naiveproxy/base/task/sequence_manager/lazy_now.h
2018-08-11 05:35:24 +00:00

42 lines
1.1 KiB
C++

// Copyright 2018 The Chromium 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 BASE_TASK_SEQUENCE_MANAGER_LAZY_NOW_H_
#define BASE_TASK_SEQUENCE_MANAGER_LAZY_NOW_H_
#include "base/base_export.h"
#include "base/optional.h"
#include "base/time/time.h"
namespace base {
class TickClock;
namespace sequence_manager {
// Now() is somewhat expensive so it makes sense not to call Now() unless we
// really need to and to avoid subsequent calls if already called once.
// LazyNow objects are expected to be short-living to represent accurate time.
class BASE_EXPORT LazyNow {
public:
explicit LazyNow(TimeTicks now);
explicit LazyNow(const TickClock* tick_clock);
LazyNow(LazyNow&& move_from) noexcept;
// Result will not be updated on any subsesequent calls.
TimeTicks Now();
private:
const TickClock* tick_clock_; // Not owned.
Optional<TimeTicks> now_;
DISALLOW_COPY_AND_ASSIGN(LazyNow);
};
} // namespace sequence_manager
} // namespace base
#endif // BASE_TASK_SEQUENCE_MANAGER_LAZY_NOW_H_