Initial Commit

absl/synchronization/notification.cc

@@ -0,0 +1,84 @@
+// Copyright 2017 The Abseil 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.
+
+#include "absl/synchronization/notification.h"
+
+#include <atomic>
+
+#include "absl/base/attributes.h"
+#include "absl/base/internal/raw_logging.h"
+#include "absl/synchronization/mutex.h"
+#include "absl/time/time.h"
+
+namespace absl {
+void Notification::Notify() {
+  MutexLock l(&this->mutex_);
+
+#ifndef NDEBUG
+  if (ABSL_PREDICT_FALSE(notified_yet_.load(std::memory_order_relaxed))) {
+    ABSL_RAW_LOG(
+        FATAL,
+        "Notify() method called more than once for Notification object %p",
+        static_cast<void *>(this));
+  }
+#endif
+
+  notified_yet_.store(true, std::memory_order_release);
+}
+
+Notification::~Notification() {
+  // Make sure that the thread running Notify() exits before the object is
+  // destructed.
+  MutexLock l(&this->mutex_);
+}
+
+static inline bool HasBeenNotifiedInternal(
+    const std::atomic<bool> *notified_yet) {
+  return notified_yet->load(std::memory_order_acquire);
+}
+
+bool Notification::HasBeenNotified() const {
+  return HasBeenNotifiedInternal(&this->notified_yet_);
+}
+
+void Notification::WaitForNotification() const {
+  if (!HasBeenNotifiedInternal(&this->notified_yet_)) {
+    this->mutex_.LockWhen(Condition(&HasBeenNotifiedInternal,
+                                    &this->notified_yet_));
+    this->mutex_.Unlock();
+  }
+}
+
+bool Notification::WaitForNotificationWithTimeout(
+    absl::Duration timeout) const {
+  bool notified = HasBeenNotifiedInternal(&this->notified_yet_);
+  if (!notified) {
+    notified = this->mutex_.LockWhenWithTimeout(
+        Condition(&HasBeenNotifiedInternal, &this->notified_yet_), timeout);
+    this->mutex_.Unlock();
+  }
+  return notified;
+}
+
+bool Notification::WaitForNotificationWithDeadline(absl::Time deadline) const {
+  bool notified = HasBeenNotifiedInternal(&this->notified_yet_);
+  if (!notified) {
+    notified = this->mutex_.LockWhenWithDeadline(
+        Condition(&HasBeenNotifiedInternal, &this->notified_yet_), deadline);
+    this->mutex_.Unlock();
+  }
+  return notified;
+}
+
+}  // namespace absl