net/quic/quic_flow_controller.h

   1 // Copyright 2014 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 #ifndef NET_QUIC_QUIC_FLOW_CONTROLLER_H_
   6 #define NET_QUIC_QUIC_FLOW_CONTROLLER_H_
   7
   8 #include "base/basictypes.h"
   9 #include "net/base/net_export.h"
  10 #include "net/quic/quic_protocol.h"
  11
  12 namespace net {
  13
  14 namespace test {
  15 class QuicFlowControllerPeer;
  16 }  // namespace test
  17
  18 class QuicConnection;
  19
  20 const QuicStreamId kConnectionLevelId = 0;
  21
  22 // QuicFlowController allows a QUIC stream or connection to perform flow
  23 // control. The stream/connection owns a QuicFlowController which keeps track of
  24 // bytes sent/received, can tell the owner if it is flow control blocked, and
  25 // can send WINDOW_UPDATE or BLOCKED frames when needed.
  26 class NET_EXPORT_PRIVATE QuicFlowController {
  27  public:
  28   QuicFlowController(QuicConnection* connection,
  29                      QuicStreamId id,
  30                      bool is_server,
  31                      QuicStreamOffset send_window_offset,
  32                      QuicStreamOffset receive_window_offset,
  33                      QuicByteCount max_receive_window);
  34   ~QuicFlowController() {}
  35
  36   // Called when we see a new highest received byte offset from the peer, either
  37   // via a data frame or a RST.
  38   // Returns true if this call changes highest_received_byte_offset_, and false
  39   // in the case where |new_offset| is <= highest_received_byte_offset_.
  40   bool UpdateHighestReceivedOffset(QuicStreamOffset new_offset);
  41
  42   // Called when bytes received from the peer are consumed locally. This may
  43   // trigger the sending of a WINDOW_UPDATE frame using |connection|.
  44   void AddBytesConsumed(QuicByteCount bytes_consumed);
  45
  46   // Called when bytes are sent to the peer.
  47   void AddBytesSent(QuicByteCount bytes_sent);
  48
  49   // Set a new send window offset.
  50   // Returns true if this increases send_window_offset_ and is now blocked.
  51   bool UpdateSendWindowOffset(QuicStreamOffset new_send_window_offset);
  52
  53   // Returns the current available send window.
  54   QuicByteCount SendWindowSize() const;
  55
  56   // Send a BLOCKED frame if appropriate.
  57   void MaybeSendBlocked();
  58
  59   // Disable flow control.
  60   void Disable();
  61
  62   // Returns true if flow control is enabled.
  63   bool IsEnabled() const;
  64
  65   // Returns true if flow control send limits have been reached.
  66   bool IsBlocked() const;
  67
  68   // Returns true if flow control receive limits have been violated by the peer.
  69   bool FlowControlViolation();
  70
  71   QuicByteCount bytes_consumed() const { return bytes_consumed_; }
  72
  73   QuicStreamOffset highest_received_byte_offset() const {
  74     return highest_received_byte_offset_;
  75   }
  76
  77  private:
  78   friend class test::QuicFlowControllerPeer;
  79
  80   // Send a WINDOW_UPDATE frame if appropriate.
  81   void MaybeSendWindowUpdate();
  82
  83   // The parent connection, used to send connection close on flow control
  84   // violation, and WINDOW_UPDATE and BLOCKED frames when appropriate.
  85   // Not owned.
  86   QuicConnection* connection_;
  87
  88   // ID of stream this flow controller belongs to. This can be 0 if this is a
  89   // connection level flow controller.
  90   QuicStreamId id_;
  91
  92   // True if flow control is enabled.
  93   bool is_enabled_;
  94
  95   // True if this is owned by a server.
  96   bool is_server_;
  97
  98   // Track number of bytes received from the peer, which have been consumed
  99   // locally.
 100   QuicByteCount bytes_consumed_;
 101
 102   // The highest byte offset we have seen from the peer. This could be the
 103   // highest offset in a data frame, or a final value in a RST.
 104   QuicStreamOffset highest_received_byte_offset_;
 105
 106   // Tracks number of bytes sent to the peer.
 107   QuicByteCount bytes_sent_;
 108
 109   // The absolute offset in the outgoing byte stream. If this offset is reached
 110   // then we become flow control blocked until we receive a WINDOW_UPDATE.
 111   QuicStreamOffset send_window_offset_;
 112
 113   // The absolute offset in the incoming byte stream. The peer should never send
 114   // us bytes which are beyond this offset.
 115   QuicStreamOffset receive_window_offset_;
 116
 117   // Largest size the receive window can grow to.
 118   QuicByteCount max_receive_window_;
 119
 120   // Keep track of the last time we sent a BLOCKED frame. We should only send
 121   // another when the number of bytes we have sent has changed.
 122   QuicStreamOffset last_blocked_send_window_offset_;
 123
 124   DISALLOW_COPY_AND_ASSIGN(QuicFlowController);
 125 };
 126
 127 }  // namespace net
 128
 129 #endif  // NET_QUIC_QUIC_FLOW_CONTROLLER_H_