Re: revprop changes and hooks

[Daniel Shahaf]

Philip Martin wrote on Tue, 15 Jun 2010 at 11:16 -0000:
> Philip Martin <philip.mar...@wandisco.com> writes:
> > Putting the get, pre hook and set into a transaction would allow the
> > action in the hook to accurately reflect the change made (or not made
> > if the transaction fails).
> 
> We don't need a new transaction to fix this, we can rev the
> svn_fs_change_rev_prop interface instead:
> 
> svn_error_t *
> svn_fs_change_rev_prop(svn_fs_t *fs,
>                        svn_revnum_t rev,
>                        const char *name,
>                        const svn_string_t *value,
>                        apr_pool_t *pool);
> 
> to include the current value of the revprop, and then reject the
> change if the current value does not match.  That should be simple
> because the FSFS implementation already takes a write lock and the BDB
> implementation already uses a transaction.
> 

Testing a patch for this ^.

Daniel

> Then the repos layer can loop (in practice only if the
> use_pre_revprop_change_hook flag is set):
> 
>        do
>          svn_fs_revision_prop(&current_value)
>          action = ...
>          svn_repos__hooks_pre_revprop_change(action)
>          error = svn_fs_change_rev_prop2(current_value, new_value)
>        while error is current value doesn't match
> 
> This doesn't alter the fact that the revprop can change at any time
> during the loop but that doesn't matter.  The revprop is unversioned
> so only the current state matters and the above will guarantee that
> the current state when the change is made is equal to the state
> validated by the pre-revprop-change hook.
> 
>