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      1 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
      2 // Use of this source code is governed by a BSD-style license that can be
      3 // found in the LICENSE file.
      4 //
      5 // Helper class to track the rate data can leave the buffer for pacing.
      6 // A leaky bucket drains the data at a constant rate regardless of fullness of
      7 // the buffer.
      8 // See http://en.wikipedia.org/wiki/Leaky_bucket for more details.
      9 
     10 #ifndef NET_QUIC_CONGESTION_CONTROL_LEAKY_BUCKET_H_
     11 #define NET_QUIC_CONGESTION_CONTROL_LEAKY_BUCKET_H_
     12 
     13 #include "base/basictypes.h"
     14 #include "net/base/net_export.h"
     15 #include "net/quic/quic_bandwidth.h"
     16 #include "net/quic/quic_clock.h"
     17 #include "net/quic/quic_protocol.h"
     18 #include "net/quic/quic_time.h"
     19 
     20 namespace net {
     21 
     22 class NET_EXPORT_PRIVATE LeakyBucket {
     23  public:
     24   explicit LeakyBucket(QuicBandwidth draining_rate);
     25 
     26   // Set the rate at which the bytes leave the buffer.
     27   void SetDrainingRate(QuicTime now, QuicBandwidth draining_rate);
     28 
     29   // Add data to the buffer.
     30   void Add(QuicTime now, QuicByteCount bytes);
     31 
     32   // Time until the buffer is empty.
     33   QuicTime::Delta TimeRemaining(QuicTime now);
     34 
     35   // Number of bytes in the buffer.
     36   QuicByteCount BytesPending(QuicTime now);
     37 
     38  private:
     39   void Update(QuicTime now);
     40 
     41   QuicByteCount bytes_;
     42   QuicTime time_last_updated_;
     43   QuicBandwidth draining_rate_;
     44 
     45   DISALLOW_COPY_AND_ASSIGN(LeakyBucket);
     46 };
     47 
     48 }  // namespace net
     49 
     50 #endif  // NET_QUIC_CONGESTION_CONTROL_LEAKY_BUCKET_H_
     51