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
14namespace base {
15namespace debug {
16class TracedValue;
17}
18class SingleThreadTaskRunner;
19}
20
21namespace cc {
22
23class CC_EXPORT TimeSourceClient {
24 public:
25  virtual void OnTimerTick() = 0;
26
27 protected:
28  virtual ~TimeSourceClient() {}
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.
34class CC_EXPORT DelayBasedTimeSource
35    : public base::RefCounted<DelayBasedTimeSource> {
36 public:
37  static scoped_refptr<DelayBasedTimeSource> Create(
38      base::TimeDelta interval, base::SingleThreadTaskRunner* task_runner);
39
40  virtual void SetClient(TimeSourceClient* client);
41
42  // TimeSource implementation
43  virtual void SetTimebaseAndInterval(base::TimeTicks timebase,
44                                      base::TimeDelta interval);
45
46  virtual base::TimeTicks SetActive(bool active);
47  virtual bool Active() const;
48
49  // Get the last and next tick times. NextTickTime() returns null when
50  // inactive.
51  virtual base::TimeTicks LastTickTime() const;
52  virtual base::TimeTicks NextTickTime() const;
53
54  // Virtual for testing.
55  virtual base::TimeTicks Now() const;
56
57  virtual void AsValueInto(base::debug::TracedValue* dict) const;
58
59 protected:
60  DelayBasedTimeSource(base::TimeDelta interval,
61                       base::SingleThreadTaskRunner* task_runner);
62  virtual ~DelayBasedTimeSource();
63
64  virtual std::string TypeString() const;
65
66  base::TimeTicks NextTickTarget(base::TimeTicks now);
67  void PostNextTickTask(base::TimeTicks now);
68  void OnTimerFired();
69
70  struct Parameters {
71    Parameters(base::TimeDelta interval, base::TimeTicks tick_target)
72        : interval(interval), tick_target(tick_target) {}
73    base::TimeDelta interval;
74    base::TimeTicks tick_target;
75  };
76
77  TimeSourceClient* client_;
78  base::TimeTicks last_tick_time_;
79
80  // current_parameters_ should only be written by PostNextTickTask.
81  // next_parameters_ will take effect on the next call to PostNextTickTask.
82  // Maintaining a pending set of parameters allows NextTickTime() to always
83  // reflect the actual time we expect OnTimerFired to be called.
84  Parameters current_parameters_;
85  Parameters next_parameters_;
86
87  bool active_;
88
89  base::SingleThreadTaskRunner* task_runner_;
90  base::WeakPtrFactory<DelayBasedTimeSource> weak_factory_;
91
92 private:
93  friend class base::RefCounted<DelayBasedTimeSource>;
94  DISALLOW_COPY_AND_ASSIGN(DelayBasedTimeSource);
95};
96
97// DelayBasedTimeSource uses base::TimeTicks::HighResNow as its timebase.
98class DelayBasedTimeSourceHighRes : public DelayBasedTimeSource {
99 public:
100  static scoped_refptr<DelayBasedTimeSourceHighRes> Create(
101        base::TimeDelta interval, base::SingleThreadTaskRunner* task_runner);
102
103  virtual base::TimeTicks Now() const OVERRIDE;
104
105 protected:
106  DelayBasedTimeSourceHighRes(base::TimeDelta interval,
107                              base::SingleThreadTaskRunner* task_runner);
108  virtual ~DelayBasedTimeSourceHighRes();
109
110  virtual std::string TypeString() const OVERRIDE;
111
112 private:
113  DISALLOW_COPY_AND_ASSIGN(DelayBasedTimeSourceHighRes);
114};
115
116}  // namespace cc
117
118#endif  // CC_SCHEDULER_DELAY_BASED_TIME_SOURCE_H_
119