Do not delete a connection until it has not received anything for 30 seconds.

webrtc/p2p/base/port.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 1110 matching lines @@
     // A connection that hasn't passed its minimum lifetime is still alive.
     // We do this to prevent connections from being pruned too quickly
     // during a network change event when two networks would be up
     // simultaneously but only for a brief period.
     return false;
   }
 
   if (receiving_) {
     // A connection that is receiving is alive.
     return false;
   }

[pthatcher1, 2015/11/11 21:04:54]

Can we just remove this check because it's covered by the last check?  Clearly
if we're receiving_ we have also received something in the last 30s.

[honghaiz3, 2015/11/12 00:27:10]

Done. I thought this could be a shortcut for early return. 

 
-  // A connection is alive until it is inactive.
-  return !active();
+  // A connection is alive if it is active (not write-timeout).
+  if (active()) {
+    return false;
+  }

[pthatcher1, 2015/11/11 21:04:54]

Can we just remove this part because it's covered by the part below?  Clearly if
we have not received anything for 30s, we'll have hit write timeout.

[honghaiz3, 2015/11/12 00:27:10]

Done. I guess OK to remove it. write-timeout depends on the time to send the
ping request. If It has not been scheduled to send ping since last ping success,
it will not hit write-timeout, although the chance that happens is pretty small.

 
-  // TODO(honghaiz): Move from using the write state to using the receiving
-  // state with something like the following:
-  // return (now > (last_received() + DEAD_CONNECTION_RECEIVE_TIMEOUT));
+  // It is dead if it has not received anything for
+  // DEAD_CONNECTION_RECEIVE_TIMEOUT milliseconds.
+  return (now > (last_received() + DEAD_CONNECTION_RECEIVE_TIMEOUT));
 }
 
 std::string Connection::ToDebugId() const {
   std::stringstream ss;
   ss << std::hex << this;
   return ss.str();
 }
 
 std::string Connection::ToString() const {
   const char CONNECT_STATE_ABBREV[2] = {
@@ skipping 146 matching lines @@
   }
 }
 
 void Connection::OnMessage(rtc::Message *pmsg) {
   ASSERT(pmsg->message_id == MSG_DELETE);
   LOG_J(LS_INFO, this) << "Connection deleted";
   SignalDestroyed(this);
   delete this;
 }
 
-uint32_t Connection::last_received() {
+uint32_t Connection::last_received() const {
   return std::max(last_data_received_,
              std::max(last_ping_received_, last_ping_response_received_));
 }
 
 size_t Connection::recv_bytes_second() {
   return recv_rate_tracker_.ComputeRate();
 }
 
 size_t Connection::recv_total_bytes() {
   return recv_rate_tracker_.TotalSampleCount();
@@ skipping 98 matching lines @@
     ASSERT(sent < 0);
     error_ = port_->GetError();
     sent_packets_discarded_++;
   } else {
     send_rate_tracker_.AddSamples(sent);
   }
   return sent;
 }
 
 }  // namespace cricket