Horton

Re: O_DIRECT on macOS

Thomas Munro <thomas.munro@gmail.com>

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From: Thomas Munro <thomas.munro@gmail.com>
To: Tom Lane <tgl@sss.pgh.pa.us>
Cc: Andres Freund <andres@anarazel.de>, pgsql-hackers <pgsql-hackers@postgresql.org>
Date: 2021-07-19T23:23:48Z
Lists: pgsql-hackers

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On Tue, Jul 20, 2021 at 2:13 AM Tom Lane <tgl@sss.pgh.pa.us> wrote:
> Hmm ... we used to have to avoid putting #if constructs in the arguments
> of macros (such as StaticAssertStmt).  Maybe that's not a thing anymore
> with C99, and in any case this whole stanza is fairly platform-specific
> so we may not run into a compiler that complains.  But my hindbrain wants
> to see this done with separate statements, eg
>
> #if defined(O_CLOEXEC)
>     StaticAssertStmt((PG_O_DIRECT & O_CLOEXEC) == 0,
>                      "PG_O_DIRECT collides with O_CLOEXEC");
> #endif

Ok, done.

While I was here again, I couldn't resist trying to extend this to
Solaris, since it looked so easy.  I don't have access, but I tested
on Illumos by undefining O_DIRECT.  Thoughts?

Commits

  1. Don't use #if inside function-like macro arguments.

  2. Support direct I/O on macOS.