[Boost-commit] svn:boost r85013 - in trunk/boost/lockfree: . detail

Subject: [Boost-commit] svn:boost r85013 - in trunk/boost/lockfree: . detail
From: tim_at_[hidden]
Date: 2013-07-12 13:48:35

Author: timblechmann
Date: 2013-07-12 13:48:35 EDT (Fri, 12 Jul 2013)
New Revision: 85013
URL: http://svn.boost.org/trac/boost/changeset/85013

Log:
lockfree: stack - avoid temporary copy when consuming via functor

Signed-off-by: Tim Blechmann <tim_at_[hidden]>

Text files modified: 
   trunk/boost/lockfree/detail/copy_payload.hpp |    17 ++++++++++++                            
   trunk/boost/lockfree/stack.hpp               |    54 ++++++++++++++++++++++----------------- 
   2 files changed, 47 insertions(+), 24 deletions(-)

Modified: trunk/boost/lockfree/detail/copy_payload.hpp
==============================================================================
--- trunk/boost/lockfree/detail/copy_payload.hpp	Fri Jul 12 13:48:06 2013	(r85012)
+++ trunk/boost/lockfree/detail/copy_payload.hpp	2013-07-12 13:48:35 EDT (Fri, 12 Jul 2013)	(r85013)
@@ -44,6 +44,23 @@
     copy_type::copy(t, u);
 }
 
+template <typename T>
+struct consume_via_copy
+{
+    consume_via_copy(T & out):
+        out(out)
+    {}
+
+    template <typename U>
+    void operator()(U & element)
+    {
+        copy_payload(element, out);
+    }
+
+    T &  out;
+};
+
+
 }}}
 
 #endif  /* BOOST_LOCKFREE_DETAIL_COPY_PAYLOAD_HPP_INCLUDED */

Modified: trunk/boost/lockfree/stack.hpp
==============================================================================
--- trunk/boost/lockfree/stack.hpp	Fri Jul 12 13:48:06 2013	(r85012)
+++ trunk/boost/lockfree/stack.hpp	2013-07-12 13:48:35 EDT (Fri, 12 Jul 2013)	(r85013)
@@ -435,21 +435,9 @@
     bool pop(U & ret)
     {
         BOOST_STATIC_ASSERT((boost::is_convertible<T, U>::value));
-        tagged_node_handle old_tos = tos.load(detail::memory_order_consume);
-
-        for (;;) {
-            node * old_tos_pointer = pool.get_pointer(old_tos);
-            if (!old_tos_pointer)
-                return false;
-
-            tagged_node_handle new_tos(old_tos_pointer->next, old_tos.get_next_tag());
+        detail::consume_via_copy<U> consumer(ret);
 
-            if (tos.compare_exchange_weak(old_tos, new_tos)) {
-                detail::copy_payload(old_tos_pointer->v, ret);
-                pool.template destruct<true>(old_tos);
-                return true;
-            }
-        }
+        return consume_one(consumer);
     }
 
 
@@ -505,24 +493,42 @@
     template <typename Functor>
     bool consume_one(Functor & f)
     {
-        T element;
-        bool success = pop(element);
-        if (success)
-            f(element);
+        tagged_node_handle old_tos = tos.load(detail::memory_order_consume);
+
+        for (;;) {
+            node * old_tos_pointer = pool.get_pointer(old_tos);
+            if (!old_tos_pointer)
+                return false;
 
-        return success;
+            tagged_node_handle new_tos(old_tos_pointer->next, old_tos.get_next_tag());
+
+            if (tos.compare_exchange_weak(old_tos, new_tos)) {
+                f(old_tos_pointer->v);
+                pool.template destruct<true>(old_tos);
+                return true;
+            }
+        }
     }
 
     /// \copydoc boost::lockfree::stack::consume_one(Functor & rhs)
     template <typename Functor>
     bool consume_one(Functor const & f)
     {
-        T element;
-        bool success = pop(element);
-        if (success)
-            f(element);
+        tagged_node_handle old_tos = tos.load(detail::memory_order_consume);
 
-        return success;
+        for (;;) {
+            node * old_tos_pointer = pool.get_pointer(old_tos);
+            if (!old_tos_pointer)
+                return false;
+
+            tagged_node_handle new_tos(old_tos_pointer->next, old_tos.get_next_tag());
+
+            if (tos.compare_exchange_weak(old_tos, new_tos)) {
+                f(old_tos_pointer->v);
+                pool.template destruct<true>(old_tos);
+                return true;
+            }
+        }
     }
 
     /** consumes all elements via a functor