Subject: [Boost-commit] svn:boost r55581 - trunk/libs/spirit/benchmarks
From: hartmut.kaiser_at_[hidden]
Date: 2009-08-14 08:46:25
Author: hkaiser
Date: 2009-08-14 08:46:24 EDT (Fri, 14 Aug 2009)
New Revision: 55581
URL: http://svn.boost.org/trac/boost/changeset/55581
Log:
Spirit: added gettimeofday based implementation for high_resolution_timer (thanks to Edward Grace)
Text files modified:
trunk/libs/spirit/benchmarks/high_resolution_timer.hpp | 123 +++++++++++++++++++++++++++++++++++++++
1 files changed, 121 insertions(+), 2 deletions(-)
Modified: trunk/libs/spirit/benchmarks/high_resolution_timer.hpp
==============================================================================
--- trunk/libs/spirit/benchmarks/high_resolution_timer.hpp (original)
+++ trunk/libs/spirit/benchmarks/high_resolution_timer.hpp 2009-08-14 08:46:24 EDT (Fri, 14 Aug 2009)
@@ -1,4 +1,5 @@
// Copyright (c) 2005-2009 Hartmut Kaiser
+// Copyright (c) 2009 Edward Grace
//
// 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)
@@ -299,7 +300,122 @@
// || !defined(_POSIX_THREAD_CPUTIME)
// || _POSIX_THREAD_CPUTIME <= 0)
-// For platforms other than Windows or Linux, simply fall back to boost::timer
+#if defined(BOOST_HAS_GETTIMEOFDAY)
+
+// For platforms that do not support _POSIX_TIMERS but do have
+// GETTIMEOFDAY, which is still preferable to std::clock()
+#include <stdexcept>
+#include <limits>
+
+namespace util
+{
+
+ ///////////////////////////////////////////////////////////////////////////
+ //
+ // high_resolution_timer
+ // A timer object measures elapsed time.
+ //
+ // Implemented with gettimeofday() for platforms that support it,
+ // such as Darwin (OS X) but do not support the previous options.
+ //
+ // Copyright (c) 2009 Edward Grace
+ //
+ ///////////////////////////////////////////////////////////////////////////
+ class high_resolution_timer
+ {
+ public:
+ high_resolution_timer()
+ {
+ start_time.tv_sec = 0;
+ start_time.tv_usec = 0;
+
+ restart();
+ }
+
+ high_resolution_timer(double t)
+ {
+ start_time.tv_sec = time_t(t);
+ start_time.tv_usec = (t - start_time.tv_sec) * 1e6;
+ }
+
+ high_resolution_timer(high_resolution_timer const& rhs)
+ : start_time(rhs.start_time)
+ {
+ }
+
+ static double now()
+ {
+ // Under some implementations gettimeofday() will always
+ // return zero. If it returns anything else however then
+ // we accept this as evidence of an error. Note we are
+ // not assuming that -1 explicitly indicates the error
+ // condition, just that non zero is indicative of the
+ // error.
+ timeval now;
+ if (gettimeofday(&now, NULL))
+ boost::throw_exception(std::runtime_error("Couldn't get current time"));
+ return double(now.tv_sec) + double(now.tv_usec) * 1e-6;
+ }
+
+ void restart()
+ {
+ if (gettimeofday(&start_time, NULL))
+ boost::throw_exception(std::runtime_error("Couldn't initialize start_time"));
+ }
+
+ double elapsed() const // return elapsed time in seconds
+ {
+ timeval now;
+ if (gettimeofday(&now, NULL))
+ boost::throw_exception(std::runtime_error("Couldn't get current time"));
+
+ if (now.tv_sec == start_time.tv_sec)
+ return double(now.tv_usec - start_time.tv_usec) * 1e-6;
+
+ return double(now.tv_usec - start_time.tv_sec) +
+ (double(now.tv_usec - start_time.tv_usec) * 1e-6);
+ }
+
+ double elapsed_max() const // return estimated maximum value for elapsed()
+ {
+ return double((std::numeric_limits<time_t>::max)() - start_time.tv_sec);
+ }
+
+ double elapsed_min() const // return minimum value for elapsed()
+ {
+ // On systems without an explicit clock_getres or similar
+ // we can only estimate an upper bound on the resolution
+ // by repeatedly calling the gettimeofday function. This
+ // is often likely to be indicative of the true
+ // resolution.
+ timeval a, b;
+ double delta(0);
+
+ if (gettimeofday(&a, NULL))
+ boost::throw_exception(std::runtime_error("Couldn't get resolution."));
+
+ // Spin around in a tight loop until we observe a change
+ // in the reported timer value.
+ do {
+ if (gettimeofday(&b, NULL))
+ boost::throw_exception(std::runtime_error("Couldn't get resolution."));
+ delta = double(b.tv_sec - a.tv_sec) +
+ double(b.tv_usec - a.tv_usec) * 1e-6;
+ } while (delta <= 0.0);
+
+ return delta;
+ }
+
+ private:
+ timeval start_time;
+ };
+
+}
+
+#else // BOOST_HAS_GETTIMEOFDAY
+
+// For platforms other than Windows or Linux, or not implementing gettimeofday
+// simply fall back to boost::timer
#include <boost/timer.hpp>
namespace util
@@ -316,5 +432,8 @@
#endif
-#endif
+#endif
+
+#endif
+