44 lines
1.1 KiB
C
44 lines
1.1 KiB
C
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// Copyright 2018 The Chromium Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style license that can be
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// found in the LICENSE file.
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#ifndef BASE_TASK_SEQUENCE_MANAGER_LAZY_NOW_H_
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#define BASE_TASK_SEQUENCE_MANAGER_LAZY_NOW_H_
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#include "base/base_export.h"
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#include "base/optional.h"
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#include "base/time/time.h"
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namespace base {
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class TickClock;
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namespace sequence_manager {
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// Now() is somewhat expensive so it makes sense not to call Now() unless we
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// really need to and to avoid subsequent calls if already called once.
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// LazyNow objects are expected to be short-living to represent accurate time.
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class BASE_EXPORT LazyNow {
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public:
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explicit LazyNow(TimeTicks now);
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explicit LazyNow(const TickClock* tick_clock);
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LazyNow(LazyNow&& move_from) noexcept;
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// Result will not be updated on any subsesequent calls.
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TimeTicks Now();
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bool has_value() const { return !!now_; }
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private:
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const TickClock* tick_clock_; // Not owned.
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Optional<TimeTicks> now_;
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DISALLOW_COPY_AND_ASSIGN(LazyNow);
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};
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} // namespace sequence_manager
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} // namespace base
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#endif // BASE_TASK_SEQUENCE_MANAGER_LAZY_NOW_H_
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