chromium/v8/src/tasks/operations-barrier.h

// Copyright 2020 the V8 project authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#ifndef V8_TASKS_OPERATIONS_BARRIER_H_
#define V8_TASKS_OPERATIONS_BARRIER_H_

#include <cstdint>

#include "src/base/macros.h"
#include "src/base/platform/condition-variable.h"
#include "src/base/platform/mutex.h"

namespace v8 {
namespace internal {

// A thread-safe barrier to manage lifetime of muti-threaded operations.
//
// The barrier is used to determine if operations are allowed, and to keep track
// of how many are currently active. Users will call TryLock() before starting
// such operations. If the call succeeds the user can run the operation and the
// barrier will keep track of it until the user signals that the operation is
// completed. No operations are allowed after CancelAndWait() is called.
//
// There is no explicit way of telling the barrier when an operation is
// completed, instead for convenience TryLock() will return a RAII
// like object that will do so on destruction.
//
// For example:
//
// OperationsBarrier barrier_;
//
// void TearDown() {
//   barrier_.CancelAndWait();
// }
//
// void MaybeRunOperation() {
//   if (token = barrier_.TryLock()) Process();
// }
//
class V8_EXPORT_PRIVATE OperationsBarrier { … };

}  // namespace internal
}  // namespace v8

#endif  // V8_TASKS_OPERATIONS_BARRIER_H_