[haiku-commits] Re: r33744 - haiku/trunk/src/kits/tracker
- From: "Alexandre Deckner" <alex@xxxxxxxxxxxx>
- To: haiku-commits@xxxxxxxxxxxxx
- Date: Sat, 24 Oct 2009 14:32:42
"Axel Dörfler" <axeld@xxxxxxxxxxxxxxxx> wrote:
> alex@xxxxxxxxxxxx wrote:
> > + if (model->InitCheck() == B_ENTRY_NOT_FOUND) {
> > + // might happen if the file was deleted shortly after
> > creation and we
> > + // were too busy to create the model in time see #4130
> > + delete model;
> > + return NULL;
> > + } else if (model->InitCheck() != B_OK) {
>
> I thought about this again, and since this happens with queries as
> well, I don't think this is the right way to handle this problem, or
> else query results are lost.
>
> AFAICT, with mails the problem is that they are first saved to a
> temporary file, and then renamed. When Tracker is too late picking up
> the query update, the file will already have been renamed at that
> time
> (ie. the above B_ENTRY_NOT_FOUND would happen, even though the file
> still exists), so it won't show it anymore.
Ah true, didn't think about that case.
>
> This problem was actually hidden by the query code (that I recently
> changed) sent remove/add notifications on rename. Maybe that wasn't
> such a bad idea after all, as it would fix this problem as long as
> the
> parent directory is updated as well at the same time (which it
> actually
> is, I just checked).
>
> In other words, since the node monitoring/query mechanism works
> asynchronously, queries are spread out all over the file system, and
> we
> have no way of tracking all file system activities yet, there is an
> inherent race condition that might not be so easy to fix (other than
> changing the BQuery code back again).
>
> What happens with the zombie models? In theory, since the inode number
> is known, Tracker might be able to resolve those, but it wouldn't
> exactly be a cheap operation.
I initially fixed the problem downstream by checking if the node wasn't
null on receiving attr changed notifications. I found it too much of a
symptom fix and was worried of putting bad models in the zombie list.
It might actually be a better solution after all.
Will have a second look.
Regards,
Alex
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