minetest/src/threading/mutex.cpp
ShadowNinja c93f7f5cea Fix synchronization issue at thread start
If a newly spawned thread called getThreadId or getThreadHandle before
the spawning thread finished saving the thread handle, then the
handle/id would be used uninitialized.  This would cause the threading
tests to fail since isCurrentThread would return false, and if Minetest
is built with C++11 support the std::thread object pointer would be
dereferenced while ininitialized, causing a segmentation fault.

This fixes the issue by using a mutex to force the spawned thread to
wait for the spawning thread to finish initializing the thread object.

An alternative way to handle this would be to also set the thread
handle/id in the started thread but this wouldn't work for C++11
builds because there's no way to get the partially constructed object.
2017-01-28 18:52:07 -05:00

117 lines
2.5 KiB
C++

/*
This file is a part of the JThread package, which contains some object-
oriented thread wrappers for different thread implementations.
Copyright (c) 2000-2006 Jori Liesenborgs (jori.liesenborgs@gmail.com)
Permission is hereby granted, free of charge, to any person obtaining a
copy of this software and associated documentation files (the "Software"),
to deal in the Software without restriction, including without limitation
the rights to use, copy, modify, merge, publish, distribute, sublicense,
and/or sell copies of the Software, and to permit persons to whom the
Software is furnished to do so, subject to the following conditions:
The above copyright notice and this permission notice shall be included in
all copies or substantial portions of the Software.
THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
DEALINGS IN THE SOFTWARE.
*/
#include "threads.h"
#ifndef USE_CPP11_MUTEX
#include "threading/mutex.h"
#include <cassert>
#define UNUSED(expr) do { (void)(expr); } while (0)
Mutex::Mutex()
{
init_mutex(false);
}
Mutex::Mutex(bool recursive)
{
init_mutex(recursive);
}
void Mutex::init_mutex(bool recursive)
{
#if USE_WIN_MUTEX
// Windows critical sections are recursive by default
UNUSED(recursive);
InitializeCriticalSection(&mutex);
#else
pthread_mutexattr_t attr;
pthread_mutexattr_init(&attr);
if (recursive)
pthread_mutexattr_settype(&attr, PTHREAD_MUTEX_RECURSIVE);
int ret = pthread_mutex_init(&mutex, &attr);
assert(!ret);
UNUSED(ret);
pthread_mutexattr_destroy(&attr);
#endif
}
Mutex::~Mutex()
{
#if USE_WIN_MUTEX
DeleteCriticalSection(&mutex);
#else
int ret = pthread_mutex_destroy(&mutex);
assert(!ret);
UNUSED(ret);
#endif
}
void Mutex::lock()
{
#if USE_WIN_MUTEX
EnterCriticalSection(&mutex);
#else
int ret = pthread_mutex_lock(&mutex);
assert(!ret);
UNUSED(ret);
#endif
}
bool Mutex::try_lock()
{
#if USE_WIN_MUTEX
return TryEnterCriticalSection(&mutex) != 0;
#else
return pthread_mutex_trylock(&mutex) == 0;
#endif
}
void Mutex::unlock()
{
#if USE_WIN_MUTEX
LeaveCriticalSection(&mutex);
#else
int ret = pthread_mutex_unlock(&mutex);
assert(!ret);
UNUSED(ret);
#endif
}
RecursiveMutex::RecursiveMutex()
: Mutex(true)
{}
#endif // C++11