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 \
  15   (perspective_ == Perspective::IS_SERVER ? "Server: " : "Client: ")
  16
  17 QuicFlowController::QuicFlowController(QuicConnection* connection,
  18                                        QuicStreamId id,
  19                                        Perspective perspective,
  20                                        QuicStreamOffset send_window_offset,
  21                                        QuicStreamOffset receive_window_offset,
  22                                        QuicByteCount max_receive_window)
  23     : connection_(connection),
  24       id_(id),
  25       perspective_(perspective),
  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   bytes_consumed_ += bytes_consumed;
  43   DVLOG(1) << ENDPOINT << "Stream " << id_ << " consumed: " << bytes_consumed_;
  44
  45   MaybeSendWindowUpdate();
  46 }
  47
  48 bool QuicFlowController::UpdateHighestReceivedOffset(
  49     QuicStreamOffset new_offset) {
  50   // Only update if offset has increased.
  51   if (new_offset <= highest_received_byte_offset_) {
  52     return false;
  53   }
  54
  55   DVLOG(1) << ENDPOINT << "Stream " << id_
  56            << " highest byte offset increased from: "
  57            << highest_received_byte_offset_ << " to " << new_offset;
  58   highest_received_byte_offset_ = new_offset;
  59   return true;
  60 }
  61
  62 void QuicFlowController::AddBytesSent(QuicByteCount bytes_sent) {
  63   if (bytes_sent_ + bytes_sent > send_window_offset_) {
  64     LOG(DFATAL) << ENDPOINT << "Stream " << id_ << " Trying to send an extra "
  65                 << bytes_sent << " bytes, when bytes_sent = " << bytes_sent_
  66                 << ", and send_window_offset_ = " << send_window_offset_;
  67     bytes_sent_ = send_window_offset_;
  68
  69     // This is an error on our side, close the connection as soon as possible.
  70     connection_->SendConnectionClose(QUIC_FLOW_CONTROL_SENT_TOO_MUCH_DATA);
  71     return;
  72   }
  73
  74   bytes_sent_ += bytes_sent;
  75   DVLOG(1) << ENDPOINT << "Stream " << id_ << " sent: " << bytes_sent_;
  76 }
  77
  78 bool QuicFlowController::FlowControlViolation() {
  79   if (highest_received_byte_offset_ > receive_window_offset_) {
  80     LOG(ERROR) << ENDPOINT << "Flow control violation on stream "
  81                << id_ << ", receive window offset: "
  82                << receive_window_offset_
  83                << ", highest received byte offset: "
  84                << highest_received_byte_offset_;
  85     return true;
  86   }
  87   return false;
  88 }
  89
  90 void QuicFlowController::MaybeSendWindowUpdate() {
  91   // Send WindowUpdate to increase receive window if
  92   // (receive window offset - consumed bytes) < (max window / 2).
  93   // This is behaviour copied from SPDY.
  94   DCHECK_LT(bytes_consumed_, receive_window_offset_);
  95   QuicStreamOffset consumed_window = receive_window_offset_ - bytes_consumed_;
  96   QuicByteCount threshold = (max_receive_window_ / 2);
  97
  98   if (consumed_window < threshold) {
  99     // Update our receive window.
 100     receive_window_offset_ += (max_receive_window_ - consumed_window);
 101
 102     DVLOG(1) << ENDPOINT << "Sending WindowUpdate frame for stream " << id_
 103              << ", consumed bytes: " << bytes_consumed_
 104              << ", consumed window: " << consumed_window
 105              << ", and threshold: " << threshold
 106              << ", and max recvw: " << max_receive_window_
 107              << ". New receive window offset is: " << receive_window_offset_;
 108
 109     // Inform the peer of our new receive window.
 110     connection_->SendWindowUpdate(id_, receive_window_offset_);
 111   }
 112 }
 113
 114 void QuicFlowController::MaybeSendBlocked() {
 115   if (SendWindowSize() == 0 &&
 116       last_blocked_send_window_offset_ < send_window_offset_) {
 117     DVLOG(1) << ENDPOINT << "Stream " << id_ << " is flow control blocked. "
 118              << "Send window: " << SendWindowSize()
 119              << ", bytes sent: " << bytes_sent_
 120              << ", send limit: " << send_window_offset_;
 121     // The entire send_window has been consumed, we are now flow control
 122     // blocked.
 123     connection_->SendBlocked(id_);
 124
 125     // Keep track of when we last sent a BLOCKED frame so that we only send one
 126     // at a given send offset.
 127     last_blocked_send_window_offset_ = send_window_offset_;
 128   }
 129 }
 130
 131 bool QuicFlowController::UpdateSendWindowOffset(
 132     QuicStreamOffset new_send_window_offset) {
 133   // Only update if send window has increased.
 134   if (new_send_window_offset <= send_window_offset_) {
 135     return false;
 136   }
 137
 138   DVLOG(1) << ENDPOINT << "UpdateSendWindowOffset for stream " << id_
 139            << " with new offset " << new_send_window_offset
 140            << " current offset: " << send_window_offset_
 141            << " bytes_sent: " << bytes_sent_;
 142
 143   const bool blocked = IsBlocked();
 144   send_window_offset_ = new_send_window_offset;
 145   return blocked;
 146 }
 147
 148 bool QuicFlowController::IsBlocked() const {
 149   return SendWindowSize() == 0;
 150 }
 151
 152 uint64 QuicFlowController::SendWindowSize() const {
 153   if (bytes_sent_ > send_window_offset_) {
 154     return 0;
 155   }
 156   return send_window_offset_ - bytes_sent_;
 157 }
 158
 159 }  // namespace net