Lazily registering hooks?

[John Yates]

What about lazing caching of hook registrations validated by plugin path/size/dtm.
Would that not support "installation" via simple copying, registration prior to any
hook evaluation and preservation of low amortized overhead?

/john
________________________________________
From: bazaar-bounces at lists.canonical.com [bazaar-bounces at lists.canonical.com] On Behalf Of Jelmer Vernooij [jelmer at samba.org]
Sent: Sunday, May 30, 2010 1:01 PM
To: John Arbash Meinel
Cc: bazaar at lists.canonical.com
Subject: Re: Lazily registering hooks?

On Sun, 2010-05-30 at 11:56 -0500, John Arbash Meinel wrote:
> Jelmer Vernooij wrote:
> > IIRC there was some discussion about this at the recent sprint during
> > UDS, but I wasn't there for it.
> >
> > One of the slowdowns for me in starting up Bazaar is importing the
> > various modules that the plugins I have installed install hooks in. E.g.
> > bzr-svn has to load bzrlib.info, bzrlib.diff, bzrlib.send,
> > bzrlib.filters, bzrlib.version_info_formats.format_rio.
> >
> > It'd be great if there was some way to lazily register hooks. I don't
> > have any good ideas on how to fix that without giving up some of the
> > benfits that our current infrastructure has (I don't want to centralize
> > all hooks in a single file). Does anybody else have ideas?
> The best I can think of still just ends up with a central registry. The
> Hook code could be localized, but it would end up saying "what bits were
> interested in my hook", and then call back to have them loaded.
That doesn't seem too bad actually, especially given this could all be done
under the covers in bzrlib.hooks (and the plugins would have to be updated, of
course).

> I don't think we can really get away from that.
>
> Well, one option is to turn the registration into config code, that only
> gets read when the hook runs, or something like that. But then the user
> has to get involved, rather than just 'installing' the plugin.
Yeah, that's probably not the best idea. The fact that plugins "just
work" is one of the nicest things about them in Bazaar.

Cheers,

Jelmer