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Diffstat (limited to 'deps/v8/src/platform/elapsed-timer.h')
-rw-r--r-- | deps/v8/src/platform/elapsed-timer.h | 120 |
1 files changed, 120 insertions, 0 deletions
diff --git a/deps/v8/src/platform/elapsed-timer.h b/deps/v8/src/platform/elapsed-timer.h new file mode 100644 index 0000000000..2311db2f52 --- /dev/null +++ b/deps/v8/src/platform/elapsed-timer.h @@ -0,0 +1,120 @@ +// Copyright 2013 the V8 project authors. All rights reserved. +// Redistribution and use in source and binary forms, with or without +// modification, are permitted provided that the following conditions are +// met: +// +// * Redistributions of source code must retain the above copyright +// notice, this list of conditions and the following disclaimer. +// * Redistributions in binary form must reproduce the above +// copyright notice, this list of conditions and the following +// disclaimer in the documentation and/or other materials provided +// with the distribution. +// * Neither the name of Google Inc. nor the names of its +// contributors may be used to endorse or promote products derived +// from this software without specific prior written permission. +// +// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS +// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT +// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR +// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT +// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, +// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT +// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, +// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY +// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT +// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE +// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. + +#ifndef V8_PLATFORM_ELAPSED_TIMER_H_ +#define V8_PLATFORM_ELAPSED_TIMER_H_ + +#include "checks.h" +#include "platform/time.h" + +namespace v8 { +namespace internal { + +class ElapsedTimer V8_FINAL BASE_EMBEDDED { + public: +#ifdef DEBUG + ElapsedTimer() : started_(false) {} +#endif + + // Starts this timer. Once started a timer can be checked with + // |Elapsed()| or |HasExpired()|, and may be restarted using |Restart()|. + // This method must not be called on an already started timer. + void Start() { + ASSERT(!IsStarted()); + start_ticks_ = Now(); +#ifdef DEBUG + started_ = true; +#endif + ASSERT(IsStarted()); + } + + // Stops this timer. Must not be called on a timer that was not + // started before. + void Stop() { + ASSERT(IsStarted()); + start_ticks_ = TimeTicks(); +#ifdef DEBUG + started_ = false; +#endif + ASSERT(!IsStarted()); + } + + // Returns |true| if this timer was started previously. + bool IsStarted() const { + ASSERT(started_ || start_ticks_.IsNull()); + ASSERT(!started_ || !start_ticks_.IsNull()); + return !start_ticks_.IsNull(); + } + + // Restarts the timer and returns the time elapsed since the previous start. + // This method is equivalent to obtaining the elapsed time with |Elapsed()| + // and then starting the timer again, but does so in one single operation, + // avoiding the need to obtain the clock value twice. It may only be called + // on a previously started timer. + TimeDelta Restart() { + ASSERT(IsStarted()); + TimeTicks ticks = Now(); + TimeDelta elapsed = ticks - start_ticks_; + ASSERT(elapsed.InMicroseconds() >= 0); + start_ticks_ = ticks; + ASSERT(IsStarted()); + return elapsed; + } + + // Returns the time elapsed since the previous start. This method may only + // be called on a previously started timer. + TimeDelta Elapsed() const { + ASSERT(IsStarted()); + TimeDelta elapsed = Now() - start_ticks_; + ASSERT(elapsed.InMicroseconds() >= 0); + return elapsed; + } + + // Returns |true| if the specified |time_delta| has elapsed since the + // previous start, or |false| if not. This method may only be called on + // a previously started timer. + bool HasExpired(TimeDelta time_delta) const { + ASSERT(IsStarted()); + return Elapsed() >= time_delta; + } + + private: + static V8_INLINE TimeTicks Now() { + TimeTicks now = TimeTicks::HighResNow(); + ASSERT(!now.IsNull()); + return now; + } + + TimeTicks start_ticks_; +#ifdef DEBUG + bool started_; +#endif +}; + +} } // namespace v8::internal + +#endif // V8_PLATFORM_ELAPSED_TIMER_H_ |