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base / task / sequence_manager / enqueue_order_generator.h [blame]
// Copyright 2019 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#ifndef BASE_TASK_SEQUENCE_MANAGER_ENQUEUE_ORDER_GENERATOR_H_
#define BASE_TASK_SEQUENCE_MANAGER_ENQUEUE_ORDER_GENERATOR_H_
#include <stdint.h>
#include <atomic>
#include "base/base_export.h"
#include "base/task/sequence_manager/enqueue_order.h"
namespace base {
namespace sequence_manager {
namespace internal {
// EnqueueOrder can't be created from a raw number in non-test code.
// EnqueueOrderGenerator is used to create it with strictly monotonic guarantee.
class BASE_EXPORT EnqueueOrderGenerator {
public:
EnqueueOrderGenerator();
EnqueueOrderGenerator(const EnqueueOrderGenerator&) = delete;
EnqueueOrderGenerator& operator=(const EnqueueOrderGenerator&) = delete;
~EnqueueOrderGenerator();
// Can be called from any thread.
EnqueueOrder GenerateNext() {
return EnqueueOrder(std::atomic_fetch_add_explicit(
&counter_, uint64_t(1), std::memory_order_relaxed));
}
private:
std::atomic<uint64_t> counter_;
};
} // namespace internal
} // namespace sequence_manager
} // namespace base
#endif // BASE_TASK_SEQUENCE_MANAGER_ENQUEUE_ORDER_GENERATOR_H_