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/*
* Copyright (c) 2018 The WebRTC project authors. All Rights Reserved.
*
* Use of this source code is governed by a BSD-style license
* that can be found in the LICENSE file in the root of the source
* tree. An additional intellectual property rights grant can be found
* in the file PATENTS. All contributing project authors may
* be found in the AUTHORS file in the root of the source tree.
*/
#include "rtc_base/numerics/sample_counter.h"
#include <limits>
#include "rtc_base/checks.h"
#include "rtc_base/numerics/safe_conversions.h"
namespace rtc {
SampleCounter::SampleCounter() = default;
SampleCounter::~SampleCounter() = default;
void SampleCounter::Add(int sample) {
if (sum_ > 0) {
RTC_DCHECK_LE(sample, std::numeric_limits<int64_t>::max() - sum_);
} else {
RTC_DCHECK_GE(sample, std::numeric_limits<int64_t>::min() - sum_);
}
sum_ += sample;
++num_samples_;
if (!max_ || sample > *max_) {
max_ = sample;
}
}
void SampleCounter::Add(const SampleCounter& other) {
if (sum_ > 0) {
RTC_DCHECK_LE(other.sum_, std::numeric_limits<int64_t>::max() - sum_);
} else {
RTC_DCHECK_GE(other.sum_, std::numeric_limits<int64_t>::min() - sum_);
}
sum_ += other.sum_;
RTC_DCHECK_LE(other.num_samples_,
std::numeric_limits<int64_t>::max() - num_samples_);
num_samples_ += other.num_samples_;
if (other.max_ && (!max_ || *max_ < *other.max_))
max_ = other.max_;
}
absl::optional<int> SampleCounter::Avg(int64_t min_required_samples) const {
RTC_DCHECK_GT(min_required_samples, 0);
if (num_samples_ < min_required_samples)
return absl::nullopt;
return rtc::dchecked_cast<int>(sum_ / num_samples_);
}
absl::optional<int> SampleCounter::Max() const {
return max_;
}
absl::optional<int64_t> SampleCounter::Sum(int64_t min_required_samples) const {
RTC_DCHECK_GT(min_required_samples, 0);
if (num_samples_ < min_required_samples)
return absl::nullopt;
return sum_;
}
int64_t SampleCounter::NumSamples() const {
return num_samples_;
}
void SampleCounter::Reset() {
*this = {};
}
SampleCounterWithVariance::SampleCounterWithVariance() = default;
SampleCounterWithVariance::~SampleCounterWithVariance() = default;
absl::optional<int64_t> SampleCounterWithVariance::Variance(
int64_t min_required_samples) const {
RTC_DCHECK_GT(min_required_samples, 0);
if (num_samples_ < min_required_samples)
return absl::nullopt;
// E[(x-mean)^2] = E[x^2] - mean^2
int64_t mean = sum_ / num_samples_;
return sum_squared_ / num_samples_ - mean * mean;
}
void SampleCounterWithVariance::Add(int sample) {
SampleCounter::Add(sample);
// Prevent overflow in squaring.
RTC_DCHECK_GT(sample, std::numeric_limits<int32_t>::min());
RTC_DCHECK_LE(int64_t{sample} * sample,
std::numeric_limits<int64_t>::max() - sum_squared_);
sum_squared_ += int64_t{sample} * sample;
}
void SampleCounterWithVariance::Add(const SampleCounterWithVariance& other) {
SampleCounter::Add(other);
RTC_DCHECK_LE(other.sum_squared_,
std::numeric_limits<int64_t>::max() - sum_squared_);
sum_squared_ += other.sum_squared_;
}
void SampleCounterWithVariance::Reset() {
*this = {};
}
} // namespace rtc
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