[ZODB-Dev] RFC: Pre-commit hooks

[Florent Guillaume]

I've added the code on a branch off 3.4:

  http://svn.zope.org/?rev=29885&view=rev

Could someone check if it's suitable and merge it ?

Florent

Jim Fulton  <jim at zope.com> wrote:
> 
> I propose to add a pre-commit hook to ZODB.
> 
> Problem
> 
>    Sometimes, applications want to execute some code when
>    a transaction is committed.  For example, one might want to
>    delay object indexing until a transaction commits, rather
>    than indexing every time an object is changed. Or, someone
>    might want to check invariants only after a set of operations.
> 
> Proposal
> 
>    We add a new method to transaction objects:
> 
>       def beforeCommitHook(hook, *args, **kw):
>           """Register a hook to call before the transaction is committed
> 
>            The provided hook will be called after the transaction's
>            commit method has been called, but before the commit process
>            has been started.  The hook will be passed the given
>            positional and keyword arguments.
> 
>            Multiple hooks can be registered and will be called in order.
>            This method can be called from executing hooks.  That is, executing
>            hooks can register more hooks.  (Applications should take care
>            to avoid creating infinite loops by recursvely registering hooks.)
> 
>            Hooks are not called and are discarded if the transaction aborts.
>            """
> 
>    We would also modify transaction commit methods to call hooks.  Hooks would
>    not be called on sub-transaction commit.  (If necessary, we could add
>    separate sub-transaction hooks, but I don't think we need this.)
> 
>    This hook is very simple to use an implement and, I think, addresses
>    the requitement much more directly than implementing special data
>    managers.
> 
> Thoughts?
> 
> Anyone up for implementing this (with a doctest, of course)?
> 
> I'd like to get this into ZODB 3.4.
> 
> Jim


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Florent Guillaume, Nuxeo (Paris, France)   CTO, Director of R&D
+33 1 40 33 71 59   http://nuxeo.com   fg at nuxeo.com