Re: [flux-dev] Status update

[Martin Lippert <mlippert@xxxxxxxxx>]

Hey!

If you remove that check for the resource to already exist, you can easily end up in endless ping-pong-games among the nodes that participate in the resource syncing.

Imagine something like this:
node A identifies a new resource and sends out a “resourceCreated” event.
node B receives the resourceCreated event, creates the resource locally, and sends out an event “resourceCreated” itself.
node A receives the resourceCreated event, creates the resource locally, and sends out an event “resourceCreated” itself.
…

You need to break this loop and avoid endless notifications.
The current implementation does this by checking whether a resource already exists locally in case a “resourceCreated” event arrives.
I think this is not perfect, since the content of that created resource could be different from the content of the locally existing resource. So it would be better to send a fingerprint of the resource around to double check for that. It would also break the loop and would be much better.

However, you still would need something like a “previous version” fingerprint, too, to avoid overriding changes and detect collisions. But that applies to “resourceChanged”, too.

Hope this helps!
-Martin






> Am 18.08.2016 um 09:41 schrieb Vershinin Fjodor <fjodor@xxxxxxxxxxxxx>:
> 
> Hi!
> Can you try to move file from outside into this directory, replacing original one?
> For example: touch ../file; mv ../file file;
> Also, you can try to move file from other partition, for example flash drive.
> I had noticed, if I move files on the same partition, then I get MOVE_TO event; 
> however on different partitions my original file is deleted, created new one, and content 
> MOVE_TO case cannot be handled by flux, because resource already exists. I am trying to figure out how to fix this.
> The first idea is to ignore if resource exists or not on node.js side as proposed in patch. What do you think?
> Fjodor
> 
> 
> 2016-08-18 10:18 GMT+03:00 Martin Lippert <mlippert@xxxxxxxxx>:
> Hey Fjodor,
> 
> not sure what exactly I should do, but here is what I did on my OS X machine:
> 
> - started your app, watching a directory
> - edited a file in that directory and pressed save (in the text editor)
> 
> -> test.txt ENTRY_MODIFY
> 
> - copied a file with the same name into that directory and pressed “replace” in the dialog
> 
> -> test.txt ENTRY_MODIFY
> 
> 
> Does that help?
> 
> Cheers,
> -Martin
> 
> 
> 
> > Am 17.08.2016 um 14:12 schrieb Vershinin Fjodor <fjodor@xxxxxxxxxxxxx>:
> >
> > For example, when I edit file on my linux machine, gnome editor creates temporary file and on saving it moves temporary file replacing original one. From java fs watcher's perspective it looks like a new file was created with the same name. Flux cannot handle this.
> > I think, this case can be handled using the same way, as flux handles changing existing files. What do you think?
> > I just tried to reproduce this issue on different machines. On Windows machine, when I try replace file, I get this sequence:
> > "ENTRY_DELETE
> > ENTRY_CREATE
> > ENTRY_MODIFY"
> > On latest linux kernel I have the same behavior. On unbuntu LTS, I get "ENTRY_CREATE" only.
> > So, it looks like kernel issue. Martin, could you have a look at Mac machine, if it is possible?
> > <App.java>_______________________________________________
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> -- 
> Thanks,
> Fjodor
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