mediarefresher: fix memory leak from dangling timers

src/channel/mediarefresher.js

@@ -44,6 +44,15 @@ MediaRefresherModule.prototype.onPreMediaChange = function (data, cb) {
     }
 };
 
+MediaRefresherModule.prototype.unload = function () {
+    try {
+        clearInterval(this._interval);
+        this._interval = null;
+    } catch (error) {
+        Logger.errlog.log(error.stack);
+    }
+};
+
 MediaRefresherModule.prototype.initGoogleDocs = function (data, cb) {
     var self = this;
     self.refreshGoogleDocs(data, cb);
@@ -66,8 +75,10 @@ MediaRefresherModule.prototype.initVimeo = function (data, cb) {
     const self = this;
     self.channel.refCounter.ref("MediaRefresherModule::initVimeo");
     Vimeo.extract(data.id).then(function (direct) {
-        if (self.dead || self.channel.dead)
+        if (self.dead || self.channel.dead) {
+            self.unload();
             return;
+        }
 
         if (self._media === data) {
             data.meta.direct = direct;
@@ -88,6 +99,7 @@ MediaRefresherModule.prototype.refreshGoogleDocs = function (media, cb) {
     var self = this;
 
     if (self.dead || self.channel.dead) {
+        self.unload();
         return;
     }
 
@@ -153,6 +165,7 @@ MediaRefresherModule.prototype.initGooglePlus = function (media, cb) {
     var self = this;
 
     if (self.dead || self.channel.dead) {
+        self.unload();
         return;
     }
 

src/server.js

@@ -195,6 +195,24 @@ Server.prototype.unloadChannel = function (chan) {
     chan.notifyModules("unload", []);
     Object.keys(chan.modules).forEach(function (k) {
         chan.modules[k].dead = true;
+        /*
+         * Automatically clean up any timeouts/intervals assigned
+         * to properties of channel modules.  Prevents a memory leak
+         * in case of forgetting to clear the timer on the "unload"
+         * module event.
+         */
+        Object.keys(chan.modules[k]).forEach(function (prop) {
+            if (chan.modules[k][prop] && chan.modules[k][prop]._onTimeout) {
+                Logger.errlog.log("Warning: detected non-null timer when unloading " +
+                        "module " + k + ": " + prop);
+                try {
+                    clearTimeout(chan.modules[k][prop]);
+                    clearInterval(chan.modules[k][prop]);
+                } catch (error) {
+                    Logger.errlog.log(error.stack);
+                }
+            }
+        });
     });
 
     for (var i = 0; i < this.channels.length; i++) {