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// 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 "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::HighResolutionNow();
ASSERT(!now.IsNull());
return now;
}
TimeTicks start_ticks_;
#ifdef DEBUG
bool started_;
#endif
};
} } // namespace v8::internal
#endif // V8_PLATFORM_ELAPSED_TIMER_H_
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