Ping backup connection at a slower rate

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 428 matching lines @@
 
   WriteState write_state() const { return write_state_; }
   bool writable() const { return write_state_ == STATE_WRITABLE; }
   bool receiving() const { return receiving_; }
 
   // Determines whether the connection has finished connecting.  This can only
   // be false for TCP connections.
   bool connected() const { return connected_; }
   bool weak() const { return !(writable() && receiving() && connected()); }
   bool active() const {
-    // TODO(honghaiz): Move from using |write_state_| to using |pruned_|.
     return write_state_ != STATE_WRITE_TIMEOUT;
   }
   // A connection is dead if it can be safely deleted.
   bool dead(uint32_t now) const;
 
   // Estimate of the round-trip time over this connection.
   uint32_t rtt() const { return rtt_; }
 
   size_t sent_total_bytes();
   size_t sent_bytes_second();
@@ skipping 58 matching lines @@
   void FailAndDestroy();
 
   // Checks that the state of this connection is up-to-date.  The argument is
   // the current time, which is compared against various timeouts.
   void UpdateState(uint32_t now);
 
   // Called when this connection should try checking writability again.
   uint32_t last_ping_sent() const { return last_ping_sent_; }
   void Ping(uint32_t now);
   void ReceivedPingResponse();
+  uint32_t last_ping_response_received() const {
+    return last_ping_response_received_;
+  }
 
   // Called whenever a valid ping is received on this connection.  This is
   // public because the connection intercepts the first ping for us.
   uint32_t last_ping_received() const { return last_ping_received_; }
   void ReceivedPing();
   // Handles the binding request; sends a response if this is a valid request.
   void HandleBindingRequest(IceMessage* msg);
 
   // Debugging description of this connection
   std::string ToDebugId() const;
@@ skipping 109 matching lines @@
            const rtc::PacketOptions& options) override;
   int GetError() override { return error_; }
 
  private:
   int error_ = 0;
 };
 
 }  // namespace cricket
 
 #endif  // WEBRTC_P2P_BASE_PORT_H_