write mutex object and typically acquire ownership of the
- read/write mutex object by setting its state to locked. They also
- ensure ownership is relinquished in the destructor. Lock objects
- also expose functions to query the lock status and to manually lock
- and unlock the read/write mutex object.</para>
-
- <para>Read/write lock objects are meant to be short lived, expected
- to be used at block scope only. The read/write lock objects are not
- <link linkend="thread.glossary.thread-safe">thread-safe</link>.
- Read/write lock objects must maintain state to indicate whether or
- not they've been locked and this state is not protected by any
- synchronization concepts. For this reason a read/write lock object
- should never be shared between multiple threads.</para>
-
- <section id="thread.concepts.ReadWriteLock">
- <title>ReadWriteLock Concept</title>
-
- <para>For a read/write lock type <code>L</code>
- and an object <code>lk</code>
- and const object <code>clk</code> of that type,
- the following expressions must be well-formed
- and have the indicated effects.</para>
-
- <table>
- <title>ReadWriteLock Expressions</title>
-
- <tgroup cols="2">
- <thead>
- <row>
- <entry>Expression</entry>
- <entry>Effects</entry>
- </row>
- </thead>
-
- <tbody>
- <row>
- <entry><code>(&lk)->~L();</code></entry>
- <entry><code>if (locked()) unlock();</code></entry>
- </row>
- <row>
- <entry><code>(&clk)->operator const void*()</code></entry>
- <entry>Returns type void*, non-zero if the associated read/write
- mutex object has been either read-locked or write-locked by
- <code>clk</code>, otherwise 0.</entry>
- </row>
- <row>
- <entry><code>clk.locked()</code></entry>
- <entry>Returns a <code>bool</code>, <code>(&clk)->operator
- const void*() != 0</code></entry>
- </row>
- <row>
- <entry><code>clk.state()</code></entry>
- <entry>Returns an enumeration constant of type <code>read_write_lock_state</code>:
- <code>read_write_lock_state::read_locked</code> if the associated read/write mutex object has been
- read-locked by <code>clk</code>, <code>read_write_lock_state::write_locked</code> if it
- has been write-locked by <code>clk</code>, and <code>read_write_lock_state::unlocked</code>
- if has not been locked by <code>clk</code>.</entry>
- </row>
- <row>
- <entry><code>clk.read_locked()</code></entry>
- <entry>Returns a <code>bool</code>, <code>(&clk)->state() == read_write_lock_state::read_locked</code>.</entry>
- </row>
- <row>
- <entry><code>clk.write_locked()</code></entry>
- <entry>Returns a <code>bool</code>, <code>(&clk)->state() == read_write_lock_state::write_locked</code>.</entry>
- </row>
- <row>
- <entry><code>lk.read_lock()</code></entry>
- <entry>
- <para>Throws <classname>boost::lock_error</classname>
- if <code>locked()</code>.</para>
-
- <para>If the associated read/write mutex
- object is already read-locked by some other
- thread, the effect depends on the
- <link linkend="thread.concepts.read-write-scheduling-policies.inter-class">inter-class scheduling policy</link>
- of the associated read/write mutex:
- either immediately obtains an additional
- read-lock on the associated read/write
- mutex, or places the current thread in the
- <link linkend="thread.glossary.thread-state">Blocked</link>
- state until the associated read/write mutex
- is unlocked, after which the current thread
- is placed in the
- <link linkend="thread.glossary.thread-state">Ready</link>
- state, eventually to be returned to the
- <link linkend="thread.glossary.thread-state">Running</link>
- state.</para>
-
- <para>If the associated read/write mutex
- object is already write-locked by some other
- thread, places the current thread in the
- <link linkend="thread.glossary.thread-state">Blocked</link>
- state until the associated read/write mutex
- is unlocked, after which the current thread
- is placed in the
- <link linkend="thread.glossary.thread-state">Ready</link>
- state, eventually to be returned to the
- <link linkend="thread.glossary.thread-state">Running</link>
- state.</para>
-
- <para>If the associated read/write mutex
- object is already locked by the same thread
- the behavior is dependent on the
- <link linkend="thread.concepts.read-write-locking-strategies">locking strategy</link>
- of the associated read/write mutex object.
- </para>
-
- <para>Postcondition: <code>state() == read_write_lock_state::read_locked</code></para>
- </entry>
- </row>
- <row>
- <entry><code>lk.write_lock()</code></entry>
-
- <entry>
- <para>Throws <classname>boost::lock_error</classname>
- if <code>locked()</code>.</para>
-
- <para>If the associated read/write mutex
- object is already locked by some other
- thread, places the current thread in the
- <link linkend="thread.glossary.thread-state">Blocked</link>
- state until the associated read/write mutex
- is unlocked, after which the current thread
- is placed in the
- <link linkend="thread.glossary.thread-state">Ready</link>
- state, eventually to be returned to the
- <link linkend="thread.glossary.thread-state">Running</link>
- state.</para>
-
- <para>If the associated read/write mutex
- object is already locked by the same thread
- the behavior is dependent on the
- <link linkend="thread.concepts.read-write-locking-strategies">locking strategy</link>
- of the associated read/write mutex object.
- </para>
-
- <para>Postcondition: <code>state() == read_write_lock_state::write_locked</code></para>
- </entry>
- </row>
- <row>
- <entry><code>lk.demote()</code></entry>
- <entry>
- <para>Throws <classname>boost::lock_error</classname>
- if <code>state() != read_write_lock_state::write_locked</code>.</para>
-
- <para>Converts the lock held on the associated read/write mutex
- object from a write-lock to a read-lock without releasing
- the lock.</para>
-
- <para>Postcondition: <code>state() == read_write_lock_state::read_locked</code></para>
- </entry>
- </row>
- <row>
- <entry><code>lk.promote()</code></entry>
- <entry>
- <para>Throws <classname>boost::lock_error</classname>
- if <code>state() != read_write_lock_state::read_locked</code>
- or if the lock cannot be promoted because another lock
- on the same mutex is already waiting to be promoted.</para>
-
- <para>Makes a blocking attempt to convert the lock held on the associated
- read/write mutex object from a read-lock to a write-lock without releasing
- the lock.</para>
- </entry>
- </row>
- <row>
- <entry><code>lk.unlock()</code></entry>
- <entry>
- <para>Throws <classname>boost::lock_error</classname>
- if <code>!locked()</code>.</para>
-
- <para>Unlocks the associated read/write mutex.</para>
-
- <para>Postcondition: <code>!locked()</code></para>
- </entry>
- </row>
- </tbody>
- </tgroup>
- </table>
- </section>
-
- <section id="thread.concepts.ScopedReadWriteLock">
- <title>ScopedReadWriteLock Concept</title>
-
- <para>A ScopedReadWriteLock is a refinement of
- <link linkend="thread.concepts.ReadWriteLock">ReadWriteLock</link>.
- For a ScopedReadWriteLock type <code>L</code>
- and an object <code>lk</code> of that type,
- and an object <code>m</code> of a type meeting the
- <link linkend="thread.concepts.ReadWriteMutex">ReadWriteMutex</link> requirements,
- and an object <code>s</code> of type <code>read_write_lock_state</code>,
- the following expressions must be well-formed
- and have the indicated effects.</para>
-
- <table>
- <title>ScopedReadWriteLock Expressions</title>
-
- <tgroup cols="2">
- <thead>
- <row>
- <entry>Expression</entry>
- <entry>Effects</entry>
- </row>
- </thead>
-
- <tbody>
- <row>
- <entry><code>L lk(m,s);</code></entry>
- <entry>Constructs an object <code>lk</code> and associates read/write mutex
- object <code>m</code> with it, then: if <code>s == read_write_lock_state::read_locked</code>, calls
- <code>read_lock()</code>; if <code>s==read_write_lock_state::write_locked</code>,
- calls <code>write_lock()</code>.</entry>
- </row>
- </tbody>
- </tgroup>
- </table>
- </section>
-
- <section id="thread.concepts.TryReadWriteLock">
- <title>TryReadWriteLock Expressions</title>
-
- <para>A TryReadWriteLock is a refinement of
- <link linkend="thread.concepts.ReadWriteLock">ReadWriteLock</link>.
- For a TryReadWriteLock type <code>L</code>
- and an object <code>lk</code> of that type,
- the following expressions must be well-formed
- and have the indicated effects.</para>
-
- <table>
- <title>TryReadWriteLock Expressions</title>
-
- <tgroup cols="2">
- <thead>
- <row>
- <entry>Expression</entry>
- <entry>Effects</entry>
- </row>
- </thead>
-
- <tbody>
- <row>
- <entry><code>lk.try_read_lock()</code></entry>
- <entry>
- <para>Throws <classname>boost::lock_error</classname>
- if locked().</para>
-
- <para>Makes a non-blocking attempt to read-lock the associated read/write
- mutex object, returning <code>true</code> if the attempt is successful,
- otherwise <code>false</code>. If the associated read/write mutex object is
- already locked by the same thread the behavior is dependent on the
- <link linkend="thread.concepts.locking-strategies">locking
- strategy</link> of the associated read/write mutex object.</para>
- </entry>
- </row>
- <row>
- <entry><code>lk.try_write_lock()</code></entry>
- <entry>
- <para>Throws <classname>boost::lock_error</classname>
- if locked().</para>
-
- <para>Makes a non-blocking attempt to write-lock the associated read/write
- mutex object, returning <code>true</code> if the attempt is successful,
- otherwise <code>false</code>. If the associated read/write mutex object is
- already locked by the same thread the behavior is dependent on the
- <link linkend="thread.concepts.locking-strategies">locking
- strategy</link> of the associated read/write mutex object.</para>
- </entry>
- </row>
- <row>
- <entry><code>lk.try_demote()</code></entry>
- <entry>
- <para>Throws <classname>boost::lock_error</classname>
- if <code>state() != read_write_lock_state::write_locked</code>.</para>
-
- <para>Makes a non-blocking attempt to convert the lock held on the associated
- read/write mutex object from a write-lock to a read-lock without releasing
- the lock, returning <code>true</code> if the attempt is successful,
- otherwise <code>false</code>.</para>
- </entry>
- </row>
- <row>
- <entry><code>lk.try_promote()</code></entry>
- <entry>
- <para>Throws <classname>boost::lock_error</classname>
- if <code>state() != read_write_lock_state::read_locked</code>.</para>
-
- <para>Makes a non-blocking attempt to convert the lock held on the associated
- read/write mutex object from a read-lock to a write-lock without releasing
- the lock, returning <code>true</code> if the attempt is successful,
- otherwise <code>false</code>.</para>
- </entry>
- </row>
- </tbody>
- </tgroup>
- </table>
- </section>
-
- <section id="thread.concepts.ScopedTryReadWriteLock">
- <title>ScopedTryReadWriteLock Expressions</title>
-
- <para>A ScopedTryReadWriteLock is a refinement of
- <link linkend="thread.concepts.TryReadWriteLock">TryReadWriteLock</link>.
- For a ScopedTryReadWriteLock type <code>L</code>
- and an object <code>lk</code> of that type,
- and an object <code>m</code> of a type meeting the
- <link linkend="thread.concepts.TryMutex">TryReadWriteMutex</link> requirements,
- and an object <code>s</code> of type <code>read_write_lock_state</code>,
- and an object <code>b</code> of type <code>blocking_mode</code>,
- the following expressions must be well-formed
- and have the indicated effects.</para>
-
- <table>
- <title>ScopedTryReadWriteLock Expressions</title>
-
- <tgroup cols="2">
- <thead>
- <row>
- <entry>Expression</entry>
- <entry>Effects</entry>
- </row>
- </thead>
-
- <tbody>
- <row>
- <entry><code>L lk(m,s,b);</code></entry>
- <entry>Constructs an object <code>lk</code> and associates read/write mutex
- object <code>m</code> with it, then: if <code>s == read_write_lock_state::read_locked</code>, calls
- <code>read_lock()</code> if <code>b</code>, otherwise <code>try_read_lock()</code>;
- if <code>s==read_write_lock_state::write_locked</code>, calls <code>write_lock()</code> if <code>b</code>,
- otherwise <code>try_write_lock</code>.</entry>
- </row>
- </tbody>
- </tgroup>
- </table>
- </section>
-
- <section id="thread.concepts.TimedReadWriteLock">
- <title>TimedReadWriteLock Concept</title>
-
- <para>A TimedReadWriteLock is a refinement of
- <link linkend="thread.concepts.TryReadWriteLock">TryReadWriteLock</link>.
- For a TimedReadWriteLock type <code>L</code>
- and an object <code>lk</code> of that type,
- and an object <code>t</code> of type <classname>boost::xtime</classname>,
- the following expressions must be well-formed
- and have the indicated effects.</para>
-
- <table>
- <title>TimedReadWriteLock Expressions</title>
-
- <tgroup cols="2">
- <thead>
- <row>
- <entry>Expression</entry>
- <entry>Effects</entry>
- </row>
- </thead>
-
- <tbody>
- <row>
- <entry><code>lk.timed_read_lock(t)</code></entry>
- <entry>
- <para>Throws <classname>boost::lock_error</classname>
- if locked().</para>
-
- <para>Makes a blocking attempt to read-lock the associated read/write mutex object,
- and returns <code>true</code> if successful within the specified time <code>t</code>,
- otherwise <code>false</code>. If the associated read/write mutex object is already
- locked by the same thread the behavior is dependent on the <link
- linkend="thread.concepts.locking-strategies">locking
- strategy</link> of the associated read/write mutex object.</para>
- </entry>
- </row>
- <row>
- <entry><code>lk.timed_write_lock(t)</code></entry>
- <entry>
- <para>Throws <classname>boost::lock_error</classname>
- if locked().</para>
-
- <para>Makes a blocking attempt to write-lock the associated read/write mutex object,
- and returns <code>true</code> if successful within the specified time <code>t</code>,
- otherwise <code>false</code>. If the associated read/write mutex object is already
- locked by the same thread the behavior is dependent on the <link
- linkend="thread.concepts.locking-strategies">locking
- strategy</link> of the associated read/write mutex object.</para>
- </entry>
- </row>
- <row>
- <entry><code>lk.timed_demote(t)</code></entry>
- <entry>
- <para>Throws <classname>boost::lock_error</classname>
- if <code>state() != read_write_lock_state::write_locked</code>.</para>
-
- <para>Makes a blocking attempt to convert the lock held on the associated
- read/write mutex object from a write-lock to a read-lock without releasing
- the lock, returning <code>true</code> if the attempt is successful
- in the specified time <code>t</code>, otherwise <code>false</code>.</para>
- </entry>
- </row>
- <row>
- <entry><code>lk.timed_promote(t)</code></entry>
- <entry>
- <para>Throws <classname>boost::lock_error</classname>
- if <code>state() != read_write_lock_state::read_locked</code>.</para>
-
- <para>Makes a blocking attempt to convert the lock held on the associated
- read/write mutex object from a read-lock to a write-lock without releasing
- the lock, returning <code>true</code> if the attempt is successful
- in the specified time <code>t</code>, otherwise <code>false</code>.</para>
- </entry>
- </row>
- </tbody>
- </tgroup>
- </table>
- </section>
-
- <section id="thread.concepts.ScopedTimedReadWriteLock">
- <title>ScopedTimedReadWriteLock Concept</title>
-
- <para>A ScopedTimedReadWriteLock is a refinement of
- <link linkend="thread.concepts.TimedReadWriteLock">TimedReadWriteLock</link>.
- For a ScopedTimedReadWriteLock type <code>L</code>
- and an object <code>lk</code> of that type,
- and an object <code>m</code> of a type meeting the
- <link linkend="thread.concepts.TimedReadWriteMutex">TimedReadWriteMutex</link> requirements,
- and an object <code>s</code> of type <code>read_write_lock_state</code>,
- and an object <code>t</code> of type <classname>boost::xtime</classname>,
- and an object <code>b</code> of type <code>blocking_mode</code>,
- the following expressions must be well-formed and have the
- indicated effects.</para>
-
- <table>
- <title>ScopedTimedReadWriteLock Expressions</title>
-
- <tgroup cols="2">
- <thead>
- <row>
- <entry>Expression</entry>
- <entry>Effects</entry>
- </row>
- </thead>
-
- <tbody>
- <row>
- <entry><code>L lk(m,s,b);</code></entry>
- <entry>Constructs an object <code>lk</code> and associates read/write mutex
- object <code>m</code> with it, then: if <code>s == read_write_lock_state::read_locked</code>, calls
- <code>read_lock()</code> if <code>b</code>, otherwise <code>try_read_lock()</code>;
- if <code>s==read_write_lock_state::write_locked</code>, calls <code>write_lock()</code> if <code>b</code>,
- otherwise <code>try_write_lock</code>.</entry>
- </row>
- <row>
- <entry><code>L lk(m,s,t);</code></entry>
- <entry>Constructs an object <code>lk</code> and associates read/write mutex
- object <code>m</code> with it, then: if <code>s == read_write_lock_state::read_locked</code>, calls
- <code>timed_read_lock(t)</code>; if <code>s==read_write_lock_state::write_locked</code>,
- calls <code>timed_write_lock(t)</code>.</entry>
- </row>
- </tbody>
- </tgroup>
- </table>
- </section>
- </section>
-
- <section id="thread.concepts.read-write-lock-models">
- <title>Lock Models</title>
-
- <para>&Boost.Thread; currently supplies six models of
- <link linkend="thread.concepts.ReadWriteLock">ReadWriteLock</link>
- and its refinements.</para>
-
- <table>
- <title>Lock Models</title>
-
- <tgroup cols="3">
- <thead>
- <row>
- <entry>Concept</entry>
- <entry>Refines</entry>
- <entry>Models</entry>
- </row>
- </thead>
-
- <tbody>
- <row>
- <entry><link linkend="thread.concepts.ReadWriteLock">ReadWriteLock</link></entry>
- <entry></entry>
- <entry></entry>
- </row>
- <row>
- <entry><link linkend="thread.concepts.ScopedReadWriteLock">ScopedReadWriteLock</link></entry>
- <entry><link linkend="thread.concepts.ReadWriteLock">ReadWriteLock</link></entry>
- <entry>
- <para><classname>boost::read_write_mutex::scoped_read_write_lock</classname></para>
- <para><classname>boost::try_read_write_mutex::scoped_read_write_lock</classname></para>
- <para><classname>boost::timed_read_write_mutex::scoped_read_write_lock</classname></para>
- </entry>
- </row>
- <row>
- <entry><link linkend="thread.concepts.TryReadWriteLock">TryReadWriteLock</link></entry>
- <entry><link linkend="thread.concepts.ReadWriteLock">ReadWriteLock</link></entry>
- <entry></entry>
- </row>
- <row>
- <entry><link linkend="thread.concepts.ScopedTryReadWriteLock">ScopedTryReadWriteLock</link></entry>
- <entry><link linkend="thread.concepts.TryReadWriteLock">TryReadWriteLock</link></entry>
- <entry>
- <para><classname>boost::try_read_write_mutex::scoped_try_read_write_lock</classname></para>
- <para><classname>boost::timed_read_write_mutex::scoped_try_read_write_lock</classname></para>
- </entry>
- </row>
- <row>
- <entry><link linkend="thread.concepts.TimedReadWriteLock">TimedReadWriteLock</link></entry>
- <entry><link linkend="thread.concepts.TryReadWriteLock">TryReadWriteLock</link></entry>
- <entry></entry>
- </row>
- <row>
- <entry><link linkend="thread.concepts.ScopedTimedReadWriteLock">ScopedTimedReadWriteLock</link></entry>
- <entry><link linkend="thread.concepts.TimedReadWriteLock">TimedReadWriteLock</link></entry>
- <entry>
- <para><classname>boost::timed_read_write_mutex::scoped_timed_read_write_lock</classname></para>
- </entry>
- </row>
- </tbody>
- </tgroup>
- </table>
- </section>
- </section>
-</section>

Deleted: branches/release/libs/thread/doc/condition-ref.xml
==============================================================================
--- branches/release/libs/thread/doc/condition-ref.xml 2008-03-17 09:59:17 EDT (Mon, 17 Mar 2008)
+++ (empty file)
@@ -1,196 +0,0 @@
-<?xml version="1.0" encoding="utf-8"?>
-<!DOCTYPE library PUBLIC "-//Boost//DTD BoostBook XML V1.0//EN"
- "http://www.boost.org/tools/boostbook/dtd/boostbook.dtd" [
- <!ENTITY % thread.entities SYSTEM "entities.xml">
- %thread.entities;
-]>
-
-<header name="boost/thread/condition.hpp"
- last-revision="$Date$">
- <namespace name="boost">
- <class name="condition">
- <inherit access="private">
- <type><classname>boost::noncopyable</classname></type>
- <purpose>Exposition only</purpose>
- </inherit>
-
- <purpose>
- <para>An object of class <classname>condition</classname> is a
- synchronization primitive used to cause a thread to wait until a
- particular shared-data condition (or time) is met.</para>
- </purpose>
-
- <description>
- <para>A <classname>condition</classname> object is always used in
- conjunction with a <link linkend="thread.concepts.mutexes">mutex</link>
- object (an object whose type is a model of a <link
- linkend="thread.concepts.Mutex">Mutex</link> or one of its
- refinements). The mutex object must be locked prior to waiting on the
- condition, which is verified by passing a lock object (an object whose
- type is a model of <link linkend="thread.concepts.Lock">Lock</link> or
- one of its refinements) to the <classname>condition</classname> object's
- wait functions. Upon blocking on the <classname>condition</classname>
- object, the thread unlocks the mutex object. When the thread returns
- from a call to one of the <classname>condition</classname> object's wait
- functions the mutex object is again locked. The tricky unlock/lock
- sequence is performed automatically by the
- <classname>condition</classname> object's wait functions.</para>
- <para>The <classname>condition</classname> type is often used to
- implement the Monitor Object and other important patterns (see
- &cite.SchmidtStalRohnertBuschmann; and &cite.Hoare74;). Monitors are one
- of the most important patterns for creating reliable multithreaded
- programs.</para>
- <para>See <xref linkend="thread.glossary"/> for definitions of <link
- linkend="thread.glossary.thread-state">thread states</link>
- blocked and ready. Note that "waiting" is a synonym for blocked.</para>
- </description>
-
- <constructor>
- <effects><simpara>Constructs a <classname>condition</classname>
- object.</simpara></effects>
- </constructor>
-
- <destructor>
- <effects><simpara>Destroys <code>*this</code>.</simpara></effects>
- </destructor>
-
- <method-group name="notification">
- <method name="notify_one">
- <type>void</type>
- <effects><simpara>If there is a thread waiting on <code>*this</code>,
- change that thread's state to ready. Otherwise there is no
- effect.</simpara></effects>
- <notes><simpara>If more than one thread is waiting on <code>*this</code>,
- it is unspecified which is made ready. After returning to a ready
- state the notified thread must still acquire the mutex again (which
- occurs within the call to one of the <classname>condition</classname>
- object's wait functions.)</simpara></notes>
- </method>
-
- <method name="notify_all">
- <type>void</type>
- <effects><simpara>Change the state of all threads waiting on
- <code>*this</code> to ready. If there are no waiting threads,
- <code>notify_all()</code> has no effect.</simpara></effects>
- </method>
- </method-group>
-
- <method-group name="waiting">
- <method name="wait">
- <template>
- <template-type-parameter name="ScopedLock"/>
- </template>
-
- <type>void</type>
-
- <parameter name="lock">
- <paramtype>ScopedLock&</paramtype>
- </parameter>
-
- <requires><simpara><code>ScopedLock</code> meets the <link
- linkend="thread.concepts.ScopedLock">ScopedLock</link>
- requirements.</simpara></requires>
- <effects><simpara>Releases the lock on the <link
- linkend="thread.concepts.mutexes">mutex object</link>
- associated with <code>lock</code>, blocks the current thread of execution
- until readied by a call to <code>this->notify_one()</code>
- or<code> this->notify_all()</code>, and then reacquires the
- lock.</simpara></effects>
- <throws><simpara><classname>lock_error</classname> if
- <code>!lock.locked()</code></simpara></throws>
- </method>
-
- <method name="wait">
- <template>
- <template-type-parameter name="ScopedLock"/>
- <template-type-parameter name="Pred"/>
- </template>
-
- <type>void</type>
-
- <parameter name="lock">
- <paramtype>ScopedLock&</paramtype>
- </parameter>
-
- <parameter name="pred">
- <paramtype>Pred</paramtype>
- </parameter>
-
- <requires><simpara><code>ScopedLock</code> meets the <link
- linkend="thread.concepts.ScopedLock">ScopedLock</link>
- requirements and the return from <code>pred()</code> is
- convertible to <code>bool</code>.</simpara></requires>
- <effects><simpara>As if: <code>while (!pred())
- wait(lock)</code></simpara></effects>
- <throws><simpara><classname>lock_error</classname> if
- <code>!lock.locked()</code></simpara></throws>
- </method>
-
- <method name="timed_wait">
- <template>
- <template-type-parameter name="ScopedLock"/>
- </template>
-
- <type>bool</type>
-
- <parameter name="lock">
- <paramtype>ScopedLock&</paramtype>
- </parameter>
-
- <parameter name="xt">
- <paramtype>const <classname>boost::xtime</classname>&</paramtype>
- </parameter>
-
- <requires><simpara><code>ScopedLock</code> meets the <link
- linkend="thread.concepts.ScopedLock">ScopedLock</link>
- requirements.</simpara></requires>
- <effects><simpara>Releases the lock on the <link
- linkend="thread.concepts.mutexes">mutex object</link>
- associated with <code>lock</code>, blocks the current thread of execution
- until readied by a call to <code>this->notify_one()</code>
- or<code> this->notify_all()</code>, or until time <code>xt</code>
- is reached, and then reacquires the lock.</simpara></effects>
- <returns><simpara><code>false</code> if time <code>xt</code> is reached,
- otherwise <code>true</code>.</simpara></returns>
- <throws><simpara><classname>lock_error</classname> if
- <code>!lock.locked()</code></simpara></throws>
- </method>
-
- <method name="timed_wait">
- <template>
- <template-type-parameter name="ScopedLock"/>
- <template-type-parameter name="Pred"/>
- </template>
-
- <type>bool</type>
-
- <parameter name="lock">
- <paramtype>ScopedLock&</paramtype>
- </parameter>
-
- <parameter name="xt">
- <paramtype>const <classname>boost::xtime</classname>&</paramtype>
- </parameter>
-
- <parameter name="pred">
- <paramtype>Pred</paramtype>
- </parameter>
-
- <requires><simpara><code>ScopedLock</code> meets the <link
- linkend="thread.concepts.ScopedLock">ScopedLock</link>
- requirements and the return from <code>pred()</code> is
- convertible to <code>bool</code>.</simpara></requires>
- <effects><simpara>As if: <code>while (!pred()) { if (!timed_wait(lock,
- xt)) return false; } return true;</code></simpara></effects>
- <returns><simpara><code>false</code> if <code>xt</code> is reached,
- otherwise <code>true</code>.</simpara></returns>
- <throws><simpara><classname>lock_error</classname> if
- <code>!lock.locked()</code></simpara></throws>
- </method>
- </method-group>
- </class>
- </namespace>
-</header>

Deleted: branches/release/libs/thread/doc/configuration.xml
==============================================================================
--- branches/release/libs/thread/doc/configuration.xml 2008-03-17 09:59:17 EDT (Mon, 17 Mar 2008)
+++ (empty file)
@@ -1,96 +0,0 @@
-<?xml version="1.0" encoding="utf-8" ?>
-<!DOCTYPE library PUBLIC "-//Boost//DTD BoostBook XML V1.0//EN"
- "http://www.boost.org/tools/boostbook/dtd/boostbook.dtd" [
- <!ENTITY % thread.entities SYSTEM "entities.xml">
- %thread.entities;
-]>
-
-<section id="thread.configuration" last-revision="$Date$">
- <title>Configuration</title>
- <para>&Boost.Thread; uses several configuration macros in <boost/config.hpp>,
- as well as configuration macros meant to be supplied by the application. These
- macros are documented here.
- </para>
- <section id="thread.configuration.public">
- <title>Library Defined Public Macros</title>
- <para>
- These macros are defined by &Boost.Thread; but are expected to be used
- by application code.
- </para>
- <informaltable>
- <tgroup cols="2">
- <thead>
- <row>
- <entry>Macro</entry>
- <entry>Meaning</entry>
- </row>
- </thead>
- <tbody>
- <row>
- <entry>BOOST_HAS_THREADS</entry>
- <entry>
- Indicates that threading support is available. This means both that there
- is a platform specific implementation for &Boost.Thread; and that
- threading support has been enabled in a platform specific manner. For instance,
- on the Win32 platform there's an implementation for &Boost.Thread;
- but unless the program is compiled against one of the multithreading runtimes
- (often determined by the compiler predefining the macro _MT) the BOOST_HAS_THREADS
- macro remains undefined.
- </entry>
- </row>
- </tbody>
- </tgroup>
- </informaltable>
- </section>
- <section id="thread.configuration.implementation">
- <title>Library Defined Implementation Macros</title>
- <para>
- These macros are defined by &Boost.Thread; and are implementation details
- of interest only to implementors.
- </para>
- <informaltable>
- <tgroup cols="2">
- <thead>
- <row>
- <entry>Macro</entry>
- <entry>Meaning</entry>
- </row>
- </thead>
- <tbody>
- <row>
- <entry>BOOST_HAS_WINTHREADS</entry>
- <entry>
- Indicates that the platform has the Microsoft Win32 threading libraries,
- and that they should be used to implement &Boost.Thread;.
- </entry>
- </row>
- <row>
- <entry>BOOST_HAS_PTHREADS</entry>
- <entry>
- Indicates that the platform has the POSIX pthreads libraries, and that
- they should be used to implement &Boost.Thread;.
- </entry>
- </row>
- <row>
- <entry>BOOST_HAS_FTIME</entry>
- <entry>
- Indicates that the implementation should use GetSystemTimeAsFileTime()
- and the FILETIME type to calculate the current time. This is an implementation
- detail used by boost::detail::getcurtime().
- </entry>
- </row>
- <row>
- <entry>BOOST_HAS_GETTTIMEOFDAY</entry>
- <entry>
- Indicates that the implementation should use gettimeofday() to calculate
- the current time. This is an implementation detail used by boost::detail::getcurtime().
- </entry>
- </row>
- </tbody>
- </tgroup>
- </informaltable>
- </section>
-</section>

Deleted: branches/release/libs/thread/doc/design.xml
==============================================================================
--- branches/release/libs/thread/doc/design.xml 2008-03-17 09:59:17 EDT (Mon, 17 Mar 2008)
+++ (empty file)
@@ -1,159 +0,0 @@
-<?xml version="1.0" encoding="utf-8"?>
-<!DOCTYPE library PUBLIC "-//Boost//DTD BoostBook XML V1.0//EN"
- "http://www.boost.org/tools/boostbook/dtd/boostbook.dtd" [
- <!ENTITY % thread.entities SYSTEM "entities.xml">
- %thread.entities;
-]>
-
-<section id="thread.design" last-revision="$Date$">
- <title>Design</title>
- <para>With client/server and three-tier architectures becoming common place
- in today's world, it's becoming increasingly important for programs to be
- able to handle parallel processing. Modern day operating systems usually
- provide some support for this through native thread APIs. Unfortunately,
- writing portable code that makes use of parallel processing in C++ is made
- very difficult by a lack of a standard interface for these native APIs.
- Further, these APIs are almost universally C APIs and fail to take
- advantage of C++'s strengths, or to address concepts unique to C++, such as
- exceptions.</para>
- <para>The &Boost.Thread; library is an attempt to define a portable interface
- for writing parallel processes in C++.</para>
- <section id="thread.design.goals">
- <title>Goals</title>
- <para>The &Boost.Thread; library has several goals that should help to set
- it apart from other solutions. These goals are listed in order of precedence
- with full descriptions below.
- <variablelist>
- <varlistentry>
- <term>Portability</term>
- <listitem>
- <para>&Boost.Thread; was designed to be highly portable. The goal is
- for the interface to be easily implemented on any platform that
- supports threads, and possibly even on platforms without native thread
- support.</para>
- </listitem>
- </varlistentry>
- <varlistentry>
- <term>Safety</term>
- <listitem>
- <para>&Boost.Thread; was designed to be as safe as possible. Writing
- <link linkend="thread.glossary.thread-safe">thread-safe</link>
- code is very difficult and successful libraries must strive to
- insulate the programmer from dangerous constructs as much as
- possible. This is accomplished in several ways:
- <itemizedlist>
- <listitem>
- <para>C++ language features are used to make correct usage easy
- (if possible) and error-prone usage impossible or at least more
- difficult. For example, see the <link
- linkend="thread.concepts.Mutex">Mutex</link> and <link
- linkend="thread.concepts.Lock">Lock</link> designs, and note
- how they interact.</para>
- </listitem>
- <listitem>
- <para>Certain traditional concurrent programming features are
- considered so error-prone that they are not provided at all. For
- example, see <xref linkend="thread.rationale.events" />.</para>
- </listitem>
- <listitem>
- <para>Dangerous features, or features which may be misused, are
- identified as such in the documentation to make users aware of
- potential pitfalls.</para>
- </listitem>
- </itemizedlist></para>
- </listitem>
- </varlistentry>
- <varlistentry>
- <term>Flexibility</term>
- <listitem>
- <para>&Boost.Thread; was designed to be flexible. This goal is often
- at odds with <emphasis>safety</emphasis>. When functionality might be
- compromised by the desire to keep the interface safe, &Boost.Thread;
- has been designed to provide the functionality, but to make it's use
- prohibitive for general use. In other words, the interfaces have been
- designed such that it's usually obvious when something is unsafe, and
- the documentation is written to explain why.</para>
- </listitem>
- </varlistentry>
- <varlistentry>
- <term>Efficiency</term>
- <listitem>
- <para>&Boost.Thread; was designed to be as efficient as
- possible. When building a library on top of another library there is
- always a danger that the result will be so much slower than the
- "native" API that programmers are inclined to ignore the higher level
- API. &Boost.Thread; was designed to minimize the chances of this
- occurring. The interfaces have been crafted to allow an implementation
- the greatest chance of being as efficient as possible. This goal is
- often at odds with the goal for <emphasis>safety</emphasis>. Every
- effort was made to ensure efficient implementations, but when in
- conflict <emphasis>safety</emphasis> has always taken
- precedence.</para>
- </listitem>
- </varlistentry>
- </variablelist></para>
- </section>
- <section>
- <title>Iterative Phases</title>
- <para>Another goal of &Boost.Thread; was to take a dynamic, iterative
- approach in its development. The computing industry is still exploring the
- concepts of parallel programming. Most thread libraries supply only simple
- primitive concepts for thread synchronization. These concepts are very
- simple, but it is very difficult to use them safely or to provide formal
- proofs for constructs built on top of them. There has been a lot of research
- into other concepts, such as in "Communicating Sequential Processes."
- &Boost.Thread; was designed in iterative steps, with each step providing
- the building blocks necessary for the next step and giving the researcher
- the tools necessary to explore new concepts in a portable manner.</para>
- <para>Given the goal of following a dynamic, iterative approach
- &Boost.Thread; shall go through several growth cycles. Each phase in its
- development shall be roughly documented here.</para>
- </section>
- <section>
- <title>Phase 1, Synchronization Primitives</title>
- <para>Boost is all about providing high quality libraries with
- implementations for many platforms. Unfortunately, there's a big problem
- faced by developers wishing to supply such high quality libraries, namely
- thread-safety. The C++ standard doesn't address threads at all, but real
- world programs often make use of native threading support. A portable
- library that doesn't address the issue of thread-safety is therefore not
- much help to a programmer who wants to use the library in his multithreaded
- application. So there's a very great need for portable primitives that will
- allow the library developer to create <link
- linkend="thread.glossary.thread-safe">thread-safe</link>
- implementations. This need far out weighs the need for portable methods to
- create and manage threads.</para>
- <para>Because of this need, the first phase of &Boost.Thread; focuses
- solely on providing portable primitive concepts for thread
- synchronization. Types provided in this phase include the
- <classname>boost::mutex</classname>,
- <classname>boost::try_mutex</classname>,
- <classname>boost::timed_mutex</classname>,
- <classname>boost::recursive_mutex</classname>,
- <classname>boost::recursive_try_mutex</classname>,
- <classname>boost::recursive_timed_mutex</classname>, and
- <classname>boost::lock_error</classname>. These are considered the "core"
- synchronization primitives, though there are others that will be added in
- later phases.</para>
- </section>
- <section id="thread.design.phase2">
- <title>Phase 2, Thread Management and Thread Specific Storage</title>
- <para>This phase addresses the creation and management of threads and
- provides a mechanism for thread specific storage (data associated with a
- thread instance). Thread management is a tricky issue in C++, so this
- phase addresses only the basic needs of multithreaded program. Later
- phases are likely to add additional functionality in this area. This
- phase of &Boost.Thread; adds the <classname>boost::thread</classname> and
- <classname>boost::thread_specific_ptr</classname> types. With these
- additions the &Boost.Thread; library can be considered minimal but
- complete.</para>
- </section>
- <section>
- <title>The Next Phase</title>
- <para>The next phase will address more advanced synchronization concepts,
- such as read/write mutexes and barriers.</para>
- </section>
-</section>

Deleted: branches/release/libs/thread/doc/entities.xml
==============================================================================
--- branches/release/libs/thread/doc/entities.xml 2008-03-17 09:59:17 EDT (Mon, 17 Mar 2008)
+++ (empty file)
@@ -1,31 +0,0 @@
-
-<!ENTITY Boost "<emphasis role='bold'>Boost</emphasis>">
-<!ENTITY Boost.Thread "<emphasis role='bold'>Boost.Thread</emphasis>">
-<!ENTITY Boost.Build "<emphasis role='bold'>Boost.Build</emphasis>">
-<!ENTITY cite.AndrewsSchneider83 "<citation><xref
-linkend='thread.bib.AndrewsSchneider83'
-endterm='thread.bib.AndrewsSchneider83.abbrev'/></citation>">
-<!ENTITY cite.Boost "<citation><xref linkend='thread.bib.Boost'
-endterm='thread.bib.Boost.abbrev'/></citation>">
-<!ENTITY cite.Hansen73 "<citation><xref linkend='thread.bib.Hansen73'
-endterm='thread.bib.Hansen73.abbrev'/></citation>">
-<!ENTITY cite.Butenhof97 "<citation><xref linkend='thread.bib.Butenhof97'
-endterm='thread.bib.Butenhof97.abbrev'/></citation>">
-<!ENTITY cite.Hoare74 "<citation><xref linkend='thread.bib.Hoare74'
-endterm='thread.bib.Hoare74.abbrev'/></citation>">
-<!ENTITY cite.ISO98 "<citation><xref linkend='thread.bib.ISO98'
-endterm='thread.bib.ISO98.abbrev'/></citation>">
-<!ENTITY cite.McDowellHelmbold89 "<citation><xref
-linkend='thread.bib.McDowellHelmbold89'
-endterm='thread.bib.McDowellHelmbold89.abbrev'/></citation>">
-<!ENTITY cite.SchmidtPyarali "<citation><xref
-linkend='thread.bib.SchmidtPyarali'
-endterm='thread.bib.SchmidtPyarali.abbrev'/></citation>">
-<!ENTITY cite.SchmidtStalRohnertBuschmann "<citation><xref
-linkend='thread.bib.SchmidtStalRohnertBuschmann'
-endterm='thread.bib.SchmidtStalRohnertBuschmann.abbrev'/></citation>">
-<!ENTITY cite.Stroustrup "<citation><xref linkend='thread.bib.Stroustrup'
-endterm='thread.bib.Stroustrup.abbrev'/></citation>">

Deleted: branches/release/libs/thread/doc/exceptions-ref.xml
==============================================================================
--- branches/release/libs/thread/doc/exceptions-ref.xml 2008-03-17 09:59:17 EDT (Mon, 17 Mar 2008)
+++ (empty file)
@@ -1,62 +0,0 @@
-<?xml version="1.0" encoding="utf-8"?>
-<!DOCTYPE library PUBLIC "-//Boost//DTD BoostBook XML V1.0//EN"
- "http://www.boost.org/tools/boostbook/dtd/boostbook.dtd" [
- <!ENTITY % thread.entities SYSTEM "entities.xml">
- %thread.entities;
-]>
-
-<header name="boost/thread/exceptions.hpp"
- last-revision="$Date$">
- <namespace name="boost">
- <class name="lock_error">
- <purpose>
- <simpara>The lock_error class defines an exception type thrown
- to indicate a locking related error has been detected.</simpara>
- </purpose>
-
- <description>
- <simpara>Examples of errors indicated by a lock_error exception
- include a lock operation which can be determined to result in a
- deadlock, or unlock operations attempted by a thread that does
- not own the lock.</simpara>
- </description>
-
- <inherit access="public">
- <type><classname>std::logical_error</classname></type>
- </inherit>
-
- <constructor>
- <effects><simpara>Constructs a <code>lock_error</code> object.
- </simpara></effects>
- </constructor>
- </class>
-
- <class name="thread_resource_error">
- <purpose>
- <simpara>The <classname>thread_resource_error</classname> class
- defines an exception type that is thrown by constructors in the
- &Boost.Thread; library when thread-related resources can not be
- acquired.</simpara>
- </purpose>
-
- <description>
- <simpara><classname>thread_resource_error</classname> is used
- only when thread-related resources cannot be acquired; memory
- allocation failures are indicated by
- <classname>std::bad_alloc</classname>.</simpara>
- </description>
-
- <inherit access="public">
- <type><classname>std::runtime_error</classname></type>
- </inherit>
-
- <constructor>
- <effects><simpara>Constructs a <code>thread_resource_error</code>
- object.</simpara></effects>
- </constructor>
- </class>
- </namespace>
-</header>

Deleted: branches/release/libs/thread/doc/faq.xml
==============================================================================
--- branches/release/libs/thread/doc/faq.xml 2008-03-17 09:59:17 EDT (Mon, 17 Mar 2008)
+++ (empty file)
@@ -1,235 +0,0 @@
-<?xml version="1.0" encoding="utf-8"?>
-<!DOCTYPE library PUBLIC "-//Boost//DTD BoostBook XML V1.0//EN"
- "http://www.boost.org/tools/boostbook/dtd/boostbook.dtd" [
- <!ENTITY % thread.entities SYSTEM "entities.xml">
- %thread.entities;
-]>
-
-<section id="thread.faq" last-revision="$Date$">
- <title>Frequently Asked Questions</title>
- <qandaset>
- <qandaentry>
- <question>
- <para>Are lock objects <link
- linkend="thread.glossary.thread-safe">thread safe</link>?</para>
- </question>
- <answer>
- <para><emphasis role="bold">No!</emphasis> Lock objects are not meant to
- be shared between threads. They are meant to be short-lived objects
- created on automatic storage within a code block. Any other usage is
- just likely to lead to errors and won't really be of actual benefit anyway.
- Share <link linkend="thread.concepts.mutexes">Mutexes</link>, not
- Locks. For more information see the <link
- linkend="thread.rationale.locks">rationale</link> behind the
- design for lock objects.</para>
- </answer>
- </qandaentry>
- <qandaentry>
- <question>
- <para>Why was &Boost.Thread; modeled after (specific library
- name)?</para>
- </question>
- <answer>
- <para>It wasn't. &Boost.Thread; was designed from scratch. Extensive
- design discussions involved numerous people representing a wide range of
- experience across many platforms. To ensure portability, the initial
- implements were done in parallel using POSIX Threads and the Win32
- threading API. But the &Boost.Thread; design is very much in the spirit
- of C++, and thus doesn't model such C based APIs.</para>
- </answer>
- </qandaentry>
- <qandaentry>
- <question>
- <para>Why wasn't &Boost.Thread; modeled after (specific library
- name)?</para>
- </question>
- <answer>
- <para>Existing C++ libraries either seemed dangerous (often failing to
- take advantage of prior art to reduce errors) or had excessive
- dependencies on library components unrelated to threading. Existing C
- libraries couldn't meet our C++ requirements, and were also missing
- certain features. For instance, the WIN32 thread API lacks condition
- variables, even though these are critical for the important Monitor
- pattern &cite.SchmidtStalRohnertBuschmann;.</para>
- </answer>
- </qandaentry>
- <qandaentry>
- <question>
- <para>Why do <link linkend="thread.concepts.mutexes">Mutexes</link>
- have noncopyable semantics?</para>
- </question>
- <answer>
- <para>To ensure that <link
- linkend="thread.glossary.deadlock">deadlocks</link> don't occur. The
- only logical form of copy would be to use some sort of shallow copy
- semantics in which multiple mutex objects could refer to the same mutex
- state. This means that if ObjA has a mutex object as part of its state
- and ObjB is copy constructed from it, then when ObjB::foo() locks the
- mutex it has effectively locked ObjA as well. This behavior can result
- in deadlock. Other copy semantics result in similar problems (if you
- think you can prove this to be wrong then supply us with an alternative
- and we'll reconsider).</para>
- </answer>
- </qandaentry>
- <qandaentry>
- <question>
- <para>How can you prevent <link
- linkend="thread.glossary.deadlock">deadlock</link> from occurring when
- a thread must lock multiple mutexes?</para>
- </question>
- <answer>
- <para>Always lock them in the same order. One easy way of doing this is
- to use each mutex's address to determine the order in which they are
- locked. A future &Boost.Thread; concept may wrap this pattern up in a
- reusable class.</para>
- </answer>
- </qandaentry>
- <qandaentry>
- <question>
- <para>Don't noncopyable <link
- linkend="thread.concepts.mutexes">Mutex</link> semantics mean that a
- class with a mutex member will be noncopyable as well?</para>
- </question>
- <answer>
- <para>No, but what it does mean is that the compiler can't generate a
- copy constructor and assignment operator, so they will have to be coded
- explicitly. This is a <emphasis role="bold">good thing</emphasis>,
- however, since the compiler generated operations would not be <link
- linkend="thread.glossary.thread-safe">thread-safe</link>. The following
- is a simple example of a class with copyable semantics and internal
- synchronization through a mutex member.</para>
-<programlisting>
-class counter
-{
-public:
- // Doesn't need synchronization since there can be no references to *this
- // until after it's constructed!
- explicit counter(int initial_value)
- : m_value(initial_value)
- {
- }
- // We only need to synchronize other for the same reason we don't have to
- // synchronize on construction!
- counter(const counter& other)
- {
- boost::mutex::scoped_lock scoped_lock(other.m_mutex);
- m_value = other.m_value;
- }
- // For assignment we need to synchronize both objects!
- const counter& operator=(const counter& other)
- {
- if (this == &other)
- return *this;
- boost::mutex::scoped_lock lock1(&m_mutex < &other.m_mutex ? m_mutex : other.m_mutex);
- boost::mutex::scoped_lock lock2(&m_mutex > &other.m_mutex ? m_mutex : other.m_mutex);
- m_value = other.m_value;
- return *this;
- }
- int value() const
- {
- boost::mutex::scoped_lock scoped_lock(m_mutex);
- return m_value;
- }
- int increment()
- {
- boost::mutex::scoped_lock scoped_lock(m_mutex);
- return ++m_value;
- }
-private:
- mutable boost::mutex m_mutex;
- int m_value;
-};
-</programlisting>
- </answer>
- </qandaentry>
- <qandaentry>
- <question>
- <para>How can you lock a <link
- linkend="thread.concepts.mutexes">Mutex</link> member in a const member
- function, in order to implement the Monitor Pattern?</para>
- </question>
- <answer>
- <para>The Monitor Pattern &cite.SchmidtStalRohnertBuschmann; mutex
- should simply be declared as mutable. See the example code above. The
- internal state of mutex types could have been made mutable, with all
- lock calls made via const functions, but this does a poor job of
- documenting the actual semantics (and in fact would be incorrect since
- the logical state of a locked mutex clearly differs from the logical
- state of an unlocked mutex). Declaring a mutex member as mutable clearly
- documents the intended semantics.</para>
- </answer>
- </qandaentry>
- <qandaentry>
- <question>
- <para>Why supply <classname>boost::condition</classname> variables rather than
- event variables?</para>
- </question>
- <answer>
- <para>Condition variables result in user code much less prone to <link
- linkend="thread.glossary.race-condition">race conditions</link> than
- event variables. See <xref linkend="thread.rationale.events" />
- for analysis. Also see &cite.Hoare74; and &cite.SchmidtStalRohnertBuschmann;.
- </para>
- </answer>
- </qandaentry>
- <qandaentry>
- <question>
- <para>Why isn't thread cancellation or termination provided?</para>
- </question>
- <answer>
- <para>There's a valid need for thread termination, so at some point
- &Boost.Thread; probably will include it, but only after we can find a
- truly safe (and portable) mechanism for this concept.</para>
- </answer>
- </qandaentry>
- <qandaentry>
- <question>
- <para>Is it safe for threads to share automatic storage duration (stack)
- objects via pointers or references?</para>
- </question>
- <answer>
- <para>Only if you can guarantee that the lifetime of the stack object
- will not end while other threads might still access the object. Thus the
- safest practice is to avoid sharing stack objects, particularly in
- designs where threads are created and destroyed dynamically. Restrict
- sharing of stack objects to simple designs with very clear and
- unchanging function and thread lifetimes. (Suggested by Darryl
- Green).</para>
- </answer>
- </qandaentry>
- <qandaentry>
- <question>
- <para>Why has class semaphore disappeared?</para>
- </question>
- <answer>
- <para>Semaphore was removed as too error prone. The same effect can be
- achieved with greater safety by the combination of a mutex and a
- condition variable.</para>
- </answer>
- </qandaentry>
- <qandaentry>
- <question>
- <para>Why doesn't the thread's ctor take at least a void* to pass any
- information along with the function? All other threading libs support
- that and it makes Boost.Threads inferiour. </para>
- </question>
- <answer>
- <para>There is no need, because Boost.Threads are superiour! First
- thing is that its ctor doesn't take a function but a functor. That
- means that you can pass an object with an overloaded operator() and
- include additional data as members in that object. Beware though that
- this object is copied, use boost::ref to prevent that. Secondly, even
- a boost::function<void (void)> can carry parameters, you only have to
- use boost::bind() to create it from any function and bind its
- parameters.</para>
- <para>That is also why Boost.Threads are superiour, because they
- don't require you to pass a type-unsafe void pointer. Rather, you can
- use the flexible Boost.Functions to create a thread entry out of
- anything that can be called.</para>
- </answer>
- </qandaentry>
- </qandaset>
-</section>

Deleted: branches/release/libs/thread/doc/glossary.xml
==============================================================================
--- branches/release/libs/thread/doc/glossary.xml 2008-03-17 09:59:17 EDT (Mon, 17 Mar 2008)
+++ (empty file)
@@ -1,304 +0,0 @@
-<?xml version="1.0" encoding="utf-8"?>
-<!DOCTYPE library PUBLIC "-//Boost//DTD BoostBook XML V1.0//EN"
- "http://www.boost.org/tools/boostbook/dtd/boostbook.dtd" [
- <!ENTITY % thread.entities SYSTEM "entities.xml">
- %thread.entities;
-]>
-
-<glossary id="thread.glossary" last-revision="$Date$">
- <title>Glossary</title>
- <para>Definitions are given in terms of the C++ Standard
- &cite.ISO98;. References to the standard are in the form [1.2.3/4], which
- represents the section number, with the paragraph number following the
- "/".</para>
- <para>Because the definitions are written in something akin to "standardese",
- they can be difficult to understand. The intent isn't to confuse, but rather
- to clarify the additional requirements &Boost.Thread; places on a C++
- implementation as defined by the C++ Standard.</para>
- <glossentry id="thread.glossary.thread">
- <glossterm>Thread</glossterm>
- <glossdef>
- <para>Thread is short for "thread of execution". A thread of execution is
- an execution environment [1.9/7] within the execution environment of a C++
- program [1.9]. The main() function [3.6.1] of the program is the initial
- function of the initial thread. A program in a multithreading environment
- always has an initial thread even if the program explicitly creates no
- additional threads.</para>
- <para>Unless otherwise specified, each thread shares all aspects of its
- execution environment with other threads in the program. Shared aspects of
- the execution environment include, but are not limited to, the
- following:</para>
- <itemizedlist>
- <listitem><para>Static storage duration (static, extern) objects
- [3.7.1].</para></listitem>
- <listitem><para>Dynamic storage duration (heap) objects [3.7.3]. Thus
- each memory allocation will return a unique addresses, regardless of the
- thread making the allocation request.</para></listitem>
- <listitem><para>Automatic storage duration (stack) objects [3.7.2]
- accessed via pointer or reference from another thread.</para></listitem>
- <listitem><para>Resources provided by the operating system. For example,
- files.</para></listitem>
- <listitem><para>The program itself. In other words, each thread is
- executing some function of the same program, not a totally different
- program.</para></listitem>
- </itemizedlist>
- <para>Each thread has its own:</para>
- <itemizedlist>
- <listitem><para>Registers and current execution sequence (program
- counter) [1.9/5].</para></listitem>
- <listitem><para>Automatic storage duration (stack) objects
- [3.7.2].</para></listitem>
- </itemizedlist>
- </glossdef>
- </glossentry>
- <glossentry id="thread.glossary.thread-safe">
- <glossterm>Thread-safe</glossterm>
- <glossdef>
- <para>A program is thread-safe if it has no <link
- linkend="thread.glossary.race-condition">race conditions</link>, does
- not <link linkend="thread.glossary.deadlock">deadlock</link>, and has
- no <link linkend="thread.glossary.priority-failure">priority
- failures</link>.</para>
- <para>Note that thread-safety does not necessarily imply efficiency, and
- than while some thread-safety violations can be determined statically at
- compile time, many thread-safety errors can only only be detected at
- runtime.</para>
- </glossdef>
- </glossentry>
- <glossentry id="thread.glossary.thread-state">
- <glossterm>Thread State</glossterm>
- <glossdef>
- <para>During the lifetime of a thread, it shall be in one of the following
- states:</para>
- <table>
- <title>Thread States</title>
- <tgroup cols="2" align="left">
- <thead>
- <row>
- <entry>State</entry>
- <entry>Description</entry>
- </row>
- </thead>
- <tbody>
- <row>
- <entry>Ready</entry>
- <entry>Ready to run, but waiting for a processor.</entry>
- </row>
- <row>
- <entry>Running</entry>
- <entry>Currently executing on a processor. Zero or more threads
- may be running at any time, with a maximum equal to the number of
- processors.</entry>
- </row>
- <row>
- <entry>Blocked</entry>
- <entry>Waiting for some resource other than a processor which is
- not currently available, or for the completion of calls to library
- functions [1.9/6]. The term "waiting" is synonymous with
- "blocked"</entry>
- </row>
- <row>
- <entry>Terminated</entry>
- <entry>Finished execution but not yet detached or joined.</entry>
- </row>
- </tbody>
- </tgroup>
- </table>
- <para>Thread state transitions shall occur only as specified:</para>
- <table>
- <title>Thread States Transitions</title>
- <tgroup cols="3" align="left">
- <thead>
- <row>
- <entry>From</entry>
- <entry>To</entry>
- <entry>Cause</entry>
- </row>
- </thead>
- <tbody>
- <row>
- <entry>[none]</entry>
- <entry>Ready</entry>
- <entry><para>Thread is created by a call to a library function.
- In the case of the initial thread, creation is implicit and
- occurs during the startup of the main() function [3.6.1].</para></entry>
- </row>
- <row>
- <entry>Ready</entry>
- <entry>Running</entry>
- <entry><para>Processor becomes available.</para></entry>
- </row>
- <row>
- <entry>Running</entry>
- <entry>Ready</entry>
- <entry>Thread preempted.</entry>
- </row>
- <row>
- <entry>Running</entry>
- <entry>Blocked</entry>
- <entry>Thread calls a library function which waits for a resource or
- for the completion of I/O.</entry>
- </row>
- <row>
- <entry>Running</entry>
- <entry>Terminated</entry>
- <entry>Thread returns from its initial function, calls a thread
- termination library function, or is canceled by some other thread
- calling a thread termination library function.</entry>
- </row>
- <row>
- <entry>Blocked</entry>
- <entry>Ready</entry>
- <entry>The resource being waited for becomes available, or the
- blocking library function completes.</entry>
- </row>
- <row>
- <entry>Terminated</entry>
- <entry>[none]</entry>
- <entry>Thread is detached or joined by some other thread calling the
- appropriate library function, or by program termination
- [3.6.3].</entry>
- </row>
- </tbody>
- </tgroup>
- </table>
- <para>[Note: if a suspend() function is added to the threading library,
- additional transitions to the blocked state will have to be added to the
- above table.]</para>
- </glossdef>
- </glossentry>
- <glossentry id="thread.glossary.race-condition">
- <glossterm>Race Condition</glossterm>
- <glossdef>
- <para>A race condition is what occurs when multiple threads read from and write
- to the same memory without proper synchronization, resulting in an incorrect
- value being read or written. The result of a race condition may be a bit
- pattern which isn't even a valid value for the data type. A race condition
- results in undefined behavior [1.3.12].</para>
- <para>Race conditions can be prevented by serializing memory access using
- the tools provided by &Boost.Thread;.</para>
- </glossdef>
- </glossentry>
- <glossentry id="thread.glossary.deadlock">
- <glossterm>Deadlock</glossterm>
- <glossdef>
- <para>Deadlock is an execution state where for some set of threads, each
- thread in the set is blocked waiting for some action by one of the other
- threads in the set. Since each is waiting on the others, none will ever
- become ready again.</para>
- </glossdef>
- </glossentry>
- <glossentry id="thread.glossary.starvation">
- <glossterm>Starvation</glossterm>
- <glossdef>
- <para>The condition in which a thread is not making sufficient progress in
- its work during a given time interval.</para>
- </glossdef>
- </glossentry>
- <glossentry id="thread.glossary.priority-failure">
- <glossterm>Priority Failure</glossterm>
- <glossdef>
- <para>A priority failure (such as priority inversion or infinite overtaking)
- occurs when threads are executed in such a sequence that required work is not
- performed in time to be useful.</para>
- </glossdef>
- </glossentry>
- <glossentry id="thread.glossary.undefined-behavior">
- <glossterm>Undefined Behavior</glossterm>
- <glossdef>
- <para>The result of certain operations in &Boost.Thread; is undefined;
- this means that those operations can invoke almost any behavior when
- they are executed.</para>
-
- <para>An operation whose behavior is undefined can work "correctly"
- in some implementations (i.e., do what the programmer thought it
- would do), while in other implementations it may exhibit almost
- any "incorrect" behavior--such as returning an invalid value,
- throwing an exception, generating an access violation, or terminating
- the process.</para>
-
- <para>Executing a statement whose behavior is undefined is a
- programming error.</para>
- </glossdef>
- </glossentry>
- <glossentry id="thread.glossary.memory-visibility">
- <glossterm>Memory Visibility</glossterm>
- <glossdef>
- <para>An address [1.7] shall always point to the same memory byte,
- regardless of the thread or processor dereferencing the address.</para>
- <para>An object [1.8, 1.9] is accessible from multiple threads if it is of
- static storage duration (static, extern) [3.7.1], or if a pointer or
- reference to it is explicitly or implicitly dereferenced in multiple
- threads.</para>
- <para>For an object accessible from multiple threads, the value of the
- object accessed from one thread may be indeterminate or different from the
- value accessed from another thread, except under the conditions specified in
- the following table. For the same row of the table, the value of an object
- accessible at the indicated sequence point in thread A will be determinate
- and the same if accessed at or after the indicated sequence point in thread
- B, provided the object is not otherwise modified. In the table, the
- "sequence point at a call" is the sequence point after the evaluation of all
- function arguments [1.9/17], while the "sequence point after a call" is the
- sequence point after the copying of the returned value... [1.9/17].</para>
- <table>
- <title>Memory Visibility</title>
- <tgroup cols="2">
- <thead>
- <row>
- <entry>Thread A</entry>
- <entry>Thread B</entry>
- </row>
- </thead>
- <tbody>
- <row>
- <entry>The sequence point at a call to a library thread-creation
- function.</entry>
- <entry>The first sequence point of the initial function in the new
- thread created by the Thread A call.</entry>
- </row>
- <row>
- <entry>The sequence point at a call to a library function which
- locks a mutex, directly or by waiting for a condition
- variable.</entry>
- <entry>The sequence point after a call to a library function which
- unlocks the same mutex.</entry>
- </row>
- <row>
- <entry>The last sequence point before thread termination.</entry>
- <entry>The sequence point after a call to a library function which
- joins the terminated thread.</entry>
- </row>
- <row>
- <entry>The sequence point at a call to a library function which
- signals or broadcasts a condition variable.</entry>
- <entry>The sequence point after the call to the library function
- which was waiting on that same condition variable or signal.</entry>
- </row>
- </tbody>
- </tgroup>
- </table>
- <para>The architecture of the execution environment and the observable
- behavior of the abstract machine [1.9] shall be the same on all
- processors.</para>
- <para>The latitude granted by the C++ standard for an implementation to
- alter the definition of observable behavior of the abstract machine to
- include additional library I/O functions [1.9/6] is extended to include
- threading library functions.</para>
- <para>When an exception is thrown and there is no matching exception handler
- in the same thread, behavior is undefined. The preferred behavior is the
- same as when there is no matching exception handler in a program
- [15.3/9]. That is, terminate() is called, and it is implementation-defined
- whether or not the stack is unwound.</para>
- </glossdef>
- </glossentry>
- <section>
- <title>Acknowledgements</title>
- <para>This document was originally written by Beman Dawes, and then much
- improved by the incorporation of comments from William Kempf, who now
- maintains the contents.</para>
- <para>The visibility rules are based on &cite.Butenhof97;.</para>
- </section>
-</glossary>

Deleted: branches/release/libs/thread/doc/implementation_notes.xml
==============================================================================
--- branches/release/libs/thread/doc/implementation_notes.xml 2008-03-17 09:59:17 EDT (Mon, 17 Mar 2008)
+++ (empty file)
@@ -1,38 +0,0 @@
-<?xml version="1.0" encoding="utf-8"?>
-<!DOCTYPE library PUBLIC "-//Boost//DTD BoostBook XML V1.0//EN"
- "http://www.boost.org/tools/boostbook/dtd/boostbook.dtd" [
- <!ENTITY % thread.entities SYSTEM "entities.xml">
- %thread.entities;
-]>
-
-<section id="thread.implementation_notes" last-revision="$Date$">
- <title>Implementation Notes</title>
- <section id="thread.implementation_notes.win32">
- <title>Win32</title>
- <para>
- In the current Win32 implementation, creating a boost::thread object
- during dll initialization will result in deadlock because the thread
- class constructor causes the current thread to wait on the thread that
- is being created until it signals that it has finished its initialization,
- and, as stated in the
- <ulink url="http://msdn.microsoft.com/library/default.asp?url=/library/en-us/dllproc/base/dllmain.asp">MSDN Library, "DllMain" article, "Remarks" section</ulink>,
- "Because DLL notifications are serialized, entry-point functions should not
- attempt to communicate with other threads or processes. Deadlocks may occur as a result."
- (Also see <ulink url="http://www.microsoft.com/msj/archive/S220.aspx">"Under the Hood", January 1996</ulink>
- for a more detailed discussion of this issue).
- </para>
- <para>
- The following non-exhaustive list details some of the situations that
- should be avoided until this issue can be addressed:
- <itemizedlist>
- <listitem>Creating a boost::thread object in DllMain() or in any function called by it.</listitem>
- <listitem>Creating a boost::thread object in the constructor of a global static object or in any function called by one.</listitem>
- <listitem>Creating a boost::thread object in MFC's CWinApp::InitInstance() function or in any function called by it.</listitem>
- <listitem>Creating a boost::thread object in the function pointed to by MFC's _pRawDllMain function pointer or in any function called by it.</listitem>
- </itemizedlist>
- </para>
- </section>
-</section>

Deleted: branches/release/libs/thread/doc/mutex-ref.xml
==============================================================================
--- branches/release/libs/thread/doc/mutex-ref.xml 2008-03-17 09:59:17 EDT (Mon, 17 Mar 2008)
+++ (empty file)
@@ -1,309 +0,0 @@
-<?xml version="1.0" encoding="utf-8"?>
-<!DOCTYPE library PUBLIC "-//Boost//DTD BoostBook XML V1.0//EN"
- "http://www.boost.org/tools/boostbook/dtd/boostbook.dtd" [
- <!ENTITY % thread.entities SYSTEM "entities.xml">
- %thread.entities;
-]>
-
-<header name="boost/thread/mutex.hpp"
- last-revision="$Date$">
- <namespace name="boost">
- <class name="mutex">
- <purpose>
- <para>The <classname>mutex</classname> class is a model of the
- <link linkend="thread.concepts.Mutex">Mutex</link> concept.</para>
- </purpose>
-
- <description>
- <para>The <classname>mutex</classname> class is a model of the
- <link linkend="thread.concepts.Mutex">Mutex</link> concept.
- It should be used to synchronize access to shared resources using
- <link linkend="thread.concepts.unspecified-locking-strategy">Unspecified</link>
- locking mechanics.</para>
-
- <para>For classes that model related mutex concepts, see
- <classname>try_mutex</classname> and <classname>timed_mutex</classname>.</para>
-
- <para>For <link linkend="thread.concepts.recursive-locking-strategy">Recursive</link>
- locking mechanics, see <classname>recursive_mutex</classname>,
- <classname>recursive_try_mutex</classname>, and <classname>recursive_timed_mutex</classname>.
- </para>
-
- <para>The <classname>mutex</classname> class supplies the following typedef,
- which <link linkend="thread.concepts.lock-models">models</link>
- the specified locking strategy:
-
- <informaltable>
- <tgroup cols="2" align="left">
- <thead>
- <row>
- <entry>Lock Name</entry>
- <entry>Lock Concept</entry>
- </row>
- </thead>
- <tbody>
- <row>
- <entry>scoped_lock</entry>
- <entry><link linkend="thread.concepts.ScopedLock">ScopedLock</link></entry>
- </row>
- </tbody>
- </tgroup>
- </informaltable>
- </para>
-
- <para>The <classname>mutex</classname> class uses an
- <link linkend="thread.concepts.unspecified-locking-strategy">Unspecified</link>
- locking strategy, so attempts to recursively lock a <classname>mutex</classname>
- object or attempts to unlock one by threads that don't own a lock on it result in
- <emphasis role="bold">undefined behavior</emphasis>.
- This strategy allows implementations to be as efficient as possible
- on any given platform. It is, however, recommended that
- implementations include debugging support to detect misuse when
- <code>NDEBUG</code> is not defined.</para>
-
- <para>Like all
- <link linkend="thread.concepts.mutex-models">mutex models</link>
- in &Boost.Thread;, <classname>mutex</classname> leaves the
- <link linkend="thread.concepts.sheduling-policies">scheduling policy</link>
- as <link linkend="thread.concepts.unspecified-scheduling-policy">Unspecified</link>.
- Programmers should make no assumptions about the order in which
- waiting threads acquire a lock.</para>
- </description>
-
- <inherit access="private">
- <type><classname>boost::noncopyable</classname></type>
- <purpose>Exposition only</purpose>
- </inherit>
-
- <typedef name="scoped_lock">
- <type><emphasis>implementation-defined</emphasis></type>
- </typedef>
-
- <constructor>
- <effects>Constructs a <classname>mutex</classname> object.
- </effects>
-
- <postconditions><code>*this</code> is in an unlocked state.
- </postconditions>
- </constructor>
-
- <destructor>
- <effects>Destroys a <classname>mutex</classname> object.</effects>
-
- <requires><code>*this</code> is in an unlocked state.</requires>
-
- <notes><emphasis role="bold">Danger:</emphasis> Destruction of a
- locked mutex is a serious programming error resulting in undefined
- behavior such as a program crash.</notes>
- </destructor>
- </class>
-
- <class name="try_mutex">
- <purpose>
- <para>The <classname>try_mutex</classname> class is a model of the
- <link linkend="thread.concepts.TryMutex">TryMutex</link> concept.</para>
- </purpose>
-
- <description>
- <para>The <classname>try_mutex</classname> class is a model of the
- <link linkend="thread.concepts.TryMutex">TryMutex</link> concept.
- It should be used to synchronize access to shared resources using
- <link linkend="thread.concepts.unspecified-locking-strategy">Unspecified</link>
- locking mechanics.</para>
-
- <para>For classes that model related mutex concepts, see
- <classname>mutex</classname> and <classname>timed_mutex</classname>.</para>
-
- <para>For <link linkend="thread.concepts.recursive-locking-strategy">Recursive</link>
- locking mechanics, see <classname>recursive_mutex</classname>,
- <classname>recursive_try_mutex</classname>, and <classname>recursive_timed_mutex</classname>.
- </para>
-
- <para>The <classname>try_mutex</classname> class supplies the following typedefs,
- which <link linkend="thread.concepts.lock-models">model</link>
- the specified locking strategies:
-
- <informaltable>
- <tgroup cols="2" align="left">
- <thead>
- <row>
- <entry>Lock Name</entry>
- <entry>Lock Concept</entry>
- </row>
- </thead>
- <tbody>
- <row>
- <entry>scoped_lock</entry>
- <entry><link linkend="thread.concepts.ScopedLock">ScopedLock</link></entry>
- </row>
- <row>
- <entry>scoped_try_lock</entry>
- <entry><link linkend="thread.concepts.ScopedTryLock">ScopedTryLock</link></entry>
- </row>
- </tbody>
- </tgroup>
- </informaltable>
- </para>
-
- <para>The <classname>try_mutex</classname> class uses an
- <link linkend="thread.concepts.unspecified-locking-strategy">Unspecified</link>
- locking strategy, so attempts to recursively lock a <classname>try_mutex</classname>
- object or attempts to unlock one by threads that don't own a lock on it result in
- <emphasis role="bold">undefined behavior</emphasis>.
- This strategy allows implementations to be as efficient as possible
- on any given platform. It is, however, recommended that
- implementations include debugging support to detect misuse when
- <code>NDEBUG</code> is not defined.</para>
-
- <para>Like all
- <link linkend="thread.concepts.mutex-models">mutex models</link>
- in &Boost.Thread;, <classname>try_mutex</classname> leaves the
- <link linkend="thread.concepts.sheduling-policies">scheduling policy</link>
- as <link linkend="thread.concepts.unspecified-scheduling-policy">Unspecified</link>.
- Programmers should make no assumptions about the order in which
- waiting threads acquire a lock.</para>
- </description>
-
- <inherit access="private">
- <type><classname>boost::noncopyable</classname></type>
- <purpose>Exposition only</purpose>
- </inherit>
-
- <typedef name="scoped_lock">
- <type><emphasis>implementation-defined</emphasis></type>
- </typedef>
-
- <typedef name="scoped_try_lock">
- <type><emphasis>implementation-defined</emphasis></type>
- </typedef>
-
- <constructor>
- <effects>Constructs a <classname>try_mutex</classname> object.
- </effects>
-
- <postconditions><code>*this</code> is in an unlocked state.
- </postconditions>
- </constructor>
-
- <destructor>
- <effects>Destroys a <classname>try_mutex</classname> object.
- </effects>
-
- <requires><code>*this</code> is in an unlocked state.</requires>
-
- <notes><emphasis role="bold">Danger:</emphasis> Destruction of a
- locked mutex is a serious programming error resulting in undefined
- behavior such as a program crash.</notes>
- </destructor>
- </class>
-
- <class name="timed_mutex">
- <purpose>
- <para>The <classname>timed_mutex</classname> class is a model of the
- <link linkend="thread.concepts.TimedMutex">TimedMutex</link> concept.</para>
- </purpose>
-
- <description>
- <para>The <classname>timed_mutex</classname> class is a model of the
- <link linkend="thread.concepts.TimedMutex">TimedMutex</link> concept.
- It should be used to synchronize access to shared resources using
- <link linkend="thread.concepts.unspecified-locking-strategy">Unspecified</link>
- locking mechanics.</para>
-
- <para>For classes that model related mutex concepts, see
- <classname>mutex</classname> and <classname>try_mutex</classname>.</para>
-
- <para>For <link linkend="thread.concepts.recursive-locking-strategy">Recursive</link>
- locking mechanics, see <classname>recursive_mutex</classname>,
- <classname>recursive_try_mutex</classname>, and <classname>recursive_timed_mutex</classname>.
- </para>
-
- <para>The <classname>timed_mutex</classname> class supplies the following typedefs,
- which <link linkend="thread.concepts.lock-models">model</link>
- the specified locking strategies:
-
- <informaltable>
- <tgroup cols="2" align="left">
- <thead>
- <row>
- <entry>Lock Name</entry>
- <entry>Lock Concept</entry>
- </row>
- </thead>
- <tbody>
- <row>
- <entry>scoped_lock</entry>
- <entry><link linkend="thread.concepts.ScopedLock">ScopedLock</link></entry>
- </row>
- <row>
- <entry>scoped_try_lock</entry>
- <entry><link linkend="thread.concepts.ScopedTryLock">ScopedTryLock</link></entry>
- </row>
- <row>
- <entry>scoped_timed_lock</entry>
- <entry><link linkend="thread.concepts.ScopedTimedLock">ScopedTimedLock</link></entry>
- </row>
- </tbody>
- </tgroup>
- </informaltable>
- </para>
-
- <para>The <classname>timed_mutex</classname> class uses an
- <link linkend="thread.concepts.unspecified-locking-strategy">Unspecified</link>
- locking strategy, so attempts to recursively lock a <classname>timed_mutex</classname>
- object or attempts to unlock one by threads that don't own a lock on it result in
- <emphasis role="bold">undefined behavior</emphasis>.
- This strategy allows implementations to be as efficient as possible
- on any given platform. It is, however, recommended that
- implementations include debugging support to detect misuse when
- <code>NDEBUG</code> is not defined.</para>
-
- <para>Like all
- <link linkend="thread.concepts.mutex-models">mutex models</link>
- in &Boost.Thread;, <classname>timed_mutex</classname> leaves the
- <link linkend="thread.concepts.sheduling-policies">scheduling policy</link>
- as <link linkend="thread.concepts.unspecified-scheduling-policy">Unspecified</link>.
- Programmers should make no assumptions about the order in which
- waiting threads acquire a lock.</para>
- </description>
-
- <inherit access="private">
- <type><classname>boost::noncopyable</classname></type>
- <purpose>Exposition only</purpose>
- </inherit>
-
- <typedef name="scoped_lock">
- <type><emphasis>implementation-defined</emphasis></type>
- </typedef>
-
- <typedef name="scoped_try_lock">
- <type><emphasis>implementation-defined</emphasis></type>
- </typedef>
-
- <typedef name="scoped_timed_lock">
- <type><emphasis>implementation-defined</emphasis></type>
- </typedef>
-
- <constructor>
- <effects>Constructs a <classname>timed_mutex</classname> object.
- </effects>
-
- <postconditions><code>*this</code> is in an unlocked state.
- </postconditions>
- </constructor>
-
- <destructor>
- <effects>Destroys a <classname>timed_mutex</classname> object.</effects>
-
- <requires><code>*this</code> is in an unlocked state.</requires>
-
- <notes><emphasis role="bold">Danger:</emphasis> Destruction of a
- locked mutex is a serious programming error resulting in undefined
- behavior such as a program crash.</notes>
- </destructor>
- </class>
- </namespace>
-</header>

Deleted: branches/release/libs/thread/doc/once-ref.xml
==============================================================================
--- branches/release/libs/thread/doc/once-ref.xml 2008-03-17 09:59:17 EDT (Mon, 17 Mar 2008)
+++ (empty file)
@@ -1,88 +0,0 @@
-<?xml version="1.0" encoding="utf-8"?>
-<!DOCTYPE library PUBLIC "-//Boost//DTD BoostBook XML V1.0//EN"
- "http://www.boost.org/tools/boostbook/dtd/boostbook.dtd" [
- <!ENTITY % thread.entities SYSTEM "entities.xml">
- %thread.entities;
-]>
-
-<header name="boost/thread/once.hpp"
- last-revision="$Date$">
- <macro name="BOOST_ONCE_INIT">
- <purpose>The <functionname>call_once</functionname> function and
- <code>once_flag</code> type (statically initialized to
- <macroname>BOOST_ONCE_INIT</macroname>) can be used to run a
- routine exactly once. This can be used to initialize data in a
- <link linkend="thread.glossary.thread-safe">thread-safe</link>
- manner.</purpose>
-
- <description>The implementation-defined macro
- <macroname>BOOST_ONCE_INIT</macroname> is a constant value used to
- initialize <code>once_flag</code> instances to indicate that the
- logically associated routine has not been run yet. See
- <functionname>call_once</functionname> for more details.</description>
- </macro>
-
- <namespace name="boost">
- <typedef name="once_flag">
- <purpose>The <functionname>call_once</functionname> function and
- <code>once_flag</code> type (statically initialized to
- <macroname>BOOST_ONCE_INIT</macroname>) can be used to run a
- routine exactly once. This can be used to initialize data in a
- <link linkend="thread.glossary.thread-safe">thread-safe</link>
- manner.</purpose>
-
- <description>The implementation-defined type <code>once_flag</code>
- is used as a flag to insure a routine is called only once.
- Instances of this type should be statically initialized to
- <macroname>BOOST_ONCE_INIT</macroname>. See
- <functionname>call_once</functionname> for more details.
- </description>
-
- <type><emphasis>implementation-defined</emphasis></type>
- </typedef>
-
- <function name="call_once">
- <purpose>The <functionname>call_once</functionname> function and
- <code>once_flag</code> type (statically initialized to
- <macroname>BOOST_ONCE_INIT</macroname>) can be used to run a
- routine exactly once. This can be used to initialize data in a
- <link linkend="thread.glossary.thread-safe">thread-safe</link>
- manner.</purpose>
-
- <description>
- <para>Example usage is as follows:</para>
- <para>
-<programlisting>//Example usage:
-boost::once_flag once = BOOST_ONCE_INIT;
-
-void init()
-{
- //...
-}
-
-void thread_proc()
-{
- boost::call_once(once, &init);
-}</programlisting>
- </para></description>
-
- <parameter name="flag">
- <paramtype>once_flag&</paramtype>
- </parameter>
-
- <parameter name="func">
- <paramtype>Function func</paramtype>
- </parameter>
-
- <effects>As if (in an atomic fashion):
- <code>if (flag == BOOST_ONCE_INIT) func();</code>. If <code>func()</code> throws an exception, it shall be as if this
-thread never invoked <code>call_once</code></effects>
-
- <postconditions><code>flag != BOOST_ONCE_INIT</code> unless <code>func()</code> throws an exception.
- </postconditions>
- </function>
- </namespace>
-</header>

Deleted: branches/release/libs/thread/doc/overview.xml
==============================================================================
--- branches/release/libs/thread/doc/overview.xml 2008-03-17 09:59:17 EDT (Mon, 17 Mar 2008)
+++ (empty file)
@@ -1,206 +0,0 @@
-<?xml version="1.0" encoding="utf-8"?>
-<!DOCTYPE library PUBLIC "-//Boost//DTD BoostBook XML V1.0//EN"
- "http://www.boost.org/tools/boostbook/dtd/boostbook.dtd" [
- <!ENTITY % thread.entities SYSTEM "entities.xml">
- %thread.entities;
-]>
-
-<section id="thread.overview" last-revision="$Date$">
- <title>Overview</title>
- <section id="thread.introduction">
- <title>Introduction</title>
- <para>&Boost.Thread; allows C++ programs to execute as multiple,
- asynchronous, independent threads-of-execution. Each thread has its own
- machine state including program instruction counter and registers. Programs
- which execute as multiple threads are called multithreaded programs to
- distinguish them from traditional single-threaded programs. The <link
- linkend="thread.glossary">glossary</link> gives a more complete description
- of the multithreading execution environment.</para>
- <para>Multithreading provides several advantages:
- <itemizedlist>
- <listitem>
- <para>Programs which would otherwise block waiting for some external
- event can continue to respond if the blocking operation is placed in a
- separate thread. Multithreading is usually an absolute requirement for
- these programs.</para>
- </listitem>
- <listitem>
- <para>Well-designed multithreaded programs may execute faster than
- single-threaded programs, particularly on multiprocessor hardware.
- Note, however, that poorly-designed multithreaded programs are often
- slower than single-threaded programs.</para>
- </listitem>
- <listitem>
- <para>Some program designs may be easier to formulate using a
- multithreaded approach. After all, the real world is
- asynchronous!</para>
- </listitem>
- </itemizedlist></para>
- </section>
- <section>
- <title>Dangers</title>
- <section>
- <title>General considerations</title>
- <para>Beyond the errors which can occur in single-threaded programs,
- multithreaded programs are subject to additional errors:
- <itemizedlist>
- <listitem>
- <para><link linkend="thread.glossary.race-condition">Race
- conditions</link></para>
- </listitem>
- <listitem>
- <para><link linkend="thread.glossary.deadlock">Deadlock</link>
- (sometimes called "deadly embrace")</para>
- </listitem>
- <listitem>
- <para><link linkend="thread.glossary.priority-failure">Priority
- failures</link> (priority inversion, infinite overtaking, starvation,
- etc.)</para>
- </listitem>
- </itemizedlist></para>
- <para>Every multithreaded program must be designed carefully to avoid these
- errors. These aren't rare or exotic failures - they are virtually guaranteed
- to occur unless multithreaded code is designed to avoid them. Priority
- failures are somewhat less common, but are nonetheless serious.</para>
- <para>The <link linkend="thread.design">&Boost.Thread; design</link>
- attempts to minimize these errors, but they will still occur unless the
- programmer proactively designs to avoid them.</para>
- <note>Please also see <xref linkend="thread.implementation_notes"/>
- for additional, implementation-specific considerations.</note>
- </section>
- <section>
- <title>Testing and debugging considerations</title>
- <para>Multithreaded programs are non-deterministic. In other words, the
- same program with the same input data may follow different execution
- paths each time it is invoked. That can make testing and debugging a
- nightmare:
- <itemizedlist>
- <listitem>
- <para>Failures are often not repeatable.</para>
- </listitem>
- <listitem>
- <para>Probe effect causes debuggers to produce very different results
- from non-debug uses.</para>
- </listitem>
- <listitem>
- <para>Debuggers require special support to show thread state.</para>
- </listitem>
- <listitem>
- <para>Tests on a single processor system may give no indication of
- serious errors which would appear on multiprocessor systems, and visa
- versa. Thus test cases should include a varying number of
- processors.</para>
- </listitem>
- <listitem>
- <para>For programs which create a varying number of threads according
- to workload, tests which don't span the full range of possibilities
- may miss serious errors.</para>
- </listitem>
- </itemizedlist></para>
- </section>
- <section>
- <title>Getting a head start</title>
- <para>Although it might appear that multithreaded programs are inherently
- unreliable, many reliable multithreaded programs do exist. Multithreading
- techniques are known which lead to reliable programs.</para>
- <para>Design patterns for reliable multithreaded programs, including the
- important <emphasis>monitor</emphasis> pattern, are presented in
- <emphasis>Pattern-Oriented Software Architecture Volume 2 - Patterns for
- Concurrent and Networked Objects</emphasis>
- &cite.SchmidtStalRohnertBuschmann;. Many important multithreading programming
- considerations (independent of threading library) are discussed in
- <emphasis>Programming with POSIX Threads</emphasis> &cite.Butenhof97;.</para>
- <para>Doing some reading before attempting multithreaded designs will
- give you a head start toward reliable multithreaded programs.</para>
- </section>
- </section>
- <section>
- <title>C++ Standard Library usage in multithreaded programs</title>
- <section>
- <title>Runtime libraries</title>
- <para>
- <emphasis role="bold">Warning:</emphasis> Multithreaded programs such as
- those using &Boost.Thread; must link to <link
- linkend="thread.glossary.thread-safe">thread-safe</link> versions of
- all runtime libraries used by the program, including the runtime library
- for the C++ Standard Library. Failure to do so will cause <link
- linkend="thread.glossary.race-condition">race conditions</link> to occur
- when multiple threads simultaneously execute runtime library functions for
- <code>new</code>, <code>delete</code>, or other language features which
- imply shared state.</para>
- </section>
- <section>
- <title>Potentially non-thread-safe functions</title>
- <para>Certain C++ Standard Library functions inherited from C are
- particular problems because they hold internal state between
- calls:
- <itemizedlist>
- <listitem>
- <para><code>rand</code></para>
- </listitem>
- <listitem>
- <para><code>strtok</code></para>
- </listitem>
- <listitem>
- <para><code>asctime</code></para>
- </listitem>
- <listitem>
- <para><code>ctime</code></para>
- </listitem>
- <listitem>
- <para><code>gmtime</code></para>
- </listitem>
- <listitem>
- <para><code>localtime</code></para>
- </listitem>
- </itemizedlist></para>
- <para>It is possible to write thread-safe implementations of these by
- using thread specific storage (see
- <classname>boost::thread_specific_ptr</classname>), and several C++
- compiler vendors do just that. The technique is well-know and is explained
- in &cite.Butenhof97;.</para>
- <para>But at least one vendor (HP-UX) does not provide thread-safe
- implementations of the above functions in their otherwise thread-safe
- runtime library. Instead they provide replacement functions with
- different names and arguments.</para>
- <para><emphasis role="bold">Recommendation:</emphasis> For the most
- portable, yet thread-safe code, use Boost replacements for the problem
- functions. See the <libraryname>Boost Random Number Library</libraryname>
- and <libraryname>Boost Tokenizer Library</libraryname>.</para>
- </section>
- </section>
- <section>
- <title>Common guarantees for all &Boost.Thread; components</title>
- <section>
- <title>Exceptions</title>
- <para>&Boost.Thread; destructors never
- throw exceptions. Unless otherwise specified, other
- &Boost.Thread; functions that do not have
- an exception-specification may throw implementation-defined
- exceptions.</para>
- <para>In particular, &Boost.Thread;
- reports failure to allocate storage by throwing an exception of type
- <code>std::bad_alloc</code> or a class derived from
- <code>std::bad_alloc</code>, failure to obtain thread resources other than
- memory by throwing an exception of type
- <classname>boost::thread_resource_error</classname>, and certain lock
- related failures by throwing an exception of type
- <classname>boost::lock_error</classname>.</para>
- <para><emphasis role="bold">Rationale:</emphasis> Follows the C++ Standard
- Library practice of allowing all functions except destructors or other
- specified functions to throw exceptions on errors.</para>
- </section>
- <section>
- <title>NonCopyable requirement</title>
- <para>&Boost.Thread; classes documented as
- meeting the NonCopyable requirement disallow copy construction and copy
- assignment. For the sake of exposition, the synopsis of such classes show
- private derivation from <classname>boost::noncopyable</classname>. Users
- should not depend on this derivation, however, as implementations are free
- to meet the NonCopyable requirement in other ways.</para>
- </section>
- </section>
-</section>

Deleted: branches/release/libs/thread/doc/rationale.xml
==============================================================================
--- branches/release/libs/thread/doc/rationale.xml 2008-03-17 09:59:17 EDT (Mon, 17 Mar 2008)
+++ (empty file)
@@ -1,438 +0,0 @@
-<?xml version="1.0" encoding="utf-8"?>
-<!DOCTYPE library PUBLIC "-//Boost//DTD BoostBook XML V1.0//EN"
- "http://www.boost.org/tools/boostbook/dtd/boostbook.dtd" [
- <!ENTITY % thread.entities SYSTEM "entities.xml">
- %thread.entities;
-]>
-
-<section id="thread.rationale" last-revision="$Date$">
- <title>Rationale</title>
- <para>This page explains the rationale behind various design decisions in the
- &Boost.Thread; library. Having the rationale documented here should explain
- how we arrived at the current design as well as prevent future rehashing of
- discussions and thought processes that have already occurred. It can also give
- users a lot of insight into the design process required for this
- library.</para>
- <section id="thread.rationale.Boost.Thread">
- <title>Rationale for the Creation of &Boost.Thread;</title>
- <para>Processes often have a degree of "potential parallelism" and it can
- often be more intuitive to design systems with this in mind. Further, these
- parallel processes can result in more responsive programs. The benefits for
- multithreaded programming are quite well known to most modern programmers,
- yet the C++ language doesn't directly support this concept.</para>
- <para>Many platforms support multithreaded programming despite the fact that
- the language doesn't support it. They do this through external libraries,
- which are, unfortunately, platform specific. POSIX has tried to address this
- problem through the standardization of a "pthread" library. However, this is
- a standard only on POSIX platforms, so its portability is limited.</para>
- <para>Another problem with POSIX and other platform specific thread
- libraries is that they are almost universally C based libraries. This leaves
- several C++ specific issues unresolved, such as what happens when an
- exception is thrown in a thread. Further, there are some C++ concepts, such
- as destructors, that can make usage much easier than what's available in a C
- library.</para>
- <para>What's truly needed is C++ language support for threads. However, the
- C++ standards committee needs existing practice or a good proposal as a
- starting point for adding this to the standard.</para>
- <para>The &Boost.Thread; library was developed to provide a C++ developer
- with a portable interface for writing multithreaded programs on numerous
- platforms. There's a hope that the library can be the basis for a more
- detailed proposal for the C++ standards committee to consider for inclusion
- in the next C++ standard.</para>
- </section>
- <section id="thread.rationale.primitives">
- <title>Rationale for the Low Level Primitives Supported in &Boost.Thread;</title>
- <para>The &Boost.Thread; library supplies a set of low level primitives for
- writing multithreaded programs, such as mutexes and condition variables. In
- fact, the first release of &Boost.Thread; supports only these low level
- primitives. However, computer science research has shown that use of these
- primitives is difficult since it's difficult to mathematically prove that a
- usage pattern is correct, meaning it doesn't result in race conditions or
- deadlocks. There are several algebras (such as CSP, CCS and Join calculus)
- that have been developed to help write provably correct parallel
- processes. In order to prove the correctness these processes must be coded
- using higher level abstractions. So why does &Boost.Thread; support the
- lower level concepts?</para>
- <para>The reason is simple: the higher level concepts need to be implemented
- using at least some of the lower level concepts. So having portable lower
- level concepts makes it easier to develop the higher level concepts and will
- allow researchers to experiment with various techniques.</para>
- <para>Beyond this theoretical application of higher level concepts, however,
- the fact remains that many multithreaded programs are written using only the
- lower level concepts, so they are useful in and of themselves, even if it's
- hard to prove that their usage is correct. Since many users will be familiar
- with these lower level concepts but unfamiliar with any of the higher
- level concepts, supporting the lower level concepts provides
- greater accessibility.</para>
- </section>
- <section id="thread.rationale.locks">
- <title>Rationale for the Lock Design</title>
- <para>Programmers who are used to multithreaded programming issues will
- quickly note that the &Boost.Thread; design for mutex lock concepts is not
- <link linkend="thread.glossary.thread-safe">thread-safe</link> (this is
- clearly documented as well). At first this may seem like a serious design
- flaw. Why have a multithreading primitive that's not thread-safe
- itself?</para>
- <para>A lock object is not a synchronization primitive. A lock object's sole
- responsibility is to ensure that a mutex is both locked and unlocked in a
- manner that won't result in the common error of locking a mutex and then
- forgetting to unlock it. This means that instances of a lock object are only
- going to be created, at least in theory, within block scope and won't be
- shared between threads. Only the mutex objects will be created outside of
- block scope and/or shared between threads. Though it's possible to create a
- lock object outside of block scope and to share it between threads, to do so
- would not be a typical usage (in fact, to do so would likely be an
- error). Nor are there any cases when such usage would be required.</para>
- <para>Lock objects must maintain some state information. In order to allow a
- program to determine if a try_lock or timed_lock was successful the lock
- object must retain state indicating the success or failure of the call made
- in its constructor. If a lock object were to have such state and remain
- thread-safe it would need to synchronize access to the state information
- which would result in roughly doubling the time of most operations. Worse,
- since checking the state can occur only by a call after construction, we'd
- have a race condition if the lock object were shared between threads.</para>
- <para>So, to avoid the overhead of synchronizing access to the state
- information and to avoid the race condition, the &Boost.Thread; library
- simply does nothing to make lock objects thread-safe. Instead, sharing a
- lock object between threads results in undefined behavior. Since the only
- proper usage of lock objects is within block scope this isn't a problem, and
- so long as the lock object is properly used there's no danger of any
- multithreading issues.</para>
- </section>
- <section id="thread.rationale.non-copyable">
- <title>Rationale for NonCopyable Thread Type</title>
- <para>Programmers who are used to C libraries for multithreaded programming
- are likely to wonder why &Boost.Thread; uses a noncopyable design for
- <classname>boost::thread</classname>. After all, the C thread types are
- copyable, and you often have a need for copying them within user
- code. However, careful comparison of C designs to C++ designs shows a flaw
- in this logic.</para>
- <para>All C types are copyable. It is, in fact, not possible to make a
- noncopyable type in C. For this reason types that represent system resources
- in C are often designed to behave very similarly to a pointer to dynamic
- memory. There's an API for acquiring the resource and an API for releasing
- the resource. For memory we have pointers as the type and alloc/free for
- the acquisition and release APIs. For files we have FILE* as the type and
- fopen/fclose for the acquisition and release APIs. You can freely copy
- instances of the types but must manually manage the lifetime of the actual
- resource through the acquisition and release APIs.</para>
- <para>C++ designs recognize that the acquisition and release APIs are error
- prone and try to eliminate possible errors by acquiring the resource in the
- constructor and releasing it in the destructor. The best example of such a
- design is the std::iostream set of classes which can represent the same
- resource as the FILE* type in C. A file is opened in the std::fstream's
- constructor and closed in its destructor. However, if an iostream were
- copyable it could lead to a file being closed twice, an obvious error, so
- the std::iostream types are noncopyable by design. This is the same design
- used by boost::thread, which is a simple and easy to understand design
- that's consistent with other C++ standard types.</para>
- <para>During the design of boost::thread it was pointed out that it would be
- possible to allow it to be a copyable type if some form of "reference
- management" were used, such as ref-counting or ref-lists, and many argued
- for a boost::thread_ref design instead. The reasoning was that copying
- "thread" objects was a typical need in the C libraries, and so presumably
- would be in the C++ libraries as well. It was also thought that
- implementations could provide more efficient reference management than
- wrappers (such as boost::shared_ptr) around a noncopyable thread
- concept. Analysis of whether or not these arguments would hold true doesn't
- appear to bear them out. To illustrate the analysis we'll first provide
- pseudo-code illustrating the six typical usage patterns of a thread
- object.</para>
- <section id="thread.rationale.non-copyable.simple">
- <title>1. Use case: Simple creation of a thread.</title>
- <programlisting>
- void foo()
- {
- create_thread(&bar);
- }
- </programlisting>
- </section>
- <section id="thread.rationale.non-copyable.joined">
- <title>2. Use case: Creation of a thread that's later joined.</title>
- <programlisting>
- void foo()
- {
- thread = create_thread(&bar);
- join(thread);
- }
- </programlisting>
- </section>
- <section id="thread.rationale.non-copyable.loop">
- <title>3. Use case: Simple creation of several threads in a loop.</title>
- <programlisting>
- void foo()
- {
- for (int i=0; i<NUM_THREADS; ++i)
- create_thread(&bar);
- }
- </programlisting>
- </section>
- <section id="thread.rationale.non-copyable.loop-join">
- <title>4. Use case: Creation of several threads in a loop which are later joined.</title>
- <programlisting>
- void foo()
- {
- for (int i=0; i<NUM_THREADS; ++i)
- threads[i] = create_thread(&bar);
- for (int i=0; i<NUM_THREADS; ++i)
- threads[i].join();
- }
- </programlisting>
- </section>
- <section id="thread.rationale.non-copyable.pass">
- <title>5. Use case: Creation of a thread whose ownership is passed to another object/method.</title>
- <programlisting>
- void foo()
- {
- thread = create_thread(&bar);
- manager.owns(thread);
- }
- </programlisting>
- </section>
- <section id="thread.rationale.non-copyable.shared">
- <title>6. Use case: Creation of a thread whose ownership is shared between multiple
- objects.</title>
- <programlisting>
- void foo()
- {
- thread = create_thread(&bar);
- manager1.add(thread);
- manager2.add(thread);
- }
- </programlisting>
- </section>
- <para>Of these usage patterns there's only one that requires reference
- management (number 6). Hopefully it's fairly obvious that this usage pattern
- simply won't occur as often as the other usage patterns. So there really
- isn't a "typical need" for a thread concept, though there is some
- need.</para>
- <para>Since the need isn't typical we must use different criteria for
- deciding on either a thread_ref or thread design. Possible criteria include
- ease of use and performance. So let's analyze both of these
- carefully.</para>
- <para>With ease of use we can look at existing experience. The standard C++
- objects that represent a system resource, such as std::iostream, are
- noncopyable, so we know that C++ programmers must at least be experienced
- with this design. Most C++ developers are also used to smart pointers such
- as boost::shared_ptr, so we know they can at least adapt to a thread_ref
- concept with little effort. So existing experience isn't going to lead us to
- a choice.</para>
- <para>The other thing we can look at is how difficult it is to use both
- types for the six usage patterns above. If we find it overly difficult to
- use a concept for any of the usage patterns there would be a good argument
- for choosing the other design. So we'll code all six usage patterns using
- both designs.</para>
- <section id="thread.rationale_comparison.non-copyable.simple">
- <title>1. Comparison: simple creation of a thread.</title>
- <programlisting>
- void foo()
- {
- thread thrd(&bar);
- }
- void foo()
- {
- thread_ref thrd = create_thread(&bar);
- }
- </programlisting>
- </section>
- <section id="thread.rationale_comparison.non-copyable.joined">
- <title>2. Comparison: creation of a thread that's later joined.</title>
- <programlisting>
- void foo()
- {
- thread thrd(&bar);
- thrd.join();
- }
- void foo()
- {
- thread_ref thrd =
- create_thread(&bar);thrd->join();
- }
- </programlisting>
- </section>
- <section id="thread.rationale_comparison.non-copyable.loop">
- <title>3. Comparison: simple creation of several threads in a loop.</title>
- <programlisting>
- void foo()
- {
- for (int i=0; i<NUM_THREADS; ++i)
- thread thrd(&bar);
- }
- void foo()
- {
- for (int i=0; i<NUM_THREADS; ++i)
- thread_ref thrd = create_thread(&bar);
- }
- </programlisting>
- </section>
- <section id="thread.rationale_comparison.non-copyable.loop-join">
- <title>4. Comparison: creation of several threads in a loop which are later joined.</title>
- <programlisting>
- void foo()
- {
- std::auto_ptr<thread> threads[NUM_THREADS];
- for (int i=0; i<NUM_THREADS; ++i)
- threads[i] = std::auto_ptr<thread>(new thread(&bar));
- for (int i= 0; i<NUM_THREADS;
- ++i)threads[i]->join();
- }
- void foo()
- {
- thread_ref threads[NUM_THREADS];
- for (int i=0; i<NUM_THREADS; ++i)
- threads[i] = create_thread(&bar);
- for (int i= 0; i<NUM_THREADS;
- ++i)threads[i]->join();
- }
- </programlisting>
- </section>
- <section id="thread.rationale_comparison.non-copyable.pass">
- <title>5. Comparison: creation of a thread whose ownership is passed to another object/method.</title>
- <programlisting>
- void foo()
- {
- thread thrd* = new thread(&bar);
- manager.owns(thread);
- }
- void foo()
- {
- thread_ref thrd = create_thread(&bar);
- manager.owns(thrd);
- }
- </programlisting>
- </section>
- <section id="thread.rationale_comparison.non-copyable.shared">
- <title>6. Comparison: creation of a thread whose ownership is shared
- between multiple objects.</title>
- <programlisting>
- void foo()
- {
- boost::shared_ptr<thread> thrd(new thread(&bar));
- manager1.add(thrd);
- manager2.add(thrd);
- }
- void foo()
- {
- thread_ref thrd = create_thread(&bar);
- manager1.add(thrd);
- manager2.add(thrd);
- }
- </programlisting>
- </section>
- <para>This shows the usage patterns being nearly identical in complexity for
- both designs. The only actual added complexity occurs because of the use of
- operator new in
- <link linkend="thread.rationale_comparison.non-copyable.loop-join">(4)</link>,
- <link linkend="thread.rationale_comparison.non-copyable.pass">(5)</link>, and
- <link linkend="thread.rationale_comparison.non-copyable.shared">(6)</link>;
- and the use of std::auto_ptr and boost::shared_ptr in
- <link linkend="thread.rationale_comparison.non-copyable.loop-join">(4)</link> and
- <link linkend="thread.rationale_comparison.non-copyable.shared">(6)</link>
- respectively. However, that's not really
- much added complexity, and C++ programmers are used to using these idioms
- anyway. Some may dislike the presence of operator new in user code, but
- this can be eliminated by proper design of higher level concepts, such as
- the boost::thread_group class that simplifies example
- <link linkend="thread.rationale_comparison.non-copyable.loop-join">(4)</link>
- down to:</para>
- <programlisting>
- void foo()
- {
- thread_group threads;
- for (int i=0; i<NUM_THREADS; ++i)
- threads.create_thread(&bar);
- threads.join_all();
- }
- </programlisting>
- <para>So ease of use is really a wash and not much help in picking a
- design.</para>
- <para>So what about performance? Looking at the above code examples,
- we can analyze the theoretical impact to performance that both designs
- have. For <link linkend="thread.rationale_comparison.non-copyable.simple">(1)</link>
- we can see that platforms that don't have a ref-counted native
- thread type (POSIX, for instance) will be impacted by a thread_ref
- design. Even if the native thread type is ref-counted there may be an impact
- if more state information has to be maintained for concepts foreign to the
- native API, such as clean up stacks for Win32 implementations.
- For <link linkend="thread.rationale_comparison.non-copyable.joined">(2)</link>
- and <link linkend="thread.rationale_comparison.non-copyable.loop">(3)</link>
- the performance impact will be identical to
- <link linkend="thread.rationale_comparison.non-copyable.simple">(1)</link>.
- For <link linkend="thread.rationale_comparison.non-copyable.loop-join">(4)</link>
- things get a little more interesting and we find that theoretically at least
- the thread_ref may perform faster since the thread design requires dynamic
- memory allocation/deallocation. However, in practice there may be dynamic
- allocation for the thread_ref design as well, it will just be hidden from
- the user. As long as the implementation has to do dynamic allocations the
- thread_ref loses again because of the reference management. For
- <link linkend="thread.rationale_comparison.non-copyable.pass">(5)</link> we see
- the same impact as we do for
- <link linkend="thread.rationale_comparison.non-copyable.loop-join">(4)</link>.
- For <link linkend="thread.rationale_comparison.non-copyable.shared">(6)</link>
- we still have a possible impact to
- the thread design because of dynamic allocation but thread_ref no longer
- suffers because of its reference management, and in fact, theoretically at
- least, the thread_ref may do a better job of managing the references. All of
- this indicates that thread wins for
- <link linkend="thread.rationale_comparison.non-copyable.simple">(1)</link>,
- <link linkend="thread.rationale_comparison.non-copyable.joined">(2)</link> and
- <link linkend="thread.rationale_comparison.non-copyable.loop">(3)</link>; with
- <link linkend="thread.rationale_comparison.non-copyable.loop-join">(4)</link>
- and <link linkend="thread.rationale_comparison.non-copyable.pass">(5)</link> the
- winner depending on the implementation and the platform but with the thread design
- probably having a better chance; and with
- <link linkend="thread.rationale_comparison.non-copyable.shared">(6)</link>
- it will again depend on the
- implementation and platform but this time we favor thread_ref
- slightly. Given all of this it's a narrow margin, but the thread design
- prevails.</para>
- <para>Given this analysis, and the fact that noncopyable objects for system
- resources are the normal designs that C++ programmers are used to dealing
- with, the &Boost.Thread; library has gone with a noncopyable design.</para>
- </section>
- <section id="thread.rationale.events">
- <title>Rationale for not providing <emphasis>Event Variables</emphasis></title>
- <para><emphasis>Event variables</emphasis> are simply far too
- error-prone. <classname>boost::condition</classname> variables are a much safer
- alternative. [Note that Graphical User Interface <emphasis>events</emphasis> are
- a different concept, and are not what is being discussed here.]</para>
- <para>Event variables were one of the first synchronization primitives. They
- are still used today, for example, in the native Windows multithreading
- API. Yet both respected computer science researchers and experienced
- multithreading practitioners believe event variables are so inherently
- error-prone that they should never be used, and thus should not be part of a
- multithreading library.</para>
- <para>Per Brinch Hansen &cite.Hansen73; analyzed event variables in some
- detail, pointing out [emphasis his] that "<emphasis>event operations force
- the programmer to be aware of the relative speeds of the sending and
- receiving processes</emphasis>". His summary:</para>
- <blockquote>
- <para>We must therefore conclude that event variables of the previous type
- are impractical for system design. <emphasis>The effect of an interaction
- between two processes must be independent of the speed at which it is
- carried out.</emphasis></para>
- </blockquote>
- <para>Experienced programmers using the Windows platform today report that
- event variables are a continuing source of errors, even after previous bad
- experiences caused them to be very careful in their use of event
- variables. Overt problems can be avoided, for example, by teaming the event
- variable with a mutex, but that may just convert a <link
- linkend="thread.glossary.race-condition">race condition</link> into another
- problem, such as excessive resource use. One of the most distressing aspects
- of the experience reports is the claim that many defects are latent. That
- is, the programs appear to work correctly, but contain hidden timing
- dependencies which will cause them to fail when environmental factors or
- usage patterns change, altering relative thread timings.</para>
- <para>The decision to exclude event variables from &Boost.Thread; has been
- surprising to some Windows programmers. They have written programs which
- work using event variables, and wonder what the problem is. It seems similar
- to the "goto considered harmful" controversy of 30 years ago. It isn't that
- events, like gotos, can't be made to work, but rather that virtually all
- programs using alternatives will be easier to write, debug, read, maintain,
- and will be less likely to contain latent defects.</para>
- <para>[Rationale provided by Beman Dawes]</para>
- </section>
-</section>

Deleted: branches/release/libs/thread/doc/read_write_mutex-ref.xml
==============================================================================
--- branches/release/libs/thread/doc/read_write_mutex-ref.xml 2008-03-17 09:59:17 EDT (Mon, 17 Mar 2008)
+++ (empty file)
@@ -1,492 +0,0 @@
-<?xml version="1.0" encoding="utf-8"?>
-<!DOCTYPE library PUBLIC "-//Boost//DTD BoostBook XML V1.0//EN"
- "http://www.boost.org/tools/boostbook/dtd/boostbook.dtd" [
- <!ENTITY % thread.entities SYSTEM "entities.xml">
- %thread.entities;
-]>
-
-<header name="boost/thread/read_write_mutex.hpp"
- last-revision="$Date$">
- <namespace name="boost">
- <namespace name="read_write_scheduling_policy">
- <enum name="read_write_scheduling_policy">
- <enumvalue name="writer_priority" />
- <enumvalue name="reader_priority" />
- <enumvalue name="alternating_many_reads" />
- <enumvalue name="alternating_single_read" />
-
- <purpose>
- <para>Specifies the
- <link linkend="thread.concepts.read-write-scheduling-policies.inter-class">inter-class sheduling policy</link>
- to use when a set of threads try to obtain different types of
- locks simultaneously.</para>
- </purpose>
-
- <description>
- <para>The only clock type supported by &Boost.Thread; is
- <code>TIME_UTC</code>. The epoch for <code>TIME_UTC</code>
- is 1970-01-01 00:00:00.</para>
- </description>
- </enum>
- </namespace>
-
- <class name="read_write_mutex">
- <purpose>
- <para>The <classname>read_write_mutex</classname> class is a model of the
- <link linkend="thread.concepts.ReadWriteMutex">ReadWriteMutex</link> concept.</para>
- <note> Unfortunately it turned out that the current implementation of Read/Write Mutex has
- some serious problems. So it was decided not to put this implementation into
- release grade code. Also discussions on the mailing list led to the
- conclusion that the current concepts need to be rethought. In particular
- the schedulings <link linkend="thread.concepts.read-write-scheduling-policies.inter-class">
- Inter-Class Scheduling Policies</link> are deemed unnecessary.
- There seems to be common belief that a fair scheme suffices.
- The following documentation has been retained however, to give
- readers of this document the opportunity to study the original design.
- </note>
- </purpose>
-
- <description>
- <para>The <classname>read_write_mutex</classname> class is a model of the
- <link linkend="thread.concepts.ReadWriteMutex">ReadWriteMutex</link> concept.
- It should be used to synchronize access to shared resources using
- <link linkend="thread.concepts.read-write-locking-strategies.unspecified">Unspecified</link>
- locking mechanics.</para>
-
- <para>For classes that model related mutex concepts, see
- <classname>try_read_write_mutex</classname> and <classname>timed_read_write_mutex</classname>.</para>
-
- <para>The <classname>read_write_mutex</classname> class supplies the following typedefs,
- which <link linkend="thread.concepts.read-write-lock-models">model</link>
- the specified locking strategies:
-
- <informaltable>
- <tgroup cols="2" align="left">
- <thead>
- <row>
- <entry>Lock Name</entry>
- <entry>Lock Concept</entry>
- </row>
- </thead>
- <tbody>
- <row>
- <entry>scoped_read_write_lock</entry>
- <entry><link linkend="thread.concepts.ScopedReadWriteLock">ScopedReadWriteLock</link></entry>
- </row>
- <row>
- <entry>scoped_read_lock</entry>
- <entry><link linkend="thread.concepts.ScopedLock">ScopedLock</link></entry>
- </row>
- <row>
- <entry>scoped_write_lock</entry>
- <entry><link linkend="thread.concepts.ScopedLock">ScopedLock</link></entry>
- </row>
- </tbody>
- </tgroup>
- </informaltable>
- </para>
-
- <para>The <classname>read_write_mutex</classname> class uses an
- <link linkend="thread.concepts.read-write-locking-strategies.unspecified">Unspecified</link>
- locking strategy, so attempts to recursively lock a <classname>read_write_mutex</classname>
- object or attempts to unlock one by threads that don't own a lock on it result in
- <emphasis role="bold">undefined behavior</emphasis>.
- This strategy allows implementations to be as efficient as possible
- on any given platform. It is, however, recommended that
- implementations include debugging support to detect misuse when
- <code>NDEBUG</code> is not defined.</para>
-
- <para>Like all
- <link linkend="thread.concepts.read-write-mutex-models">read/write mutex models</link>
- in &Boost.Thread;, <classname>read_write_mutex</classname> has two types of
- <link linkend="thread.concepts.read-write-scheduling-policies">scheduling policies</link>, an
- <link linkend="thread.concepts.read-write-scheduling-policies.inter-class">inter-class sheduling policy</link>
- between threads trying to obtain different types of locks and an
- <link linkend="thread.concepts.read-write-scheduling-policies.intra-class">intra-class sheduling policy</link>
- between threads trying to obtain the same type of lock.
- The <classname>read_write_mutex</classname> class allows the
- programmer to choose what
- <link linkend="thread.concepts.read-write-scheduling-policies.inter-class">inter-class sheduling policy</link>
- will be used; however, like all read/write mutex models,
- <classname>read_write_mutex</classname> leaves the
- <link linkend="thread.concepts.read-write-scheduling-policies.intra-class">intra-class sheduling policy</link> as
- <link linkend="thread.concepts.read-write-locking-strategies.unspecified">Unspecified</link>.
- </para>
-
- <note>Self-deadlock is virtually guaranteed if a thread tries to
- lock the same <classname>read_write_mutex</classname> multiple times
- unless all locks are read-locks (but see below)</note>
- </description>
-
- <inherit access="private">
- <type><classname>boost::noncopyable</classname></type>
- <purpose>Exposition only</purpose>
- </inherit>
-
- <inherit access="private">
- <type><classname>boost::noncopyable</classname></type>
- <purpose>Exposition only</purpose>
- </inherit>
-
- <typedef name="scoped_read_write_lock">
- <type><emphasis>implementation-defined</emphasis></type>
- </typedef>
-
- <typedef name="scoped_read_lock">
- <type><emphasis>implementation-defined</emphasis></type>
- </typedef>
-
- <typedef name="scoped_write_lock">
- <type><emphasis>implementation-defined</emphasis></type>
- </typedef>
-
- <constructor>
- <parameter name="count">
- <paramtype>boost::read_write_scheduling_policy</paramtype>
- </parameter>
-
- <effects>Constructs a <classname>read_write_mutex</classname> object.
- </effects>
-
- <postconditions><code>*this</code> is in an unlocked state.
- </postconditions>
- </constructor>
-
- <destructor>
- <effects>Destroys a <classname>read_write_mutex</classname> object.</effects>
-
- <requires><code>*this</code> is in an unlocked state.</requires>
-
- <notes><emphasis role="bold">Danger:</emphasis> Destruction of a
- locked mutex is a serious programming error resulting in undefined
- behavior such as a program crash.</notes>
- </destructor>
- </class>
-
- <class name="try_read_write_mutex">
- <purpose>
- <para>The <classname>try_read_write_mutex</classname> class is a model of the
- <link linkend="thread.concepts.TryReadWriteMutex">TryReadWriteMutex</link> concept.</para>
- <note> Unfortunately it turned out that the current implementation of Read/Write Mutex has
- some serious problems. So it was decided not to put this implementation into
- release grade code. Also discussions on the mailing list led to the
- conclusion that the current concepts need to be rethought. In particular
- the schedulings <link linkend="thread.concepts.read-write-scheduling-policies.inter-class">
- Inter-Class Scheduling Policies</link> are deemed unnecessary.
- There seems to be common belief that a fair scheme suffices.
- The following documentation has been retained however, to give
- readers of this document the opportunity to study the original design.
- </note>
- </purpose>
-
- <description>
- <para>The <classname>try_read_write_mutex</classname> class is a model of the
- <link linkend="thread.concepts.TryReadWriteMutex">TryReadWriteMutex</link> concept.
- It should be used to synchronize access to shared resources using
- <link linkend="thread.concepts.read-write-locking-strategies.unspecified">Unspecified</link>
- locking mechanics.</para>
-
- <para>For classes that model related mutex concepts, see
- <classname>read_write_mutex</classname> and <classname>timed_read_write_mutex</classname>.</para>
-
- <para>The <classname>try_read_write_mutex</classname> class supplies the following typedefs,
- which <link linkend="thread.concepts.read-write-lock-models">model</link>
- the specified locking strategies:
-
- <informaltable>
- <tgroup cols="2" align="left">
- <thead>
- <row>
- <entry>Lock Name</entry>
- <entry>Lock Concept</entry>
- </row>
- </thead>
- <tbody>
- <row>
- <entry>scoped_read_write_lock</entry>
- <entry><link linkend="thread.concepts.ScopedReadWriteLock">ScopedReadWriteLock</link></entry>
- </row>
- <row>
- <entry>scoped_try_read_write_lock</entry>
- <entry><link linkend="thread.concepts.ScopedTryReadWriteLock">ScopedTryReadWriteLock</link></entry>
- </row>
- <row>
- <entry>scoped_read_lock</entry>
- <entry><link linkend="thread.concepts.ScopedLock">ScopedLock</link></entry>
- </row>
- <row>
- <entry>scoped_try_read_lock</entry>
- <entry><link linkend="thread.concepts.ScopedTryLock">ScopedTryLock</link></entry>
- </row>
- <row>
- <entry>scoped_write_lock</entry>
- <entry><link linkend="thread.concepts.ScopedLock">ScopedLock</link></entry>
- </row>
- <row>
- <entry>scoped_try_write_lock</entry>
- <entry><link linkend="thread.concepts.ScopedTryLock">ScopedTryLock</link></entry>
- </row>
- </tbody>
- </tgroup>
- </informaltable>
- </para>
-
- <para>The <classname>try_read_write_mutex</classname> class uses an
- <link linkend="thread.concepts.read-write-locking-strategies.unspecified">Unspecified</link>
- locking strategy, so attempts to recursively lock a <classname>try_read_write_mutex</classname>
- object or attempts to unlock one by threads that don't own a lock on it result in
- <emphasis role="bold">undefined behavior</emphasis>.
- This strategy allows implementations to be as efficient as possible
- on any given platform. It is, however, recommended that
- implementations include debugging support to detect misuse when
- <code>NDEBUG</code> is not defined.</para>
-
- <para>Like all
- <link linkend="thread.concepts.read-write-mutex-models">read/write mutex models</link>
- in &Boost.Thread;, <classname>try_read_write_mutex</classname> has two types of
- <link linkend="thread.concepts.read-write-scheduling-policies">scheduling policies</link>, an
- <link linkend="thread.concepts.read-write-scheduling-policies.inter-class">inter-class sheduling policy</link>
- between threads trying to obtain different types of locks and an
- <link linkend="thread.concepts.read-write-scheduling-policies.intra-class">intra-class sheduling policy</link>
- between threads trying to obtain the same type of lock.
- The <classname>try_read_write_mutex</classname> class allows the
- programmer to choose what
- <link linkend="thread.concepts.read-write-scheduling-policies.inter-class">inter-class sheduling policy</link>
- will be used; however, like all read/write mutex models,
- <classname>try_read_write_mutex</classname> leaves the
- <link linkend="thread.concepts.read-write-scheduling-policies.intra-class">intra-class sheduling policy</link> as
- <link linkend="thread.concepts.unspecified-scheduling-policy">Unspecified</link>.
- </para>
-
- <note>Self-deadlock is virtually guaranteed if a thread tries to
- lock the same <classname>try_read_write_mutex</classname> multiple times
- unless all locks are read-locks (but see below)</note>
- </description>
-
- <inherit access="private">
- <type><classname>boost::noncopyable</classname></type>
- <purpose>Exposition only</purpose>
- </inherit>
-
- <typedef name="scoped_read_write_lock">
- <type><emphasis>implementation-defined</emphasis></type>
- </typedef>
-
- <typedef name="scoped_try_read_write_lock">
- <type><emphasis>implementation-defined</emphasis></type>
- </typedef>
-
- <typedef name="scoped_read_lock">
- <type><emphasis>implementation-defined</emphasis></type>
- </typedef>
-
- <typedef name="scoped_try_read_lock">
- <type><emphasis>implementation-defined</emphasis></type>
- </typedef>
-
- <typedef name="scoped_write_lock">
- <type><emphasis>implementation-defined</emphasis></type>
- </typedef>
-
- <typedef name="scoped_try_write_lock">
- <type><emphasis>implementation-defined</emphasis></type>
- </typedef>
-
- <constructor>
- <parameter name="count">
- <paramtype>boost::read_write_scheduling_policy</paramtype>
- </parameter>
-
- <effects>Constructs a <classname>try_read_write_mutex</classname> object.
- </effects>
-
- <postconditions><code>*this</code> is in an unlocked state.
- </postconditions>
- </constructor>
-
- <destructor>
- <effects>Destroys a <classname>try_read_write_mutex</classname> object.</effects>
-
- <requires><code>*this</code> is in an unlocked state.</requires>
-
- <notes><emphasis role="bold">Danger:</emphasis> Destruction of a
- locked mutex is a serious programming error resulting in undefined
- behavior such as a program crash.</notes>
- </destructor>
- </class>
-
- <class name="timed_read_write_mutex">
- <purpose>
- <para>The <classname>timed_read_write_mutex</classname> class is a model of the
- <link linkend="thread.concepts.TimedReadWriteMutex">TimedReadWriteMutex</link> concept.</para>
- <note> Unfortunately it turned out that the current implementation of Read/Write Mutex has
- some serious problems. So it was decided not to put this implementation into
- release grade code. Also discussions on the mailing list led to the
- conclusion that the current concepts need to be rethought. In particular
- the schedulings <link linkend="thread.concepts.read-write-scheduling-policies.inter-class">
- Inter-Class Scheduling Policies</link> are deemed unnecessary.
- There seems to be common belief that a fair scheme suffices.
- The following documentation has been retained however, to give
- readers of this document the opportunity to study the original design.
- </note>
- </purpose>
-
- <description>
- <para>The <classname>timed_read_write_mutex</classname> class is a model of the
- <link linkend="thread.concepts.TimedReadWriteMutex">TimedReadWriteMutex</link> concept.
- It should be used to synchronize access to shared resources using
- <link linkend="thread.concepts.read-write-locking-strategies.unspecified">Unspecified</link>
- locking mechanics.</para>
-
- <para>For classes that model related mutex concepts, see
- <classname>read_write_mutex</classname> and <classname>try_read_write_mutex</classname>.</para>
-
- <para>The <classname>timed_read_write_mutex</classname> class supplies the following typedefs,
- which <link linkend="thread.concepts.read-write-lock-models">model</link>
- the specified locking strategies:
-
- <informaltable>
- <tgroup cols="2" align="left">
- <thead>
- <row>
- <entry>Lock Name</entry>
- <entry>Lock Concept</entry>
- </row>
- </thead>
- <tbody>
- <row>
- <entry>scoped_read_write_lock</entry>
- <entry><link linkend="thread.concepts.ScopedReadWriteLock">ScopedReadWriteLock</link></entry>
- </row>
- <row>
- <entry>scoped_try_read_write_lock</entry>
- <entry><link linkend="thread.concepts.ScopedTryReadWriteLock">ScopedTryReadWriteLock</link></entry>
- </row>
- <row>
- <entry>scoped_timed_read_write_lock</entry>
- <entry><link linkend="thread.concepts.ScopedTimedReadWriteLock">ScopedTimedReadWriteLock</link></entry>
- </row>
- <row>
- <entry>scoped_read_lock</entry>
- <entry><link linkend="thread.concepts.ScopedLock">ScopedLock</link></entry>
- </row>
- <row>
- <entry>scoped_try_read_lock</entry>
- <entry><link linkend="thread.concepts.ScopedTryLock">ScopedTryLock</link></entry>
- </row>
- <row>
- <entry>scoped_timed_read_lock</entry>
- <entry><link linkend="thread.concepts.ScopedTimedLock">ScopedTimedLock</link></entry>
- </row>
- <row>
- <entry>scoped_write_lock</entry>
- <entry><link linkend="thread.concepts.ScopedLock">ScopedLock</link></entry>
- </row>
- <row>
- <entry>scoped_try_write_lock</entry>
- <entry><link linkend="thread.concepts.ScopedTryLock">ScopedTryLock</link></entry>
- </row>
- <row>
- <entry>scoped_timed_write_lock</entry>
- <entry><link linkend="thread.concepts.ScopedTimedLock">ScopedTimedLock</link></entry>
- </row>
- </tbody>
- </tgroup>
- </informaltable>
- </para>
-
- <para>The <classname>timed_read_write_mutex</classname> class uses an
- <link linkend="thread.concepts.read-write-locking-strategies.unspecified">Unspecified</link>
- locking strategy, so attempts to recursively lock a <classname>timed_read_write_mutex</classname>
- object or attempts to unlock one by threads that don't own a lock on it result in
- <emphasis role="bold">undefined behavior</emphasis>.
- This strategy allows implementations to be as efficient as possible
- on any given platform. It is, however, recommended that
- implementations include debugging support to detect misuse when
- <code>NDEBUG</code> is not defined.</para>
-
- <para>Like all
- <link linkend="thread.concepts.read-write-mutex-models">read/write mutex models</link>
- in &Boost.Thread;, <classname>timed_read_write_mutex</classname> has two types of
- <link linkend="thread.concepts.read-write-scheduling-policies">scheduling policies</link>, an
- <link linkend="thread.concepts.read-write-scheduling-policies.inter-class">inter-class sheduling policy</link>
- between threads trying to obtain different types of locks and an
- <link linkend="thread.concepts.read-write-scheduling-policies.intra-class">intra-class sheduling policy</link>
- between threads trying to obtain the same type of lock.
- The <classname>timed_read_write_mutex</classname> class allows the
- programmer to choose what
- <link linkend="thread.concepts.read-write-scheduling-policies.inter-class">inter-class sheduling policy</link>
- will be used; however, like all read/write mutex models,
- <classname>timed_read_write_mutex</classname> leaves the
- <link linkend="thread.concepts.read-write-scheduling-policies.intra-class">intra-class sheduling policy</link> as
- <link linkend="thread.concepts.unspecified-scheduling-policy">Unspecified</link>.
- </para>
-
- <note>Self-deadlock is virtually guaranteed if a thread tries to
- lock the same <classname>timed_read_write_mutex</classname> multiple times
- unless all locks are read-locks (but see below)</note>
- </description>
-
- <typedef name="scoped_read_write_lock">
- <type><emphasis>implementation-defined</emphasis></type>
- </typedef>
-
- <typedef name="scoped_try_read_write_lock">
- <type><emphasis>implementation-defined</emphasis></type>
- </typedef>
-
- <typedef name="scoped_timed_read_write_lock">
- <type><emphasis>implementation-defined</emphasis></type>
- </typedef>
-
- <typedef name="scoped_read_lock">
- <type><emphasis>implementation-defined</emphasis></type>
- </typedef>
-
- <typedef name="scoped_try_read_lock">
- <type><emphasis>implementation-defined</emphasis></type>
- </typedef>
-
- <typedef name="scoped_timed_read_lock">
- <type><emphasis>implementation-defined</emphasis></type>
- </typedef>
-
- <typedef name="scoped_write_lock">
- <type><emphasis>implementation-defined</emphasis></type>
- </typedef>
-
- <typedef name="scoped_try_write_lock">
- <type><emphasis>implementation-defined</emphasis></type>
- </typedef>
-
- <typedef name="scoped_timed_write_lock">
- <type><emphasis>implementation-defined</emphasis></type>
- </typedef>
-
- <constructor>
- <parameter name="count">
- <paramtype>boost::read_write_scheduling_policy</paramtype>
- </parameter>
-
- <effects>Constructs a <classname>timed_read_write_mutex</classname> object.
- </effects>
-
- <postconditions><code>*this</code> is in an unlocked state.
- </postconditions>
- </constructor>
-
- <destructor>
- <effects>Destroys a <classname>timed_read_write_mutex</classname> object.</effects>
-
- <requires><code>*this</code> is in an unlocked state.</requires>
-
- <notes><emphasis role="bold">Danger:</emphasis> Destruction of a
- locked mutex is a serious programming error resulting in undefined
- behavior such as a program crash.</notes>
- </destructor>
- </class>
- </namespace>
-</header>

Deleted: branches/release/libs/thread/doc/recursive_mutex-ref.xml
==============================================================================
--- branches/release/libs/thread/doc/recursive_mutex-ref.xml 2008-03-17 09:59:17 EDT (Mon, 17 Mar 2008)
+++ (empty file)
@@ -1,306 +0,0 @@
-<?xml version="1.0" encoding="utf-8"?>
-<!DOCTYPE library PUBLIC "-//Boost//DTD BoostBook XML V1.0//EN"
- "http://www.boost.org/tools/boostbook/dtd/boostbook.dtd" [
- <!ENTITY % thread.entities SYSTEM "entities.xml">
- %thread.entities;
-]>
-
-<header name="boost/thread/recursive_mutex.hpp"
- last-revision="$Date$">
- <namespace name="boost">
- <class name="recursive_mutex">
- <purpose>
- <para>The <classname>recursive_mutex</classname> class is a model of the
- <link linkend="thread.concepts.Mutex">Mutex</link> concept.</para>
- </purpose>
-
- <description>
- <para>The <classname>recursive_mutex</classname> class is a model of the
- <link linkend="thread.concepts.Mutex">Mutex</link> concept.
- It should be used to synchronize access to shared resources using
- <link linkend="thread.concepts.recursive-locking-strategy">Recursive</link>
- locking mechanics.</para>
-
- <para>For classes that model related mutex concepts, see
- <classname>recursive_try_mutex</classname> and <classname>recursive_timed_mutex</classname>.</para>
-
- <para>For <link linkend="thread.concepts.unspecified-locking-strategy">Unspecified</link>
- locking mechanics, see <classname>mutex</classname>,
- <classname>try_mutex</classname>, and <classname>timed_mutex</classname>.
- </para>
-
- <para>The <classname>recursive_mutex</classname> class supplies the following typedef,
- which models the specified locking strategy:
-
- <table>
- <title>Supported Lock Types</title>
- <tgroup cols="2" align="left">
- <thead>
- <row>
- <entry>Lock Name</entry>
- <entry>Lock Concept</entry>
- </row>
- </thead>
- <tbody>
- <row>
- <entry>scoped_lock</entry>
- <entry><link linkend="thread.concepts.ScopedLock">ScopedLock</link></entry>
- </row>
- </tbody>
- </tgroup>
- </table>
- </para>
-
- <para>The <classname>recursive_mutex</classname> class uses a
- <link linkend="thread.concepts.recursive-locking-strategy">Recursive</link>
- locking strategy, so attempts to recursively lock a
- <classname>recursive_mutex</classname> object
- succeed and an internal "lock count" is maintained.
- Attempts to unlock a <classname>recursive_mutex</classname> object
- by threads that don't own a lock on it result in
- <emphasis role="bold">undefined behavior</emphasis>.</para>
-
- <para>Like all
- <link linkend="thread.concepts.mutex-models">mutex models</link>
- in &Boost.Thread;, <classname>recursive_mutex</classname> leaves the
- <link linkend="thread.concepts.sheduling-policies">scheduling policy</link>
- as <link linkend="thread.concepts.unspecified-scheduling-policy">Unspecified</link>.
- Programmers should make no assumptions about the order in which
- waiting threads acquire a lock.</para>
- </description>
-
- <inherit access="private">
- <type><classname>boost::noncopyable</classname></type>
- <purpose>Exposition only</purpose>
- </inherit>
-
- <typedef name="scoped_lock">
- <type><emphasis>implementation-defined</emphasis></type>
- </typedef>
-
- <constructor>
- <effects>Constructs a <classname>recursive_mutex</classname> object.
- </effects>
-
- <postconditions><code>*this</code> is in an unlocked state.
- </postconditions>
- </constructor>
-
- <destructor>
- <effects>Destroys a <classname>recursive_mutex</classname> object.</effects>
-
- <requires><code>*this</code> is in an unlocked state.</requires>
-
- <notes><emphasis role="bold">Danger:</emphasis> Destruction of a
- locked mutex is a serious programming error resulting in undefined
- behavior such as a program crash.</notes>
- </destructor>
- </class>
-
- <class name="recursive_try_mutex">
- <purpose>
- <para>The <classname>recursive_try_mutex</classname> class is a model of the
- <link linkend="thread.concepts.TryMutex">TryMutex</link> concept.</para>
- </purpose>
-
- <description>
- <para>The <classname>recursive_try_mutex</classname> class is a model of the
- <link linkend="thread.concepts.TryMutex">TryMutex</link> concept.
- It should be used to synchronize access to shared resources using
- <link linkend="thread.concepts.recursive-locking-strategy">Recursive</link>
- locking mechanics.</para>
-
- <para>For classes that model related mutex concepts, see
- <classname>recursive_mutex</classname> and <classname>recursive_timed_mutex</classname>.</para>
-
- <para>For <link linkend="thread.concepts.unspecified-locking-strategy">Unspecified</link>
- locking mechanics, see <classname>mutex</classname>,
- <classname>try_mutex</classname>, and <classname>timed_mutex</classname>.
- </para>
-
- <para>The <classname>recursive_try_mutex</classname> class supplies the following typedefs,
- which model the specified locking strategies:
-
- <table>
- <title>Supported Lock Types</title>
- <tgroup cols="2" align="left">
- <thead>
- <row>
- <entry>Lock Name</entry>
- <entry>Lock Concept</entry>
- </row>
- </thead>
- <tbody>
- <row>
- <entry>scoped_lock</entry>
- <entry><link linkend="thread.concepts.ScopedLock">ScopedLock</link></entry>
- </row>
- <row>
- <entry>scoped_try_lock</entry>
- <entry><link linkend="thread.concepts.ScopedTryLock">ScopedTryLock</link></entry>
- </row>
- </tbody>
- </tgroup>
- </table>
- </para>
-
- <para>The <classname>recursive_try_mutex</classname> class uses a
- <link linkend="thread.concepts.recursive-locking-strategy">Recursive</link>
- locking strategy, so attempts to recursively lock a
- <classname>recursive_try_mutex</classname> object
- succeed and an internal "lock count" is maintained.
- Attempts to unlock a <classname>recursive_mutex</classname> object
- by threads that don't own a lock on it result in
- <emphasis role="bold">undefined behavior</emphasis>.</para>
-
- <para>Like all
- <link linkend="thread.concepts.mutex-models">mutex models</link>
- in &Boost.Thread;, <classname>recursive_try_mutex</classname> leaves the
- <link linkend="thread.concepts.sheduling-policies">scheduling policy</link>
- as <link linkend="thread.concepts.unspecified-scheduling-policy">Unspecified</link>.
- Programmers should make no assumptions about the order in which
- waiting threads acquire a lock.</para>
- </description>
-
- <inherit access="private">
- <type><classname>boost::noncopyable</classname></type>
- <purpose>Exposition only</purpose>
- </inherit>
-
- <typedef name="scoped_lock">
- <type><emphasis>implementation-defined</emphasis></type>
- </typedef>
-
- <typedef name="scoped_try_lock">
- <type><emphasis>implementation-defined</emphasis></type>
- </typedef>
-
- <constructor>
- <effects>Constructs a <classname>recursive_try_mutex</classname> object.
- </effects>
-
- <postconditions><code>*this</code> is in an unlocked state.
- </postconditions>
- </constructor>
-
- <destructor>
- <effects>Destroys a <classname>recursive_try_mutex</classname> object.
- </effects>
-
- <requires><code>*this</code> is in an unlocked state.</requires>
-
- <notes><emphasis role="bold">Danger:</emphasis> Destruction of a
- locked mutex is a serious programming error resulting in undefined
- behavior such as a program crash.</notes>
- </destructor>
- </class>
-
- <class name="recursive_timed_mutex">
- <purpose>
- <para>The <classname>recursive_timed_mutex</classname> class is a model of the
- <link linkend="thread.concepts.TimedMutex">TimedMutex</link> concept.</para>
- </purpose>
-
- <description>
- <para>The <classname>recursive_timed_mutex</classname> class is a model of the
- <link linkend="thread.concepts.TimedMutex">TimedMutex</link> concept.
- It should be used to synchronize access to shared resources using
- <link linkend="thread.concepts.recursive-locking-strategy">Recursive</link>
- locking mechanics.</para>
-
- <para>For classes that model related mutex concepts, see
- <classname>recursive_mutex</classname> and <classname>recursive_try_mutex</classname>.</para>
-
- <para>For <link linkend="thread.concepts.unspecified-locking-strategy">Unspecified</link>
- locking mechanics, see <classname>mutex</classname>,
- <classname>try_mutex</classname>, and <classname>timed_mutex</classname>.
- </para>
-
- <para>The <classname>recursive_timed_mutex</classname> class supplies the following typedefs,
- which model the specified locking strategies:
-
- <table>
- <title>Supported Lock Types</title>
- <tgroup cols="2" align="left">
- <thead>
- <row>
- <entry>Lock Name</entry>
- <entry>Lock Concept</entry>
- </row>
- </thead>
- <tbody>
- <row>
- <entry>scoped_lock</entry>
- <entry><link linkend="thread.concepts.ScopedLock">ScopedLock</link></entry>
- </row>
- <row>
- <entry>scoped_try_lock</entry>
- <entry><link linkend="thread.concepts.ScopedTryLock">ScopedTryLock</link></entry>
- </row>
- <row>
- <entry>scoped_timed_lock</entry>
- <entry><link linkend="thread.concepts.ScopedTimedLock">ScopedTimedLock</link></entry>
- </row>
- </tbody>
- </tgroup>
- </table>
- </para>
-
- <para>The <classname>recursive_timed_mutex</classname> class uses a
- <link linkend="thread.concepts.recursive-locking-strategy">Recursive</link>
- locking strategy, so attempts to recursively lock a
- <classname>recursive_timed_mutex</classname> object
- succeed and an internal "lock count" is maintained.
- Attempts to unlock a <classname>recursive_mutex</classname> object
- by threads that don't own a lock on it result in
- <emphasis role="bold">undefined behavior</emphasis>.</para>
-
- <para>Like all
- <link linkend="thread.concepts.mutex-models">mutex models</link>
- in &Boost.Thread;, <classname>recursive_timed_mutex</classname> leaves the
- <link linkend="thread.concepts.sheduling-policies">scheduling policy</link>
- as <link linkend="thread.concepts.unspecified-scheduling-policy">Unspecified</link>.
- Programmers should make no assumptions about the order in which
- waiting threads acquire a lock.</para>
- </description>
-
- <inherit access="private">
- <type><classname>boost::noncopyable</classname></type>
- <purpose>Exposition only</purpose>
- </inherit>
-
- <typedef name="scoped_lock">
- <type><emphasis>implementation-defined</emphasis></type>
- </typedef>
-
- <typedef name="scoped_try_lock">
- <type><emphasis>implementation-defined</emphasis></type>
- </typedef>
-
- <typedef name="scoped_timed_lock">
- <type><emphasis>implementation-defined</emphasis></type>
- </typedef>
-
- <constructor>
- <effects>Constructs a <classname>recursive_timed_mutex</classname> object.
- </effects>
-
- <postconditions><code>*this</code> is in an unlocked state.
- </postconditions>
- </constructor>
-
- <destructor>
- <effects>Destroys a <classname>recursive_timed_mutex</classname> object.</effects>
-
- <requires><code>*this</code> is in an unlocked state.</requires>
-
- <notes><emphasis role="bold">Danger:</emphasis> Destruction of a
- locked mutex is a serious programming error resulting in undefined
- behavior such as a program crash.</notes>
- </destructor>
- </class>
- </namespace>
-</header>

Deleted: branches/release/libs/thread/doc/reference.xml
==============================================================================
--- branches/release/libs/thread/doc/reference.xml 2008-03-17 09:59:17 EDT (Mon, 17 Mar 2008)
+++ (empty file)
@@ -1,30 +0,0 @@
-<?xml version="1.0" encoding="utf-8"?>
-<!DOCTYPE library PUBLIC "-//Boost//DTD BoostBook XML V1.0//EN"
- "http://www.boost.org/tools/boostbook/dtd/boostbook.dtd" [
- <!ENTITY % thread.entities SYSTEM "entities.xml">
- %thread.entities;
-]>
-
-<library-reference id="thread.reference"
- last-revision="$Date$"
- xmlns:xi="http://www.w3.org/2001/XInclude">
- <xi:include href="barrier-ref.xml"/>
- <xi:include href="condition-ref.xml"/>
- <xi:include href="exceptions-ref.xml"/>
- <xi:include href="mutex-ref.xml"/>
- <xi:include href="once-ref.xml"/>
- <xi:include href="recursive_mutex-ref.xml"/>
-
- <xi:include href="read_write_mutex-ref.xml"/>
- <xi:include href="thread-ref.xml"/>
- <xi:include href="tss-ref.xml"/>
- <xi:include href="xtime-ref.xml"/>
-</library-reference>

Deleted: branches/release/libs/thread/doc/release_notes.xml
==============================================================================
--- branches/release/libs/thread/doc/release_notes.xml 2008-03-17 09:59:17 EDT (Mon, 17 Mar 2008)
+++ (empty file)
@@ -1,204 +0,0 @@
-<?xml version="1.0" encoding="utf-8"?>
-<!DOCTYPE library PUBLIC "-//Boost//DTD BoostBook XML V1.0//EN"
- "http://www.boost.org/tools/boostbook/dtd/boostbook.dtd" [
- <!ENTITY % thread.entities SYSTEM "entities.xml">
- %thread.entities;
-]>
-
-<section id="thread.release_notes" last-revision="$Date$">
- <title>Release Notes</title>
- <section id="thread.release_notes.boost_1_34_0">
- <title>Boost 1.34.0</title>
-
- <section id="thread.release_notes.boost_1_34_0.change_log.maintainance">
- <title>New team of maintainers</title>
-
- <para>
- Since the original author William E. Kempf no longer is available to
- maintain the &Boost.Thread; library, a new team has been formed
- in an attempt to continue the work on &Boost.Thread;.
- Fortunately William E. Kempf has given
- <ulink url="http://listarchives.boost.org/Archives/boost/2006/09/110143.php">
- permission </ulink>
- to use his work under the boost license.
- </para>
- <para>
- The team currently consists of
- <itemizedlist>
- <listitem>
- Anthony Williams, for the Win32 platform,
- </listitem>
- <listitem>
- Roland Schwarz, for the linux platform, and various "housekeeping" tasks.
- </listitem>
- </itemizedlist>
- Volunteers for other platforms are welcome!
- </para>
- <para>
- As the &Boost.Thread; was kind of orphaned over the last release, this release
- attempts to fix the known bugs. Upcoming releases will bring in new things.
- </para>
- </section>
-
- <section id="thread.release_notes.boost_1_34_0.change_log.read_write_mutex">
- <title>read_write_mutex still broken</title>
-
- <para>
- <note>
- It has been decided not to release the Read/Write Mutex, since the current
- implementation suffers from a serious bug. The documentation of the concepts
- has been included though, giving the interested reader an opportunity to study the
- original concepts. Please refer to the following links if you are interested
- which problems led to the decision to held back this mutex type.The issue
- has been discovered before 1.33 was released and the code has
- been omitted from that release. A reworked mutex is expected to appear in 1.35.
- Also see:
- <ulink url="http://listarchives.boost.org/Archives/boost/2005/08/92307.php">
- read_write_mutex bug</ulink>
- and
- <ulink url="http://listarchives.boost.org/Archives/boost/2005/09/93180.php">
- read_write_mutex fundamentally broken in 1.33</ulink>
- </note>
- </para>
- </section>
-
- </section>
- <section id="thread.release_notes.boost_1_32_0">
- <title>Boost 1.32.0</title>
-
- <section id="thread.release_notes.boost_1_32_0.change_log.documentation">
- <title>Documentation converted to BoostBook</title>
-
- <para>The documentation was converted to BoostBook format,
- and a number of errors and inconsistencies were
- fixed in the process.
- Since this was a fairly large task, there are likely to be
- more errors and inconsistencies remaining. If you find any,
- please report them!</para>
- </section>
-
- <section id="thread.release_notes.boost_1_32_0.change_log.static_link">
- <title>Statically-link build option added</title>
-
- <para>The option to link &Boost.Thread; as a static
- library has been added (with some limitations on Win32 platforms).
- This feature was originally removed from an earlier version
- of Boost because <classname>boost::thread_specific_ptr</classname>
- required that &Boost.Thread; be dynamically linked in order
- for its cleanup functionality to work on Win32 platforms.
- Because this limitation never applied to non-Win32 platforms,
- because significant progress has been made in removing
- the limitation on Win32 platforms (many thanks to
- Aaron LaFramboise and Roland Scwarz!), and because the lack
- of static linking is one of the most common complaints of
- &Boost.Thread; users, this decision was reversed.</para>
-
- <para>On non-Win32 platforms:
- To choose the dynamically linked version of &Boost.Thread;
- using Boost's auto-linking feature, #define BOOST_THREAD_USE_DLL;
- to choose the statically linked version,
- #define BOOST_THREAD_USE_LIB.
- If neither symbols is #defined, the default will be chosen.
- Currently the default is the statically linked version.</para>
-
- <para>On Win32 platforms using VC++:
- Use the same #defines as for non-Win32 platforms
- (BOOST_THREAD_USE_DLL and BOOST_THREAD_USE_LIB).
- If neither is #defined, the default will be chosen.
- Currently the default is the statically linked version
- if the VC++ run-time library is set to
- "Multi-threaded" or "Multi-threaded Debug", and
- the dynamically linked version
- if the VC++ run-time library is set to
- "Multi-threaded DLL" or "Multi-threaded Debug DLL".</para>
-
- <para>On Win32 platforms using compilers other than VC++:
- Use the same #defines as for non-Win32 platforms
- (BOOST_THREAD_USE_DLL and BOOST_THREAD_USE_LIB).
- If neither is #defined, the default will be chosen.
- Currently the default is the dynamically linked version
- because it has not yet been possible to implement automatic
- tss cleanup in the statically linked version for compilers
- other than VC++, although it is hoped that this will be
- possible in a future version of &Boost.Thread;.
-
- Note for advanced users: &Boost.Thread; provides several "hook"
- functions to allow users to experiment with the statically
- linked version on Win32 with compilers other than VC++.
- These functions are on_process_enter(), on_process_exit(),
- on_thread_enter(), and on_thread_exit(), and are defined
- in tls_hooks.cpp. See the comments in that file for more
- information.</para>
- </section>
-
- <section id="thread.release_notes.boost_1_32_0.change_log.barrier">
- <title>Barrier functionality added</title>
-
- <para>A new class, <classname>boost::barrier</classname>, was added.</para>
- </section>
-
- <section id="thread.release_notes.boost_1_32_0.change_log.read_write_mutex">
- <title>Read/write mutex functionality added</title>
-
- <para>New classes,
- <classname>boost::read_write_mutex</classname>,
- <classname>boost::try_read_write_mutex</classname>, and
- <classname>boost::timed_read_write_mutex</classname>
- were added.
-
- <note>Since the read/write mutex and related classes are new,
- both interface and implementation are liable to change
- in future releases of &Boost.Thread;.
- The lock concepts and lock promotion in particular are
- still under discussion and very likely to change.</note>
- </para>
- </section>
-
- <section id="thread.release_notes.boost_1_32_0.change_log.thread_specific_ptr">
- <title>Thread-specific pointer functionality changed</title>
-
- <para>The <classname>boost::thread_specific_ptr</classname>
- constructor now takes an optional pointer to a cleanup function that
- is called to release the thread-specific data that is being pointed
- to by <classname>boost::thread_specific_ptr</classname> objects.</para>
-
- <para>Fixed: the number of available thread-specific storage "slots"
- is too small on some platforms.</para>
-
- <para>Fixed: <functionname>thread_specific_ptr::reset()</functionname>
- doesn't check error returned by <functionname>tss::set()</functionname>
- (the <functionname>tss::set()</functionname> function now throws
- if it fails instead of returning an error code).</para>
-
- <para>Fixed: calling
- <functionname>boost::thread_specific_ptr::reset()</functionname> or
- <functionname>boost::thread_specific_ptr::release()</functionname>
- causes double-delete: once when
- <functionname>boost::thread_specific_ptr::reset()</functionname> or
- <functionname>boost::thread_specific_ptr::release()</functionname>
- is called and once when
- <functionname>boost::thread_specific_ptr::~thread_specific_ptr()</functionname>
- is called.</para>
- </section>
-
- <section id="thread.release_notes.boost_1_32_0.change_log.mutex">
- <title>Mutex implementation changed for Win32</title>
-
- <para>On Win32, <classname>boost::mutex</classname>,
- <classname>boost::try_mutex</classname>, <classname>boost::recursive_mutex</classname>,
- and <classname>boost::recursive_try_mutex</classname> now use a Win32 critical section
- whenever possible; otherwise they use a Win32 mutex. As before,
- <classname>boost::timed_mutex</classname> and
- <classname>boost::recursive_timed_mutex</classname> use a Win32 mutex.</para>
- </section>
-
- <section id="thread.release_notes.boost_1_32_0.change_log.wince">
- <title>Windows CE support improved</title>
-
- <para>Minor changes were made to make Boost.Thread work on Windows CE.</para>
- </section>
- </section>
-</section>

Deleted: branches/release/libs/thread/doc/thread-ref.xml
==============================================================================
--- branches/release/libs/thread/doc/thread-ref.xml 2008-03-17 09:59:17 EDT (Mon, 17 Mar 2008)
+++ (empty file)
@@ -1,270 +0,0 @@
-<?xml version="1.0" encoding="utf-8"?>
-<!DOCTYPE library PUBLIC "-//Boost//DTD BoostBook XML V1.0//EN"
- "http://www.boost.org/tools/boostbook/dtd/boostbook.dtd" [
- <!ENTITY % thread.entities SYSTEM "entities.xml">
- %thread.entities;
-]>
-
-<header name="boost/thread/thread.hpp"
- last-revision="$Date$">
- <namespace name="boost">
- <class name="thread">
- <purpose>
- <para>The <classname>thread</classname> class represents threads of
- execution, and provides the functionality to create and manage
- threads within the &Boost.Thread; library. See
- <xref linkend="thread.glossary"/> for a precise description of
- <link linkend="thread.glossary.thread">thread of execution</link>,
- and for definitions of threading-related terms and of thread states such as
- <link linkend="thread.glossary.thread-state">blocked</link>.</para>
- </purpose>
-
- <description>
- <para>A <link linkend="thread.glossary.thread">thread of execution</link>
- has an initial function. For the program's initial thread, the initial
- function is <code>main()</code>. For other threads, the initial
- function is <code>operator()</code> of the function object passed to
- the <classname>thread</classname> object's constructor.</para>
-
- <para>A thread of execution is said to be "finished"
- or to have "finished execution" when its initial function returns or
- is terminated. This includes completion of all thread cleanup
- handlers, and completion of the normal C++ function return behaviors,
- such as destruction of automatic storage (stack) objects and releasing
- any associated implementation resources.</para>
-
- <para>A thread object has an associated state which is either
- "joinable" or "non-joinable".</para>
-
- <para>Except as described below, the policy used by an implementation
- of &Boost.Thread; to schedule transitions between thread states is
- unspecified.</para>
-
- <para><note>Just as the lifetime of a file may be different from the
- lifetime of an <code>iostream</code> object which represents the file, the lifetime
- of a thread of execution may be different from the
- <classname>thread</classname> object which represents the thread of
- execution. In particular, after a call to <code>join()</code>,
- the thread of execution will no longer exist even though the
- <classname>thread</classname> object continues to exist until the
- end of its normal lifetime. The converse is also possible; if
- a <classname>thread</classname> object is destroyed without
- <code>join()</code> first having been called, the thread of execution
- continues until its initial function completes.</note></para>
- </description>
-
- <inherit access="private">
- <type><classname>boost::noncopyable</classname></type>
- <purpose>Exposition only</purpose>
- </inherit>
-
- <constructor>
- <effects>Constructs a <classname>thread</classname> object
- representing the current thread of execution.</effects>
-
- <postconditions><code>*this</code> is non-joinable.</postconditions>
-
- <notes><emphasis role="bold">Danger:</emphasis>
- <code>*this</code> is valid only within the current thread.</notes>
- </constructor>
-
- <constructor specifiers="explicit">
- <parameter name="threadfunc">
- <paramtype>const boost::function0<void>&</paramtype>
- </parameter>
-
- <effects>
- Starts a new thread of execution and constructs a
- <classname>thread</classname> object representing it.
- Copies <code>threadfunc</code> (which in turn copies
- the function object wrapped by <code>threadfunc</code>)
- to an internal location which persists for the lifetime
- of the new thread of execution. Calls <code>operator()</code>
- on the copy of the <code>threadfunc</code> function object
- in the new thread of execution.
- </effects>
-
- <postconditions><code>*this</code> is joinable.</postconditions>
-
- <throws><code>boost::thread_resource_error</code> if a new thread
- of execution cannot be started.</throws>
- </constructor>
-
- <destructor>
- <effects>Destroys <code>*this</code>. The actual thread of
- execution may continue to execute after the
- <classname>thread</classname> object has been destroyed.
- </effects>
-
- <notes>If <code>*this</code> is joinable the actual thread
- of execution becomes "detached". Any resources used
- by the thread will be reclaimed when the thread of execution
- completes. To ensure such a thread of execution runs to completion
- before the <classname>thread</classname> object is destroyed, call
- <code>join()</code>.</notes>
- </destructor>
-
- <method-group name="comparison">
- <method name="operator==" cv="const">
- <type>bool</type>
-
- <parameter name="rhs">
- <type>const thread&</type>
- </parameter>
-
- <requires>The thread is non-terminated or <code>*this</code>
- is joinable.</requires>
-
- <returns><code>true</code> if <code>*this</code> and
- <code>rhs</code> represent the same thread of
- execution.</returns>
- </method>
-
- <method name="operator!=" cv="const">
- <type>bool</type>
-
- <parameter name="rhs">
- <type>const thread&</type>
- </parameter>
-
- <requires>The thread is non-terminated or <code>*this</code>
- is joinable.</requires>
-
- <returns><code>!(*this==rhs)</code>.</returns>
- </method>
- </method-group>
-
- <method-group name="modifier">
- <method name="join">
- <type>void</type>
-
- <requires><code>*this</code> is joinable.</requires>
-
- <effects>The current thread of execution blocks until the
- initial function of the thread of execution represented by
- <code>*this</code> finishes and all resources are
- reclaimed.</effects>
-
- <postcondition><code>*this</code> is non-joinable.</postcondition>
-
- <notes>If <code>*this == thread()</code> the result is
- implementation-defined. If the implementation doesn't
- detect this the result will be
- <link linkend="thread.glossary.deadlock">deadlock</link>.
- </notes>
- </method>
- </method-group>
-
- <method-group name="static">
- <method name="sleep" specifiers="static">
- <type>void</type>
-
- <parameter name="xt">
- <paramtype>const <classname>xtime</classname>&</paramtype>
- </parameter>
-
- <effects>The current thread of execution blocks until
- <code>xt</code> is reached.</effects>
- </method>
-
- <method name="yield" specifiers="static">
- <type>void</type>
-
- <effects>The current thread of execution is placed in the
- <link linkend="thread.glossary.thread-state">ready</link>
- state.</effects>
-
- <notes>
- <simpara>Allow the current thread to give up the rest of its
- time slice (or other scheduling quota) to another thread.
- Particularly useful in non-preemptive implementations.</simpara>
- </notes>
- </method>
- </method-group>
- </class>
-
- <class name="thread_group">
- <purpose>
- The <classname>thread_group</classname> class provides a container
- for easy grouping of threads to simplify several common thread
- creation and management idioms.
- </purpose>
-
- <inherit access="private">
- <type><classname>boost::noncopyable</classname></type>
- <purpose>Exposition only</purpose>
- </inherit>
-
-
- <constructor>
- <effects>Constructs an empty <classname>thread_group</classname>
- container.</effects>
- </constructor>
-
- <destructor>
- <effects>Destroys each contained thread object. Destroys <code>*this</code>.</effects>
-
- <notes>Behavior is undefined if another thread references
- <code>*this </code> during the execution of the destructor.
- </notes>
- </destructor>
-
- <method-group name="modifier">
- <method name="create_thread">
- <type><classname>thread</classname>*</type>
-
- <parameter name="threadfunc">
- <paramtype>const boost::function0<void>&</paramtype>
- </parameter>
-
- <effects>Creates a new <classname>thread</classname> object
- that executes <code>threadfunc</code> and adds it to the
- <code>thread_group</code> container object's list of managed
- <classname>thread</classname> objects.</effects>
-
- <returns>Pointer to the newly created
- <classname>thread</classname> object.</returns>
- </method>
-
- <method name="add_thread">
- <type>void</type>
-
- <parameter name="thrd">
- <paramtype><classname>thread</classname>*</paramtype>
- </parameter>
-
- <effects>Adds <code>thrd</code> to the
- <classname>thread_group</classname> object's list of managed
- <classname>thread</classname> objects. The <code>thrd</code>
- object must have been allocated via <code>operator new</code> and will
- be deleted when the group is destroyed.</effects>
- </method>
-
- <method name="remove_thread">
- <type>void</type>
-
- <parameter name="thrd">
- <paramtype><classname>thread</classname>*</paramtype>
- </parameter>
-
- <effects>Removes <code>thread</code> from <code>*this</code>'s
- list of managed <classname>thread</classname> objects.</effects>
-
- <throws><emphasis role="bold">???</emphasis> if
- <code>thrd</code> is not in <code>*this</code>'s list
- of managed <classname>thread</classname> objects.</throws>
- </method>
-
- <method name="join_all">
- <type>void</type>
-
- <effects>Calls <code>join()</code> on each of the managed
- <classname>thread</classname> objects.</effects>
- </method>
- </method-group>
- </class>
- </namespace>
-</header>

Deleted: branches/release/libs/thread/doc/thread.xml
==============================================================================
--- branches/release/libs/thread/doc/thread.xml 2008-03-17 09:59:17 EDT (Mon, 17 Mar 2008)
+++ (empty file)
@@ -1,48 +0,0 @@
-<?xml version="1.0" encoding="utf-8"?>
-<!DOCTYPE library PUBLIC "-//Boost//DTD BoostBook XML V1.0//EN"
- "http://www.boost.org/tools/boostbook/dtd/boostbook.dtd" [
- <!ENTITY % thread.entities SYSTEM "entities.xml">
- %thread.entities;
-]>
-
-<library name="Thread" dirname="thread" id="thread"
-last-revision="$Date$"
-xmlns:xi="http://www.w3.org/2001/XInclude">
- <libraryinfo>
- <author>
- <firstname>William</firstname>
- <othername>E.</othername>
- <surname>Kempf</surname>
- </author>
- <copyright>
- <year>2001</year>
- <year>2002</year>
- <year>2003</year>
- <holder>William E. Kempf</holder>
- </copyright>
- <legalnotice>
- <para>Subject to the Boost Software License, Version 1.0.
- (See accompanying file LICENSE_1_0.txt or http://www.boost.org/LICENSE_1_0.txt)</para>
- </legalnotice>
- <librarypurpose>Portable C++ multi-threading</librarypurpose>
- <librarycategory name="category:concurrent" />
- <title>Boost.Thread</title>
- </libraryinfo>
- <title>Boost.Thread</title>
- <xi:include href="overview.xml"/>
- <xi:include href="design.xml"/>
- <xi:include href="concepts.xml"/>
- <xi:include href="rationale.xml"/>
- <xi:include href="reference.xml"/>
- <xi:include href="faq.xml"/>
- <xi:include href="configuration.xml"/>
- <xi:include href="build.xml"/>
- <xi:include href="implementation_notes.xml"/>
- <xi:include href="release_notes.xml"/>
- <xi:include href="glossary.xml"/>
- <xi:include href="acknowledgements.xml"/>
- <xi:include href="bibliography.xml"/>
-</library>

Deleted: branches/release/libs/thread/doc/tss-ref.xml
==============================================================================
--- branches/release/libs/thread/doc/tss-ref.xml 2008-03-17 09:59:17 EDT (Mon, 17 Mar 2008)
+++ (empty file)
@@ -1,206 +0,0 @@
-<?xml version="1.0" encoding="utf-8"?>
-<!DOCTYPE library PUBLIC "-//Boost//DTD BoostBook XML V1.0//EN"
- "http://www.boost.org/tools/boostbook/dtd/boostbook.dtd" [
- <!ENTITY % thread.entities SYSTEM "entities.xml">
- %thread.entities;
-]>
-
-<header name="boost/thread/tss.hpp"
- last-revision="$Date$">
- <namespace name="boost">
- <class name="thread_specific_ptr">
- <purpose>
- The <classname>thread_specific_ptr</classname> class defines
- an interface for using thread specific storage.
- </purpose>
-
- <description>
- <para>Thread specific storage is data associated with
- individual threads and is often used to make operations
- that rely on global data
- <link linkend="thread.glossary.thread-safe">thread-safe</link>.
- </para>
-
- <para>Template <classname>thread_specific_ptr</classname>
- stores a pointer to an object obtained on a thread-by-thread
- basis and calls a specified cleanup handler on the contained
- pointer when the thread terminates. The cleanup handlers are
- called in the reverse order of construction of the
- <classname>thread_specific_ptr</classname>s, and for the
- initial thread are called by the destructor, providing the
- same ordering guarantees as for normal declarations. Each
- thread initially stores the null pointer in each
- <classname>thread_specific_ptr</classname> instance.</para>
-
- <para>The template <classname>thread_specific_ptr</classname>
- is useful in the following cases:
- <itemizedlist>
- <listitem>An interface was originally written assuming
- a single thread of control and it is being ported to a
- multithreaded environment.</listitem>
-
- <listitem>Each thread of control invokes sequences of
- methods that share data that are physically unique
- for each thread, but must be logically accessed
- through a globally visible access point instead of
- being explicitly passed.</listitem>
- </itemizedlist>
- </para>
- </description>
-
- <inherit access="private">
- <type><classname>boost::noncopyable</classname></type>
- <purpose>Exposition only</purpose>
- </inherit>
-
- <constructor>
- <requires>The expression <code>delete get()</code> is well
- formed.</requires>
-
- <effects>A thread-specific data key is allocated and visible to
- all threads in the process. Upon creation, the value
- <code>NULL</code> will be associated with the new key in all
- active threads. A cleanup method is registered with the key
- that will call <code>delete</code> on the value associated
- with the key for a thread when it exits. When a thread exits,
- if a key has a registered cleanup method and the thread has a
- non-<code>NULL</code> value associated with that key, the value
- of the key is set to <code>NULL</code> and then the cleanup
- method is called with the previously associated value as its
- sole argument. The order in which registered cleanup methods
- are called when a thread exits is undefined. If after all the
- cleanup methods have been called for all non-<code>NULL</code>
- values, there are still some non-<code>NULL</code> values
- with associated cleanup handlers the result is undefined
- behavior.</effects>
-
- <throws><classname>boost::thread_resource_error</classname> if
- the necessary resources can not be obtained.</throws>
-
- <notes>There may be an implementation specific limit to the
- number of thread specific storage objects that can be created,
- and this limit may be small.</notes>
-
- <rationale>The most common need for cleanup will be to call
- <code>delete</code> on the associated value. If other forms
- of cleanup are required the overloaded constructor should be
- called instead.</rationale>
- </constructor>
-
- <constructor>
- <parameter name="cleanup">
- <paramtype>void (*cleanup)(void*)</paramtype>
- </parameter>
-
- <effects>A thread-specific data key is allocated and visible to
- all threads in the process. Upon creation, the value
- <code>NULL</code> will be associated with the new key in all
- active threads. The <code>cleanup</code> method is registered
- with the key and will be called for a thread with the value
- associated with the key for that thread when it exits. When a
- thread exits, if a key has a registered cleanup method and the
- thread has a non-<code>NULL</code> value associated with that
- key, the value of the key is set to <code>NULL</code> and then
- the cleanup method is called with the previously associated
- value as its sole argument. The order in which registered
- cleanup methods are called when a thread exits is undefined.
- If after all the cleanup methods have been called for all
- non-<code>NULL</code> values, there are still some
- non-<code>NULL</code> values with associated cleanup handlers
- the result is undefined behavior.</effects>
-
- <throws><classname>boost::thread_resource_error</classname> if
- the necessary resources can not be obtained.</throws>
-
- <notes>There may be an implementation specific limit to the
- number of thread specific storage objects that can be created,
- and this limit may be small.</notes>
-
- <rationale>There is the occasional need to register
- specialized cleanup methods, or to register no cleanup method
- at all (done by passing <code>NULL</code> to this constructor.
- </rationale>
- </constructor>
-
- <destructor>
- <effects>Deletes the thread-specific data key allocated by the
- constructor. The thread-specific data values associated with
- the key need not be <code>NULL</code>. It is the responsibility
- of the application to perform any cleanup actions for data
- associated with the key.</effects>
-
- <notes>Does not destroy any data that may be stored in any
- thread's thread specific storage. For this reason you should
- not destroy a <classname>thread_specific_ptr</classname> object
- until you are certain there are no threads running that have
- made use of its thread specific storage.</notes>
-
- <rationale>Associated data is not cleaned up because registered
- cleanup methods need to be run in the thread that allocated the
- associated data to be guarranteed to work correctly. There's no
- safe way to inject the call into another thread's execution
- path, making it impossible to call the cleanup methods safely.
- </rationale>
- </destructor>
-
- <method-group name="modifier functions">
- <method name="release">
- <type>T*</type>
-
- <postconditions><code>*this</code> holds the null pointer
- for the current thread.</postconditions>
-
- <returns><code>this->get()</code> prior to the call.</returns>
-
- <rationale>This method provides a mechanism for the user to
- relinquish control of the data associated with the
- thread-specific key.</rationale>
- </method>
-
- <method name="reset">
- <type>void</type>
-
- <parameter name="p">
- <paramtype>T*</paramtype>
- <default>0</default>
- </parameter>
-
- <effects>If <code>this->get() != p &&
- this->get() != NULL</code> then call the
- associated cleanup function.</effects>
-
- <postconditions><code>*this</code> holds the pointer
- <code>p</code> for the current thread.</postconditions>
- </method>
- </method-group>
-
- <method-group name="observer functions">
- <method name="get" cv="const">
- <type>T*</type>
-
- <returns>The object stored in thread specific storage for
- the current thread for <code>*this</code>.</returns>
-
- <notes>Each thread initially returns 0.</notes>
- </method>
-
- <method name="operator->" cv="const">
- <type>T*</type>
-
- <returns><code>this->get()</code>.</returns>
- </method>
-
- <method name="operator*()" cv="const">
- <type>T&</type>
-
- <requires><code>this->get() != 0</code></requires>
-
- <returns><code>this->get()</code>.</returns>
- </method>
- </method-group>
- </class>
- </namespace>
-</header>

Deleted: branches/release/libs/thread/doc/xtime-ref.xml
==============================================================================
--- branches/release/libs/thread/doc/xtime-ref.xml 2008-03-17 09:59:17 EDT (Mon, 17 Mar 2008)
+++ (empty file)
@@ -1,82 +0,0 @@
-<?xml version="1.0" encoding="utf-8"?>
-<!DOCTYPE library PUBLIC "-//Boost//DTD BoostBook XML V1.0//EN"
- "http://www.boost.org/tools/boostbook/dtd/boostbook.dtd" [
- <!ENTITY % thread.entities SYSTEM "entities.xml">
- %thread.entities;
-]>
-
-<header name="boost/thread/xtime.hpp"
- last-revision="$Date$">
- <namespace name="boost">
- <enum name="xtime_clock_types">
- <enumvalue name="TIME_UTC" />
-
- <purpose>
- <para>Specifies the clock type to use when creating
- an object of type <classname>xtime</classname>.</para>
- </purpose>
-
- <description>
- <para>The only clock type supported by &Boost.Thread; is
- <code>TIME_UTC</code>. The epoch for <code>TIME_UTC</code>
- is 1970-01-01 00:00:00.</para>
- </description>
- </enum>
-
- <struct name="xtime">
- <purpose>
- <simpara>An object of type <classname>xtime</classname>
- defines a time that is used to perform high-resolution time operations.
- This is a temporary solution that will be replaced by a more robust time
- library once available in Boost.</simpara>
- </purpose>
-
- <description>
- <simpara>The <classname>xtime</classname> type is used to represent a point on
- some time scale or a duration in time. This type may be proposed for the C standard by
- Markus Kuhn. &Boost.Thread; provides only a very minimal implementation of this
- proposal; it is expected that a full implementation (or some other time
- library) will be provided in Boost as a separate library, at which time &Boost.Thread;
- will deprecate its own implementation.</simpara>
-
- <simpara><emphasis role="bold">Note</emphasis> that the resolution is
- implementation specific. For many implementations the best resolution
- of time is far more than one nanosecond, and even when the resolution
- is reasonably good, the latency of a call to <code>xtime_get()</code>
- may be significant. For maximum portability, avoid durations of less than
- one second.</simpara>
- </description>
-
- <free-function-group name="creation">
- <function name="xtime_get">
- <type>int</type>
-
- <parameter name="xtp">
- <paramtype><classname>xtime</classname>*</paramtype>
- </parameter>
-
- <parameter name="clock_type">
- <paramtype>int</paramtype>
- </parameter>
-
- <postconditions>
- <simpara><code>xtp</code> represents the current point in
- time as a duration since the epoch specified by
- <code>clock_type</code>.</simpara>
- </postconditions>
-
- <returns>
- <simpara><code>clock_type</code> if successful, otherwise 0.</simpara>
- </returns>
- </function>
- </free-function-group>
-
- <data-member name="sec">
- <type><emphasis>platform-specific-type</emphasis></type>
- </data-member>
- </struct>
- </namespace>
-</header>

Next message: eric_at_[hidden]: "[Boost-commit] svn:boost r43675 - in branches/release: . libs/xpressive/doc"
Previous message: anthony_at_[hidden]: "[Boost-commit] svn:boost r43673 - in branches/release: boost/thread/pthread boost/thread/win32 libs/thread/test"

Date view	Thread view	Subject view	Author view