Dampening connection switch.

webrtc/p2p/base/p2ptransportchannel.h

 /*
  *  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 208 matching lines @@
   void UpdateConnectionStates();
   void RequestSortAndStateUpdate();
   // Start pinging if we haven't already started, and we now have a connection
   // that's pingable.
   void MaybeStartPinging();
 
   // The methods below return a positive value if a is preferable to b,
   // a negative value if b is preferable, and 0 if they're equally preferable.
   int CompareConnectionStates(const cricket::Connection* a,
                               const cricket::Connection* b) const;
+  int CompareConnectionWriteAndConnectedStates(
+      const cricket::Connection* a,
+      const cricket::Connection* b) const;
   int CompareConnectionCandidates(const cricket::Connection* a,
                                   const cricket::Connection* b) const;
   // Compares two connections based on the connection states
   // (writable/receiving/connected), nomination states, last data received time,
-  // and static preferences. Does not include latency. Used by both sorting
-  // and ShouldSwitchSelectedConnection().
+  // and static preferences, and latency. Used by sorting connections.
   // Returns a positive value if |a| is better than |b|.
   int CompareConnections(const cricket::Connection* a,
                          const cricket::Connection* b) const;
+  int CompareConnectionsWithoutStates(const cricket::Connection* a,
+                                      const cricket::Connection* b) const;
+  // This is similar to CompareConnectionStates except that if the selected
+  // connection is not receiving and the new connection is receiving, return a
+  // negative value (indicating the new connection is better) only if the new
+  // connection has been in receiving state for |receiving_dampening_interval_|
+  // milliseconds. If the new connection is receiving but is dampened by this
+  // mechanism, set |connection_dampened| to be true.
+  int CompareConnectionStatesWithDampening(
+      const cricket::Connection* selected_conn,
+      const cricket::Connection* new_conn,
+      bool* connection_dampened) const;
 
   bool PresumedWritable(const cricket::Connection* conn) const;
 
-  bool ShouldSwitchSelectedConnection(const cricket::Connection* selected,
-                                      const cricket::Connection* conn) const;
   void SortConnectionsAndUpdateState();
   void SwitchSelectedConnection(Connection* conn);
   void UpdateState();
   void HandleAllTimedOut();
   void MaybeStopPortAllocatorSessions();
   TransportChannelState ComputeState() const;
 
   Connection* GetBestConnectionOnNetwork(rtc::Network* network) const;
   bool CreateConnections(const Candidate& remote_candidate,
                          PortInterface* origin_port);
@@ skipping 47 matching lines @@
   void OnReadyToSend(Connection* connection);
   void OnConnectionDestroyed(Connection *connection);
 
   void OnNominated(Connection* conn);
 
   void OnMessage(rtc::Message* pmsg) override;
   void OnCheckAndPing();
   void OnRegatherOnFailedNetworks();
 
   // Returns true if the new_connection should be selected for transmission.
-  bool ShouldSwitchSelectedConnection(Connection* new_connection) const;
+  bool ShouldSwitchSelectedConnection(Connection* new_connection);
 
   void PruneConnections();
   bool IsBackupConnection(const Connection* conn) const;
 
   Connection* FindConnectionToPing(int64_t now);
   Connection* FindOldestConnectionNeedingTriggeredCheck(int64_t now);
   // Between |conn1| and |conn2|, this function returns the one which should
   // be pinged first.
   Connection* SelectMostPingableConnection(Connection* conn1,
                                            Connection* conn2);
@@ skipping 38 matching lines @@
   // |connections_| is a sorted list with the first one always be the
   // |selected_connection_| when it's not nullptr. The combination of
   // |pinged_connections_| and |unpinged_connections_| has the same
   // connections as |connections_|. These 2 sets maintain whether a
   // connection should be pinged next or not.
   std::vector<Connection *> connections_;
   std::set<Connection*> pinged_connections_;
   std::set<Connection*> unpinged_connections_;
 
   Connection* selected_connection_ = nullptr;
+  Connection* pending_selected_connection_ = nullptr;
 
   std::vector<RemoteCandidate> remote_candidates_;
   bool sort_dirty_;  // indicates whether another sort is needed right now
   bool had_connection_ = false;  // if connections_ has ever been nonempty
   typedef std::map<rtc::Socket::Option, int> OptionMap;
   OptionMap options_;
   std::string ice_ufrag_;
   std::string ice_pwd_;
   std::vector<IceParameters> remote_ice_parameters_;
   IceMode remote_ice_mode_;
   IceRole ice_role_;
   uint64_t tiebreaker_;
   IceGatheringState gathering_state_;
 
   int check_receiving_interval_;
   int64_t last_ping_sent_ms_ = 0;
   int weak_ping_interval_ = WEAK_PING_INTERVAL;
   TransportChannelState state_ = TransportChannelState::STATE_INIT;
   IceConfig config_;
   int last_sent_packet_id_ = -1;  // -1 indicates no packet was sent before.
   bool started_pinging_ = false;
+  bool was_strong_ = false;
 
   RTC_DISALLOW_COPY_AND_ASSIGN(P2PTransportChannel);
 };
 
 }  // namespace cricket
 
 #endif  // WEBRTC_P2P_BASE_P2PTRANSPORTCHANNEL_H_