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Re: svn_fs/svn_repo repository lock API

From: Philip Martin <philip.martin_at_wandisco.com>
Date: Wed, 22 Aug 2012 23:26:51 +0100

Johan Corveleyn <jcorvel_at_gmail.com> writes:

> Ok, let me try to decipher what that means for users.
>
> - New commit will block: does this mean that 'svn commit -mm somefile'
> will simply hang (until the repository is unfrozen, or until the
> client-side timeout is reached)? Can it be cancelled?
>
> - Commit in progress will block when trying to convert the transaction
> into a revision: so the running 'svn commit -mm somefile' will hang at
> the end (after transmitting file contents, but before the "Committed
> Revision XXX" notification), until the repository is unfrozen, or
> until the client-side timeout is reached, right? Can it be cancelled?
> What happens if I cancel, or if the client-side timeout is reached
> (will the repository still commit the transaction when it's unfrozen;
> will my working copy still be ok)?
>
>> I'm currently using BDB's svn_repos lock for the BDB freeze so that
>> makes a BDB repository completely unreadable while frozen. No BDB
>> commits can start while frozen. Starting a BDB freeze has to wait for
>> in-progress commits to finish.
>
> Does that mean that a new 'svn commit -mm somefile' will error out? Or
> will it hang until unfrozen or until client-side timeout?
>
> Wouldn't we want the same behavior, at least for the end-user,
> regardless of BDB or FSFS (or other backends)?
>
> If all of this is not really decided yet, what is the intention? Is
> this still under discussion? Shouldn't we decide on the desired
> behavior before the feature is implemented?

I haven't changed how we block on the write-lock: the block doesn't
timeout it waits for the lock to be released. The client may timeout
waiting for the RA layer.

If we want to introduce some new "freeze lock" with different behaviour
from the write-lock then we would need to bump the repository format as
old releases simply would not look at any new lock.

I suppose we could change how 1.8 blocks on the write-locks but we
obviously can't change existing releases.

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Received on 2012-08-23 00:27:31 CEST

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