// 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(); bool has_value() const { return !!now_; } private: const TickClock* tick_clock_; // Not owned. Optional now_; DISALLOW_COPY_AND_ASSIGN(LazyNow); }; } // namespace sequence_manager } // namespace base #endif // BASE_TASK_SEQUENCE_MANAGER_LAZY_NOW_H_