@soundworks/core
Version:
Open-source creative coding framework for distributed applications based on Web technologies
257 lines (231 loc) • 7.3 kB
JavaScript
import { getTime } from '@ircam/sc-utils';
import {
PING_INTERVAL,
PING_MESSAGE,
PONG_MESSAGE,
} from '../common/constants.js';
import {
packStringMessage,
unpackStringMessage,
} from '../common/sockets-utils.js';
import {
kSocketsLatencyStatsWorker,
kSocketsDebugPreventHeartBeat,
kSocketsDeleteSocket,
} from './ServerSockets.js';
export const kSocketClientId = Symbol('soundworks:socket-client-id');
export const kSocketTerminate = Symbol('soundworks:socket-terminate');
/**
* Simple publish / subscribe wrapper built on top of the
* [ws](https://github.com/websockets/ws) library.
*
* An instance of {@link ServerSocket} is automatically created per client
* when it connects (see {@link SeverClient#socket}).
*
* _Important: In most cases, you should consider using a {@link SharedState}
* rather than directly using the Socket instance._
*
* @hideconstructor
*/
class ServerSocket {
#socket = null;
#sockets = null;
#listeners = new Map();
#heartbeatId = null;
constructor(ws, sockets) {
/**
* `ws` socket instance configured with `binaryType=blob` (string)
* @type {object}
*/
this.#socket = ws;
/**
* Reference to the sockets object, is mainly dedicated to allow
* broadcasting from a given socket instance.
*
* @type {ServerSockets}
* @example
* socket.sockets.broadcast('my-room', this, 'update-value', 1);
*/
this.#sockets = sockets;
// @todo - review
const msg = {
type: 'add-measurement',
value: {
ping: 0,
pong: 0,
},
};
let heartbeatMissed = 0;
// heartbeat system (run only on string socket), adapted from:
// https://github.com/websockets/ws#how-to-detect-and-close-broken-connections
this.#socket.addEventListener('message', e => {
if (e.data === PONG_MESSAGE) {
heartbeatMissed = 0;
msg.value.pong = getTime();
this.#sockets[kSocketsLatencyStatsWorker].postMessage(msg);
// do not propagate ping / pong messages
return;
}
const [channel, args] = unpackStringMessage(e.data);
this.#dispatchEvent(channel, ...args);
});
this.#heartbeatId = setInterval(() => {
// we didn't receive the pong message
if (heartbeatMissed > 0) {
// Emit a 'close' event to go trough all the disconnection pipeline
//
// @note - this seems to create false positive disconnections when
// client is busy, e.g. when loading large sound files so let's just warn
// until we gather more feedback
// cf. https://making.close.com/posts/reliable-websockets/
console.warn(`ClientSocket (id: ${this[kSocketClientId]}) did not respond to ping message in time (missed: ${heartbeatMissed}, interval: ${PING_INTERVAL})`);
// this.#dispatchEvent('close');
// return;
}
heartbeatMissed += 1;
msg.value.ping = getTime();
this.#socket.send(PING_MESSAGE);
}, PING_INTERVAL);
// for testing purpose
if (this.#sockets[kSocketsDebugPreventHeartBeat] === true) {
clearInterval(this.#heartbeatId);
}
// propagate "native" events
[
'close',
'error',
'message',
'open',
'ping',
'pong',
'unexpected-response',
'upgrade',
].forEach(eventName => {
this.#socket.addEventListener(eventName, e => {
this.#dispatchEvent(eventName, e.data);
});
});
}
/**
* Dispatch an event to the listeners of the given channel.
* @param {string} channel - Channel name.
* @param {...*} args - Content of the message.
*/
#dispatchEvent(channel, ...args) {
if (this.#listeners.has(channel)) {
const callbacks = this.#listeners.get(channel);
callbacks.forEach(callback => callback(...args));
}
}
/**
* Removes all listeners and immediately close the web socket.
*
* Is automatically called when socket is closed on the client side or when
* Server is stopped
*
* @private
*/
[kSocketTerminate]() {
// clear ping / pong interval
clearInterval(this.#heartbeatId);
// remove socket from all rooms
this.#sockets[kSocketsDeleteSocket](this);
// clear references to sockets
this.#sockets = null;
// clear all listeners
this.#listeners.clear();
// clear native listeners
[
'close',
'error',
'message',
'open',
'ping',
'pong',
'unexpected-response',
'upgrade',
].forEach(eventName => this.#socket.removeAllListeners(eventName));
// terminate the socket
this.#socket.terminate();
}
/**
* Reference to the @link{ServerSockets} instance.
*/
get sockets() {
return this.#sockets;
}
/**
* Ready state of the underlying socket instance.
*
* @see {@link https://developer.mozilla.org/en-US/docs/Web/API/WebSocket/readyState}
* @type {number}
*/
get readyState() {
return this.#socket.readyState;
}
/**
* Send messages with JSON compatible data types on a given channel.
*
* @param {string} channel - Channel name.
* @param {...*} args - Payload of the message. As many arguments as needed, of
* JSON compatible data types (i.e. string, number, boolean, object, array and null).
*/
send(channel, ...args) {
const msg = packStringMessage(channel, ...args);
// ## Status codes:
// CONNECTING = 0; Socket has been created. The connection is not yet open.
// OPEN = 1; The connection is open and ready to communicate.
// CLOSING = 2; The connection is in the process of closing.
// CLOSED = 3; The connection is closed or couldn't be opened.
if (this.#socket.readyState === 1) {
this.#socket.send(msg, (err) => {
if (err) {
console.error(`ServerSocket failed to send message:`, channel, args, err.message);
}
});
}
}
/**
* Listen messages with JSON compatible data types on a given channel.
*
* @param {string} channel - Channel name.
* @param {Function} callback - Callback to execute when a message is received.
* Arguments of the callback function will match the arguments sent using the
* {@link ServerSocket#send} method.
*/
addListener(channel, callback) {
if (!this.#listeners.has(channel)) {
this.#listeners.set(channel, new Set());
}
const callbacks = this.#listeners.get(channel);
callbacks.add(callback);
}
/**
* Remove a listener of messages with JSON compatible data types from a given channel.
*
* @param {string} channel - Channel name.
* @param {Function} callback - Callback to remove.
*/
removeListener(channel, callback) {
if (this.#listeners.has(channel)) {
const callbacks = this.#listeners.get(channel);
callbacks.delete(callback);
if (callbacks.size === 0) {
this.#listeners.delete(channel);
}
}
}
/**
* Remove all listeners of messages with JSON compatible data types.
*
* @param {string} channel - Channel name.
*/
removeAllListeners(channel = null) {
if (channel === null) {
this.#listeners.clear();
} else if (this.#listeners.has(channel)) {
this.#listeners.delete(channel);
}
}
}
export default ServerSocket;