From cfef4c324ac300c0ad120f0fcee376159de84a0c Mon Sep 17 00:00:00 2001 From: Jonathan Wakely Date: Thu, 11 Oct 2018 17:37:23 +0100 Subject: [PATCH] PR libstdc++/80538 Only call sleep for non-zero values Avoid a system call when no sleep is required. Sleep in a loop (actually two loops) to handle interruption by signals. PR libstdc++/80538 * src/c++11/thread.cc (this_thread::__sleep_for) [_GLIBCXX_HAVE_SLEEP]: Only call sleep for non-zero values. Loop while sleep call is interrupted and until steady_clock shows requested duration has elapsed. (!_GLIBCXX_HAVE_USLEEP]: Use the _GLIBCXX_HAVE_SLEEP code path, but avoiding the usleep call. * testsuite/30_threads/this_thread/60421.cc: Test repeated signal interruptions. From-SVN: r265044 --- libstdc++-v3/ChangeLog | 10 ++++++ libstdc++-v3/src/c++11/thread.cc | 35 ++++++++++++++----- .../testsuite/30_threads/this_thread/60421.cc | 15 ++++++-- 3 files changed, 48 insertions(+), 12 deletions(-) diff --git a/libstdc++-v3/ChangeLog b/libstdc++-v3/ChangeLog index 13698961910..b92fdf14cac 100644 --- a/libstdc++-v3/ChangeLog +++ b/libstdc++-v3/ChangeLog @@ -1,5 +1,15 @@ 2018-10-11 Jonathan Wakely + PR libstdc++/80538 + * src/c++11/thread.cc (this_thread::__sleep_for) + [_GLIBCXX_HAVE_SLEEP]: Only call sleep for non-zero values. + Loop while sleep call is interrupted and until steady_clock + shows requested duration has elapsed. + (!_GLIBCXX_HAVE_USLEEP]: Use the _GLIBCXX_HAVE_SLEEP code path, but + avoiding the usleep call. + * testsuite/30_threads/this_thread/60421.cc: Test repeated + signal interruptions. + * include/bits/allocator.h (operator==(const allocator<_Tp>&, const allocator<_Tp>)) (operator!=(const allocator<_Tp>&, const allocator<_Tp>)): Replace diff --git a/libstdc++-v3/src/c++11/thread.cc b/libstdc++-v3/src/c++11/thread.cc index c62cb71bf99..564eae6f166 100644 --- a/libstdc++-v3/src/c++11/thread.cc +++ b/libstdc++-v3/src/c++11/thread.cc @@ -194,18 +194,35 @@ namespace this_thread while (::nanosleep(&__ts, &__ts) == -1 && errno == EINTR) { } #elif defined(_GLIBCXX_HAVE_SLEEP) -# ifdef _GLIBCXX_HAVE_USLEEP - ::sleep(__s.count()); - if (__ns.count() > 0) + const auto target = chrono::steady_clock::now() + __s + __ns; + while (true) { - long __us = __ns.count() / 1000; - if (__us == 0) - __us = 1; - ::usleep(__us); - } + unsigned secs = __s.count(); + if (__ns.count() > 0) + { +# ifdef _GLIBCXX_HAVE_USLEEP + long us = __ns.count() / 1000; + if (us == 0) + us = 1; + ::usleep(us); # else - ::sleep(__s.count() + (__ns.count() >= 1000000)); + if (__ns.count() > 1000000 || secs == 0) + ++secs; // No sub-second sleep function, so round up. # endif + } + + if (secs > 0) + { + // Sleep in a loop to handle interruption by signals: + while ((secs = ::sleep(secs))) + { } + } + const auto now = chrono::steady_clock::now(); + if (now >= target) + break; + __s = chrono::duration_cast(target - now); + __ns = chrono::duration_cast(target - (now + __s)); + } #elif defined(_GLIBCXX_HAVE_WIN32_SLEEP) unsigned long ms = __ns.count() / 1000000; if (__ns.count() > 0 && ms == 0) diff --git a/libstdc++-v3/testsuite/30_threads/this_thread/60421.cc b/libstdc++-v3/testsuite/30_threads/this_thread/60421.cc index e7d69a49fb6..cd8d2fdd6f3 100644 --- a/libstdc++-v3/testsuite/30_threads/this_thread/60421.cc +++ b/libstdc++-v3/testsuite/30_threads/this_thread/60421.cc @@ -53,10 +53,19 @@ test02() sleeping = true; std::this_thread::sleep_for(time); result = std::chrono::system_clock::now() >= (start + time); + sleeping = false; }); - while (!sleeping) { } - std::this_thread::sleep_for(std::chrono::milliseconds(500)); - pthread_kill(t.native_handle(), SIGUSR1); + while (!sleeping) + { + // Wait for the thread to start sleeping. + } + while (sleeping) + { + // The sleeping thread should finish eventually, + // even if continually interrupted after less than a second: + std::this_thread::sleep_for(std::chrono::milliseconds(500)); + pthread_kill(t.native_handle(), SIGUSR1); + } t.join(); VERIFY( result ); } -- 2.30.2