Misc fixes and improvements (#6143)

* `setup` command fixes and improvements

- Enable using the `./nodebb setup` command for auto-setup with a JSON argument
- Change CLI so package-install and dependency install are separate steps
- Fix #6142

* Prevent compiling templates multiple times

- Multiple requests for same template get pooled
- Hopefully fixes the "templateFunction is not a function" error which happens if site is restarted during high-traffic times

* More helpful upgrade template

src/middleware/index.js

@@ -203,12 +203,19 @@ middleware.delayLoading = function (req, res, next) {
 };
 
 var viewsDir = nconf.get('views_dir');
+var workingCache = {};
+
 middleware.templatesOnDemand = function (req, res, next) {
 	var filePath = req.filePath || path.join(viewsDir, req.path);
 	if (!filePath.endsWith('.js')) {
 		return next();
 	}
 
+	if (workingCache[filePath]) {
+		workingCache[filePath].push(next);
+		return;
+	}
+
 	async.waterfall([
 		function (cb) {
 			file.exists(filePath, cb);
@@ -218,6 +225,14 @@ middleware.templatesOnDemand = function (req, res, next) {
 				return next();
 			}
 
+			// need to check here again
+			// because compilation could have started since last check
+			if (workingCache[filePath]) {
+				workingCache[filePath].push(next);
+				return;
+			}
+
+			workingCache[filePath] = [next];
 			fs.readFile(filePath.replace(/\.js$/, '.tpl'), 'utf8', cb);
 		},
 		function (source, cb) {
@@ -229,5 +244,12 @@ middleware.templatesOnDemand = function (req, res, next) {
 		function (compiled, cb) {
 			fs.writeFile(filePath, compiled, cb);
 		},
-	], next);
+	], function (err) {
+		var arr = workingCache[filePath];
+		workingCache[filePath] = null;
+
+		arr.forEach(function (callback) {
+			callback(err);
+		});
+	});
 };