Stop a session when a new connection becomes writable.

webrtc/p2p/base/p2ptransportchannel.cc

 /*
  *  Copyright 2004 The WebRTC Project Authors. All rights reserved.
  *
  *  Use of this source code is governed by a BSD-style license
  *  that can be found in the LICENSE file in the root of the source
  *  tree. An additional intellectual property rights grant can be found
  *  in the file PATENTS.  All contributing project authors may
  *  be found in the AUTHORS file in the root of the source tree.
  */
 
@@ skipping 197 matching lines @@
                                          PortAllocator* allocator)
     : TransportChannelImpl(transport_name, component),
       transport_(transport),
       allocator_(allocator),
       worker_thread_(rtc::Thread::Current()),
       incoming_only_(false),
       error_(0),
       best_connection_(NULL),
       pending_best_connection_(NULL),
       sort_dirty_(false),
-      was_writable_(false),
       remote_ice_mode_(ICEMODE_FULL),
       ice_role_(ICEROLE_UNKNOWN),
       tiebreaker_(0),
       remote_candidate_generation_(0),
       gathering_state_(kIceGatheringNew),
       check_receiving_delay_(MIN_CHECK_RECEIVING_DELAY * 5),
       receiving_timeout_(MIN_CHECK_RECEIVING_DELAY * 50) {
   uint32_t weak_ping_delay = ::strtoul(
       webrtc::field_trial::FindFullName("WebRTC-StunInterPacketDelay").c_str(),
       nullptr, 10);
   if (weak_ping_delay) {
     weak_ping_delay_ =  weak_ping_delay;
   }
 }
 
 P2PTransportChannel::~P2PTransportChannel() {
   ASSERT(worker_thread_ == rtc::Thread::Current());
 
   for (size_t i = 0; i < allocator_sessions_.size(); ++i)
     delete allocator_sessions_[i];
 }
 
 // Add the allocator session to our list so that we know which sessions
 // are still active.
 void P2PTransportChannel::AddAllocatorSession(PortAllocatorSession* session) {
+  ASSERT(worker_thread_ == rtc::Thread::Current());
+
   session->set_generation(static_cast<uint32_t>(allocator_sessions_.size()));
   allocator_sessions_.push_back(session);
 
   // We now only want to apply new candidates that we receive to the ports
   // created by this new session because these are replacing those of the
   // previous sessions.
   ports_.clear();
 
   session->SignalPortReady.connect(this, &P2PTransportChannel::OnPortReady);
   session->SignalCandidatesReady.connect(
@@ skipping 817 matching lines @@
   bool receiving = false;
   for (const Connection* connection : connections_) {
     if (connection->receiving()) {
       receiving = true;
       break;
     }
   }
   set_receiving(receiving);
 }
 
-// We checked the status of our connections and we had at least one that
-// was writable, go into the writable state.
-void P2PTransportChannel::HandleWritable() {
-  ASSERT(worker_thread_ == rtc::Thread::Current());
-  if (writable()) {
+void P2PTransportChannel::MaybeStopPortAllocatorSessions() {
+  if (!IsGettingPorts()) {
     return;
   }
 
   for (PortAllocatorSession* session : allocator_sessions_) {
     if (!session->IsGettingPorts()) {
       continue;
     }
     // If gathering continually, keep the last session running so that it
     // will gather candidates if the networks change.
     if (gather_continually_ && session == allocator_sessions_.back()) {
       session->ClearGettingPorts();
       break;
     }
     session->StopGettingPorts();
   }
+}
 
-  was_writable_ = true;
-  set_writable(true);
+// Go into the writable state and notify upper layer if it was not before.
+void P2PTransportChannel::HandleWritable() {
+  ASSERT(worker_thread_ == rtc::Thread::Current());
+  if (!writable()) {
+    set_writable(true);
+  }
 }
 
 // Notify upper layer about channel not writable state, if it was before.
 void P2PTransportChannel::HandleNotWritable() {
   ASSERT(worker_thread_ == rtc::Thread::Current());
-  if (was_writable_) {
-    was_writable_ = false;
+  if (writable()) {
     set_writable(false);
   }
 }
 
 // If all connections timed out, delete them all.
 void P2PTransportChannel::HandleAllTimedOut() {
   for (Connection* connection : connections_) {
     connection->Destroy();
   }
 }
@@ skipping 163 matching lines @@
   // connection and role is controlled.
   if (ice_role_ == ICEROLE_CONTROLLED) {
     if (connection == pending_best_connection_ && connection->writable()) {
       pending_best_connection_ = NULL;
       LOG(LS_INFO) << "Switching best connection on controlled side"
                    << " because it's now writable: " << connection->ToString();
       SwitchBestConnectionTo(connection);
     }
   }
 
+  // May stop the session after at least one connection becomes strong

[pthatcher1, 2015/11/04 15:06:14]

strong => strongly connected

[pthatcher1, 2015/11/04 15:06:14]

the session => allocator sessions

[honghaiz3, 2015/11/04 18:27:12]

Done.

[honghaiz3, 2015/11/04 18:27:12]

Done.

+  // after starting to get ports. It is not enough to check that the connection
+  // becomes writable because the connection may be changing from

[pthatcher1, 2015/11/04 15:06:14]

writable => weakly connected

[honghaiz3, 2015/11/04 18:27:12]

Done.

+  // (writable, receiving) to (writable, not receiving).
+  if (!connection->weak()) {
+    MaybeStopPortAllocatorSessions();
+  }
+
   // We have to unroll the stack before doing this because we may be changing
   // the state of connections while sorting.
   RequestSort();
 }
 
 // When a connection is removed, edit it out, and then update our best
 // connection.
 void P2PTransportChannel::OnConnectionDestroyed(Connection* connection) {
   ASSERT(worker_thread_ == rtc::Thread::Current());
 
@@ skipping 71 matching lines @@
   SignalSentPacket(this, sent_packet);
 }
 
 void P2PTransportChannel::OnReadyToSend(Connection* connection) {
   if (connection == best_connection_ && writable()) {
     SignalReadyToSend(this);
   }
 }
 
 }  // namespace cricket