Sockets: make killing workers clean up connections properly (smogon#3645

)

If the connections aren't destroyed when the worker is disconnected,
its process will not exit until the remaining connections have closed.
This cleans them up manually so using Sockets.killWorker or
Sockets.killPid does not force any users connected over that worker to
refresh twice in order to reconnect to the server.

This also makes workers respawn automatically after being killed, which
they weren't doing before.

sockets.js

@@ -62,23 +62,27 @@ if (cluster.isMaster) {
 		return worker;
 	};
 
-	cluster.on('disconnect', worker => {
-		// worker crashed, try our best to clean up
-		require('./crashlogger')(new Error(`Worker ${worker.id} abruptly died`), "The main process");
-
-		// this could get called during cleanup; prevent it from crashing
-		// note: overwriting Worker#send is unnecessary in Node.js v7.0.0 and above
-		// see https://github.com/nodejs/node/commit/8c53d2fe9f102944cc1889c4efcac7a86224cf0a
-		worker.send = () => {};
-
-		let count = 0;
-		Users.connections.forEach(connection => {
-			if (connection.worker === worker) {
-				Users.socketDisconnect(worker, worker.id, connection.socketid);
-				count++;
-			}
-		});
-		console.error(`${count} connections were lost.`);
+	cluster.on('exit', (worker, code, signal) => {
+		if (code === null && signal === 'SIGTERM') {
+			// worker was killed by Sockets.killWorker or Sockets.killPid
+		} else {
+			// worker crashed, try our best to clean up
+			require('./crashlogger')(new Error(`Worker ${worker.id} abruptly died`), "The main process");
+
+			// this could get called during cleanup; prevent it from crashing
+			// note: overwriting Worker#send is unnecessary in Node.js v7.0.0 and above
+			// see https://github.com/nodejs/node/commit/8c53d2fe9f102944cc1889c4efcac7a86224cf0a
+			worker.send = () => {};
+
+			let count = 0;
+			Users.connections.forEach(connection => {
+				if (connection.worker === worker) {
+					Users.socketDisconnect(worker, worker.id, connection.socketid);
+					count++;
+				}
+			});
+			console.error(`${count} connections were lost.`);
+		}
 
 		// don't delete the worker, so we can investigate it if necessary.
 
@@ -118,10 +122,14 @@ if (cluster.isMaster) {
 				count++;
 			}
 		});
+		console.log(`${count} connections were lost.`);
+
 		try {
-			worker.kill();
+			worker.disconnect();
+			worker.kill('SIGTERM');
 		} catch (e) {}
 		workers.delete(worker.id);
+
 		return count;
 	};
 
@@ -423,8 +431,21 @@ if (cluster.isMaster) {
 		}
 	});
 
-	process.on('disconnect', () => {
-		process.exit();
+	// Clean up any remaining connections on disconnect. If this isn't done,
+	// the process will not exit until any remaining connections have been destroyed.
+	// Afterwards, the worker process will die on its own.
+	process.once('disconnect', () => {
+		sockets.forEach(socket => {
+			try {
+				socket.end();
+				socket.destroy();
+			} catch (e) {}
+		});
+		sockets.clear();
+		channels.clear();
+		subchannels.clear();
+		app.close();
+		if (appssl) appssl.close();
 	});
 
 	// this is global so it can be hotpatched if necessary