Sockets: Go rewrite

Fixes smogon#2943

config/config-example.js

@@ -25,14 +25,22 @@ exports.workers = 1;
 // TODO: allow SSL to actually be possible to use for third-party servers at
 // some point.
 
+// golang - toggle using Go instead of Node for sockets workers
+//   Node workers are more unstable at handling connections because of bugs in
+//   sockjs-node, but sending/receiving messages over connections on Go workers
+//   is slightly slower due to the extra work involved in performing IPC with
+//   them safely. This should be left set to false unless you know what you are
+//   doing.
+exports.golang = false;
+
 // proxyip - proxy IPs with trusted X-Forwarded-For headers
 //   This can be either false (meaning not to trust any proxies) or an array
 //   of strings. Each string should be either an IP address or a subnet given
 //   in CIDR notation. You should usually leave this as `false` unless you
 //   know what you are doing.
 exports.proxyip = false;
 
-// ofe - write heapdumps if sockets.js workers run out of memory.
+// ofe - write heapdumps if Node sockets workers run out of memory
 //   If you wish to enable this, you will need to install ofe, as it is not a
 //   installed by default:
 //     $ npm install --no-save ofe

dev-tools/sockets.js

@@ -0,0 +1,35 @@
+'use strict';
+
+const {Session, SockJSConnection} = require('sockjs/lib/transport');
+
+const chars = 'abcdefghijklmnopqrstuvwxyz1234567890-';
+let sessionidCount = 0;
+
+/**
+ * @return string
+ */
+function generateSessionid() {
+	let ret = '';
+	let idx = sessionidCount;
+	for (let i = 0; i < 8; i++) {
+		ret = chars[idx % chars.length] + ret;
+		idx = idx / chars.length | 0;
+	}
+	sessionidCount++;
+	return ret;
+}
+
+/**
+ * @param {string} sessionid
+ * @param {{options: {{}}} config
+ * @return SockJSConnection
+ */
+exports.createSocket = function (sessionid = generateSessionid(), config = {options: {}}) {
+	let session = new Session(sessionid, config);
+	let socket = new SockJSConnection(session);
+	socket.remoteAddress = '127.0.0.1';
+	socket.protocol = 'websocket';
+	return socket;
+};
+
+// TODO: move worker mocks here, use require('../sockets-workers').Multiplexer to stub IPC

package.json

@@ -47,10 +47,14 @@
   "private": true,
   "license": "MIT",
   "devDependencies": {
+    "@types/cloud-env": "^0.2.0",
+    "@types/node": "^8.0.28",
+    "@types/node-static": "^0.7.0",
+    "@types/nodemailer": "^1.3.33",
+    "@types/ofe": "^0.5.0",
+    "@types/sockjs": "^0.3.31",
     "eslint": "^4.0.0",
     "mocha": "^3.0.0",
-    "@types/node": "^8.0.1",
-    "@types/nodemailer": "^1.3.33",
     "typescript": "^2.5.0-dev.20170622"
   }
 }

pokemon-showdown

@@ -40,6 +40,88 @@ try {
 }
 
 if (!process.argv[2] || /^[0-9]+$/.test(process.argv[2])) {
+	// Check if the server is configured to use Go, and ensure the required
+	// environment variables and dependencies are available if that is the case
+
+	let config;
+	try {
+		config = require('./config/config');
+	} catch (e) {}
+
+	if (config && config.golang) {
+		// GOPATH and GOROOT are optional to a degree, but we need them in order
+		// to be able to handle Go dependencies. Since Go only cares about the
+		// first path in the list, so will we.
+		const GOPATH = child_process.execSync('go env GOPATH', {stdio: null, encoding: 'utf8'})
+			.trim()
+			.split(path.delimiter)[0]
+			.replace(/^"(.*)"$/, '$1');
+		if (!GOPATH) {
+			// Should never happen, but it does on Bash on Ubuntu on Windows.
+			console.error('There is no $GOPATH environment variable set.');
+			process.exit(1);
+		}
+
+		const dependencies = ['github.com/gorilla/mux', 'github.com/igm/sockjs-go/sockjs'];
+		let packages = child_process.execSync('go list all', {stdio: null, encoding: 'utf8'});
+		for (let dep of dependencies) {
+			if (!packages.includes(dep)) {
+				console.log(`Installing ${dep}...`);
+				child_process.execSync(`go install ${dep}`, {stdio: 'inherit'});
+			}
+		}
+
+		let stat;
+		let needsSrcDir = false;
+		try {
+			stat = fs.lstatSync(path.resolve(GOPATH, 'src/github.com/Zarel'));
+		} catch (e) {
+			needsSrcDir = true;
+		} finally {
+			if (stat && !stat.isDirectory()) {
+				needsSrcDir = true;
+			}
+		}
+
+		let srcPath = path.resolve(process.cwd(), 'sockets');
+		let tarPath = path.resolve(GOPATH, 'src/github.com/Zarel/Pokemon-Showdown/sockets');
+		if (needsSrcDir) {
+			try {
+				fs.mkdirSync(path.resolve(GOPATH, 'src/github.com/Zarel'));
+				fs.mkdirSync(path.resolve(GOPATH, 'src/github.com/Zarel/Pokemon-Showdown'));
+			} catch (e) {
+				console.error(`Cannot make go source directory for the sockets library files! Symlink them manually from ${srcPath} to ${tarPath}`);
+				process.exit(1);
+			}
+		}
+
+		try {
+			stat = fs.lstatSync(tarPath);
+		} catch (e) {}
+
+		if (!stat || !stat.isSymbolicLink()) {
+			// Windows requires administrator privileges to make symlinks, so we
+			// make junctions instead. For our purposes they're compatible enough
+			// with symlinks on UNIX-like OSes.
+			let symlinkType = (process.platform === 'win32') ? 'junction' : 'dir';
+			try {
+				fs.symlinkSync(srcPath, tarPath, symlinkType);
+			} catch (e) {
+				console.error(`Cannot make go source directory for the sockets library files! Symlink them manually from ${srcPath} to ${tarPath}`);
+				process.exit(1);
+			}
+		}
+
+		console.log('Building Go source libs...');
+		try {
+			child_process.execSync('go install github.com/Zarel/Pokemon-Showdown/sockets', {stdio: 'inherit'});
+		} catch (e) {
+			// Go will show the errors that caused compiling Go's files to fail, so
+			// there's no reason to bother logging anything of our own.
+			process.exit(1);
+		}
+	}
+
 	// Start the server. We manually load app.js so it can be configured to run as
 	// the main module, rather than this file being considered the main module.
 	// This ensures any dependencies that were just installed can be found when