1 files changed, 101 insertions, 0 deletions
diff --git a/third_party/libwebrtc/api/numerics/samples_stats_counter.cc b/third_party/libwebrtc/api/numerics/samples_stats_counter.cc
new file mode 100644
index 0000000000..4eb0cde299
--- /dev/null
+++ b/third_party/libwebrtc/api/numerics/samples_stats_counter.cc
@@ -0,0 +1,101 @@
+/*
+ *  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 "api/numerics/samples_stats_counter.h"
+
+#include <algorithm>
+#include <cmath>
+
+#include "absl/algorithm/container.h"
+#include "rtc_base/time_utils.h"
+
+namespace webrtc {
+
+SamplesStatsCounter::SamplesStatsCounter() = default;
+SamplesStatsCounter::SamplesStatsCounter(size_t expected_samples_count) {
+  samples_.reserve(expected_samples_count);
+}
+
+SamplesStatsCounter::~SamplesStatsCounter() = default;
+SamplesStatsCounter::SamplesStatsCounter(const SamplesStatsCounter&) = default;
+SamplesStatsCounter& SamplesStatsCounter::operator=(
+    const SamplesStatsCounter&) = default;
+SamplesStatsCounter::SamplesStatsCounter(SamplesStatsCounter&&) = default;
+SamplesStatsCounter& SamplesStatsCounter::operator=(SamplesStatsCounter&&) =
+    default;
+
+void SamplesStatsCounter::AddSample(double value) {
+  AddSample(StatsSample{value, Timestamp::Micros(rtc::TimeMicros())});
+}
+
+void SamplesStatsCounter::AddSample(StatsSample sample) {
+  stats_.AddSample(sample.value);
+  samples_.push_back(sample);
+  sorted_ = false;
+}
+
+void SamplesStatsCounter::AddSamples(const SamplesStatsCounter& other) {
+  stats_.MergeStatistics(other.stats_);
+  samples_.insert(samples_.end(), other.samples_.begin(), other.samples_.end());
+  sorted_ = false;
+}
+
+double SamplesStatsCounter::GetPercentile(double percentile) {
+  RTC_DCHECK(!IsEmpty());
+  RTC_CHECK_GE(percentile, 0);
+  RTC_CHECK_LE(percentile, 1);
+  if (!sorted_) {
+    absl::c_sort(samples_, [](const StatsSample& a, const StatsSample& b) {
+      return a.value < b.value;
+    });
+    sorted_ = true;
+  }
+  const double raw_rank = percentile * (samples_.size() - 1);
+  double int_part;
+  double fract_part = std::modf(raw_rank, &int_part);
+  size_t rank = static_cast<size_t>(int_part);
+  if (fract_part >= 1.0) {
+    // It can happen due to floating point calculation error.
+    rank++;
+    fract_part -= 1.0;
+  }
+
+  RTC_DCHECK_GE(rank, 0);
+  RTC_DCHECK_LT(rank, samples_.size());
+  RTC_DCHECK_GE(fract_part, 0);
+  RTC_DCHECK_LT(fract_part, 1);
+  RTC_DCHECK(rank + fract_part == raw_rank);
+
+  const double low = samples_[rank].value;
+  const double high = samples_[std::min(rank + 1, samples_.size() - 1)].value;
+  return low + fract_part * (high - low);
+}
+
+SamplesStatsCounter operator*(const SamplesStatsCounter& counter,
+                              double value) {
+  SamplesStatsCounter out;
+  for (const auto& sample : counter.GetTimedSamples()) {
+    out.AddSample(
+        SamplesStatsCounter::StatsSample{sample.value * value, sample.time});
+  }
+  return out;
+}
+
+SamplesStatsCounter operator/(const SamplesStatsCounter& counter,
+                              double value) {
+  SamplesStatsCounter out;
+  for (const auto& sample : counter.GetTimedSamples()) {
+    out.AddSample(
+        SamplesStatsCounter::StatsSample{sample.value / value, sample.time});
+  }
+  return out;
+}
+
+}  // namespace webrtc