Comments on Java Thoughts: Spawning a thread for a lengthy operation in Wicke...

I've tried this, but if I try to write out the fil...

2008-08-18T04:26:00.000-07:00

I've tried this, but if I try to write out the file (uploadFile.writeTo) in the thread it sometimes fails with a "read error". if I move the writeTo into the main submit button processing it works fine. Do you know of any potential problems in doing this?

andy, you can reenable the buttons using the same ...

2008-05-06T17:09:00.000-07:00

andy, you can reenable the buttons using the same technique as for the spinner:

final Button cancel = new Button("cancel")
{
private static final long serialVersionUID = 691332069442892669L;

@Override
public void onSubmit()
{
setResponsePage(HomePage.class);
}
@Override
public boolean isEnabled()
{
return !getMySession().isUploading();
}
};
cancel.add(new AjaxSelfUpdatingTimerBehavior(Duration.seconds(5)));
myform.add(cancel);

However, this doesn't work for the Browse button, at least on IE. The file upload control is a different beast.

This is great and just what I've been looking for....

2008-05-04T04:35:00.000-07:00

This is great and just what I've been looking for.

My only thing now is that if somebody uploads a file, when it's complete I get the 'upload complete' message. But all the fields are still disabled until I exit the page and re-enter it.

Is there any way to re-enable the buttons once the upload is complete automatically?

Thanks
Andrew

Philip, I'm glad I could help you.Lars, thanks for...

2008-04-24T09:41:00.000-07:00

Philip, I'm glad I could help you.

Lars, thanks for pointing out this potential problem. It did not turn out to be an issue in my testing, I believe because I only allow one Wicket Thread and the ImportThread per user session. The issue might occur if I allowed multiple ImportThreads per user session. However, since what you suggest is a better practice, I've made the change.

Hi,There is a visibility issue in your example. Th...

2008-04-23T23:39:00.000-07:00

Hi,

There is a visibility issue in your example. The uploading and uploadComplete flag are accessed by two different Threads (Wicket's Thread and the ImportThread). If you don't do proper locking or declare those properties as volatile it might happen that a change to one of those properties is never seen by the other Thread. The JVM allows this behavior for optimization reasons.
Too prevent the visibility problem I suggest you declare the uploading and uploadComplete flags as volatile. This forces the JVM to write the changes made to those properties to main memory and is therefor seen by all Threads.

Wow! This is _exactly_ the code sample I have bee...

2008-04-23T19:54:00.000-07:00

Wow! This is _exactly_ the code sample I have been looking for. Thanks so much for taking the time to post it!

Cheers,
Philip