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:
+  // |depth| is in bytes. |rate| is specified in bytes/second. Zero depth

[Irfan, 2016/09/29 22:22:41]

bytes/second is a bit odd to track (for debug etc.,) since BW is measured in bps
or kbps.

Suggest doing kbps or bps and adding a suffix to the name to clarify (say
xyz_kbps_)

[Sergey Ulanov, 2016/09/29 23:25:20]

I think it's best to use the same units for depth and rate (I also find it more
natural to measure speed in B/s instead of b/s as it makes all calculation
simpler). And in general depth and rate don't have to be bytes, as this class
can be used to rate-limit anything, not only byte stream. Updated this comment
to say that depth is measured in "drops" and rate is "drops/second", where drops
can be bytes, bits or anything else, depending on the consumer.

+  // value indicates a bucket of infinite size.
+  LeakyBucket(int depth, int rate);
+  ~LeakyBucket();
+
+  // If the bucket can fit |size| bytes then adds them and returns true.
+  // Otherwise returns false.
+  bool RefillOrSpill(int size, 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_; }
+  int level() { return level_; }
+
+ private:
+  void UpdateLevel(base::TimeTicks now);
+
+  int depth_;
+  int rate_;
+
+  int level_;

[Irfan, 2016/09/29 22:22:41]

document what level means ?  may be call it current_level

[Sergey Ulanov, 2016/09/29 23:25:20]

Done.

+  base::TimeTicks last_update_;
+
+  DISALLOW_COPY_AND_ASSIGN(LeakyBucket);
+};
+
+}  // namespace remoting
+
+#endif  // REMOTING_BASE_LEAKY_BUCKET_H_