[Zope-dev] deciding whether to do work in tpc_vote or tpc_finish

[Chris Withers]

Laurence Rowe wrote:
> On 8 June 2010 12:59, Chris Withers <chris at simplistix.co.uk> wrote:
>> Laurence Rowe wrote:
>>> it fails you will end up in an inconsistent state whatever. It's just
>>> that with the maildir implementation, it pretty much can't fail as it
>>> is only a rename and that should always succeed. Really, it should
>>> register as an after commit hook instead.
>> How do I do that?
> 
> transaction.get().addAfterCommitHook(callable, args, kwargs)

Hmm, I realised from looking at the code this morning that this won't.
The reason being that there's no equivalent AfterAbortHook where I can 
abort the messaging transaction in the event of transaction-package 
transaction abort.

I see these things called "synchronizers", though... what are they and 
what is their intended purpose? Where are they documented?

>> My other thought was to have it commit the message send in tpc_vote, and
>> make sure it sorts before zope.sqlalchemy. That way, if the message send
>> fails, the "transaction" will be aborted, and that will include rolling back
>> the zope.sqlalchemy session rather than committing it.
> 
> In that case if the sqlalchemy commit fails, you still sent the message.

Yeah, I guess given that, of the possible failure modes, I'd prefer the 
message not to be sent in the event of sqlalchemy commit failure, I 
should have it sort after sqlalchemy...

cheers,

Chris

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