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From Ted Dunning <ted.dunn...@gmail.com>
Subject Re: Lock recipes and the lock path
Date Tue, 20 Sep 2011 21:17:05 GMT
Multi ops might help here although there might be some difficult because all
we have is an existence check and not a non-existence check.

One way to hack that is to have each normal file operation be a multi that
looks like this:

    create lock, modify file, delete lock

The lock will never be visible since it is created and deleted in a single
atomic operation.  This does guarantee that the modification will never
succeed if the lock file already exists.

The cleanup can proceed like this:

     create lock
     get children
     delete old files with large multi-op
     delete lock

This should be pretty darned fast since only for round-trips are required.

On Tue, Sep 20, 2011 at 12:37 PM, Jordan Zimmerman
<jzimmerman@netflix.com>wrote:

> How can you safely clean up the path for each member ID lock? There
> doesn't seem to be an atomic way to do it. If one process is cleaning up
> for example "/locks/members/12345", it can't be sure than another process
> might need to get a lock on that member ID. I.e. There's never a safe
> point to delete "/locals/members/12345".
>

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