Horton

Re: Allowing printf("%m") only where it actually works

Tom Lane <tgl@sss.pgh.pa.us>

View thread View on postgr.es
From: Tom Lane <tgl@sss.pgh.pa.us>
To: Andres Freund <andres@anarazel.de>
Cc: Michael Paquier <michael@paquier.xyz>, Thomas Munro <thomas.munro@enterprisedb.com>, Alvaro Herrera <alvherre@2ndquadrant.com>, PostgreSQL Hackers <pgsql-hackers@lists.postgresql.org>
Date: 2018-09-26T21:41:36Z
Lists: pgsql-hackers 
Andres Freund <andres@anarazel.de> writes:
> I'm not saying we shouldn't default to our printf - in fact I think we
> probably past due to use a faster float->string conversion than we
> portably get from the OS - but I don't think we can default to our
> sprintf without doing something about the float conversion performance.

Well, if you're unhappy about snprintf.c's performance, you could review
https://commitfest.postgresql.org/19/1763/
so I can push that.  In my tests, that got us down to circa 10% penalty
for float conversions.

More generally, I'm not averse to having our own float conversion code
if someone wants to put in the effort.  Performance aside, it'd be nice
to eliminate cross-platform differences in float output so we could get
rid of some of the Windows-specific regression result files.

			regards, tom lane

Commits

  1. In pg_log_generic(), be more paranoid about preserving errno.

  2. Make src/common/exec.c's error logging less ugly.

  3. Select appropriate PG_PRINTF_ATTRIBUTE for recent NetBSD.

  4. Fix detection of the result type of strerror_r().

  5. Try another way to detect the result type of strerror_r().

  6. Clean up *printf macros to avoid conflict with format archetypes.

  7. Fix link failures due to snprintf/strerror changes.

  8. Implement %m in src/port/snprintf.c, and teach elog.c to rely on that.

  9. Always use our own versions of *printf().

  10. Incorporate strerror_r() into src/port/snprintf.c, too.

  11. Convert elog.c's useful_strerror() into a globally-used strerror wrapper.

  12. Revert "Distinguish printf-like functions that support %m from those that don't."

  13. Produce compiler errors if errno is referenced inside elog/ereport calls.

  14. Distinguish printf-like functions that support %m from those that don't.

  15. Fix unportable usage of printf("%m").

  16. Be more robust when strerror() doesn't give a useful result.