cc/scheduler/delay_based_time_source.h

   1 // Copyright 2011 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 #ifndef CC_SCHEDULER_DELAY_BASED_TIME_SOURCE_H_
   6 #define CC_SCHEDULER_DELAY_BASED_TIME_SOURCE_H_
   7
   8 #include <string>
   9
  10 #include "base/memory/weak_ptr.h"
  11 #include "base/values.h"
  12 #include "cc/base/cc_export.h"
  13
  14 namespace base { class SingleThreadTaskRunner; }
  15
  16 namespace cc {
  17
  18 class CC_EXPORT TimeSourceClient {
  19  public:
  20   virtual void OnTimerTick() = 0;
  21
  22  protected:
  23   virtual ~TimeSourceClient() {}
  24 };
  25
  26 // This timer implements a time source that achieves the specified interval
  27 // in face of millisecond-precision delayed callbacks and random queueing
  28 // delays. DelayBasedTimeSource uses base::TimeTicks::Now as its timebase.
  29 class CC_EXPORT DelayBasedTimeSource
  30     : public base::RefCounted<DelayBasedTimeSource> {
  31  public:
  32   static scoped_refptr<DelayBasedTimeSource> Create(
  33       base::TimeDelta interval, base::SingleThreadTaskRunner* task_runner);
  34
  35   virtual void SetClient(TimeSourceClient* client);
  36
  37   // TimeSource implementation
  38   virtual void SetTimebaseAndInterval(base::TimeTicks timebase,
  39                                       base::TimeDelta interval);
  40
  41   virtual base::TimeTicks SetActive(bool active);
  42   virtual bool Active() const;
  43
  44   // Get the last and next tick times. NextTickTime() returns null when
  45   // inactive.
  46   virtual base::TimeTicks LastTickTime() const;
  47   virtual base::TimeTicks NextTickTime() const;
  48
  49   // Virtual for testing.
  50   virtual base::TimeTicks Now() const;
  51
  52   virtual scoped_ptr<base::Value> AsValue() const;
  53
  54  protected:
  55   DelayBasedTimeSource(base::TimeDelta interval,
  56                        base::SingleThreadTaskRunner* task_runner);
  57   virtual ~DelayBasedTimeSource();
  58
  59   virtual std::string TypeString() const;
  60
  61   base::TimeTicks NextTickTarget(base::TimeTicks now);
  62   void PostNextTickTask(base::TimeTicks now);
  63   void OnTimerFired();
  64
  65   struct Parameters {
  66     Parameters(base::TimeDelta interval, base::TimeTicks tick_target)
  67         : interval(interval), tick_target(tick_target) {}
  68     base::TimeDelta interval;
  69     base::TimeTicks tick_target;
  70   };
  71
  72   TimeSourceClient* client_;
  73   base::TimeTicks last_tick_time_;
  74
  75   // current_parameters_ should only be written by PostNextTickTask.
  76   // next_parameters_ will take effect on the next call to PostNextTickTask.
  77   // Maintaining a pending set of parameters allows NextTickTime() to always
  78   // reflect the actual time we expect OnTimerFired to be called.
  79   Parameters current_parameters_;
  80   Parameters next_parameters_;
  81
  82   bool active_;
  83
  84   base::SingleThreadTaskRunner* task_runner_;
  85   base::WeakPtrFactory<DelayBasedTimeSource> weak_factory_;
  86
  87  private:
  88   friend class base::RefCounted<DelayBasedTimeSource>;
  89   DISALLOW_COPY_AND_ASSIGN(DelayBasedTimeSource);
  90 };
  91
  92 // DelayBasedTimeSource uses base::TimeTicks::HighResNow as its timebase.
  93 class DelayBasedTimeSourceHighRes : public DelayBasedTimeSource {
  94  public:
  95   static scoped_refptr<DelayBasedTimeSourceHighRes> Create(
  96         base::TimeDelta interval, base::SingleThreadTaskRunner* task_runner);
  97
  98   virtual base::TimeTicks Now() const OVERRIDE;
  99
 100  protected:
 101   DelayBasedTimeSourceHighRes(base::TimeDelta interval,
 102                               base::SingleThreadTaskRunner* task_runner);
 103   virtual ~DelayBasedTimeSourceHighRes();
 104
 105   virtual std::string TypeString() const OVERRIDE;
 106
 107  private:
 108   DISALLOW_COPY_AND_ASSIGN(DelayBasedTimeSourceHighRes);
 109 };
 110
 111 }  // namespace cc
 112
 113 #endif  // CC_SCHEDULER_DELAY_BASED_TIME_SOURCE_H_