net/quic/quic_flow_controller.cc

   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 #include "net/quic/quic_flow_controller.h"
   6
   7 #include "base/basictypes.h"
   8 #include "net/quic/quic_connection.h"
   9 #include "net/quic/quic_flags.h"
  10 #include "net/quic/quic_protocol.h"
  11
  12 namespace net {
  13
  14 #define ENDPOINT (is_server_ ? "Server: " : " Client: ")
  15
  16 QuicFlowController::QuicFlowController(QuicConnection* connection,
  17                                        QuicStreamId id,
  18                                        bool is_server,
  19                                        QuicStreamOffset send_window_offset,
  20                                        QuicStreamOffset receive_window_offset,
  21                                        QuicByteCount max_receive_window)
  22     : connection_(connection),
  23       id_(id),
  24       is_enabled_(true),
  25       is_server_(is_server),
  26       bytes_consumed_(0),
  27       highest_received_byte_offset_(0),
  28       bytes_sent_(0),
  29       send_window_offset_(send_window_offset),
  30       receive_window_offset_(receive_window_offset),
  31       max_receive_window_(max_receive_window),
  32       last_blocked_send_window_offset_(0) {
  33   DVLOG(1) << ENDPOINT << "Created flow controller for stream " << id_
  34            << ", setting initial receive window offset to: "
  35            << receive_window_offset_
  36            << ", max receive window to: "
  37            << max_receive_window_
  38            << ", setting send window offset to: " << send_window_offset_;
  39 }
  40
  41 void QuicFlowController::AddBytesConsumed(QuicByteCount bytes_consumed) {
  42   if (!IsEnabled()) {
  43     return;
  44   }
  45
  46   bytes_consumed_ += bytes_consumed;
  47   DVLOG(1) << ENDPOINT << "Stream " << id_ << " consumed: " << bytes_consumed_;
  48
  49   MaybeSendWindowUpdate();
  50 }
  51
  52 bool QuicFlowController::UpdateHighestReceivedOffset(
  53     QuicStreamOffset new_offset) {
  54   if (!IsEnabled()) {
  55     return false;
  56   }
  57
  58   // Only update if offset has increased.
  59   if (new_offset <= highest_received_byte_offset_) {
  60     return false;
  61   }
  62
  63   DVLOG(1) << ENDPOINT << "Stream " << id_
  64            << " highest byte offset increased from: "
  65            << highest_received_byte_offset_ << " to " << new_offset;
  66   highest_received_byte_offset_ = new_offset;
  67   return true;
  68 }
  69
  70 void QuicFlowController::AddBytesSent(QuicByteCount bytes_sent) {
  71   if (!IsEnabled()) {
  72     return;
  73   }
  74
  75   if (bytes_sent_ + bytes_sent > send_window_offset_) {
  76     LOG(DFATAL) << ENDPOINT << "Stream " << id_ << " Trying to send an extra "
  77                 << bytes_sent << " bytes, when bytes_sent = " << bytes_sent_
  78                 << ", and send_window_offset_ = " << send_window_offset_;
  79     bytes_sent_ = send_window_offset_;
  80
  81     // This is an error on our side, close the connection as soon as possible.
  82     connection_->SendConnectionClose(QUIC_FLOW_CONTROL_SENT_TOO_MUCH_DATA);
  83     return;
  84   }
  85
  86   bytes_sent_ += bytes_sent;
  87   DVLOG(1) << ENDPOINT << "Stream " << id_ << " sent: " << bytes_sent_;
  88 }
  89
  90 bool QuicFlowController::FlowControlViolation() {
  91   if (!IsEnabled()) {
  92     return false;
  93   }
  94
  95   if (highest_received_byte_offset_ > receive_window_offset_) {
  96     LOG(ERROR) << ENDPOINT << "Flow control violation on stream "
  97                << id_ << ", receive window offset: "
  98                << receive_window_offset_
  99                << ", highest received byte offset: "
 100                << highest_received_byte_offset_;
 101     return true;
 102   }
 103   return false;
 104 }
 105
 106 void QuicFlowController::MaybeSendWindowUpdate() {
 107   if (!IsEnabled()) {
 108     return;
 109   }
 110
 111   // Send WindowUpdate to increase receive window if
 112   // (receive window offset - consumed bytes) < (max window / 2).
 113   // This is behaviour copied from SPDY.
 114   DCHECK_LT(bytes_consumed_, receive_window_offset_);
 115   QuicStreamOffset consumed_window = receive_window_offset_ - bytes_consumed_;
 116   QuicByteCount threshold = (max_receive_window_ / 2);
 117
 118   if (consumed_window < threshold) {
 119     // Update our receive window.
 120     receive_window_offset_ += (max_receive_window_ - consumed_window);
 121
 122     DVLOG(1) << ENDPOINT << "Sending WindowUpdate frame for stream " << id_
 123              << ", consumed bytes: " << bytes_consumed_
 124              << ", consumed window: " << consumed_window
 125              << ", and threshold: " << threshold
 126              << ", and max recvw: " << max_receive_window_
 127              << ". New receive window offset is: " << receive_window_offset_;
 128
 129     // Inform the peer of our new receive window.
 130     connection_->SendWindowUpdate(id_, receive_window_offset_);
 131   }
 132 }
 133
 134 void QuicFlowController::MaybeSendBlocked() {
 135   if (!IsEnabled()) {
 136     return;
 137   }
 138
 139   if (SendWindowSize() == 0 &&
 140       last_blocked_send_window_offset_ < send_window_offset_) {
 141     DVLOG(1) << ENDPOINT << "Stream " << id_ << " is flow control blocked. "
 142              << "Send window: " << SendWindowSize()
 143              << ", bytes sent: " << bytes_sent_
 144              << ", send limit: " << send_window_offset_;
 145     // The entire send_window has been consumed, we are now flow control
 146     // blocked.
 147     connection_->SendBlocked(id_);
 148
 149     // Keep track of when we last sent a BLOCKED frame so that we only send one
 150     // at a given send offset.
 151     last_blocked_send_window_offset_ = send_window_offset_;
 152   }
 153 }
 154
 155 bool QuicFlowController::UpdateSendWindowOffset(
 156     QuicStreamOffset new_send_window_offset) {
 157   if (!IsEnabled()) {
 158     return false;
 159   }
 160
 161   // Only update if send window has increased.
 162   if (new_send_window_offset <= send_window_offset_) {
 163     return false;
 164   }
 165
 166   DVLOG(1) << ENDPOINT << "UpdateSendWindowOffset for stream " << id_
 167            << " with new offset " << new_send_window_offset
 168            << " current offset: " << send_window_offset_
 169            << " bytes_sent: " << bytes_sent_;
 170
 171   const bool blocked = IsBlocked();
 172   send_window_offset_ = new_send_window_offset;
 173   return blocked;
 174 }
 175
 176 void QuicFlowController::Disable() {
 177   is_enabled_ = false;
 178 }
 179
 180 bool QuicFlowController::IsEnabled() const {
 181   return is_enabled_;
 182 }
 183
 184 bool QuicFlowController::IsBlocked() const {
 185   return IsEnabled() && SendWindowSize() == 0;
 186 }
 187
 188 uint64 QuicFlowController::SendWindowSize() const {
 189   if (bytes_sent_ > send_window_offset_) {
 190     return 0;
 191   }
 192   return send_window_offset_ - bytes_sent_;
 193 }
 194
 195 }  // namespace net