80 lines
2.4 KiB
C++
80 lines
2.4 KiB
C++
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/*
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* Copyright (c) 2017 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 "rtc_base/numerics/histogram_percentile_counter.h"
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#include <algorithm>
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#include <cmath>
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#include "rtc_base/checks.h"
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namespace rtc {
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HistogramPercentileCounter::HistogramPercentileCounter(
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uint32_t long_tail_boundary)
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: histogram_low_(size_t{long_tail_boundary}),
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long_tail_boundary_(long_tail_boundary),
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total_elements_(0),
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total_elements_low_(0) {}
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HistogramPercentileCounter::~HistogramPercentileCounter() = default;
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void HistogramPercentileCounter::Add(const HistogramPercentileCounter& other) {
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for (uint32_t value = 0; value < other.long_tail_boundary_; ++value) {
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Add(value, other.histogram_low_[value]);
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}
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for (const auto& it : histogram_high_) {
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Add(it.first, it.second);
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}
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}
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void HistogramPercentileCounter::Add(uint32_t value, size_t count) {
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if (value < long_tail_boundary_) {
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histogram_low_[value] += count;
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total_elements_low_ += count;
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} else {
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histogram_high_[value] += count;
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}
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total_elements_ += count;
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}
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void HistogramPercentileCounter::Add(uint32_t value) {
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Add(value, 1);
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}
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absl::optional<uint32_t> HistogramPercentileCounter::GetPercentile(
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float fraction) {
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RTC_CHECK_LE(fraction, 1.0);
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RTC_CHECK_GE(fraction, 0.0);
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if (total_elements_ == 0)
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return absl::nullopt;
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size_t elements_to_skip = static_cast<size_t>(
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std::max(0.0f, std::ceil(total_elements_ * fraction) - 1));
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if (elements_to_skip >= total_elements_)
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elements_to_skip = total_elements_ - 1;
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if (elements_to_skip < total_elements_low_) {
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for (uint32_t value = 0; value < long_tail_boundary_; ++value) {
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if (elements_to_skip < histogram_low_[value])
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return value;
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elements_to_skip -= histogram_low_[value];
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}
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} else {
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elements_to_skip -= total_elements_low_;
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for (const auto& it : histogram_high_) {
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if (elements_to_skip < it.second)
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return it.first;
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elements_to_skip -= it.second;
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}
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}
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RTC_NOTREACHED();
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return absl::nullopt;
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}
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} // namespace rtc
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