tick_clock.h 1.3 KB
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// Copyright (c) 2012 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.

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#ifndef BUTIL_TICK_CLOCK_H_
#define BUTIL_TICK_CLOCK_H_
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#include "butil/base_export.h"
#include "butil/time/time.h"
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namespace butil {
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// A TickClock is an interface for objects that vend TimeTicks.  It is
// intended to be able to test the behavior of classes with respect to
// non-decreasing time.
//
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// See DefaultTickClock (butil/time/default_tick_clock.h) for the default
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// implementation that simply uses TimeTicks::Now().
//
// (Other implementations that use TimeTicks::HighResNow() or
// TimeTicks::NowFromSystemTime() should be added as needed.)
//
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// See SimpleTestTickClock (butil/test/simple_test_tick_clock.h) for a
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// simple test implementation.
//
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// See Clock (butil/time/clock.h) for the equivalent interface for Times.
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class BUTIL_EXPORT TickClock {
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 public:
  virtual ~TickClock();

  // NowTicks() must be safe to call from any thread.  The caller may
  // assume that NowTicks() is monotonic (but not strictly monotonic).
  // In other words, the returned TimeTicks will never decrease with
  // time, although they might "stand still".
  virtual TimeTicks NowTicks() = 0;
};

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}  // namespace butil
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#endif  // BUTIL_TICK_CLOCK_H_