ID Generation produces non unique IDs

asked 2008-06-20 07:49:02 +0800

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Orignial message at:
https://sourceforge.net/forum/message.php?msg_id=5043569

By: draymann

[moved from General, text updated]
Hi there,

I experienced problems with the generated IDs. I have a large list (data-bound) and got the message "Not unique in ID space of ..." although all explicitely given IDs were different. I managed to fix this error by explicitley giving the listitem a calculated ID (starting from listitem-0). I then changed the mold to paging. On my WINDOWS PC all was fine, but on a LINUX machine I got the same error message again (maybe not for the listitems but for something different?). The difference between the two systems let me think of a problem with threads or something like that.

The workaround was to implement my own IdGenerator that generates unique IDs in a threadsafe way. Now, all works fine. I attached my IdGenerator to the end of this post for reference. It's just a first prototype: it is quite simple and for sure it can be improved in one or another way. Though, I haven't experienced any problem with it up to now.

I am also trying to setup an example for the malfunction in the following days.
I hope I am able to reproduce the problem with artificial data too.

Do you know if there's a problem with the standard way IDs are generated? Is the generation properly synchronized?

Kind regards,

Dominik


================== IdGenerator ================== public class IdGenerator implements org.zkoss.zk.ui.sys.IdGenerator {
private Object _lockObject = new Object();
private long _id = 0;

@Override
public String nextComponentUuid(Desktop arg0, Component arg1) {
synchronized (_lockObject) {
String id = "component-" + _id;
_id++;
return id;
}

}

@Override
public String nextDesktopId(Desktop arg0) {
synchronized (_lockObject) {
String id = "desktop-" + _id;
_id++;
return id;
}
}

@Override
public String nextPageUuid(Page arg0) {
synchronized (_lockObject) {
String id = "page-" + _id;
_id++;
return id;
}
}

}