123456789101112131415161718192021222324252627282930313233343536373839404142434445464748495051525354555657585960616263646566676869 |
- // 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.
- #include "media/capture/content/smooth_event_sampler.h"
- #include <stdint.h>
- #include <algorithm>
- #include "base/trace_event/trace_event.h"
- namespace media {
- SmoothEventSampler::SmoothEventSampler(base::TimeDelta min_capture_period)
- : token_bucket_(base::TimeDelta::Max()) {
- SetMinCapturePeriod(min_capture_period);
- }
- void SmoothEventSampler::SetMinCapturePeriod(base::TimeDelta period) {
- DCHECK_GT(period, base::TimeDelta());
- if (period == min_capture_period_)
- return;
- min_capture_period_ = period;
- token_bucket_capacity_ = period + period / 2;
- token_bucket_ = std::min(token_bucket_capacity_, token_bucket_);
- }
- void SmoothEventSampler::ConsiderPresentationEvent(base::TimeTicks event_time) {
- DCHECK(!event_time.is_null());
- // Add tokens to the bucket based on advancement in time. Then, re-bound the
- // number of tokens in the bucket. Overflow occurs when there is too much
- // time between events (a common case), or when RecordSample() is not being
- // called often enough (a bug). On the other hand, if RecordSample() is being
- // called too often (e.g., as a reaction to IsOverdueForSamplingAt()), the
- // bucket will underflow.
- if (!current_event_.is_null()) {
- if (current_event_ < event_time) {
- token_bucket_ += event_time - current_event_;
- if (token_bucket_ > token_bucket_capacity_)
- token_bucket_ = token_bucket_capacity_;
- }
- TRACE_COUNTER1("gpu.capture", "MirroringTokenBucketUsec",
- std::max<int64_t>(0, token_bucket_.InMicroseconds()));
- }
- current_event_ = event_time;
- }
- bool SmoothEventSampler::ShouldSample() const {
- return token_bucket_ >= min_capture_period_;
- }
- void SmoothEventSampler::RecordSample() {
- token_bucket_ -= min_capture_period_;
- if (token_bucket_.is_negative())
- token_bucket_ = base::TimeDelta();
- TRACE_COUNTER1("gpu.capture", "MirroringTokenBucketUsec",
- std::max<int64_t>(0, token_bucket_.InMicroseconds()));
- if (HasUnrecordedEvent())
- last_sample_ = current_event_;
- }
- bool SmoothEventSampler::HasUnrecordedEvent() const {
- return !current_event_.is_null() && current_event_ != last_sample_;
- }
- } // namespace media
|