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/*-------------------------------------------------------------------------
*
* pthread_barrier_wait.c
* Implementation of pthread_barrier_t support for platforms lacking it.
*
* Portions Copyright (c) 1996-2022, PostgreSQL Global Development Group
*
* IDENTIFICATION
* src/port/pthread_barrier_wait.c
*
*-------------------------------------------------------------------------
*/
#include "c.h"
#include "port/pg_pthread.h"
int
pthread_barrier_init(pthread_barrier_t *barrier, const void *attr, int count)
{
int error;
barrier->sense = false;
barrier->count = count;
barrier->arrived = 0;
if ((error = pthread_cond_init(&barrier->cond, NULL)) != 0)
return error;
if ((error = pthread_mutex_init(&barrier->mutex, NULL)) != 0)
{
pthread_cond_destroy(&barrier->cond);
return error;
}
return 0;
}
int
pthread_barrier_wait(pthread_barrier_t *barrier)
{
bool initial_sense;
pthread_mutex_lock(&barrier->mutex);
/* We have arrived at the barrier. */
barrier->arrived++;
Assert(barrier->arrived <= barrier->count);
/* If we were the last to arrive, release the others and return. */
if (barrier->arrived == barrier->count)
{
barrier->arrived = 0;
barrier->sense = !barrier->sense;
pthread_mutex_unlock(&barrier->mutex);
pthread_cond_broadcast(&barrier->cond);
return PTHREAD_BARRIER_SERIAL_THREAD;
}
/* Wait for someone else to flip the sense. */
initial_sense = barrier->sense;
do
{
pthread_cond_wait(&barrier->cond, &barrier->mutex);
} while (barrier->sense == initial_sense);
pthread_mutex_unlock(&barrier->mutex);
return 0;
}
int
pthread_barrier_destroy(pthread_barrier_t *barrier)
{
pthread_cond_destroy(&barrier->cond);
pthread_mutex_destroy(&barrier->mutex);
return 0;
}
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