/*
* __wt_cond_signal --
* Signal a waiting thread.
*/
int
__wt_cond_signal(WT_SESSION_IMPL *session, WT_CONDVAR *cond)
{
WT_DECL_RET;
int locked;
locked = 0;
/*
* !!!
* This function MUST handle a NULL session handle.
*/
if (session != NULL)
WT_RET(__wt_verbose(session, WT_VERB_MUTEX,
"signal %s cond (%p)", cond->name, cond));
/* Fast path if already signalled. */
if (cond->waiters == -1)
return (0);
if (cond->waiters > 0 || !__wt_atomic_casi32(&cond->waiters, 0, -1)) {
WT_ERR(pthread_mutex_lock(&cond->mtx));
locked = 1;
WT_ERR(pthread_cond_broadcast(&cond->cond));
}
err: if (locked)
WT_TRET(pthread_mutex_unlock(&cond->mtx));
if (ret == 0)
return (0);
WT_RET_MSG(session, ret, "pthread_cond_broadcast");
}
/*
* __wt_cond_signal --
* Signal a waiting thread.
*/
void
__wt_cond_signal(WT_SESSION_IMPL *session, WT_CONDVAR *cond)
{
WT_DECL_RET;
__wt_verbose(session, WT_VERB_MUTEX, "signal %s", cond->name);
/*
* Our callers often set flags to cause a thread to exit. Add a barrier
* to ensure exit flags are seen by the sleeping threads, otherwise we
* can wake up a thread, it immediately goes back to sleep, and we'll
* hang. Use a full barrier (we may not write before waiting on thread
* join).
*/
WT_FULL_BARRIER();
/*
* Fast path if we are in (or can enter), a state where the next waiter
* will return immediately as already signaled.
*/
if (cond->waiters == -1 ||
(cond->waiters == 0 && __wt_atomic_casi32(&cond->waiters, 0, -1)))
return;
EnterCriticalSection(&cond->mtx);
WakeAllConditionVariable(&cond->cond);
LeaveCriticalSection(&cond->mtx);
}
/*
* __wt_cond_signal --
* Signal a waiting thread.
*/
int
__wt_cond_signal(WT_SESSION_IMPL *session, WT_CONDVAR *cond)
{
WT_DECL_RET;
bool locked;
locked = false;
/*
* !!!
* This function MUST handle a NULL session handle.
*/
if (session != NULL)
WT_RET(__wt_verbose(session, WT_VERB_MUTEX,
"signal %s cond (%p)", cond->name, cond));
/* Fast path if already signalled. */
if (cond->waiters == -1)
return (0);
if (cond->waiters > 0 || !__wt_atomic_casi32(&cond->waiters, 0, -1)) {
EnterCriticalSection(&cond->mtx);
locked = true;
WakeAllConditionVariable(&cond->cond);
}
if (locked)
LeaveCriticalSection(&cond->mtx);
if (ret == 0)
return (0);
WT_RET_MSG(session, ret, "WakeAllConditionVariable");
}
