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.

git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/branches/gcc-4_9-branch@210557 138bc75d-0d04-0410-961f-82ee72b054a4

3 files changed, 96 insertions, 10 deletions

diff --git a/libstdc++-v3/ChangeLog b/libstdc++-v3/ChangeLog
index b78daca58ca..3ade6310e4e 100644
--- a/libstdc++-v3/ChangeLog
+++ b/libstdc++-v3/ChangeLog
@@ -1,3 +1,13 @@
+2014-05-16  Jonathan Wakely  <jwakely@redhat.com>
+
+	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.
+
 2014-05-08  Joshua Gay  <jgay@gnu.org>
 
 	PR libstdc++/61117
diff --git a/libstdc++-v3/include/std/future b/libstdc++-v3/include/std/future
index 717ce7105df..998e90a9856 100644
--- a/libstdc++-v3/include/std/future
+++ b/libstdc++-v3/include/std/future
@@ -365,12 +365,14 @@ _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_baseV2::_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));
       }
 
@@ -485,7 +487,6 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
           lock_guard<mutex> __lock(_M_mutex);
           _M_result.swap(__res);
         }
-        _M_cond.notify_all();
         __set = true;
       }
 
@@ -495,6 +496,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
       virtual void _M_complete_async() { }
 
       // Return true if state contains a deferred function.
+      // Caller must own _M_mutex.
       virtual bool _M_has_deferred() const { return false; }
     };
 
@@ -1007,22 +1009,25 @@ _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));
       }
     };
 
@@ -1105,15 +1110,17 @@ _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));
       }
     };
 
@@ -1190,8 +1197,9 @@ _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));
       }
     };
 
@@ -1217,8 +1225,9 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
   inline void
   promise<void>::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 00000000000..269268b989b
--- /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
+// <http://www.gnu.org/licenses/>.
+
+// libstdc++/60966
+// This test hangs if std::promise::~promise() destroys the
+// shared state before std::promise::set_value() finishes using it.
+
+#include <future>
+#include <thread>
+#include <vector>
+
+const int THREADS = 10;
+
+void run_task(std::promise<void>* pr)
+{
+  std::this_thread::sleep_for(std::chrono::milliseconds(100));
+  pr->set_value();
+}
+
+int main()
+{
+  std::vector<std::promise<void>*> tasks(THREADS);
+  std::vector<std::thread> threads(THREADS);
+  std::vector<std::future<void>> futures(THREADS);
+
+  for (int i = 0; i < THREADS; ++i)
+  {
+    std::promise<void>* task = new std::promise<void>;
+    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<void>(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();
+}