[QUESTION] How to judge the collection of local candidates is finished?

[echomlv]

In our application scenario, we want to send the answer after collecting the candidates，and we found the following callback function，it says "if PCHAR is NULL then candidate gathering is done." .

/**
 * @brief RtcOnIceCandidate is fired when new iceCandidate is found. if PCHAR is NULL then candidate gathering is done.
 *
 * Reference: https://www.w3.org/TR/webrtc/#dom-rtcpeerconnection-onicecandidate
 */
typedef VOID (*RtcOnIceCandidate)(UINT64, PCHAR);

But, after testing, it seems that it is related to the timeout period, and NULL will only be returned when it times out.
guessed by modifying the value of iceLocalCandidateGatheringTimeout configuration and printing logs

    UINT32 iceLocalCandidateGatheringTimeout; //!< Maximum time ice will wait for gathering STUN and RELAY candidates. Once
                                              //!< it's reached, ice will proceed with whatever candidate it current has. Use default value if 0.

Is there any way to judge like google's webrtc implementation ？

 /* --method 1*/
let pc = new RTCPeerConnection();
pc.onicegatheringstatechange = ev => {
  let connection = ev.target;

  switch(connection.iceGatheringState) {
    case "gathering":
      /* collection of candidates has begun */
      break;
    case "complete":
      /* collection of candidates is finished */
      break;
  }
}


 /* --method 2*/
let pc = new RTCPeerConnection();
pc.onicecandidate = function(event) {
  if (event.candidate) {
    /* Code for each candidate */
    /* Send the candidate to the remote peer */
  } else {
    /* All ICE candidates have been sent */
  }
}

Need help on this.

Thanks.

[alitofresko]

It is a very interesting stuff.
I too am in the same situation.
I'm sure it's not a default behaviour, but for some reason we got a gathering complete callback only after the timeout.
I hope someone can show us the correct way to solve this problem.