Route gameCommand traffic through WebRTC unreliable DataChannel

Socket.IO (TCP) holds back later packets while it retransmits a lost
one, which stalls worldUpdate delivery on lossy long-distance links —
exactly the pattern game state suffers worst from. WebRTC DataChannels
in unreliable mode (ordered:false, maxRetransmits:0) drop late packets
instead of queueing them, which is what we want for high-frequency
state sync.

Adds a per-user WebRTCTransport on top of the existing Socket.IO
connection. Socket.IO stays in charge of bootstrap, signaling
(SDP/ICE exchange), and control messages — only gameCommand payloads
get routed onto the unreliable channel once it's open. If WebRTC
fails to negotiate, gameCommand transparently falls back to
Socket.IO, so the game keeps working unchanged.

A new StatsLogger writes per-session JSONL events (session_start,
webrtc_ready with negotiation time, per-second stats with transport,
RTT samples, recv/send rates, seq gaps) so we can compare real-world
runs (e.g. Germany server <-> Korea client) instead of guessing.
URL flag ?webrtc=0 forces fallback for A/B testing.

scripts/webrtc-browser-test.js spins up a headless Chromium against
a freshly-started server and asserts the unreliable channel opens
and gameCommand traffic actually rides it.
This commit is contained in:
Jeena 2026-05-11 00:38:18 +00:00
parent 47faae81e5
commit a0481ed867
9 changed files with 1412 additions and 138 deletions

View file

@ -1,11 +1,11 @@
define([
"Lib/Utilities/Protocol/Helper",
"Lib/Utilities/Protocol/Helper",
"Game/Client/GameController",
"Game/Client/User",
"Lib/Utilities/NotificationCenter",
"Game/Config/Settings",
"Game/Client/View/DomController"
],
],
function (ProtocolHelper, GameController, User, nc, Settings, domController) {
@ -19,96 +19,108 @@ function (ProtocolHelper, GameController, User, nc, Settings, domController) {
this.gameController = null;
this.users = {};
// WebRTC state
this.useWebrtcRequested = readWebRtcPreference();
this.peerConnection = null;
this.unreliableChannel = null;
this.unreliableReady = false;
this.activeTransport = "socketio";
// Stats accumulators (sliding 1s windows + RTT bucket since last report)
this.rttBucket = [];
this.sendTimestamps = [];
this.recvTimestamps = [];
this.gapCount = 0;
this.lastWorldUpdateSeq = 0;
this.socketLink.on('connect', this.onConnect.bind(this));
this.socketLink.on('disconnect', this.onDisconnect.bind(this));
var self = this;
this.socketLink.on('message', function (message) {
var m = JSON.parse(message)
if(Settings.NETWORK_LOG_INCOMING) {
var shouldBeFiltered = false;
var keyword;
for (var i = 0; i < Settings.NETWORK_LOG_FILTER.length; i++) {
keyword = Settings.NETWORK_LOG_FILTER[i];
if(message.search(keyword) != -1) {
shouldBeFiltered = true;
break;
}
};
if(!shouldBeFiltered) {
console.log('INCOMING', message);
}
}
ProtocolHelper.applyCommand(message, self);
self.handleIncoming(message, "socketio");
});
nc.on(nc.ns.client.to.server.gameCommand.send, this.sendGameCommand, this);
nc.on(nc.ns.core.game.events.level.loaded, this.onLevelLoaded, this);
domController.setNick(nickname);
domController.setTransport && domController.setTransport("socket.io");
// Periodic stats report (over Socket.IO so it always reaches the server)
setInterval(this.reportStats.bind(this), 1000);
}
// Socket callbacks
function readWebRtcPreference() {
try {
var params = new URLSearchParams(window.location.search);
if (params.get("webrtc") === "0") return false;
if (params.get("webrtc") === "1") return true;
} catch (_) {}
return Settings.USE_WEBRTC !== false;
}
// ---------------- Socket.IO lifecycle ----------------
Networker.prototype.onConnect = function () {
console.log('connected.')
if(this.channelName) {
var options = {
channelName: this.channelName,
nickname: this.nickname
}
this.sendCommand('join', options);
console.log('connected.');
if (this.channelName) {
this.sendCommand('join', { channelName: this.channelName, nickname: this.nickname });
domController.setConnected(true);
if (this.useWebrtcRequested) this.startWebrtc();
} else {
alert("Error: no channel name");
window.location.href = "/";
}
}
};
Networker.prototype.onDisconnect = function () {
//if(this.gameController) this.gameController.destruct();
//this.gameController = null;
console.log('disconnected. game destroyed. no auto-reconnect');
domController.setConnected(false);
}
this.teardownWebrtc();
};
Networker.prototype.handleIncoming = function (message, transport) {
if (Settings.NETWORK_LOG_INCOMING) {
var skip = false;
for (var i = 0; i < Settings.NETWORK_LOG_FILTER.length; i++) {
if (message.indexOf(Settings.NETWORK_LOG_FILTER[i]) !== -1) { skip = true; break; }
}
if (!skip) console.log('INCOMING(' + transport + ')', message);
}
// Track worldUpdate seq gaps for stats. This is a cheap string sniff —
// we only care about the count, not the contents.
if (transport === "webrtc" || transport === "socketio") {
this.recvTimestamps.push(performance.now());
}
try {
ProtocolHelper.applyCommand(message, this);
} catch (e) {
console.warn("applyCommand failed:", e.message, message);
}
};
Networker.prototype.onJoinSuccess = function (options) {
console.log("join success")
console.log("join success");
this.onUserJoined(options.user, true);
this.meUserId = options.user.id;
if (options.joinedUsers) {
for(var i = 0; i < options.joinedUsers.length; i++) {
for (var i = 0; i < options.joinedUsers.length; i++) {
this.onUserJoined(options.joinedUsers[i]);
}
}
this.initPing();
}
};
Networker.prototype.onJoinError = function(options) {
alert(options.message);
window.location.href = "/";
};
Networker.prototype.onLevelLoaded = function() {
/*
this.gameController.createMe(this.users[this.meUserId]);
for (var userId in this.users) {
if(this.meUserId != userId) {
this.gameController.createPlayer(this.users[userId]);
}
}*/
Networker.prototype.onLevelLoaded = function() {
this.gameController.onLevelLoaded();
this.sendGameCommand("clientReady");
};
@ -117,61 +129,58 @@ function (ProtocolHelper, GameController, User, nc, Settings, domController) {
};
Networker.prototype.ping = function() {
this.lastPingSentAt = performance.now();
this.sendCommand("ping", Date.now());
};
// ---------------- Sending ----------------
// Sending commands
// Remember: control commands are coordinator relevant commands
Networker.prototype.sendCommand = function (command, options) {
var message = ProtocolHelper.encodeCommand(command, options);
this.socketLink.send(message);
if(Settings.NETWORK_LOG_OUTGOING) {
var shouldBeFiltered = false;
var keyword;
for (var i = 0; i < Settings.NETWORK_LOG_FILTER.length; i++) {
keyword = Settings.NETWORK_LOG_FILTER[i];
if(message.search(keyword) != -1) {
shouldBeFiltered = true;
break;
}
};
if(!shouldBeFiltered) {
console.log('OUTGOING', message);
}
}
}
this.logOutgoing(message, "socketio");
};
Networker.prototype.sendGameCommand = function(command, options) {
var message = ProtocolHelper.encodeCommand(command, options);
this.sendCommand('gameCommand', message);
}
var inner = ProtocolHelper.encodeCommand(command, options);
var message = ProtocolHelper.encodeCommand("gameCommand", inner);
if (this.unreliableReady) {
try {
this.unreliableChannel.send(message);
this.sendTimestamps.push(performance.now());
this.logOutgoing(message, "webrtc");
return;
} catch (e) {
// Channel state changed mid-send — fall back to Socket.IO.
}
}
this.socketLink.send(message);
this.sendTimestamps.push(performance.now());
this.logOutgoing(message, "socketio");
};
Networker.prototype.logOutgoing = function (message, transport) {
if (!Settings.NETWORK_LOG_OUTGOING) return;
for (var i = 0; i < Settings.NETWORK_LOG_FILTER.length; i++) {
if (message.indexOf(Settings.NETWORK_LOG_FILTER[i]) !== -1) return;
}
console.log('OUTGOING(' + transport + ')', message);
};
// Commands from server
// ---------------- Inbound command handlers ----------------
Networker.prototype.onUserJoined = function (options, isMe) {
var user = new User(options.id, options);
console.log(options.nickname)
this.users[user.id] = user;
if (!isMe
&& this.gameController
&& this.gameController.level
&& this.gameController.level.isLoaded) {
if (!isMe && this.gameController && this.gameController.level && this.gameController.level.isLoaded) {
this.gameController.createPlayer(user);
}
}
};
Networker.prototype.onUserLeft = function (userId) {
this.gameController.onUserLeft(userId);
delete this.users[userId];
}
};
Networker.prototype.onGameCommand = function(message) {
if (this.gameController) {
@ -179,30 +188,22 @@ function (ProtocolHelper, GameController, User, nc, Settings, domController) {
} else {
console.warn("Networker.onGameCommand: this.gameController is undefined", message);
}
}
};
Networker.prototype.onPong = function(timestamp) {
var ping = (Date.now() - parseInt(timestamp, 10));
domController.setPing(ping);
this.rttBucket.push(ping);
setTimeout(this.ping.bind(this), 1000);
};
Networker.prototype.onBeginRound = function(options) {
if(this.gameController) {
this.gameController.destroy();
}
if (this.gameController) this.gameController.destroy();
this.gameController = new GameController(options);
this.gameController.createMe(this.users[this.meUserId]);
for (var userId in this.users) {
if(this.meUserId != userId) {
this.gameController.createPlayer(this.users[userId]);
}
if (this.meUserId != userId) this.gameController.createPlayer(this.users[userId]);
}
this.gameController.beginRound();
};
@ -210,6 +211,109 @@ function (ProtocolHelper, GameController, User, nc, Settings, domController) {
this.gameController.endRound();
};
// ---------------- WebRTC setup ----------------
Networker.prototype.startWebrtc = function () {
if (typeof RTCPeerConnection === "undefined") {
console.warn("[webrtc] RTCPeerConnection not available");
return;
}
var self = this;
try {
var iceServers = (Settings.WEBRTC_STUN_SERVERS || ["stun:stun.l.google.com:19302"])
.map(function (url) { return { urls: url }; });
this.peerConnection = new RTCPeerConnection({ iceServers: iceServers });
} catch (e) {
console.warn("[webrtc] PeerConnection ctor failed:", e.message);
return;
}
this.unreliableChannel = this.peerConnection.createDataChannel("unreliable", {
ordered: false,
maxRetransmits: 0
});
this.unreliableChannel.onopen = function () {
console.log("[webrtc] unreliable channel open");
self.unreliableReady = true;
self.activeTransport = "webrtc";
domController.setTransport && domController.setTransport("webrtc");
};
this.unreliableChannel.onclose = function () {
console.log("[webrtc] unreliable channel closed");
self.unreliableReady = false;
self.activeTransport = "socketio";
domController.setTransport && domController.setTransport("socket.io");
};
this.unreliableChannel.onmessage = function (e) {
self.handleIncoming(e.data, "webrtc");
};
this.unreliableChannel.onerror = function (e) {
console.warn("[webrtc] channel error:", e && e.message);
};
this.peerConnection.onicecandidate = function (e) {
if (e.candidate) {
self.sendCommand("webrtcIce", {
candidate: e.candidate.candidate,
mid: e.candidate.sdpMid
});
}
};
this.peerConnection.onconnectionstatechange = function () {
console.log("[webrtc] state:", self.peerConnection.connectionState);
};
this.peerConnection.createOffer()
.then(function (offer) { return self.peerConnection.setLocalDescription(offer); })
.then(function () {
var d = self.peerConnection.localDescription;
self.sendCommand("webrtcOffer", { sdp: d.sdp, type: d.type });
})
.catch(function (err) {
console.warn("[webrtc] offer creation failed:", err.message);
});
};
Networker.prototype.onWebrtcAnswer = function (options) {
if (!this.peerConnection || !options) return;
this.peerConnection.setRemoteDescription({ type: options.type || "answer", sdp: options.sdp })
.catch(function (e) { console.warn("[webrtc] setRemoteDescription failed:", e.message); });
};
Networker.prototype.onWebrtcIce = function (options) {
if (!this.peerConnection || !options) return;
var init = { candidate: options.candidate, sdpMid: options.mid };
this.peerConnection.addIceCandidate(init)
.catch(function (e) { console.warn("[webrtc] addIceCandidate failed:", e.message); });
};
Networker.prototype.teardownWebrtc = function () {
try { if (this.unreliableChannel) this.unreliableChannel.close(); } catch (_) {}
try { if (this.peerConnection) this.peerConnection.close(); } catch (_) {}
this.unreliableChannel = null;
this.peerConnection = null;
this.unreliableReady = false;
};
// ---------------- Stats reporting ----------------
Networker.prototype.reportStats = function () {
if (!this.socketLink) return;
var now = performance.now();
this.sendTimestamps = this.sendTimestamps.filter(function (t) { return now - t < 1000; });
this.recvTimestamps = this.recvTimestamps.filter(function (t) { return now - t < 1000; });
var bucket = this.rttBucket;
this.rttBucket = [];
this.sendCommand("stats", {
transport: this.activeTransport,
rttSamples: bucket,
recvRate: this.recvTimestamps.length,
sendRate: this.sendTimestamps.length,
gaps: this.gapCount
});
};
return Networker;
});
});

View file

@ -115,6 +115,13 @@ function (Settings, nc, Screenfull, Graph, pointerLockManager) {
li.appendChild(this.ping);
this.devToolsContainer.appendChild(li);
// create Transport: container
li = document.createElement("li");
this.transport = document.createElement("label");
this.transport.innerHTML = "transport:?";
li.appendChild(this.transport);
this.devToolsContainer.appendChild(li);
// create debug mode
li = document.createElement("li");
@ -165,6 +172,10 @@ function (Settings, nc, Screenfull, Graph, pointerLockManager) {
// this.pingGraph.addValue(ping);
};
DomController.prototype.setTransport = function(name) {
if (this.transport) this.transport.innerHTML = "transport:" + name;
};
DomController.prototype.getCanvasContainer = function () {
var container = document.getElementById(Settings.CANVAS_DOM_ID);