This ensures that the standard timed mutexes use steady_clock for
relative timeouts and the same clock as pthread_mutex_timedlock for
absolute timeouts.
I'm not adding a new test as the only ones I could come up with
involve waiting for longer than is suitable in a testcase, and don't
reliably fail on all systems anyway.
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.
Tested x86_64-linux, committed to trunk. I would like to commit this
to the 4.8 branch too, but I'm undecided whether it's suitable.
commit 1f2401b0338fefaaa521ebf202e563a6c673b47e
Author: Jonathan Wakely <jwakely....@gmail.com>
Date: Mon Nov 11 12:40:01 2013 +0000
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.
diff --git a/libstdc++-v3/include/std/mutex b/libstdc++-v3/include/std/mutex
index 40b2e31..da2ca0c 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
