120 lines
3.6 KiB
C++
120 lines
3.6 KiB
C++
/*
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* Copyright (c) 2013 The WebRTC project authors. All Rights Reserved.
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*
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* Use of this source code is governed by a BSD-style license
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* that can be found in the LICENSE file in the root of the source
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* tree. An additional intellectual property rights grant can be found
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* in the file PATENTS. All contributing project authors may
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* be found in the AUTHORS file in the root of the source tree.
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*/
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#include "webrtc/base/rate_statistics.h"
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#include <algorithm>
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#include "webrtc/base/checks.h"
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namespace webrtc {
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RateStatistics::RateStatistics(int64_t window_size_ms, float scale)
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: buckets_(new Bucket[window_size_ms]()),
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accumulated_count_(0),
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num_samples_(0),
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oldest_time_(-window_size_ms),
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oldest_index_(0),
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scale_(scale),
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max_window_size_ms_(window_size_ms),
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current_window_size_ms_(max_window_size_ms_) {}
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RateStatistics::~RateStatistics() {}
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void RateStatistics::Reset() {
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accumulated_count_ = 0;
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num_samples_ = 0;
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oldest_time_ = -max_window_size_ms_;
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oldest_index_ = 0;
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current_window_size_ms_ = max_window_size_ms_;
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for (int64_t i = 0; i < max_window_size_ms_; i++)
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buckets_[i] = Bucket();
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}
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void RateStatistics::Update(size_t count, int64_t now_ms) {
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if (now_ms < oldest_time_) {
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// Too old data is ignored.
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return;
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}
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EraseOld(now_ms);
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// First ever sample, reset window to start now.
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if (!IsInitialized())
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oldest_time_ = now_ms;
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uint32_t now_offset = static_cast<uint32_t>(now_ms - oldest_time_);
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RTC_DCHECK_LT(now_offset, max_window_size_ms_);
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uint32_t index = oldest_index_ + now_offset;
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if (index >= max_window_size_ms_)
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index -= max_window_size_ms_;
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buckets_[index].sum += count;
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++buckets_[index].samples;
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accumulated_count_ += count;
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++num_samples_;
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}
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rtc::Optional<uint32_t> RateStatistics::Rate(int64_t now_ms) {
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EraseOld(now_ms);
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// If window is a single bucket or there is only one sample in a data set that
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// has not grown to the full window size, treat this as rate unavailable.
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int64_t active_window_size = now_ms - oldest_time_ + 1;
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if (num_samples_ == 0 || active_window_size <= 1 ||
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(num_samples_ <= 1 && active_window_size < current_window_size_ms_)) {
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return rtc::Optional<uint32_t>();
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}
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float scale = scale_ / active_window_size;
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return rtc::Optional<uint32_t>(
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static_cast<uint32_t>(accumulated_count_ * scale + 0.5f));
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}
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void RateStatistics::EraseOld(int64_t now_ms) {
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if (!IsInitialized())
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return;
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// New oldest time that is included in data set.
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int64_t new_oldest_time = now_ms - current_window_size_ms_ + 1;
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// New oldest time is older than the current one, no need to cull data.
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if (new_oldest_time <= oldest_time_)
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return;
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// Loop over buckets and remove too old data points.
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while (num_samples_ > 0 && oldest_time_ < new_oldest_time) {
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const Bucket& oldest_bucket = buckets_[oldest_index_];
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RTC_DCHECK_GE(accumulated_count_, oldest_bucket.sum);
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RTC_DCHECK_GE(num_samples_, oldest_bucket.samples);
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accumulated_count_ -= oldest_bucket.sum;
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num_samples_ -= oldest_bucket.samples;
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buckets_[oldest_index_] = Bucket();
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if (++oldest_index_ >= max_window_size_ms_)
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oldest_index_ = 0;
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++oldest_time_;
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}
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oldest_time_ = new_oldest_time;
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}
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bool RateStatistics::SetWindowSize(int64_t window_size_ms, int64_t now_ms) {
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if (window_size_ms <= 0 || window_size_ms > max_window_size_ms_)
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return false;
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current_window_size_ms_ = window_size_ms;
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EraseOld(now_ms);
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return true;
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}
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bool RateStatistics::IsInitialized() {
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return oldest_time_ != -max_window_size_ms_;
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}
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} // namespace webrtc
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