Early connection migration in QUIC.

net/quic/quic_stream_factory.cc

 // Copyright (c) 2012 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_stream_factory.h"
 
 #include <algorithm>
 #include <set>
 #include <utility>
 
@@ skipping 553 matching lines @@
     int max_disabled_reasons,
     int threshold_public_resets_post_handshake,
     int threshold_timeouts_with_open_streams,
     int socket_receive_buffer_size,
     bool delay_tcp_race,
     int max_server_configs_stored_in_properties,
     bool close_sessions_on_ip_change,
     bool disable_quic_on_timeout_with_open_streams,
     int idle_connection_timeout_seconds,
     bool migrate_sessions_on_network_change,
+    bool migrate_sessions_early,
     const QuicTagVector& connection_options)
     : require_confirmation_(true),
       host_resolver_(host_resolver),
       client_socket_factory_(client_socket_factory),
       http_server_properties_(http_server_properties),
       transport_security_state_(transport_security_state),
       cert_transparency_verifier_(cert_transparency_verifier),
       quic_crypto_client_stream_factory_(quic_crypto_client_stream_factory),
       random_generator_(random_generator),
       clock_(clock),
@@ skipping 29 matching lines @@
           threshold_public_resets_post_handshake),
       socket_receive_buffer_size_(socket_receive_buffer_size),
       delay_tcp_race_(delay_tcp_race),
       yield_after_packets_(kQuicYieldAfterPacketsRead),
       yield_after_duration_(QuicTime::Delta::FromMilliseconds(
           kQuicYieldAfterDurationMilliseconds)),
       close_sessions_on_ip_change_(close_sessions_on_ip_change),
       migrate_sessions_on_network_change_(
           migrate_sessions_on_network_change &&
           NetworkChangeNotifier::AreNetworkHandlesSupported()),
+      migrate_sessions_early_(migrate_sessions_early &&
+                              migrate_sessions_on_network_change_),
       port_seed_(random_generator_->RandUint64()),
       check_persisted_supports_quic_(true),
       has_initialized_data_(false),
       task_runner_(nullptr),
       weak_factory_(this) {
   if (disable_quic_on_timeout_with_open_streams)
     threshold_timeouts_with_open_streams_ = 1;
   DCHECK(transport_security_state_);
   DCHECK(http_server_properties_);
   crypto_config_.set_user_agent_id(user_agent_id);
@@ skipping 20 matching lines @@
   if (!IsEcdsaSupported())
     crypto_config_.DisableEcdsa();
   // When disk cache is used to store the server configs, HttpCache code calls
   // |set_quic_server_info_factory| if |quic_server_info_factory_| wasn't
   // created.
   if (max_server_configs_stored_in_properties > 0) {
     quic_server_info_factory_.reset(
         new PropertiesBasedQuicServerInfoFactory(http_server_properties_));
   }
 
-  DCHECK(
-      !(close_sessions_on_ip_change_ && migrate_sessions_on_network_change_));
+  DCHECK(!close_sessions_on_ip_change_ || !migrate_sessions_on_network_change_);
+  DCHECK(migrate_sessions_on_network_change_ || !migrate_sessions_early_);

[Ryan Hamilton, 2016/02/02 04:19:59]

Can you add comments for these two blocks? These expressions are not immediately
understandable.

[Jana, 2016/02/02 06:53:53]

Done.

   if (migrate_sessions_on_network_change_) {
     NetworkChangeNotifier::AddNetworkObserver(this);
   } else if (close_sessions_on_ip_change_) {
     NetworkChangeNotifier::AddIPAddressObserver(this);
   }
 }
 
 QuicStreamFactory::~QuicStreamFactory() {
   CloseAllSessions(ERR_ABORTED, QUIC_INTERNAL_ERROR);
   while (!all_sessions_.empty()) {
@@ skipping 556 matching lines @@
       if (force_close) {
         session->CloseSessionOnError(ERR_NETWORK_CHANGED,
                                      QUIC_CONNECTION_MIGRATION_NO_NEW_NETWORK);
       }
       continue;
     }
     MigrateSessionToNetwork(session, new_network);
   }
 }
 
 void QuicStreamFactory::MaybeMigrateSessionEarly(

[Ryan Hamilton, 2016/02/02 04:19:59]

Was this landed post-review, or did I miss it in the previous CL?

[Jana, 2016/02/02 06:53:53]

This got added post-LGTM, and I am pretty sure it was due to some git magic that
I f***ed up. I most certainly didn't intend to add this code in, since it wasn't
getting used. Apologies.

     QuicChromiumClientSession* session) {
-  if (session->GetNumActiveStreams() == 0) {
+  if (!migrate_sessions_early_ || (session->GetNumActiveStreams() == 0)) {
     return;
   }
   NetworkChangeNotifier::NetworkHandle current_network =
       session->GetDefaultSocket()->GetBoundNetwork();
   NetworkChangeNotifier::NetworkHandle new_network =
       FindAlternateNetwork(current_network);
   if (new_network == NetworkChangeNotifier::kInvalidNetworkHandle) {
     // No alternate network found.
     return;
   }
@@ skipping 371 matching lines @@
   // Since the session was active, there's no longer an
   // HttpStreamFactoryImpl::Job running which can mark it broken, unless the TCP
   // job also fails. So to avoid not using QUIC when we otherwise could, we mark
   // it as recently broken, which means that 0-RTT will be disabled but we'll
   // still race.
   http_server_properties_->MarkAlternativeServiceRecentlyBroken(
       alternative_service);
 }
 
 }  // namespace net