extern "C" int pthread_cond_wait(pthread_cond_t *cond, pthread_mutex_t *mutex)
{
WRAPPER_HEADER(int, pthread_cond_wait, _real_pthread_cond_wait, cond, mutex);
/*
* pthread_cond_wait() internally consists of three events:
* pthread_mutex_unlock()
* block on cond-var cond
* pthread_mutex_lock()
* Ideally we would like to log the pthread_mutex_{lock,unlock} calls, but
* since libpthread is making internal calls, we are unable to do so.
*
* Due to our inablility to force threads to acquire the mutex during REPLAY,
* on broadcast calls, all threads blocked on condition variable wake up and
* start to executing inside the critical section without acquiring the
* mutex. This is * totally undesired and incorrect.
*
* The solution is to make threads wait until the thread executing inside the
* critical section has left the critical section (This is done either by and
* explicit call to pthread_mutex_unlock() or a call to pthread_cond_wait()
* which involves unlocking the mutex).
*
* In order to do so, we introduce a _fake_ pthread_mutex_unlock() call (The
* call is fake in the sense that _real_XXX version is never called during
* record or replay). This extra log event makes sure that the other threads
* have to wait until the thread in critical section is able to process this
* event, hence making sure that only one thread is executing in the critical
* section during REPLAY.
*/
FAKE_BASIC_SYNC_WRAPPER(int, pthread_mutex_unlock, mutex);
if (SYNC_IS_REPLAY) {
WRAPPER_REPLAY(pthread_cond_wait);
} else if (SYNC_IS_RECORD) {
dmtcp::ThreadInfo::setOptionalEvent();
retval = _real_pthread_cond_wait(cond, mutex);
dmtcp::ThreadInfo::unsetOptionalEvent();
WRAPPER_LOG_WRITE_ENTRY(pthread_cond_wait);
}
return retval;
}
extern "C" int
pthread_cond_wait(pthread_cond_t *cond, pthread_mutex_t *mutex)
{
return _real_pthread_cond_wait(cond, mutex);
}
