start/stop hook guarantees

William Reade william.reade at
Wed Dec 7 08:56:14 UTC 2011

On Tue, 2011-12-06 at 17:48 -0200, Gustavo Niemeyer wrote:
> That said, there's some uncomfortable confusion going on here that is
> an eye-opener. With all the background you have, if you can't clearly
> and comfortably understand and define the behavior of "start" and
> "stop", I don't have many hopes that anyone else will. People are also
> unhappy with the whole "non-idempotent" start hook, and while I don't
> think it's reasonable to expect people to write idempotent hooks, I
> can correlate with the overall problem they're trying to solve.

The confusion stems from the fact that I didn't think I was supposed to be
defining the behaviour of "start" and "stop"; I thought there were accepted
definitions I was building from, and I assumed that the codebase reflected
those. You seemed surprised by what the code did; I'd been taking the code
as the primary source of truth, and was surprised that the behaviour wasn't
actually what was intended.

That is to say, I can comfortably understand either definition of "stop" [0],
and I don't believe anyone else will have a problem with either definition;
the confusion stems purely from the fact that we have two competing

> I think we have a very good chance to revamp that mechanism a bit, and
> solve all of these problems. I already have some ideas in mind, but
> please give me a day to think about this problem. I'll try to write
> something in the plane and come back to you tomorrow here in the list
> (will be in San Francisco, so maybe too late for you).

That's great, thank you very much; I look forward to reading about it :).


[0] I'm sorry I hastily mischaracterised yours in the previous email; I know
it doesn't *necessarily* mean "going away forever".

> --
> Gustavo Niemeyer
> -- I'm not absolutely sure of anything.

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