1 files changed, 122 insertions, 0 deletions
diff --git a/src/core/lib/gpr/sync.cc b/src/core/lib/gpr/sync.cc
new file mode 100644
index 0000000000..347ffcd00e
--- /dev/null
+++ b/src/core/lib/gpr/sync.cc
@@ -0,0 +1,122 @@
+/*
+ *
+ * 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);
+}