147 lines
3.2 KiB
C
147 lines
3.2 KiB
C
/* $OpenBSD: rthread_barrier.c,v 1.5 2020/04/06 00:01:08 pirofti Exp $ */
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/*
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* Copyright (c) 2012 Paul Irofti <paul@irofti.net>
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*
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* Permission to use, copy, modify, and/or distribute this software for any
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* purpose with or without fee is hereby granted, provided that the above
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* copyright notice and this permission notice appear in all copies.
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*
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* THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
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* WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
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* MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
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* ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
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* WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
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* ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
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* OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
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*/
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#include <errno.h>
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#include <stdlib.h>
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#include <pthread.h>
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#include "rthread.h"
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int
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pthread_barrier_init(pthread_barrier_t *barrier, pthread_barrierattr_t *attr,
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unsigned int count) {
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int rc = 0;
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pthread_barrier_t b = NULL;
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if (barrier == NULL)
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return (EINVAL);
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if (count == 0)
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return (EINVAL);
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if (attr != NULL) {
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if (*attr == NULL)
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return (EINVAL);
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if ((*attr)->pshared != PTHREAD_PROCESS_PRIVATE)
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return (ENOTSUP);
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}
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b = calloc(1, sizeof *b);
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if (b == NULL)
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return (ENOMEM);
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if ((rc = pthread_mutex_init(&b->mutex, NULL)))
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goto err;
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if ((rc = pthread_cond_init(&b->cond, NULL)))
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goto err;
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b->threshold = count;
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*barrier = b;
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return (0);
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err:
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if (b) {
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if (b->mutex)
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pthread_mutex_destroy(&b->mutex);
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if (b->cond)
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pthread_cond_destroy(&b->cond);
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free(b);
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}
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return (rc);
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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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int rc;
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pthread_barrier_t b;
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if (barrier == NULL || *barrier == NULL)
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return (EINVAL);
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if ((rc = pthread_mutex_lock(&(*barrier)->mutex)))
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return (rc);
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b = *barrier;
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if (b->out > 0 || b->in > 0) {
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pthread_mutex_unlock(&b->mutex);
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return (EBUSY);
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}
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*barrier = NULL;
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pthread_mutex_unlock(&b->mutex);
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pthread_mutex_destroy(&b->mutex);
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pthread_cond_destroy(&b->cond);
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free(b);
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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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pthread_barrier_t b;
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int rc, old_state, gen;
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int done = 0;
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if (barrier == NULL || *barrier == NULL)
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return (EINVAL);
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if ((rc = pthread_setcancelstate(PTHREAD_CANCEL_DISABLE, &old_state)))
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return (rc);
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b = *barrier;
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if ((rc = pthread_mutex_lock(&b->mutex)))
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goto cancel;
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_rthread_debug(6, "in: %d, threshold: %d\n", b->in, b->threshold);
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if (++b->in == b->threshold) {
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b->out = b->in - 1;
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b->in = 0;
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b->generation++;
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if ((rc = pthread_cond_signal(&b->cond)))
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goto err;
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done = 1;
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_rthread_debug(6, "threshold reached\n");
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} else {
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gen = b->generation;
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_rthread_debug(6, "waiting on condition\n");
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do {
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if ((rc = pthread_cond_wait(&b->cond, &b->mutex)))
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goto err;
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} while (gen == b->generation);
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b->out--; /* mark thread exit */
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if ((rc = pthread_cond_signal(&b->cond)))
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goto err;
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}
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err:
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if ((rc = pthread_mutex_unlock(&b->mutex)))
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return (rc);
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cancel:
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rc = pthread_setcancelstate(old_state, NULL);
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if (rc == 0 && done)
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rc = PTHREAD_BARRIER_SERIAL_THREAD;
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return (rc);
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}
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