When talking >=QUIC_VERSION_22, regularly send updated bandwidth

net/quic/quic_server_session.cc

 // Copyright 2014 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.
 
 #include "net/quic/quic_server_session.h"
 
 #include "base/logging.h"
+#include "net/quic/crypto/source_address_token.h"
 #include "net/quic/quic_connection.h"
 #include "net/quic/quic_flags.h"
 #include "net/quic/quic_spdy_server_stream.h"
 #include "net/quic/reliable_quic_stream.h"
 
 namespace net {
 
 QuicServerSession::QuicServerSession(
     const QuicConfig& config,
     QuicConnection* connection,
     QuicPerConnectionPacketWriter* connection_packet_writer,
     QuicServerSessionVisitor* visitor)
     : QuicSession(connection, config),
       connection_packet_writer_(connection_packet_writer),
-      visitor_(visitor) {}
+      bandwidth_estimate_sent_to_client_(QuicBandwidth::Zero()),
+      last_server_config_update_time_(QuicTime::Zero()) {}
 
 QuicServerSession::~QuicServerSession() {}
 
 void QuicServerSession::InitializeSession(
     const QuicCryptoServerConfig& crypto_config) {
   QuicSession::InitializeSession();
   crypto_stream_.reset(CreateQuicCryptoServerStream(crypto_config));
 }
 
 QuicCryptoServerStream* QuicServerSession::CreateQuicCryptoServerStream(
@@ skipping 22 matching lines @@
     crypto_stream_->CancelOutstandingCallbacks();
   }
   visitor_->OnConnectionClosed(connection()->connection_id(), error);
 }
 
 void QuicServerSession::OnWriteBlocked() {
   QuicSession::OnWriteBlocked();
   visitor_->OnWriteBlocked(connection());
 }
 
+void QuicServerSession::OnCongestionWindowChange(QuicTime now) {
+  if (connection()->version() <= QUIC_VERSION_21) {
+    return;
+  }
+
+  // If not enough time has passed since the last time we sent an update to the
+  // client, then return early.
+  const QuicSentPacketManager& sent_packet_manager =
+      connection()->sent_packet_manager();
+  int64 srtt_ms =
+      sent_packet_manager.GetRttStats()->SmoothedRtt().ToMilliseconds();
+  int64 now_ms = now.Subtract(last_server_config_update_time_).ToMilliseconds();
+  if (now_ms < (kMinIntervalBetweenServerConfigUpdatesRTTs * srtt_ms) ||
+      now_ms < kMinIntervalBetweenServerConfigUpdatesMs) {
+    return;
+  }
+
+  // If the bandwidth recorder does not have a valid estimate, return early.
+  const QuicSustainedBandwidthRecorder& bandwidth_recorder =
+      sent_packet_manager.SustainedBandwidthRecorder();
+  if (!bandwidth_recorder.HasEstimate()) {
+    return;
+  }
+
+  // The bandwidth recorder has recorded at least one sustained bandwidth
+  // estimate. Check that it's substantially different from the last one that
+  // we sent to the client, and if so, send the new one.
+  QuicBandwidth new_bandwidth_estimate = bandwidth_recorder.BandwidthEstimate();
+
+  int64 bandwidth_delta =
+      std::abs(new_bandwidth_estimate.ToBitsPerSecond() -
+               bandwidth_estimate_sent_to_client_.ToBitsPerSecond());
+
+  // Define "substantial" difference as a 50% increase or decrease from the
+  // last estimate.
+  bool substantial_difference =
+      bandwidth_delta >
+      0.5 * bandwidth_estimate_sent_to_client_.ToBitsPerSecond();
+  if (!substantial_difference) {
+    return;
+  }
+
+  bandwidth_estimate_sent_to_client_ = new_bandwidth_estimate;
+  DVLOG(1) << "Server: sending new bandwidth estimate (KBytes/s): "
+           << bandwidth_estimate_sent_to_client_.ToKBytesPerSecond();
+
+  // Include max bandwidth in the update.
+  QuicBandwidth max_bandwidth_estimate =
+      bandwidth_recorder.MaxBandwidthEstimate();
+  int32 max_bandwidth_timestamp = bandwidth_recorder.MaxBandwidthTimestamp();
+
+  // Fill the proto before passing it to the crypto stream to send.
+  CachedNetworkParameters cached_network_params;
+  cached_network_params.set_bandwidth_estimate_bytes_per_second(
+      bandwidth_estimate_sent_to_client_.ToBytesPerSecond());
+  cached_network_params.set_max_bandwidth_estimate_bytes_per_second(
+      max_bandwidth_estimate.ToBytesPerSecond());
+  cached_network_params.set_max_bandwidth_timestamp_seconds(
+      max_bandwidth_timestamp);
+  cached_network_params.set_min_rtt_ms(
+      sent_packet_manager.GetRttStats()->min_rtt().ToMilliseconds());
+  cached_network_params.set_previous_connection_state(
+      bandwidth_recorder.EstimateRecordedDuringSlowStart()
+          ? CachedNetworkParameters::SLOW_START
+          : CachedNetworkParameters::CONGESTION_AVOIDANCE);
+  if (!serving_region_.empty()) {
+    cached_network_params.set_serving_region(serving_region_);
+  }
+
+  crypto_stream_->SendServerConfigUpdate(&cached_network_params);
+  last_server_config_update_time_ = now;
+}
+
 bool QuicServerSession::ShouldCreateIncomingDataStream(QuicStreamId id) {
   if (id % 2 == 0) {
     DVLOG(1) << "Invalid incoming even stream_id:" << id;
     connection()->SendConnectionClose(QUIC_INVALID_STREAM_ID);
     return false;
   }
   if (GetNumOpenStreams() >= get_max_open_streams()) {
     DVLOG(1) << "Failed to create a new incoming stream with id:" << id
              << " Already " << GetNumOpenStreams() << " open.";
     connection()->SendConnectionClose(QUIC_TOO_MANY_OPEN_STREAMS);
@@ skipping 14 matching lines @@
 QuicDataStream* QuicServerSession::CreateOutgoingDataStream() {
   DLOG(ERROR) << "Server push not yet supported";
   return NULL;
 }
 
 QuicCryptoServerStream* QuicServerSession::GetCryptoStream() {
   return crypto_stream_.get();
 }
 
 }  // namespace net