Horton

Re: repeat() function, CHECK_FOR_INTERRUPTS(), and unlikely()

Michael Paquier <michael@paquier.xyz>

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From: Michael Paquier <michael@paquier.xyz>
To: Tom Lane <tgl@sss.pgh.pa.us>
Cc: Joe Conway <mail@joeconway.com>, PostgreSQL-development <pgsql-hackers@postgreSQL.org>
Date: 2020-05-27T07:29:27Z
Lists: pgsql-hackers 
On Mon, May 25, 2020 at 11:14:39AM -0400, Tom Lane wrote:
> Perhaps I'm an optimist, but I think that eventually we will figure out
> how to make unlikely() work for MSVC.  In the meantime we might as well
> let it work for gcc-on-Windows builds.

I am less optimistic than that, but there is hope.  This was mentioned
as something considered for implementation in April 2019:
https://developercommunity.visualstudio.com/idea/488669/please-add-likelyunlikely-builtins.html

> I think that each of those tests should have a separate unlikely() marker,
> since the whole point here is that we don't expect either of those tests
> to yield true in the huge majority of CHECK_FOR_INTERRUPTS executions.

+1.  I am not sure that the addition of unlikely() should be
backpatched though, that's not something usually done.
--
Michael

Commits

  1. Add unlikely() to CHECK_FOR_INTERRUPTS()

  2. Add CHECK_FOR_INTERRUPTS() to the repeat() function