Gracefully shutdown node_helpers (Fixes #1056)

Updated documentation


Corrected Typo in Documentation


Style correction

CHANGELOG.md

@@ -12,6 +12,7 @@ This project adheres to [Semantic Versioning](http://semver.org/).
 ### Added
 - Add option to use [Nunjucks](https://mozilla.github.io/nunjucks/) templates in modules. (See `helloworld` module as an example.)
 - Add Bulgarian translations for MagicMirror² and Alert module
+- Add graceful shutdown of modules by calling `stop` function of each `node_helper` on SIGINT before exiting.
 
 ### Updated
 

js/app.js

@@ -236,6 +236,33 @@ var App = function() {
 			});
 		});
 	};
+
+	/* stop()
+	 * This methods stops the core app.
+	 * This calls each node_helper's STOP() function, if it exists.
+	 * Added to fix #1056
+	 */
+	this.stop = function() {
+		for (var h in nodeHelpers) {
+			var nodeHelper = nodeHelpers[h];
+			if (typeof nodeHelper.stop === "function") {
+				nodeHelper.stop();
+			}
+		}
+	};
+
+	/* Listen for SIGINT signal and call stop() function.
+	 *
+	 * Added to fix #1056
+	 * Note: this is only used if running `server-only`. Otherwise
+	 * this.stop() is called by app.on("before-quit"... in `electron.js`
+	 */
+	process.on("SIGINT", () => {
+		console.log("[SIGINT] Received. Shutting down server...");
+		setTimeout(() => { process.exit(0); }, 3000);  // Force quit after 3 seconds
+		this.stop();
+		process.exit(0);
+	});
 };
 
 module.exports = new App();

js/electron.js

@@ -96,6 +96,20 @@ app.on("activate", function() {
 	}
 });
 
+/* This method will be called when SIGINT is received and will call
+ * each node_helper's stop function if it exists. Added to fix #1056
+ *
+ * Note: this is only used if running Electron. Otherwise
+ * core.stop() is called by process.on("SIGINT"... in `app.js`
+ */
+app.on("before-quit", (event) => {
+	console.log("Shutting down server...");
+	event.preventDefault();
+	setTimeout(() => { process.exit(0); }, 3000); // Force-quit after 3 seconds.
+	core.stop();
+	process.exit(0);
+});
+
 // Start the core application if server is run on localhost
 // This starts all node helpers and starts the webserver.
 if (["localhost", "127.0.0.1", "::1", "::ffff:127.0.0.1", undefined].indexOf(config.address) > -1) {

modules/README.md

@@ -555,6 +555,17 @@ start: function() {
 }
 ````
 
+#### `stop()`
+This method is called when the MagicMirror server receives a `SIGINT` command and is shutting down. This method should include any commands needed to close any open connections, stop any sub-processes and gracefully exit the module.
+
+**Example:**
+````javascript
+stop: function() {
+	console.log("Shutting down MyModule");
+	this.connection.close();
+}
+````
+
 #### `socketNotificationReceived: function(notification, payload)`
 With this method, your node helper can receive notifications from your modules. When this method is called, it has 2 arguments: