// 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.
#ifndef BASE_TICK_CLOCK_H_
#define BASE_TICK_CLOCK_H_
#include "base/base_export.h"
#include "base/time/time.h"
namespace base {
// 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.
//
// See DefaultTickClock (base/time/default_tick_clock.h) for the default
// implementation that simply uses TimeTicks::Now().
//
// (Other implementations that use TimeTicks::HighResNow() or
// TimeTicks::NowFromSystemTime() should be added as needed.)
//
// See SimpleTestTickClock (base/test/simple_test_tick_clock.h) for a
// simple test implementation.
//
// See Clock (base/time/clock.h) for the equivalent interface for Times.
class BASE_EXPORT TickClock {
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;
};
} // namespace base
#endif // BASE_TICK_CLOCK_H_