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/*
*
* Copyright 2015, Google Inc.
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are
* met:
*
* * Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* * Redistributions in binary form must reproduce the above
* copyright notice, this list of conditions and the following disclaimer
* in the documentation and/or other materials provided with the
* distribution.
* * Neither the name of Google Inc. nor the names of its
* contributors may be used to endorse or promote products derived from
* this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
* A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
* OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
* LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*
*/
/* Generic implementation of synchronization primitives. */
#include <grpc/support/log.h>
#include <grpc/support/sync.h>
#include <grpc/support/atm.h>
/* Number of mutexes to allocate for events, to avoid lock contention.
Should be a prime. */
enum { event_sync_partitions = 31 };
/* Events are partitioned by address to avoid lock contention. */
static struct sync_array_s {
gpr_mu mu;
gpr_cv cv;
} sync_array[event_sync_partitions];
/* This routine is executed once on first use, via event_once */
static gpr_once event_once = GPR_ONCE_INIT;
static void event_initialize(void) {
int i;
for (i = 0; i != event_sync_partitions; i++) {
gpr_mu_init(&sync_array[i].mu);
gpr_cv_init(&sync_array[i].cv);
}
}
/* Hash ev into an element of sync_array[]. */
static struct sync_array_s *hash(gpr_event *ev) {
return &sync_array[((uintptr_t)ev) % event_sync_partitions];
}
void gpr_event_init(gpr_event *ev) {
gpr_once_init(&event_once, &event_initialize);
ev->state = 0;
}
void gpr_event_set(gpr_event *ev, void *value) {
struct sync_array_s *s = hash(ev);
gpr_mu_lock(&s->mu);
GPR_ASSERT(gpr_atm_acq_load(&ev->state) == 0);
gpr_atm_rel_store(&ev->state, (gpr_atm)value);
gpr_cv_broadcast(&s->cv);
gpr_mu_unlock(&s->mu);
GPR_ASSERT(value != NULL);
}
void *gpr_event_get(gpr_event *ev) {
return (void *)gpr_atm_acq_load(&ev->state);
}
void *gpr_event_wait(gpr_event *ev, gpr_timespec abs_deadline) {
void *result = (void *)gpr_atm_acq_load(&ev->state);
if (result == NULL) {
struct sync_array_s *s = hash(ev);
gpr_mu_lock(&s->mu);
do {
result = (void *)gpr_atm_acq_load(&ev->state);
} while (result == NULL && !gpr_cv_wait(&s->cv, &s->mu, abs_deadline));
gpr_mu_unlock(&s->mu);
}
return result;
}
void gpr_ref_init(gpr_refcount *r, int n) { gpr_atm_rel_store(&r->count, n); }
void gpr_ref(gpr_refcount *r) { gpr_atm_no_barrier_fetch_add(&r->count, 1); }
void gpr_refn(gpr_refcount *r, int n) {
gpr_atm_no_barrier_fetch_add(&r->count, n);
}
int gpr_unref(gpr_refcount *r) {
gpr_atm prior = gpr_atm_full_fetch_add(&r->count, -1);
GPR_ASSERT(prior > 0);
return prior == 1;
}
void gpr_stats_init(gpr_stats_counter *c, intptr_t n) {
gpr_atm_rel_store(&c->value, n);
}
void gpr_stats_inc(gpr_stats_counter *c, intptr_t inc) {
gpr_atm_no_barrier_fetch_add(&c->value, inc);
}
intptr_t gpr_stats_read(const gpr_stats_counter *c) {
/* don't need acquire-load, but we have no no-barrier load yet */
return gpr_atm_acq_load(&c->value);
}
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