Re: BufferAlloc: don't take two simultaneous locks

At Fri, 11 Mar 2022 12:34:32 +0300, Yura Sokolov <y.sokolov@postgrespro.ru> wrote in
> В Пт, 11/03/2022 в 15:49 +0900, Kyotaro Horiguchi пишет:
> > At Fri, 11 Mar 2022 15:30:30 +0900 (JST), Kyotaro Horiguchi <horikyota.ntt@g> > BufTableDelete(BufferTag *tagPtr,
uint32hashcode, bool reuse) 
> >
> > BufTableDelete considers both reuse and !reuse cases but
> > BufTableInsert doesn't and always does HASH_ASSIGN.  That looks
> > odd. We should use HASH_ENTER here.  Thus I think it is more
> > reasonable that HASH_ENTRY uses the stashed entry if exists and
> > needed, or returns it to freelist if exists but not needed.
> >
> > What do you think about this?
>
> Well... I don't like it but I don't mind either.
>
> Code in HASH_ENTER and HASH_ASSIGN cases differs much.
> On the other hand, probably it is possible to merge it carefuly.
> I'll try.

Honestly, I'm not sure it wins on performance basis. It just came from
interface consistency (mmm. a bit different, maybe.. convincibility?).

regards.
--
Kyotaro Horiguchi
NTT Open Source Software Center