Hi T.J.,
thank you for your reply. You are right about the idle-flag, I already
renamed it :)
I followed your advice and moved up the "idle = false" thing, but it
does not work so well.
With a slow connection the code below works fine:
var MessageQueue = Class.create({
initialize: function(url) {
this.url = url;
this.queue = [];
this.busy = false;
},
add: function(message) {
if (this.busy) this.queue.push(message)
else this.push(message);
},
push: function(message) {
this.busy = true;
new Ajax.Request(this.url, {
onSuccess: function() {
alert(message);
this.busy = false;
if (this.queue.size() > 0) {
this.push("queued: " + this.queue.shift());
}
}.bind(this)
});
}
});
var mq = new MessageQueue("/ajax_html_echo/");
mq.add("First");
mq.add("Second");
mq.add("Third");
But when the backend is fast and you type the hell out of your
keyboard, it seems, that the part
this.push("queued: " + this.queue.shift());
is never reached. There is no output with "queued:"
My thought was, that when new messages arrive, while a request is in
progess, to store them until the request is finished. Then all
messages in the stack should be sent until the busy-flag is set to
false. Therefore I had it below the if-condition.
I saw that the guys at jQuery use a sentinel "inprogress" which they
unshift/shift to/from the array. But I don't know if that would be
helpful here.
It would be super great if you have the time, to have a second look at
it!
Thank you so much
On 13 Aug., 10:18, "T.J. Crowder" <[email protected]> wrote:
> Hi,
>
> Your "idle" flag -- which you seem to use to mean "busy processing a
> request", which I found *really* confusing at first :-) -- is getting
> cleared inappropriately whenever you pull something from your queue. I
> don't know that that's the problem, but it's probably wrong. The error
> is in your onComplete function:
>
> if (this.queue.size() > 0) {
> console.log("queue-size > 0, so enqueue next item");
> this.push("queued: " + this.queue.shift());}
>
> this.idle = false; // <=== Error if `if` above was true
>
> If there's something in the queue, you call `push`, which sets the
> flag, starts a new async request, and returns. But then you clear the
> flag, so the next time `add` gets called, it'll think it should call
> `push` rather than `queue.push` even though there's an outstanding
> request.
>
> If you just move the `this.idle = false;` line above the `if`
> statement, it should sort out this issue. Whether it solves the
> problems you described I can't say, but I suspect it'll solve at least
> some of them.
>
> HTH,
> --
> T.J. Crowder
> Independent Software Consultant
> tj / crowder software / comwww.crowdersoftware.com
>
> On Aug 12, 7:55 pm, Moo <[email protected]> wrote:
>
>
>
> > Hi there,
>
> > I want to ensure, that messages are posted in the order, they come in
> > the stack. My tests at jsFiddle were okay, but with a quick backend
> > (where the requests are processed very fast) the order is crap.
> > Sometimes items are posted twice. Is there anybody who can help me
> > out? Thank you all!
>
> > var MessageQueue = Class.create({
> > initialize: function(url) {
> > this.url = url;
> > this.queue = [];
> > this.idle = false;
> > },
> > add: function(message) {
> > if (this.idle) {
> > console.log("idle, so saved to queue: " + message);
> > this.queue.push(message);
> > } else {
> > console.log("not idle, so pushed directly: " + message);
> > this.push(message);
> > }
> > },
> > push: function(message) {
> > this.idle = true;
> > console.log("Ajax.Request will be called now!");
> > new Ajax.Request(this.url + "&message=" +
> > encodeURIComponent(message), {
> > onComplete: function() {
> > console.log("successfully sent: " + message);
> > if (this.queue.size() > 0) {
> > console.log("queue-size > 0, so enqueue next item");
> > this.push("queued: " + this.queue.shift());
> > }
> > this.idle = false;
> > }.bind(this)
> > });
> > }
>
> > });- Zitierten Text ausblenden -
>
> - Zitierten Text anzeigen -
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