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/*
*
* Copyright 2015 gRPC authors.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*
*/
/* Generic implementation of synchronization primitives. */
#include <grpc/support/atm.h>
#include <grpc/support/log.h>
#include <grpc/support/sync.h>
#include <assert.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 != nullptr);
}
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 == nullptr) {
struct sync_array_s* s = hash(ev);
gpr_mu_lock(&s->mu);
do {
result = (void*)gpr_atm_acq_load(&ev->state);
} while (result == nullptr && !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_ref_non_zero(gpr_refcount* r) {
#ifndef NDEBUG
gpr_atm prior = gpr_atm_no_barrier_fetch_add(&r->count, 1);
assert(prior > 0);
#else
gpr_ref(r);
#endif
}
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;
}
int gpr_ref_is_unique(gpr_refcount* r) {
return gpr_atm_acq_load(&r->count) == 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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