I forgot to include this new file in the last commit. Oops.

src/pubsub/client.ts

@@ -0,0 +1,195 @@
+import { EventEmitter } from "../utilities/events";
+import { set_equals, shallow_object_equals } from "../utilities/object";
+
+export type PubSubClientEvents = {
+	connect: [event: Event];
+	disconnect: [event: Event | null];
+	error: [event: Event];
+	message: [event: {
+		topic: string,
+		data: any
+	}];
+}
+
+enum State {
+	Disconnected,
+	Connecting,
+	Connected
+}
+
+
+export function enumerateSubs(topic: string) {
+	// I initially tried using a generator for this, but
+	// using an array builder is faster. Less function overhead
+	// since we're iterating the whole thing anyways, and
+	// as long as we don't hit our memory limit on the worker
+	// I really don't care about memory.
+	let idx = topic.length;
+	const out = [topic];
+	while ((idx = topic.lastIndexOf('/', idx - 1)) !== -1)
+		out.push(`${topic.slice(0, idx)}/*`);
+	out.push('*');
+	return out;
+}
+
+
+export class PubSubClient extends EventEmitter<PubSubClientEvents> {
+
+	_ws: WebSocket | null = null;
+	_topics: Set<string> = new Set();
+	_live_topics: Set<string> = new Set();
+
+	_want_connection = false;
+	_state = State.Disconnected;
+
+	_reconnectTimer: ReturnType<typeof setTimeout> | null = null;
+	_failedConnections = 0;
+
+	constructor() {
+		super();
+
+		this._performReconnect = this._performReconnect.bind(this);
+
+	}
+
+	_reconnect(wantDelay: boolean = true) {
+		if ( this._reconnectTimer )
+			return;
+
+		let delay = 250 + (wantDelay
+			? Math.floor(this._failedConnections * (Math.random() * 5000) + 5000)
+			: 0);
+		this._reconnectTimer = setTimeout(this._performReconnect, delay);
+	}
+
+	_performReconnect() {
+
+		this._reconnectTimer = null;
+
+		if (this._ws) {
+			this._ws.close();
+			this._ws = null;
+			this._state = State.Disconnected;
+		}
+
+		this._live_topics = new Set(this._topics);
+
+		if ( ! this._live_topics.size )
+			return;
+
+		this._state = State.Connecting;
+
+		const url = new URL(`wss://pubsub.workers.frankerfacez.com/ws`);
+		if ( this._live_topics.size > 10 )
+			url.searchParams.append('t', '*');
+		else
+			for(const topic of this._live_topics)
+				url.searchParams.append('t', topic);
+
+		const ws = this._ws = new WebSocket(url.toString());
+
+		ws.addEventListener('open', evt => {
+			this._state = State.Connected;
+			this._failedConnections = 0;
+			this.emit('connect', evt);
+		});
+
+		ws.addEventListener('error', evt => {
+			this.emit('error', evt);
+		});
+
+		ws.addEventListener('close', evt => {
+			this._ws = null;
+			this._state = State.Disconnected;
+			this.emit('disconnect', evt);
+			if (this._want_connection)
+				this._reconnect();
+		});
+
+		ws.addEventListener('message', evt => {
+			if (typeof evt.data === 'string') {
+				let packet: {topic: string; data: any};
+				try {
+					packet = JSON.parse(evt.data);
+				} catch(err) {
+					return;
+				}
+
+				if (!packet.topic || typeof packet.topic !== 'string')
+					return;
+
+				// Validate that we really want this topic.
+				if (this._live_topics.size > 10 && ! this._live_topics.has(packet.topic)) {
+					let found = false;
+					for(const sub of enumerateSubs(packet.topic)) {
+						if (this._live_topics.has(sub)) {
+							found = true;
+							break;
+						}
+					}
+					if (!found)
+						return;
+				}
+
+				this.emit('message', packet);
+			}
+		});
+
+	}
+
+	get connected() {
+		return this._state === State.Connected;
+	}
+
+	get connecting() {
+		return this._state === State.Connecting;
+	}
+
+	get disconnected() {
+		return this._state === State.Disconnected;
+	}
+
+	connect() {
+		this._want_connection = true;
+		this._reconnect(false);
+	}
+
+	disconnect() {
+		this._want_connection = false;
+		this._failedConnections = 0;
+		if (this._reconnectTimer) {
+			clearTimeout(this._reconnectTimer);
+			this._reconnectTimer = null;
+		}
+		if (this._ws) {
+			this._ws.close();
+			this._ws = null;
+			this._state = State.Disconnected;
+			this.emit('disconnect', null);
+		}
+	}
+
+	subscribe(topics: string | string[]) {
+		if (!Array.isArray(topics))
+			topics = [topics];
+
+		for(const topic of topics)
+			this._topics.add(topic);
+
+		if (this._want_connection && !set_equals(this._topics, this._live_topics))
+			this._reconnect();
+	}
+
+	unsubscribe(topics: string | string[]) {
+		if (!Array.isArray(topics))
+			topics = [topics];
+
+		for(const topic of topics)
+			this._topics.delete(topic);
+
+		if (this._want_connection && !set_equals(this._topics, this._live_topics))
+			this._reconnect();
+	}
+
+
+}