[WICKET-4661] Ajax channel busy flag not properly cleared upon SUCCESSFUL callback executions

• Type: Bug
• Status: Resolved
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 6.0.0-beta3
• Fix Version/s: 6.0.0
• Component/s: wicket
• Assignee: Sven Meier
• Reporter: Christian Oldiges
• Created: 18/Jul/12 13:59
• Updated: 20/Jul/12 06:27
• Resolved: 20/Jul/12 06:27

Description

The error is triggered if a custom AjaxChannel is defined using code like this in an AjaxEventbehavior:

@Override
         protected void updateAjaxAttributes(AjaxRequestAttributes attributes) {
                super.updateAjaxAttributes(attributes);
                attributes.setChannel(new AjaxChannel("mychannel", Type.DROP));
         }

Note: The channel type does NOT matter. Neither DROP nor QUEUE work.

My guess is, the fact the a named ajax channel is used results in the client side re-using the JavaScript Wicket.Channel instances.

In a re-used instance, the busy flag needs to be properly cleared after successfully executing an ajax call and its callback which is NOT done in the currently implemented code:

schedule: function (callback) {
			if (this.busy === false) {
				this.busy = true;
				try {
					return callback();
				} catch (exception) {
					this.busy = false;
					Wicket.Log.error("An error occurred while executing Ajax request:" + exception);
				}
			} else {
				Wicket.Log.info("Channel busy - postponing...");

A better, working solution would be:

schedule: function (callback) {
			if (this.busy === false) {
				this.busy = true;
				try {
					var callbackResult = callback();
					this.busy = false;
					return callbackResult;
				} catch (exception) {
					this.busy = false;
					Wicket.Log.error("An error occurred while executing Ajax request:" + exception);
				}
			} else {
				Wicket.Log.info("Channel busy - postponing...");