fb8fc5391e
This is done by changing the RateStatistics so that it resets its window when the accumulator is empty. It also keeps a dynamic window, so that the rates computed before a full window worth of data has been received will be computed over a smaller window. This means that the rate will be closer to the true rate, but with a higher variance. BUG=webrtc:5773 R=perkj@webrtc.org, sprang@webrtc.org Review URL: https://codereview.webrtc.org/1908893003 . Cr-Commit-Position: refs/heads/master@{#12470}
89 lines
2.4 KiB
C++
89 lines
2.4 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(uint32_t window_size_ms, float scale)
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: num_buckets_(window_size_ms + 1), // N ms in (N+1) buckets.
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buckets_(new size_t[num_buckets_]()),
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accumulated_count_(0),
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oldest_time_(0),
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oldest_index_(0),
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scale_(scale) {}
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RateStatistics::~RateStatistics() {}
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void RateStatistics::Reset() {
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accumulated_count_ = 0;
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oldest_time_ = 0;
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oldest_index_ = 0;
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for (int i = 0; i < num_buckets_; i++) {
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buckets_[i] = 0;
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}
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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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int now_offset = static_cast<int>(now_ms - oldest_time_);
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RTC_DCHECK_LT(now_offset, num_buckets_);
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int index = oldest_index_ + now_offset;
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if (index >= num_buckets_) {
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index -= num_buckets_;
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}
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buckets_[index] += count;
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accumulated_count_ += count;
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}
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uint32_t RateStatistics::Rate(int64_t now_ms) {
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EraseOld(now_ms);
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float scale = scale_ / (now_ms - oldest_time_ + 1);
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return 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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int64_t new_oldest_time = now_ms - num_buckets_ + 1;
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if (new_oldest_time <= oldest_time_) {
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if (accumulated_count_ == 0)
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oldest_time_ = now_ms;
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return;
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}
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while (oldest_time_ < new_oldest_time) {
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size_t count_in_oldest_bucket = buckets_[oldest_index_];
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RTC_DCHECK_GE(accumulated_count_, count_in_oldest_bucket);
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accumulated_count_ -= count_in_oldest_bucket;
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buckets_[oldest_index_] = 0;
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if (++oldest_index_ >= num_buckets_) {
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oldest_index_ = 0;
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}
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++oldest_time_;
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if (accumulated_count_ == 0) {
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// This guarantees we go through all the buckets at most once, even if
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// |new_oldest_time| is far greater than |oldest_time_|.
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new_oldest_time = now_ms;
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break;
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}
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}
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oldest_time_ = new_oldest_time;
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}
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} // namespace webrtc
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