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Re: [patch] proposed fix for libstdc++/54352
- From: Jonathan Wakely <jwakely dot gcc at gmail dot com>
- To: "libstdc++" <libstdc++ at gcc dot gnu dot org>, gcc-patches <gcc-patches at gcc dot gnu dot org>
- Date: Sun, 21 Jul 2013 20:21:30 +0100
- Subject: Re: [patch] proposed fix for libstdc++/54352
- References: <CAH6eHdSWwnhirSQ9u5qsSzKHyEObO1dg8iVLyeE9bOLkbfoXwQ at mail dot gmail dot com>
On 16 June 2013 15:35, Jonathan Wakely wrote:
> In order to conform to [thread.condition.condvarany]/5 and fix this
> PR we need an ABI change to std::condition_variable_any, so that its
> internal mutex can outlive the condition_variable_any while there are
> threads blocked on the mutex, which this patch does by using a
> shared_ptr to hold the mutex and making waiting threads share
> ownership of that mutex.
> The ABI change is handled similarly to the recent chrono::steady_clock
> changes, using an inline namespace for the new versions and continuing
> to export the old version from the library for compatibility with old
> Any thoughts or suggestions on improving this before I commit it to trunk?
> I can no longer reproduce the valgrind errors, except by hacking in
> changes to std::mutex to cause races, so I haven't been able to write
> a test case that fails without this change, but I believe it's still
> necessary for correctness.
> PR libstdc++/54352
> * include/std/condition_variable (condition_variable_any): Move into
> inline namespace _V2 and replace mutex member with shared_ptr<mutex>.
> * src/c++11/condition_variable.cc (condition_variable_any): Move
> definitions to ...
> * src/c++11/compatibility-condvar.cc (condition_variable_any): Here.
> * src/Makefile.am: Add new source file.
> * src/Makefile.in: Regenerate.
I've just committed this to trunk.