From 6162239973a3a10ae49c3cea0c1008d4f9c69b5b Mon Sep 17 00:00:00 2001
From: Jonathan Wakely <jwakely.gcc@gmail.com>
Date: Mon, 11 Nov 2013 13:33:48 +0000
Subject: [PATCH] re PR libstdc++/54562 (mutex and condition variable timers)

	PR libstdc++/54562
	* include/std/mutex (__timed_mutex_impl::__clock_t): Use
	high_resolution_clock for absolute timeouts, because
	pthread_mutex_timedlock uses CLOCK_REALTIME not CLOCK_MONOTONIC.
	(__timed_mutex_impl::_M_try_lock_for): Use steady_clock for relative
	timeouts as per [thread.req.timing].
	(__timed_mutex_impl::_M_try_lock_until<Clock,Duration>): Convert to
	__clock_t time point instead of using _M_try_lock_for.

From-SVN: r204672
---
 libstdc++-v3/ChangeLog         | 11 +++++++++++
 libstdc++-v3/include/std/mutex | 24 ++++++++++--------------
 2 files changed, 21 insertions(+), 14 deletions(-)

diff --git a/libstdc++-v3/ChangeLog b/libstdc++-v3/ChangeLog
index 2244435322d..38c70c583e8 100644
--- a/libstdc++-v3/ChangeLog
+++ b/libstdc++-v3/ChangeLog
@@ -1,3 +1,14 @@
+2013-11-11  Jonathan Wakely  <jwakely.gcc@gmail.com>
+
+	PR libstdc++/54562
+	* include/std/mutex (__timed_mutex_impl::__clock_t): Use
+	high_resolution_clock for absolute timeouts, because
+	pthread_mutex_timedlock uses CLOCK_REALTIME not CLOCK_MONOTONIC.
+	(__timed_mutex_impl::_M_try_lock_for): Use steady_clock for relative
+	timeouts as per [thread.req.timing].
+	(__timed_mutex_impl::_M_try_lock_until<Clock,Duration>): Convert to
+	__clock_t time point instead of using _M_try_lock_for.
+
 2013-11-09  Jonathan Wakely  <jwakely.gcc@gmail.com>
 
 	PR libstdc++/58982
diff --git a/libstdc++-v3/include/std/mutex b/libstdc++-v3/include/std/mutex
index 40b2e31dc7f..da2ca0cfe94 100644
--- a/libstdc++-v3/include/std/mutex
+++ b/libstdc++-v3/include/std/mutex
@@ -203,21 +203,17 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
     class __timed_mutex_impl
     {
     protected:
-#ifdef _GLIBCXX_USE_CLOCK_MONOTONIC
-      typedef chrono::steady_clock 	  	__clock_t;
-#else
       typedef chrono::high_resolution_clock 	__clock_t;
-#endif
 
       template<typename _Rep, typename _Period>
 	bool
 	_M_try_lock_for(const chrono::duration<_Rep, _Period>& __rtime)
 	{
-	  auto __rt = chrono::duration_cast<__clock_t::duration>(__rtime);
-	  if (ratio_greater<__clock_t::period, _Period>())
+	  using chrono::steady_clock;
+	  auto __rt = chrono::duration_cast<steady_clock::duration>(__rtime);
+	  if (ratio_greater<steady_clock::period, _Period>())
 	    ++__rt;
-
-	  return _M_try_lock_until(__clock_t::now() + __rt);
+	  return _M_try_lock_until(steady_clock::now() + __rt);
 	}
 
       template<typename _Duration>
@@ -225,11 +221,8 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
 	_M_try_lock_until(const chrono::time_point<__clock_t,
 						   _Duration>& __atime)
 	{
-	  chrono::time_point<__clock_t, chrono::seconds> __s =
-	    chrono::time_point_cast<chrono::seconds>(__atime);
-
-	  chrono::nanoseconds __ns =
-	    chrono::duration_cast<chrono::nanoseconds>(__atime - __s);
+	  auto __s = chrono::time_point_cast<chrono::seconds>(__atime);
+	  auto __ns = chrono::duration_cast<chrono::nanoseconds>(__atime - __s);
 
 	  __gthread_time_t __ts = {
 	    static_cast<std::time_t>(__s.time_since_epoch().count()),
@@ -243,7 +236,10 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
       template<typename _Clock, typename _Duration>
 	bool
 	_M_try_lock_until(const chrono::time_point<_Clock, _Duration>& __atime)
-	{ return _M_try_lock_for(__atime - _Clock::now()); }
+	{
+	  auto __rtime = __atime - _Clock::now();
+	  return _M_try_lock_until(__clock_t::now() + __rtime);
+	}
     };
 
   /// timed_mutex