Measure bandwidth for chromoting video channel

remoting/base/rate_counter.cc

+// Copyright (c) 2011 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "remoting/base/rate_counter.h"
+
+namespace remoting {
+
+RateCounter::RateCounter(base::TimeDelta time_window)
+    : time_window_(time_window),
+      sum_(0) {
+}
+
+RateCounter::~RateCounter() {
+}
+
+void RateCounter::Record(int64 value) {
+  base::Time current_time = base::Time::Now();
+  Evict(current_time);
+
+  base::AutoLock auto_lock(lock_);
+  sum_ += value;
+  data_points_.push(std::make_pair(current_time, value));
+}
+
+double RateCounter::Rate() {
+  Evict(base::Time::Now());
+
+  base::AutoLock auto_lock(lock_);
+  return static_cast<double>(base::Time::kMillisecondsPerSecond) * sum_ /
+      time_window_.InMilliseconds();
+}
+
+void RateCounter::Evict(base::Time current_time) {
+  base::AutoLock auto_lock(lock_);
+
+  // Remove data points outside of the window.
+  base::Time window_start = current_time - time_window_;
+
+  while (!data_points_.empty()) {
+    if (data_points_.front().first > window_start)
+      break;
+
+    sum_ -= data_points_.front().second;
+    data_points_.pop();
+  }
+}
+
+}  // namespace remoting