Reloads the page when focus leaves to dispose MUC room. Adds exponential backoff to focus polling.

app.js

         generateRoomName();
     }
 
-    var elem = $iq({to: config.hosts.focus, type: 'set'});
-    elem.c('conference', {
-        xmlns: 'http://jitsi.org/protocol/focus',
-        room: roomName
-    });
-    elem.up();
-    connection.sendIQ(elem,
-        function (result) {
-            console.info("Focus replied ", result);
-            if ('true' === $(result).find('conference').attr('ready')) {
-                doJoinAfterFocus();
-            } else {
-                console.info("Waiting for the focus...");
-                window.setTimeout(
-                    function () {
-                        doJoin();
-                    }, 3000);
-            }
-        },
-        function (error) {
-            console.warn(error);
-        }
-    );
+    Moderator.allocateConferenceFocus(
+        roomName, doJoinAfterFocus);
 }
 
 function doJoinAfterFocus() {

moderator.js

-/* global $, config, connection, Etherpad, Toolbar, VideoLayout */
+/* global $, $iq, config, connection, Etherpad, hangUp, Strophe, Toolbar,
+   Util, VideoLayout */
 /**
  * Contains logic responsible for enabling/disabling functionality available
  * only to moderator users.
  */
 var Moderator = (function (my) {
 
+    var getNextTimeout = Util.createExpBackoffTimer(1000);
+
     my.isModerator = function () {
         return connection.emuc.isModerator();
     };
                 Moderator.onModeratorStatusChanged(Moderator.isModerator());
             }
         );
+
+        $(document).bind(
+            'left.muc',
+            function (event, jid) {
+                console.info("Someone left is it focus ? " + jid);
+                var resource = Strophe.getResourceFromJid(jid);
+                if (resource === 'focus') {
+                    console.info(
+                        "Focus has left the room - leaving conference");
+                    //hangUp();
+                    // We'd rather reload to have everything re-initialized
+                    location.reload();
+                }
+            }
+        );
+    };
+
+    my.allocateConferenceFocus = function (roomName, callback) {
+        var elem = $iq({to: config.hosts.focus, type: 'set'});
+        elem.c('conference', {
+            xmlns: 'http://jitsi.org/protocol/focus',
+            room: roomName
+        });
+        elem.up();
+        connection.sendIQ(elem,
+            function (result) {
+                if ('true' === $(result).find('conference').attr('ready')) {
+                    // Reset timer
+                    getNextTimeout(true);
+                    callback();
+                } else {
+                    var waitMs = getNextTimeout();
+                    console.info("Waiting for the focus... " + waitMs);
+                    window.setTimeout(
+                        function () {
+                            Moderator.allocateConferenceFocus(roomName, callback);
+                        }, waitMs);
+                }
+            },
+            function (error) {
+                var waitMs = getNextTimeout();
+                console.error("Focus error, retry after " + waitMs, error);
+                window.setTimeout(
+                    function () {
+                        Moderator.allocateConferenceFocus(roomName, callback);
+                    }, waitMs);
+            }
+        );
     };
 
     return my;

util.js

         element.setAttribute("data-container", "body");
     };
 
+    my.createExpBackoffTimer = function (step) {
+        var count = 1;
+        return function (reset) {
+            // Reset call
+            if (reset) {
+                count = 1;
+                return;
+            }
+            // Calculate next timeout
+            var timeout = Math.pow(2, count - 1);
+            count += 1;
+            return timeout * step;
+        };
+    };
+
     return my;
 }(Util || {}));