78 lines
1.7 KiB
C
78 lines
1.7 KiB
C
/*-------------------------------------------------------------------------
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*
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* pthread_barrier_wait.c
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* Implementation of pthread_barrier_t support for platforms lacking it.
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*
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* Portions Copyright (c) 1996-2024, PostgreSQL Global Development Group
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*
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* IDENTIFICATION
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* src/port/pthread_barrier_wait.c
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*
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*-------------------------------------------------------------------------
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*/
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#include "c.h"
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#include "port/pg_pthread.h"
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int
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pthread_barrier_init(pthread_barrier_t *barrier, const void *attr, int count)
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{
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int error;
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barrier->sense = false;
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barrier->count = count;
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barrier->arrived = 0;
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if ((error = pthread_cond_init(&barrier->cond, NULL)) != 0)
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return error;
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if ((error = pthread_mutex_init(&barrier->mutex, NULL)) != 0)
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{
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pthread_cond_destroy(&barrier->cond);
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return error;
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}
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return 0;
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}
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int
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pthread_barrier_wait(pthread_barrier_t *barrier)
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{
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bool initial_sense;
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pthread_mutex_lock(&barrier->mutex);
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/* We have arrived at the barrier. */
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barrier->arrived++;
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Assert(barrier->arrived <= barrier->count);
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/* If we were the last to arrive, release the others and return. */
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if (barrier->arrived == barrier->count)
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{
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barrier->arrived = 0;
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barrier->sense = !barrier->sense;
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pthread_mutex_unlock(&barrier->mutex);
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pthread_cond_broadcast(&barrier->cond);
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return PTHREAD_BARRIER_SERIAL_THREAD;
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}
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/* Wait for someone else to flip the sense. */
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initial_sense = barrier->sense;
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do
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{
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pthread_cond_wait(&barrier->cond, &barrier->mutex);
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} while (barrier->sense == initial_sense);
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pthread_mutex_unlock(&barrier->mutex);
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return 0;
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}
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int
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pthread_barrier_destroy(pthread_barrier_t *barrier)
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{
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pthread_cond_destroy(&barrier->cond);
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pthread_mutex_destroy(&barrier->mutex);
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return 0;
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}
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