blob: c250eb486e100b83e0b5e99b04adba49a5fe522c (
plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
|
// Copyright (c) 2015 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#ifndef MEDIA_CAPTURE_SMOOTH_EVENT_SAMPLER_H_
#define MEDIA_CAPTURE_SMOOTH_EVENT_SAMPLER_H_
#include "base/time/time.h"
#include "media/base/media_export.h"
namespace media {
// Filters a sequence of events to achieve a target frequency.
class MEDIA_EXPORT SmoothEventSampler {
public:
SmoothEventSampler(base::TimeDelta min_capture_period,
int redundant_capture_goal);
// Get/Set minimum capture period. When setting a new value, the state of the
// sampler is retained so that sampling will continue smoothly.
base::TimeDelta min_capture_period() const { return min_capture_period_; }
void SetMinCapturePeriod(base::TimeDelta p);
// Add a new event to the event history, and consider whether it ought to be
// sampled. The event is not recorded as a sample until RecordSample() is
// called.
void ConsiderPresentationEvent(base::TimeTicks event_time);
// Returns true if the last event considered should be sampled.
bool ShouldSample() const;
// Operates on the last event added by ConsiderPresentationEvent(), marking
// it as sampled. After this point we are current in the stream of events, as
// we have sampled the most recent event.
void RecordSample();
// Returns true if, at time |event_time|, sampling should occur because too
// much time will have passed relative to the last event and/or sample.
bool IsOverdueForSamplingAt(base::TimeTicks event_time) const;
// Returns true if ConsiderPresentationEvent() has been called since the last
// call to RecordSample().
bool HasUnrecordedEvent() const;
private:
base::TimeDelta min_capture_period_;
const int redundant_capture_goal_;
base::TimeDelta token_bucket_capacity_;
base::TimeTicks current_event_;
base::TimeTicks last_sample_;
int overdue_sample_count_;
base::TimeDelta token_bucket_;
DISALLOW_COPY_AND_ASSIGN(SmoothEventSampler);
};
} // namespace media
#endif // MEDIA_CAPTURE_SMOOTH_EVENT_SAMPLER_H_
|
