Add network cost as part of the connection comparison.

webrtc/p2p/base/port.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 278 matching lines @@
   // Called when the socket is currently able to send.
   void OnReadyToSend();
 
   // Called when the Connection discovers a local peer reflexive candidate.
   // Returns the index of the new local candidate.
   size_t AddPrflxCandidate(const Candidate& local);
 
   void set_candidate_filter(uint32_t candidate_filter) {
     candidate_filter_ = candidate_filter;
   }
+  int32_t network_cost() const { return network_cost_; }
 
  protected:
   enum {
     MSG_DEAD = 0,
     MSG_FIRST_AVAILABLE
   };
 
   void set_type(const std::string& type) { type_ = type; }
 
   void AddAddress(const rtc::SocketAddress& address,
@@ skipping 79 matching lines @@
   // Information to use when going through a proxy.
   std::string user_agent_;
   rtc::ProxyInfo proxy_;
 
   // Candidate filter is pushed down to Port such that each Port could
   // make its own decision on how to create candidates. For example,
   // when IceTransportsType is set to relay, both RelayPort and
   // TurnPort will hide raddr to avoid local address leakage.
   uint32_t candidate_filter_;
 
+  // A virtual cost perceived by the user based on the network type. It is

[pthatcher1, 2016/02/04 23:16:21]

You should say, usually according to network type (WiFi vs. Cellular).  I could
be other things.

[honghaiz3, 2016/02/05 01:36:46]

Done.

+  // used to determine the rank of connections.

[pthatcher1, 2016/02/04 23:16:21]

Instead of talking about rank, just say that cost takes precedence over
priority.

[honghaiz3, 2016/02/05 01:36:46]

Done.

+  uint32_t network_cost_;
+
   friend class Connection;
 };
 
 // Represents a communication link between a port on the local client and a
 // port on the remote client.
 class Connection : public rtc::MessageHandler,
     public sigslot::has_slots<> {
  public:
   struct SentPing {
     SentPing(const std::string id, uint32_t sent_time)
@@ skipping 145 matching lines @@
   // controlling side.
   sigslot::signal1<Connection*> SignalNominated;
 
   // Invoked when Connection receives STUN error response with 487 code.
   void HandleRoleConflictFromPeer();
 
   State state() const { return state_; }
 
   IceMode remote_ice_mode() const { return remote_ice_mode_; }
 
+  int ComputeNetworkCost() const;
+
   // Update the ICE password of the remote candidate if |ice_ufrag| matches
   // the candidate's ufrag, and the candidate's passwrod has not been set.
   void MaybeSetRemoteIceCredentials(const std::string& ice_ufrag,
                                     const std::string& ice_pwd);
 
   // If |remote_candidate_| is peer reflexive and is equivalent to
   // |new_candidate| except the type, update |remote_candidate_| to
   // |new_candidate|.
   void MaybeUpdatePeerReflexiveCandidate(const Candidate& new_candidate);
 
@@ skipping 80 matching lines @@
            const rtc::PacketOptions& options) override;
   int GetError() override { return error_; }
 
  private:
   int error_ = 0;
 };
 
 }  // namespace cricket
 
 #endif  // WEBRTC_P2P_BASE_PORT_H_