1 // Copyright (c) 2012 The Chromium Authors. All rights reserved. 2 // Use of this source code is governed by a BSD-style license that can be 3 // found in the LICENSE file. 4 5 #ifndef BASE_TIME_TICK_CLOCK_H_ 6 #define BASE_TIME_TICK_CLOCK_H_ 7 8 #include "base/base_export.h" 9 #include "base/time/time.h" 10 11 namespace base { 12 13 // A TickClock is an interface for objects that vend TimeTicks. It is 14 // intended to be able to test the behavior of classes with respect to 15 // non-decreasing time. 16 // 17 // See DefaultTickClock (base/time/default_tick_clock.h) for the default 18 // implementation that simply uses TimeTicks::Now(). 19 // 20 // (Other implementations that use TimeTicks::NowFromSystemTime() should 21 // be added as needed.) 22 // 23 // See SimpleTestTickClock (base/test/simple_test_tick_clock.h) for a 24 // simple test implementation. 25 // 26 // See Clock (base/time/clock.h) for the equivalent interface for Times. 27 class BASE_EXPORT TickClock { 28 public: 29 virtual ~TickClock(); 30 31 // NowTicks() must be safe to call from any thread. The caller may 32 // assume that NowTicks() is monotonic (but not strictly monotonic). 33 // In other words, the returned TimeTicks will never decrease with 34 // time, although they might "stand still". 35 virtual TimeTicks NowTicks() = 0; 36 }; 37 38 } // namespace base 39 40 #endif // BASE_TIME_TICK_CLOCK_H_ 41
