From f33a43f9f7eab7482837662821abb7fd02cb4350 Mon Sep 17 00:00:00 2001 From: Mike Crowe Date: Mon, 5 Oct 2020 11:12:38 +0100 Subject: libstdc++: Use correct duration for atomic_futex wait on custom clock [PR 91486] As Jonathan Wakely pointed out[1], my change in commit f9ddb696a289cc48d24d3d23c0b324cb88de9573 should have been rounding to the target clock duration type rather than the input clock duration type in __atomic_futex_unsigned::_M_load_when_equal_until just as (e.g.) condition_variable does. As well as fixing this, let's create a rather contrived test that fails with the previous code, but unfortunately only when run on a machine with an uptime of over 208.5 days, and even then not always. [1] https://gcc.gnu.org/pipermail/libstdc++/2020-September/051004.html libstdc++-v3/ChangeLog: PR libstdc++/91486 * include/bits/atomic_futex.h: (__atomic_futex_unsigned::_M_load_when_equal_until): Use target clock duration type when rounding. * testsuite/30_threads/async/async.cc (test_pr91486_wait_for): Rename from test_pr91486. (float_steady_clock): New class for test. (test_pr91486_wait_until): New test. --- libstdc++-v3/include/bits/atomic_futex.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'libstdc++-v3/include') diff --git a/libstdc++-v3/include/bits/atomic_futex.h b/libstdc++-v3/include/bits/atomic_futex.h index aa137a7..6093be0 100644 --- a/libstdc++-v3/include/bits/atomic_futex.h +++ b/libstdc++-v3/include/bits/atomic_futex.h @@ -235,7 +235,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION const __clock_t::time_point __s_entry = __clock_t::now(); const auto __delta = __atime - __c_entry; const auto __s_atime = __s_entry + - chrono::__detail::ceil<_Duration>(__delta); + chrono::__detail::ceil<__clock_t::duration>(__delta); if (_M_load_when_equal_until(__val, __mo, __s_atime)) return true; __c_entry = _Clock::now(); -- cgit v1.1