Pace outgoing frames in frame scheduler to match target bitrate.

remoting/base/leaky_bucket.h

+// Copyright 2016 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.
+
+#ifndef REMOTING_BASE_LEAKY_BUCKET_H_
+#define REMOTING_BASE_LEAKY_BUCKET_H_
+
+#include "base/macros.h"
+#include "base/time/time.h"
+
+namespace remoting {
+
+class LeakyBucket {
+ public:
+  static const int kUnlimitedDepth = -1;
+
+  // |depth| specifies depth of the bucket in drops. kUnlimitedDepth indicate
+  // that bucket size is unlimited. |rate| is specified in drops per second.
+  LeakyBucket(int depth, int rate);
+  ~LeakyBucket();
+
+  // If the bucket can fit |drops| then adds them and returns true. Otherwise
+  // returns false.
+  bool RefillOrSpill(int drops, base::TimeTicks now);
+
+  // Updates rate.
+  void UpdateRate(int new_rate, base::TimeTicks now);
+
+  // Returns time when the bucket will be empty. The returned value may be in
+  // the past.
+  base::TimeTicks GetEmptyTime();
+
+  int rate() { return rate_; }
+
+ private:
+  void UpdateLevel(base::TimeTicks now);
+
+  int depth_;
+  int rate_;
+
+  // |current_level_| stores water level at |level_updated_time_|. Updated in
+  // UpdateLevel(), which is called from RefillOrSpill() and UpdateRate().
+  int current_level_;
+  base::TimeTicks level_updated_time_;
+
+  DISALLOW_COPY_AND_ASSIGN(LeakyBucket);
+};
+
+}  // namespace remoting
+
+#endif  // REMOTING_BASE_LEAKY_BUCKET_H_