add max queue length for notifications (#46)

js/mainApiMgr.js

@@ -383,9 +383,10 @@ electron.ipcMain.on(apiProxyCmds.addEvent, function(event, args) {
     /* eslint-enable no-console */
 
     let obj = liveObjs[args.objId];
-    let callbackFunc = function() {
+    let callbackFunc = function(result) {
         event.sender.send(apiProxyCmds.eventCallback, {
-            callbackId: args.callbackId
+            callbackId: args.callbackId,
+            result: result
         });
     }
     obj._callbacks[args.callbackId] = callbackFunc;

js/notify/electron-notify.js

@@ -16,6 +16,10 @@ const app = electron.app;
 const BrowserWindow = electron.BrowserWindow;
 const ipc = electron.ipcMain;
 
+// maximum number of notifications that can be queued, after limit is
+// reached then error func callback will be invoked.
+const MAX_QUEUE_SIZE = 30;
+
 let AnimationQueue = require('./AnimationQueue.js');
 
 // Array of windows with currently showing notifications
@@ -225,12 +229,26 @@ function setupConfig() {
 
 
 function notify(notification) {
+    if (notificationQueue.length >= MAX_QUEUE_SIZE) {
+        var id = latestID;
+        incrementId();
+        if (typeof notification.onErrorFunc === 'function') {
+            setTimeout(function() {
+                notification.onErrorFunc({
+                    id: id,
+                    error: 'max notification queue size reached: ' + MAX_QUEUE_SIZE
+                });
+            }, 0);
+        }
+        return id;
+    }
+
     // Is it an object and only one argument?
     if (arguments.length === 1 && typeof notification === 'object') {
         let notf = Object.assign({}, notification);
         // Use object instead of supplied parameters
-        notf.id = latestID
-        latestID++
+        notf.id = latestID;
+        incrementId();
         animationQueue.push({
             func: showNotification,
             args: [ notf ]
@@ -241,6 +259,10 @@ function notify(notification) {
     return null;
 }
 
+function incrementId() {
+    latestID++;
+}
+
 function showNotification(notificationObj) {
     return new Promise(function(resolve) {
         // Can we show it?

js/notify/notifyImpl.js

@@ -19,7 +19,8 @@ class Notify {
             color: options.color,
             onShowFunc: onShow.bind(this),
             onClickFunc: onClick.bind(this),
-            onCloseFunc: onClose.bind(this)
+            onCloseFunc: onClose.bind(this),
+            onErrorFunc: onError.bind(this)
         });
 
         this._data = options.data || null;
@@ -43,6 +44,17 @@ class Notify {
                 this.destroy();
             }
         }
+
+        function onError(arg) {
+            if (arg.id === this._id) {
+                // don't raise error event if handler doesn't exist, node
+                // will throw an exception
+                if (this.emitter.eventNames().includes('error')) {
+                    this.emitter.emit('error', arg.error || 'notification error');
+                }
+                this.destroy();
+            }
+        }
     }
 
     close() {

js/notify/notifyInterface.js

@@ -46,7 +46,7 @@ class Notify {
     get data() {}
 
     /**
-     * add event listeners for 'click' and 'close' events
+     * add event listeners for 'click', 'close', 'show', 'error' events
      *
      * @param {String} event  event to listen for
      * @param {func}   cb     callback invoked when event occurs
@@ -54,7 +54,7 @@ class Notify {
     addEventListener(event, cb) {}
 
     /**
-     * remove event listeners for 'click' and 'close' events
+     * remove event listeners for 'click', 'close', 'show', 'error' events
      *
      * @param {String} event  event to stop listening for.
      * @param {func}   cb     callback associated with original addEventListener

js/preload/createProxy.js

@@ -112,7 +112,8 @@ function addEventHandler(target) {
             if (arg.callbackId === callbackId) {
                 callback({
                     target: this,
-                    type: eventName
+                    type: eventName,
+                    result: arg.result
                 });
             }
         }.bind(this);