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Re: Exclusive Locking: design in a nutshell

From: Branko Čibej <brane_at_xbc.nu>
Date: 2004-05-21 08:41:58 CEST

Ben Collins-Sussman wrote:

>On Thu, 2004-05-20 at 13:23, Branko Čibej wrote:
>
>
>
>>The DAV spec speaks of shared (read and write) locks, but doesn't
>>specify how they behave. Therefore we can do anything that's reasonable.
>>IMHO the only thing that's reasonable is for all clients that have a
>>shared lock on the same object to see the same contents. Ergo,
>>transaction-per-lock.
>>
>>
>
>I really don't like the idea of "lock holders" seeing one thing when
>they GET, and the rest of the world seeing something else. It goes
>against the very principles of Subversion, as Jani pointed out.
>
>
That's not how I understood his post. What he said was that if a PUT on
a locked file were visible at once to everyone, then you could see
different trees for the _same_ revision depending on when you looked.

OTOH it is the most logical thing in the world for a locker to see
different contents of the locked resource than anyone else, after all
that's one of the reasons to lock it in the first place. Remember that
from the SVN command-line client's point of view, that will never happen
because the write is part of a commit. But it is a useful notion for
filesystem behaviour, and the different-contents-at-same-revision arent
a problem because the locker _expects_ the contents to change after a write.

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Received on Fri May 21 08:44:24 2004

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