javascript - Are RTCDataChannels guaranteed to open after the ICE state becomes connected?

Question

During high CPU load, in Firefox, an RTCDataChannel's onopen event fires before the RTCPeerConnection's oniceconnectionstatechange. I'm wondering if there is anything in the spec regarding the order in which the two events fire, and how to ensure that oniceconnectionstatechange fires first.

              | Chrome 88                         | Firefox 85
--------------+-----------------------------------+------------------------------------
Low CPU load  | oniceconnectionstatechange first  | oniceconnectionstatechange first
              | onopen second                     | onopen second
--------------+-----------------------------------+------------------------------------
High CPU load | oniceconnectionstatechange first  | onopen first?
              | onopen second                     | oniceconnectionstatechange second

This is the code I'm using to test:

(async function()
{
    var p1 = new RTCPeerConnection();
    var p2 = new RTCPeerConnection();
    
    p1.channel = p1.createDataChannel("channel", { negotiated: true, id: 88 });
    p2.channel = p2.createDataChannel("channel", { negotiated: true, id: 88 });
    
    p1.onicecandidate = function(e)
    {
        if(e.candidate)
            p2.addIceCandidate(e.candidate);
    };
    
    p2.onicecandidate = function(e)
    {
        if(e.candidate)
            p1.addIceCandidate(e.candidate);
    };
    
    p1.oniceconnectionstatechange = function()
    {
        if(p1.iceConnectionState === "connected")
            console.log("P1 PeerConnection connected");
    };
    
    p2.oniceconnectionstatechange = function()
    {
        if(p2.iceConnectionState === "connected")
            console.log("P2 PeerConnection connected");
    };
    
    p1.channel.onopen = function()
    {
        console.log("P1 DataChannel opened");
    };
    
    p2.channel.onopen = function()
    {
        console.log("P2 DataChannel opened");
    };
    
    var offer = await p1.createOffer();
    await p1.setLocalDescription(offer);
    await p2.setRemoteDescription(offer);
    
    var answer = await p2.createAnswer();
    await p2.setLocalDescription(answer);
    await p1.setRemoteDescription(answer);
})();

//create some load
requestAnimationFrame(renderingLoopTest); //comment this line for no load
function renderingLoopTest()
{
    var lag = Date.now();
    while(Date.now() - lag < 60);
    requestAnimationFrame(renderingLoopTest);
}

question from:https://stackoverflow.com/questions/66067571/are-rtcdatachannels-guaranteed-to-open-after-the-ice-state-becomes-connected

Answer 1

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