Problems when storing WebSocket connection handle objects using jQuery.data() -- what's the best thing to do?
I have an asynchronous queue worker running as a Tornado script on my server -- it hosts a subclass of Tornado's PeriodicTask, which consumes events from Redis. To monitor the queue, I set up a tornado.websocket.WebSocketHandler
subclass on a URL, and then encapsulated the client WebSocket JavaScript in a jQuery plugin (here is the full code).
The idea is, you can have a number of queues on the server, and so you can use the jQuery module to set up a widget that specifically monitors that queue. At the moment, the logic is dead simple -- the widgets merely indicate how many tasks are enqueued in their target queue.
Here's the init code in question:
/* init: */ function (_options) {
options = $.extend(options, _options);
var self = this;
self.data('recently', [0,0,0,0,0,0,0,0,0]);
self.data('options', options);
self.data('sock', null);
var sock = null;
if ('endpoint' in options && options['endpoint']) {
sock = new WebSocket(options['endpoint']);
sock.onopen = function () {};
sock.onclose = function () {};
sock.onmessage = function (e) {
var d = $.parseJSON(e.data);
if (options.queuename in d) {
var qlen = d[options.queuename]
lastvalues = self.data('recently');
lastvalues.shift();
lastvalues.push(qlen);
if (lastvalues.every(function (itm) { return itm == 0; })) {
self.each(function () {
var elem = $(this);
elem.html("<b>Currently Idle</b>");
});
} else {
self.each(function () {
var elem = $(this);
elem.html("<b>" + qlen + "</b> Queued Signals");
});
}
self.data('recently', lastvalues);
}
}
}
self.data('sock', sock);
return self.each(function () {
var elem = $(this);
elem.data('sock', sock);
});
}
The javascript uses window.setInterval()
to periodically send a message to the socket; the server replies with the status of the queue for which it was asked, and the socket's frontend callback update开发者_JAVA百科s the DOM.
But the problem is: after a few minutes of this sort of polling -- set off specifically by navigating between pages containing the client socket code -- the sockets fail by throwing an exception with a message like DOM_ERROR_11
and a message that the socket object is no longer valid.
Once the page enters this error condition, I have to restart both the browser and the server websocket script to get everything to start up again.
... Is there a better way to set things up than I have (with the window.setInterval()
and whatnot)?
Well, it's probably not the best idea to keep a heavy object attached to DOM
You could alternatively have a global storage (probably a dictionary) with keys to sockets mapping, and only store the key as a DOM obj attribute
精彩评论