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      1 /*
      2  * Copyright 2015 Google Inc.
      3  *
      4  * Use of this source code is governed by a BSD-style license that can be
      5  * found in the LICENSE file.
      6  */
      7 
      8 #ifndef TimingStateMachine_DEFINED
      9 #define TimingStateMachine_DEFINED
     10 
     11 #include "Benchmark.h"
     12 #include "SkTArray.h"
     13 #include "Timer.h"
     14 
     15 class SkCanvas;
     16 
     17 /*
     18  * Manages a timer via a state machine.  Can be used by modules to time benchmarks
     19  *
     20  * Clients call nextFrame, and must handle any requests from the timing state machine, specifically
     21  * to reset.  When kTimingFinished_ParentEvents is returned, then lastMeasurement() will return the
     22  * timing and loops() will return the number of loops used to time.
     23  *
     24  * A client may continue timing the same benchmark indefinitely.  To advance to the next
     25  * benchmark, the client should call nextBenchmark.
     26  */
     27 class TimingStateMachine {
     28 public:
     29     TimingStateMachine();
     30 
     31     enum ParentEvents {
     32         kReset_ParentEvents,
     33         kTiming_ParentEvents,
     34         kTimingFinished_ParentEvents,// This implies parent can read lastMeasurement() and must
     35                                      // reset
     36     };
     37 
     38     ParentEvents nextFrame(bool preWarmBetweenSamples);
     39 
     40     /*
     41      * The caller should call this when they are ready to move to the next benchmark.
     42      */
     43     void nextBenchmark();
     44 
     45     /*
     46      * When TimingStateMachine returns kTimingFinished_ParentEvents, then the owner can call
     47      * lastMeasurement() to get the time
     48      */
     49     double lastMeasurement() const { return fLastMeasurement; }
     50 
     51     int loops() const { return fLoops; }
     52 
     53 private:
     54     enum State {
     55         kPreWarm_State,
     56         kTiming_State,
     57     };
     58     enum InnerState {
     59         kTuning_InnerState,
     60         kTiming_InnerState,
     61     };
     62 
     63     int fCurrentFrame;
     64     int fLoops;
     65     double fLastMeasurement;
     66     double fStartTime;
     67     State fState;
     68     InnerState fInnerState;
     69 };
     70 
     71 #endif
     72