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 { class SingleThreadTaskRunner; }
15
16namespace cc {
17
18class 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.
29class 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.
93class 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_
114