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/* Copyright (C) 2018 the mpv developers
*
* Permission to use, copy, modify, and/or distribute this software for any
* purpose with or without fee is hereby granted, provided that the above
* copyright notice and this permission notice appear in all copies.
*
* THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
* WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
* MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
* ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
* WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
* ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
* OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
*/
#include <assert.h>
#include <string.h>
#include "thread_tools.h"
uintptr_t mp_waiter_wait(struct mp_waiter *waiter)
{
pthread_mutex_lock(&waiter->lock);
while (!waiter->done)
pthread_cond_wait(&waiter->wakeup, &waiter->lock);
pthread_mutex_unlock(&waiter->lock);
uintptr_t ret = waiter->value;
// We document that after mp_waiter_wait() the waiter object becomes
// invalid. (It strictly returns only after mp_waiter_wakeup() has returned,
// and the object is "single-shot".) So destroy it here.
// Normally, we expect that the system uses futexes, in which case the
// following functions will do nearly nothing. This is true for Windows
// and Linux. But some lesser OSes still might allocate kernel objects
// when initializing mutexes, so destroy them here.
pthread_mutex_destroy(&waiter->lock);
pthread_cond_destroy(&waiter->wakeup);
memset(waiter, 0xCA, sizeof(*waiter)); // for debugging
return ret;
}
void mp_waiter_wakeup(struct mp_waiter *waiter, uintptr_t value)
{
pthread_mutex_lock(&waiter->lock);
assert(!waiter->done);
waiter->done = true;
waiter->value = value;
pthread_cond_signal(&waiter->wakeup);
pthread_mutex_unlock(&waiter->lock);
}
bool mp_waiter_poll(struct mp_waiter *waiter)
{
pthread_mutex_lock(&waiter->lock);
bool r = waiter->done;
pthread_mutex_unlock(&waiter->lock);
return r;
}
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