[patch] Update catch(...) handlers to deal with __forced_unwind
Jonathan Wakely
jwakely@redhat.com
Mon Jun 2 15:45:00 GMT 2014
On 14/05/14 20:37 +0100, Jonathan Wakely wrote:
>Failing to rethrow a __forced_unwind exception is very bad.
>
>This patch ensures we rethrow them in async tasks, and makes the
>shared state ready with a broken_promise so that waiting threads
>don't block forever. That seems reasonable to me, does anyone have any
>better ideas?
>
>Tested x86_64-linux, will wait for feedback before committing.
Committed to trunk.
>commit 8d4a49e0391269380b160bd277339f740716de0c
>Author: Jonathan Wakely <jwakely@redhat.com>
>Date: Tue May 13 15:35:29 2014 +0100
>
> * include/std/condition_variable (condition_variable_any::_Unlock): Do
> not swallow __forced_unwind.
> * include/std/future (__future_base::_Task_setter): Likewise.
> (__future_base::_Async_state_impl): Turn __forced_unwind into broken
> promise and rethrow.
> * include/std/mutex (try_lock): Likewise.
> * testsuite/30_threads/async/forced_unwind.cc: New.
> * testsuite/30_threads/packaged_task/forced_unwind.cc: New.
>
>diff --git a/libstdc++-v3/include/std/condition_variable b/libstdc++-v3/include/std/condition_variable
>index fc111dd..921cb83 100644
>--- a/libstdc++-v3/include/std/condition_variable
>+++ b/libstdc++-v3/include/std/condition_variable
>@@ -189,7 +189,14 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
> ~_Unlock() noexcept(false)
> {
> if (uncaught_exception())
>- __try { _M_lock.lock(); } __catch(...) { }
>+ {
>+ __try
>+ { _M_lock.lock(); }
>+ __catch(const __cxxabiv1::__forced_unwind&)
>+ { __throw_exception_again; }
>+ __catch(...)
>+ { }
>+ }
> else
> _M_lock.lock();
> }
>diff --git a/libstdc++-v3/include/std/future b/libstdc++-v3/include/std/future
>index 717ce71..8972ecf 100644
>--- a/libstdc++-v3/include/std/future
>+++ b/libstdc++-v3/include/std/future
>@@ -1231,6 +1231,10 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
> {
> _M_result->_M_set(_M_fn());
> }
>+ __catch(const __cxxabiv1::__forced_unwind&)
>+ {
>+ __throw_exception_again; // will cause broken_promise
>+ }
> __catch(...)
> {
> _M_result->_M_error = current_exception();
>@@ -1250,6 +1254,10 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
> {
> _M_fn();
> }
>+ __catch(const __cxxabiv1::__forced_unwind&)
>+ {
>+ __throw_exception_again; // will cause broken_promise
>+ }
> __catch(...)
> {
> _M_result->_M_error = current_exception();
>@@ -1510,7 +1518,17 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
> : _M_result(new _Result<_Res>()), _M_fn(std::move(__fn))
> {
> _M_thread = std::thread{ [this] {
>- _M_set_result(_S_task_setter(_M_result, _M_fn));
>+ __try
>+ {
>+ _M_set_result(_S_task_setter(_M_result, _M_fn));
>+ }
>+ __catch (const __cxxabiv1::__forced_unwind&)
>+ {
>+ // make the shared state ready on thread cancellation
>+ if (static_cast<bool>(_M_result))
>+ this->_M_break_promise(std::move(_M_result));
>+ __throw_exception_again;
>+ }
> } };
> }
>
>diff --git a/libstdc++-v3/include/std/mutex b/libstdc++-v3/include/std/mutex
>index 3d70754..f6b851c 100644
>--- a/libstdc++-v3/include/std/mutex
>+++ b/libstdc++-v3/include/std/mutex
>@@ -44,6 +44,7 @@
> #include <bits/functexcept.h>
> #include <bits/gthr.h>
> #include <bits/move.h> // for std::swap
>+#include <bits/cxxabi_forced.h>
>
> #ifdef _GLIBCXX_USE_C99_STDINT_TR1
>
>@@ -631,6 +632,8 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
> auto __locks = std::tie(__l1, __l2, __l3...);
> __try
> { __try_lock_impl<0>::__do_try_lock(__locks, __idx); }
>+ __catch(const __cxxabiv1::__forced_unwind&)
>+ { __throw_exception_again; }
> __catch(...)
> { }
> return __idx;
>diff --git a/libstdc++-v3/testsuite/30_threads/async/forced_unwind.cc b/libstdc++-v3/testsuite/30_threads/async/forced_unwind.cc
>new file mode 100644
>index 0000000..7b0a492
>--- /dev/null
>+++ b/libstdc++-v3/testsuite/30_threads/async/forced_unwind.cc
>@@ -0,0 +1,45 @@
>+// { dg-do run { target *-*-linux* *-*-gnu* } }
>+// { dg-options " -std=gnu++11 -pthread" { target *-*-linux* *-*-gnu* } }
>+// { 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/>.
>+
>+// Test (non-standard) handling of __forced_unwind exception.
>+
>+#include <future>
>+#include <stdexcept>
>+#include <pthread.h>
>+#include <testsuite_hooks.h>
>+
>+void f() { pthread_exit(nullptr); }
>+
>+int main()
>+{
>+ auto fut = std::async(std::launch::async, f);
>+ try
>+ {
>+ fut.get();
>+ throw std::logic_error("Unreachable");
>+ }
>+ catch (const std::future_error& e)
>+ {
>+ VERIFY( e.code() == std::future_errc::broken_promise );
>+ }
>+}
>diff --git a/libstdc++-v3/testsuite/30_threads/packaged_task/forced_unwind.cc b/libstdc++-v3/testsuite/30_threads/packaged_task/forced_unwind.cc
>new file mode 100644
>index 0000000..235ab17
>--- /dev/null
>+++ b/libstdc++-v3/testsuite/30_threads/packaged_task/forced_unwind.cc
>@@ -0,0 +1,48 @@
>+// { dg-do run { target *-*-linux* *-*-gnu* } }
>+// { dg-options " -std=gnu++11 -pthread" { target *-*-linux* *-*-gnu* } }
>+// { 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/>.
>+
>+// Test (non-standard) handling of __forced_unwind exception.
>+
>+#include <future>
>+#include <stdexcept>
>+#include <pthread.h>
>+#include <testsuite_hooks.h>
>+
>+void f() { pthread_exit(nullptr); }
>+
>+int main()
>+{
>+ std::packaged_task<void()> p(f);
>+ auto fut = p.get_future();
>+ std::thread t(std::move(p));
>+ try
>+ {
>+ fut.get();
>+ throw std::logic_error("Unreachable");
>+ }
>+ catch (const std::future_error& e)
>+ {
>+ VERIFY( e.code() == std::future_errc::broken_promise );
>+ }
>+ t.join();
>+}
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