Re: have SLRU truncation use callbacks

Excerpts from Kevin Grittner's message of jue sep 29 14:51:38 -0300 2011:
> Alvaro Herrera <alvherre@alvh.no-ip.org> wrote:
>  
> > But I think these changes stand on their own, merely on code
> > clarity grounds).
>  
> After a quick scan, I think it helps with that.  This was a messy
> area to deal with in SSI given the old API; with this change I think
> we could make that part of the SSI code clearer and maybe clean up
> unneeded files in a couple places where cleanup under the old API
> was judged not to be worth the code complexity needed to make it
> happen.

Thanks for the review.  I just pushed this.  Note I didn't touch the
predicate.c stuff at all -- I leave that to you, if you're so inclined :-)

-- 
Álvaro Herrera <alvherre@commandprompt.com>
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