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// Copyright 2014 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#ifndef BASE_TIMER_LAP_TIMER_H_
#define BASE_TIMER_LAP_TIMER_H_
#include "base/base_export.h"
#include "base/sequence_checker.h"
#include "base/time/time.h"
namespace base {
// LapTimer is used to calculate average times per "Lap" in perf tests.
// NextLap increments the lap counter, used in counting the per lap averages.
// If you initialize the LapTimer with a non zero |warmup_laps|, it will ignore
// the times for that many laps at the start.
// If you set the |time_limit| then you can use HasTimeLimitExpired() to see if
// the current accumulated time has crossed that threshold, with an optimization
// that it only tests this every |check_interval| laps.
//
// See base/timer/lap_timer_unittest.cc for a usage example.
//
class BASE_EXPORT LapTimer {
public:
enum class TimerMethod {
// Measures CPU time consumed by the thread running the LapTimer.
kUseThreadTicks,
// Measures elapsed wall time (default).
kUseTimeTicks
};
LapTimer(int warmup_laps,
TimeDelta time_limit,
int check_interval,
TimerMethod timing_method = TimerMethod::kUseTimeTicks);
// Create LapTimer with sensible default values.
LapTimer(TimerMethod timing_method = TimerMethod::kUseTimeTicks);
LapTimer(const LapTimer&) = delete;
LapTimer& operator=(const LapTimer&) = delete;
// Sets the timer back to its starting state.
void Reset();
// Sets the start point to now.
void Start();
// Returns true if there are no more warmup laps to do.
bool IsWarmedUp() const;
// Advance the lap counter and update the accumulated time.
// The accumulated time is only updated every check_interval laps.
// If accumulating then the start point will also be updated.
void NextLap();
// Returns true if the stored time has exceeded the time limit specified.
// May cause a call to Store().
bool HasTimeLimitExpired() const;
// The average time taken per lap.
TimeDelta TimePerLap() const;
// The number of laps per second.
float LapsPerSecond() const;
// The number of laps recorded.
int NumLaps() const;
private:
// Returns true if all lap times have been timed. Only true every n'th
// lap, where n = check_interval.
bool HasTimedAllLaps() const;
// Returns the current accumulated time.
TimeDelta GetAccumulatedTime() const;
const int warmup_laps_;
const TimeDelta time_limit_;
const int check_interval_;
const TimerMethod method_;
ThreadTicks start_thread_ticks_;
TimeTicks start_time_ticks_;
ThreadTicks last_timed_lap_end_thread_ticks_;
TimeTicks last_timed_lap_end_ticks_;
int num_laps_;
int remaining_warmups_ = 0;
int remaining_no_check_laps_ = 0;
SEQUENCE_CHECKER(sequence_checker_);
};
} // namespace base
#endif // BASE_TIMER_LAP_TIMER_H_
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