110 lines
3.2 KiB
C++
110 lines
3.2 KiB
C++
/*
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* Copyright (c) 2018 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/sample_counter.h"
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#include <limits>
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#include "rtc_base/checks.h"
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#include "rtc_base/numerics/safe_conversions.h"
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namespace rtc {
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SampleCounter::SampleCounter() = default;
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SampleCounter::~SampleCounter() = default;
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void SampleCounter::Add(int sample) {
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if (sum_ > 0) {
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RTC_DCHECK_LE(sample, std::numeric_limits<int64_t>::max() - sum_);
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} else {
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RTC_DCHECK_GE(sample, std::numeric_limits<int64_t>::min() - sum_);
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}
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sum_ += sample;
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++num_samples_;
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if (!max_ || sample > *max_) {
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max_ = sample;
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}
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}
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void SampleCounter::Add(const SampleCounter& other) {
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if (sum_ > 0) {
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RTC_DCHECK_LE(other.sum_, std::numeric_limits<int64_t>::max() - sum_);
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} else {
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RTC_DCHECK_GE(other.sum_, std::numeric_limits<int64_t>::min() - sum_);
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}
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sum_ += other.sum_;
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RTC_DCHECK_LE(other.num_samples_,
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std::numeric_limits<int64_t>::max() - num_samples_);
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num_samples_ += other.num_samples_;
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if (other.max_ && (!max_ || *max_ < *other.max_))
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max_ = other.max_;
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}
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absl::optional<int> SampleCounter::Avg(int64_t min_required_samples) const {
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RTC_DCHECK_GT(min_required_samples, 0);
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if (num_samples_ < min_required_samples)
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return absl::nullopt;
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return rtc::dchecked_cast<int>(sum_ / num_samples_);
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}
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absl::optional<int> SampleCounter::Max() const {
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return max_;
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}
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absl::optional<int64_t> SampleCounter::Sum(int64_t min_required_samples) const {
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RTC_DCHECK_GT(min_required_samples, 0);
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if (num_samples_ < min_required_samples)
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return absl::nullopt;
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return sum_;
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}
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int64_t SampleCounter::NumSamples() const {
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return num_samples_;
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}
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void SampleCounter::Reset() {
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*this = {};
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}
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SampleCounterWithVariance::SampleCounterWithVariance() = default;
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SampleCounterWithVariance::~SampleCounterWithVariance() = default;
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absl::optional<int64_t> SampleCounterWithVariance::Variance(
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int64_t min_required_samples) const {
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RTC_DCHECK_GT(min_required_samples, 0);
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if (num_samples_ < min_required_samples)
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return absl::nullopt;
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// E[(x-mean)^2] = E[x^2] - mean^2
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int64_t mean = sum_ / num_samples_;
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return sum_squared_ / num_samples_ - mean * mean;
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}
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void SampleCounterWithVariance::Add(int sample) {
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SampleCounter::Add(sample);
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// Prevent overflow in squaring.
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RTC_DCHECK_GT(sample, std::numeric_limits<int32_t>::min());
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RTC_DCHECK_LE(int64_t{sample} * sample,
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std::numeric_limits<int64_t>::max() - sum_squared_);
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sum_squared_ += int64_t{sample} * sample;
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}
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void SampleCounterWithVariance::Add(const SampleCounterWithVariance& other) {
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SampleCounter::Add(other);
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RTC_DCHECK_LE(other.sum_squared_,
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std::numeric_limits<int64_t>::max() - sum_squared_);
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sum_squared_ += other.sum_squared_;
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}
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void SampleCounterWithVariance::Reset() {
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*this = {};
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}
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} // namespace rtc
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