Change the number of emulated connections in QUIC's congestion control

net/quic/quic_sent_packet_manager.cc

 // Copyright 2013 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_sent_packet_manager.h"
 
 #include <algorithm>
 
 #include "base/logging.h"
 #include "base/stl_util.h"
@@ skipping 60 matching lines @@
       is_server_(is_server),
       clock_(clock),
       stats_(stats),
       debug_delegate_(nullptr),
       network_change_visitor_(nullptr),
       send_algorithm_(SendAlgorithmInterface::Create(clock,
                                                      &rtt_stats_,
                                                      congestion_control_type,
                                                      stats)),
       loss_algorithm_(LossDetectionInterface::Create(loss_type)),
+      n_connection_simulation_(false),
       receive_buffer_bytes_(kDefaultSocketReceiveBuffer),
       least_packet_awaited_by_peer_(1),
       first_rto_transmission_(0),
       consecutive_rto_count_(0),
       consecutive_tlp_count_(0),
       consecutive_crypto_retransmission_count_(0),
       pending_timer_transmission_count_(0),
       max_tail_loss_probes_(kDefaultMaxTailLossProbes),
       using_pacing_(false),
       handshake_confirmed_(false) {
@@ skipping 27 matching lines @@
       ContainsQuicTag(config.ReceivedConnectionOptions(), kRENO)) {
     send_algorithm_.reset(
         SendAlgorithmInterface::Create(clock_, &rtt_stats_, kReno, stats_));
   }
   if (HasClientSentConnectionOption(config, kPACE)) {
     EnablePacing();
   }
   if (HasClientSentConnectionOption(config, k1CON)) {
     send_algorithm_->SetNumEmulatedConnections(1);
   }
+  if (HasClientSentConnectionOption(config, kNCON)) {
+    n_connection_simulation_ = true;
+  }
   if (HasClientSentConnectionOption(config, kNTLP)) {
     max_tail_loss_probes_ = 0;
   }
   if (config.HasReceivedConnectionOptions() &&
       ContainsQuicTag(config.ReceivedConnectionOptions(), kTIME)) {
     loss_algorithm_.reset(LossDetectionInterface::Create(kTime));
   }
   if (config.HasReceivedSocketReceiveBuffer()) {
     receive_buffer_bytes_ =
         max(kMinSocketReceiveBuffer,
             static_cast<QuicByteCount>(config.ReceivedSocketReceiveBuffer()));
   }
   send_algorithm_->SetFromConfig(config, is_server_);
 
   if (network_change_visitor_ != nullptr) {
     network_change_visitor_->OnCongestionWindowChange(GetCongestionWindow());
   }
 }
 
+void QuicSentPacketManager::SetNumOpenStreams(size_t num_streams) {
+  if (n_connection_simulation_) {
+    // Ensure the number of connections is between 1 and 5.
+    send_algorithm_->SetNumEmulatedConnections(
+        min<size_t>(5, max<size_t>(1, num_streams)));
+  }
+}
+
 bool QuicSentPacketManager::HasClientSentConnectionOption(
     const QuicConfig& config, QuicTag tag) const {
   if (is_server_) {
     if (config.HasReceivedConnectionOptions() &&
         ContainsQuicTag(config.ReceivedConnectionOptions(), tag)) {
       return true;
     }
   } else if (config.HasSendConnectionOptions() &&
              ContainsQuicTag(config.SendConnectionOptions(), tag)) {
     return true;
@@ skipping 725 matching lines @@
   // Set up a pacing sender with a 1 millisecond alarm granularity, the same as
   // the default granularity of the Linux kernel's FQ qdisc.
   using_pacing_ = true;
   send_algorithm_.reset(
       new PacingSender(send_algorithm_.release(),
                        QuicTime::Delta::FromMilliseconds(1),
                        kInitialUnpacedBurst));
 }
 
 }  // namespace net