Add network cost as part of the connection comparison.

webrtc/p2p/base/candidate.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.
  */
 
 #ifndef WEBRTC_P2P_BASE_CANDIDATE_H_
 #define WEBRTC_P2P_BASE_CANDIDATE_H_
 
 #include <limits.h>
 #include <math.h>
 
 #include <algorithm>
 #include <iomanip>
 #include <sstream>
 #include <string>
 
 #include "webrtc/p2p/base/constants.h"
 #include "webrtc/base/basictypes.h"
 #include "webrtc/base/helpers.h"
 #include "webrtc/base/network.h"
 #include "webrtc/base/socketaddress.h"
 
 namespace cricket {
 
+const uint32_t kMaxNetworkCost = 0xFFFF;

[pthatcher1, 2016/02/12 00:07:12]

Can we make it something that is going to look reasonable in the SDP/signalling?
 LIke, 1,000?  That would be equivalent to a 10 second RTT with 10ms resolution,
which sounds like a reasonable max, and would look good in the signalling. 
Plus, it would leave us plenty of head room for things in the future.

[honghaiz3, 2016/02/12 19:28:43]

Changed to 999. (digit 9 is a better convention to be the maximum number for
human being (or maybe just me)).

[pthatcher1, 2016/02/12 20:05:26]

Sounds good.

+
 // Candidate for ICE based connection discovery.
 
 class Candidate {
  public:
   // TODO: Match the ordering and param list as per RFC 5245
   // candidate-attribute syntax. http://tools.ietf.org/html/rfc5245#section-15.1
   Candidate()
       : id_(rtc::CreateRandomString(8)),
         component_(0),
         priority_(0),
@@ skipping 91 matching lines @@
   const std::string generation_str() const {
     std::ostringstream ost;
     ost << generation_;
     return ost.str();
   }
   void set_generation_str(const std::string& str) {
     std::istringstream ist(str);
     ist >> generation_;
   }
 
+  // |network_cost| measures the cost/penalty of using this candidate. A network
+  // cost of 0 indicates this candidate can be used freely. A value of
+  // |kMaxNetworkCost| indicates it should be used only as the last resort.
+  void set_network_cost(uint32_t network_cost) {
+    ASSERT(network_cost <= kMaxNetworkCost);
+    network_cost_ = network_cost;
+  }
+  uint32_t network_cost() const { return network_cost_; }
+
   const std::string& foundation() const {
     return foundation_;
   }
 
   void set_foundation(const std::string& foundation) {
     foundation_ = foundation;
   }
 
   const rtc::SocketAddress & related_address() const {
     return related_address_;
@@ skipping 53 matching lines @@
     return (type_preference << 24) |
            (local_preference << 8) |
            (256 - component_);
   }
 
  private:
   std::string ToStringInternal(bool sensitive) const {
     std::ostringstream ost;
     std::string address = sensitive ? address_.ToSensitiveString() :
                                       address_.ToString();
-    ost << "Cand[" << foundation_ << ":" << component_ << ":"
-        << protocol_ << ":" << priority_ << ":"
-        << address << ":" << type_ << ":" << related_address_ << ":"
-        << username_ << ":" << password_ << "]";
+    ost << "Cand[" << foundation_ << ":" << component_ << ":" << protocol_
+        << ":" << priority_ << ":" << address << ":" << type_ << ":"
+        << related_address_ << ":" << username_ << ":" << password_ << ":"
+        << network_cost_ << "]";
     return ost.str();
   }
 
   std::string id_;
   int component_;
   std::string protocol_;
   std::string relay_protocol_;
   rtc::SocketAddress address_;
   uint32_t priority_;
   std::string username_;
   std::string password_;
   std::string type_;
   std::string network_name_;
   rtc::AdapterType network_type_;
   uint32_t generation_;
   std::string foundation_;
   rtc::SocketAddress related_address_;
   std::string tcptype_;
+  uint32_t network_cost_ = 0;
 };
 
 // Used during parsing and writing to map component to channel name
 // and back.  This is primarily for converting old G-ICE candidate
 // signalling to new ICE candidate classes.
 class CandidateTranslator {
  public:
   virtual ~CandidateTranslator() {}
   virtual bool GetChannelNameFromComponent(
       int component, std::string* channel_name) const = 0;
   virtual bool GetComponentFromChannelName(
       const std::string& channel_name, int* component) const = 0;
 };
 
 }  // namespace cricket
 
 #endif  // WEBRTC_P2P_BASE_CANDIDATE_H_