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