Re: Dllist public/private part - Mailing list pgsql-hackers

From Tom Lane
Subject Re: Dllist public/private part
Date
Msg-id 20988.1057020299@sss.pgh.pa.us
Whole thread Raw
In response to Dllist public/private part  ("Mendola Gaetano" <mendola@bigfoot.com>)
List pgsql-hackers
"Mendola Gaetano" <mendola@bigfoot.com> writes:
> I'm improving the Dllist in these direction:

AFAIR, catcache.c is the *only* remaining backend customer for Dllist,
and so any improvement for Dllist that breaks catcache is hardly an
improvement, no?

> 1) Avoid "if" statements in insertion/remove phase, for instance now the
> AddHeader appear like this:

<shrug> ... unless you can convert DLAddHead into a inline macro,
I doubt there'll be any visible performance difference.

> 2) Not using a malloc but using a "special" malloc that not perform
>    a malloc for each request but do a BIG malloc at first request...

It would make more sense to migrate Dllist to use palloc.  That's not
compatible with its use in frontend libpq; I've been speculating about
splitting off libpq to have a separate implementation instead of trying
to share code.  I believe libpq only uses Dllist for the
pending-notify-events list, for which the code is poorly optimized
anyway (we don't need a doubly-linked list for that).
        regards, tom lane


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