[Zope3-Users] Re: FW: ZODB storage ways

[Brian Sutherland]

On Tue, Apr 04, 2006 at 10:37:57AM +0200, j.kartnaller wrote:
> Here is how I automate the commit process :
> 
> <code>
> from zope.interface import implements
> 
> from transaction import manager
> from transaction.interfaces import IDataManager, ISynchronizer
> 
> from sqlalchemy import objectstore
> 
> 
> class AlchemyDataManager(object):
>      """Takes care of the transaction process in zope.
>      """
>      implements(IDataManager)
> 
>      def abort(self):
>          objectstore.clear()
> 
>      def tpc_begin(self, trans):
>          pass
> 
>      def commit(self, trans):
>          pass
> 
>      def tpc_vote(self, trans):
>          pass
> 
>      def tpc_finish(self, trans):
>          objectstore.commit()
>          objectstore.clear()

Er, just something I learnt the hard way from working on SQLOS, is that
you should send all the SQL over the line in the first phase of the TPC
but save the final "COMMIT" until the last phase.

>      def tpc_abort(self, trans):
>          objectstore.clear()
> 
>      def sortKey(self):
>          return str(id(self))
> 
> 
> class TransactionSynchronizer:
>      """Synchronizer to add a alchemy data manager to the new transaction.
> 
>      Let's check that it implements the interface correctly:
> 
>          >>> from zope.interface import verify
>          >>> synch = CacheSynchronizer()
>          >>> verify.verifyObject(ISynchronizer, synch)
>          True
>      """
>      implements(ISynchronizer)
> 
>      def afterCompletion(self, transaction):
>          pass
> 
>      def beforeCompletion(self, transaction):
>          pass
> 
>      def newTransaction(self, trans):
>          trans.join(AlchemyDataManager())
> 
> _synch = TransactionSynchronizer()
> manager.registerSynch(_synch)

You also copied one of my bugs here;) If you are working in a
threaded environment, the synchronizer needs to be registered
in every thread.

> </code>
> 
> It automatically commits or aborts as ZODB would do.
> 
> I borrowed most of it from SQLOS.
> 
> Warning : this code is not tested under all circumstances !
> 
> Jürgen
> > from interfaces import IUser

-- 
Brian Sutherland

Metropolis - "it's the first movie with a robot. And she's a woman.
              And she's EVIL!!"