1 files changed, 109 insertions, 0 deletions
diff --git a/third_party/libwebrtc/rtc_base/numerics/sample_counter.cc b/third_party/libwebrtc/rtc_base/numerics/sample_counter.cc
new file mode 100644
index 0000000000..16a8e25098
--- /dev/null
+++ b/third_party/libwebrtc/rtc_base/numerics/sample_counter.cc
@@ -0,0 +1,109 @@
+/*
+ *  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