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/cancelable_callback.h"
  11 #include "base/memory/weak_ptr.h"
  12 #include "base/values.h"
  13 #include "cc/base/cc_export.h"
  14
  15 namespace base {
  16 namespace trace_event {
  17 class TracedValue;
  18 }
  19 class SingleThreadTaskRunner;
  20 }
  21
  22 namespace cc {
  23 class CC_EXPORT DelayBasedTimeSourceClient {
  24  public:
  25   virtual void OnTimerTick() = 0;
  26
  27  protected:
  28   virtual ~DelayBasedTimeSourceClient() {}
  29 };
  30
  31 // This timer implements a time source that achieves the specified interval
  32 // in face of millisecond-precision delayed callbacks and random queueing
  33 // delays. DelayBasedTimeSource uses base::TimeTicks::Now as its timebase.
  34 class CC_EXPORT DelayBasedTimeSource {
  35  public:
  36   static scoped_ptr<DelayBasedTimeSource> Create(
  37       base::TimeDelta interval,
  38       base::SingleThreadTaskRunner* task_runner) {
  39     return make_scoped_ptr(new DelayBasedTimeSource(interval, task_runner));
  40   }
  41
  42   virtual ~DelayBasedTimeSource();
  43
  44   void SetClient(DelayBasedTimeSourceClient* client);
  45
  46   void SetTimebaseAndInterval(base::TimeTicks timebase,
  47                               base::TimeDelta interval);
  48
  49   base::TimeDelta Interval() const;
  50
  51   // Returns the time for the last missed tick.
  52   base::TimeTicks SetActive(bool active);
  53   bool Active() const;
  54
  55   // Get the last and next tick times. NextTickTime() returns null when
  56   // inactive.
  57   base::TimeTicks LastTickTime() const;
  58   base::TimeTicks NextTickTime() const;
  59
  60   virtual void AsValueInto(base::trace_event::TracedValue* dict) const;
  61
  62  protected:
  63   DelayBasedTimeSource(base::TimeDelta interval,
  64                        base::SingleThreadTaskRunner* task_runner);
  65
  66   // Virtual for testing.
  67   virtual base::TimeTicks Now() const;
  68   virtual std::string TypeString() const;
  69
  70  private:
  71   base::TimeTicks NextTickTarget(base::TimeTicks now) const;
  72
  73   void PostNextTickTask(base::TimeTicks now);
  74   void ResetTickTask(base::TimeTicks now);
  75
  76   void OnTimerTick();
  77
  78   DelayBasedTimeSourceClient* client_;
  79
  80   bool active_;
  81
  82   base::TimeTicks timebase_;
  83   base::TimeDelta interval_;
  84
  85   base::TimeTicks last_tick_time_;
  86   base::TimeTicks next_tick_time_;
  87
  88   base::CancelableClosure tick_closure_;
  89
  90   base::SingleThreadTaskRunner* task_runner_;
  91
  92   base::WeakPtrFactory<DelayBasedTimeSource> weak_factory_;
  93
  94   DISALLOW_COPY_AND_ASSIGN(DelayBasedTimeSource);
  95 };
  96
  97 }  // namespace cc
  98
  99 #endif  // CC_SCHEDULER_DELAY_BASED_TIME_SOURCE_H_