Dampening connection switch.

webrtc/p2p/base/p2ptransportchannel.h

Index: webrtc/p2p/base/p2ptransportchannel.h
diff --git a/webrtc/p2p/base/p2ptransportchannel.h b/webrtc/p2p/base/p2ptransportchannel.h
index 14cda683f5bf499358c0d77cf7220464e9553745..a268be97e198e2143c717309ec8606b4b5ef6635 100644
--- a/webrtc/p2p/base/p2ptransportchannel.h
+++ b/webrtc/p2p/base/p2ptransportchannel.h
@@ -226,20 +226,32 @@ class P2PTransportChannel : public TransportChannelImpl,
   // 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();
@@ -307,7 +319,7 @@ class P2PTransportChannel : public TransportChannelImpl,
   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;
@@ -366,6 +378,7 @@ class P2PTransportChannel : public TransportChannelImpl,
   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
@@ -387,6 +400,7 @@ class P2PTransportChannel : public TransportChannelImpl,
   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);
 };