Repo created

TMessagesProj/jni/voip/webrtc/absl/synchronization/blocking_counter.cc

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+// 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
+//
+//      https://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/blocking_counter.h"
+
+#include <atomic>
+
+#include "absl/base/internal/raw_logging.h"
+#include "absl/base/internal/tracing.h"
+
+namespace absl {
+ABSL_NAMESPACE_BEGIN
+
+namespace {
+
+// Return whether int *arg is true.
+bool IsDone(void *arg) { return *reinterpret_cast<bool *>(arg); }
+
+}  // namespace
+
+BlockingCounter::BlockingCounter(int initial_count)
+    : count_(initial_count),
+      num_waiting_(0),
+      done_{initial_count == 0 ? true : false} {
+  ABSL_RAW_CHECK(initial_count >= 0, "BlockingCounter initial_count negative");
+}
+
+bool BlockingCounter::DecrementCount() {
+  int count = count_.fetch_sub(1, std::memory_order_acq_rel) - 1;
+  ABSL_RAW_CHECK(count >= 0,
+                 "BlockingCounter::DecrementCount() called too many times");
+  if (count == 0) {
+    base_internal::TraceSignal(this, TraceObjectKind());
+    MutexLock l(&lock_);
+    done_ = true;
+    return true;
+  }
+  return false;
+}
+
+void BlockingCounter::Wait() {
+  base_internal::TraceWait(this, TraceObjectKind());
+  {
+    MutexLock l(&this->lock_);
+
+    // only one thread may call Wait(). To support more than one thread,
+    // implement a counter num_to_exit, like in the Barrier class.
+    ABSL_RAW_CHECK(num_waiting_ == 0, "multiple threads called Wait()");
+    num_waiting_++;
+
+    this->lock_.Await(Condition(IsDone, &this->done_));
+
+    // At this point, we know that all threads executing DecrementCount
+    // will not touch this object again.
+    // Therefore, the thread calling this method is free to delete the object
+    // after we return from this method.
+  }
+  base_internal::TraceContinue(this, TraceObjectKind());
+}
+
+ABSL_NAMESPACE_END
+}  // namespace absl