From: Jonathan Wakely Date: Tue, 3 Jun 2014 17:58:56 +0000 (+0100) Subject: backport: re PR libstdc++/60966 (std::call_once sometime hangs) X-Git-Tag: releases/gcc-4.8.4~432 X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=0717f51a35cb2a2253ee787a8bbfdcd330ff437a;p=thirdparty%2Fgcc.git backport: re PR libstdc++/60966 (std::call_once sometime hangs) Backport from mainline 2014-05-16 Jonathan Wakely PR libstdc++/60966 * include/std/future (__future_base::_State_baseV2::_M_set_result): Signal condition variable after call_once returns. (__future_base::_State_baseV2::_M_do_set): Do not signal here. (promise::set_value, promise::set_exception): Increment the reference count on the shared state until the function returns. * testsuite/30_threads/promise/60966.cc: New. From-SVN: r211198 --- diff --git a/libstdc++-v3/ChangeLog b/libstdc++-v3/ChangeLog index 4736ae490143..4c32b06a8315 100644 --- a/libstdc++-v3/ChangeLog +++ b/libstdc++-v3/ChangeLog @@ -6,6 +6,17 @@ PR libstdc++/60734 * include/bits/stl_tree.h (_Rb_tree::_M_end): Fix invalid cast. + Backport from mainline + 2014-05-16 Jonathan Wakely + + PR libstdc++/60966 + * include/std/future (__future_base::_State_baseV2::_M_set_result): + Signal condition variable after call_once returns. + (__future_base::_State_baseV2::_M_do_set): Do not signal here. + (promise::set_value, promise::set_exception): Increment the reference + count on the shared state until the function returns. + * testsuite/30_threads/promise/60966.cc: New. + 2014-05-29 Jonathan Wakely * include/tr2/bool_set: Use UTF-8 for accented characters. diff --git a/libstdc++-v3/include/std/future b/libstdc++-v3/include/std/future index 00dc978f5c77..507c395eca80 100644 --- a/libstdc++-v3/include/std/future +++ b/libstdc++-v3/include/std/future @@ -351,12 +351,14 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION void _M_set_result(function<_Ptr_type()> __res, bool __ignore_failure = false) { - bool __set = __ignore_failure; + bool __set = false; // all calls to this function are serialized, // side-effects of invoking __res only happen once call_once(_M_once, &_State_base::_M_do_set, this, ref(__res), ref(__set)); - if (!__set) + if (__set) + _M_cond.notify_all(); + else if (!__ignore_failure) __throw_future_error(int(future_errc::promise_already_satisfied)); } @@ -471,7 +473,6 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION lock_guard __lock(_M_mutex); _M_result.swap(__res); } - _M_cond.notify_all(); __set = true; } @@ -983,22 +984,25 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION void set_value(const _Res& __r) { + auto __future = _M_future; auto __setter = _State::__setter(this, __r); - _M_future->_M_set_result(std::move(__setter)); + __future->_M_set_result(std::move(__setter)); } void set_value(_Res&& __r) { + auto __future = _M_future; auto __setter = _State::__setter(this, std::move(__r)); - _M_future->_M_set_result(std::move(__setter)); + __future->_M_set_result(std::move(__setter)); } void set_exception(exception_ptr __p) { + auto __future = _M_future; auto __setter = _State::__setter(__p, this); - _M_future->_M_set_result(std::move(__setter)); + __future->_M_set_result(std::move(__setter)); } }; @@ -1081,15 +1085,17 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION void set_value(_Res& __r) { + auto __future = _M_future; auto __setter = _State::__setter(this, __r); - _M_future->_M_set_result(std::move(__setter)); + __future->_M_set_result(std::move(__setter)); } void set_exception(exception_ptr __p) { + auto __future = _M_future; auto __setter = _State::__setter(__p, this); - _M_future->_M_set_result(std::move(__setter)); + __future->_M_set_result(std::move(__setter)); } }; @@ -1166,8 +1172,9 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION void set_exception(exception_ptr __p) { + auto __future = _M_future; auto __setter = _State::__setter(__p, this); - _M_future->_M_set_result(std::move(__setter)); + __future->_M_set_result(std::move(__setter)); } }; @@ -1193,8 +1200,9 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION inline void promise::set_value() { + auto __future = _M_future; auto __setter = _State::__setter(this); - _M_future->_M_set_result(std::move(__setter)); + __future->_M_set_result(std::move(__setter)); } diff --git a/libstdc++-v3/testsuite/30_threads/promise/60966.cc b/libstdc++-v3/testsuite/30_threads/promise/60966.cc new file mode 100644 index 000000000000..269268b989b9 --- /dev/null +++ b/libstdc++-v3/testsuite/30_threads/promise/60966.cc @@ -0,0 +1,67 @@ +// { dg-do run { target *-*-freebsd* *-*-netbsd* *-*-linux* *-*-gnu* *-*-solaris* *-*-cygwin *-*-darwin* powerpc-ibm-aix* } } +// { dg-options " -std=gnu++11 -pthread" { target *-*-freebsd* *-*-netbsd* *-*-linux* *-*-gnu* powerpc-ibm-aix* } } +// { dg-options " -std=gnu++11 -pthreads" { target *-*-solaris* } } +// { dg-options " -std=gnu++11 " { target *-*-cygwin *-*-darwin* } } +// { dg-require-cstdint "" } +// { dg-require-gthreads "" } +// { dg-require-atomic-builtins "" } + +// Copyright (C) 2014 Free Software Foundation, Inc. +// +// This file is part of the GNU ISO C++ Library. This library is free +// software; you can redistribute it and/or modify it under the +// terms of the GNU General Public License as published by the +// Free Software Foundation; either version 3, or (at your option) +// any later version. + +// This library is distributed in the hope that it will be useful, +// but WITHOUT ANY WARRANTY; without even the implied warranty of +// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the +// GNU General Public License for more details. + +// You should have received a copy of the GNU General Public License along +// with this library; see the file COPYING3. If not see +// . + +// libstdc++/60966 +// This test hangs if std::promise::~promise() destroys the +// shared state before std::promise::set_value() finishes using it. + +#include +#include +#include + +const int THREADS = 10; + +void run_task(std::promise* pr) +{ + std::this_thread::sleep_for(std::chrono::milliseconds(100)); + pr->set_value(); +} + +int main() +{ + std::vector*> tasks(THREADS); + std::vector threads(THREADS); + std::vector> futures(THREADS); + + for (int i = 0; i < THREADS; ++i) + { + std::promise* task = new std::promise; + tasks[i] = task; + futures[i] = task->get_future(); + threads[i] = std::thread(run_task, task); + } + + for (int i = 0; i < THREADS; ++i) + { + // the temporary future releases the state as soon as wait() returns + std::future(std::move(futures[i])).wait(); + // state is ready, should now be safe to delete promise, so it + // releases the shared state too + delete tasks[i]; + } + + for (auto& t : threads) + t.join(); +}