Re: --enable-thread-safety broken + patch regressions - Mailing list pgsql-hackers

Lee Kindness wrote:
> Bruce, the changes you made yesterday to configure for
> --enable-thread-safety have broken the build, at least for Linux on
> Redhat 9.

OK, how did I break things?  Can you show me the failure.

> Also, I took the opportunity to look at port/threads.c. It is missing
> important functionality compaired to the patch I originally
> submitted. For getpwuid_r, gethostbyname_r and strerror_r there are
> three possible scenarios:
> 
> 1. The OS doesn't have it (but the non _r function can still be thread
> safe (i.e. HPUX 11)).
> 
> 2. The OS has it, but the implmentation doesn't match the POSIX spec.
> 
> 3. The OS has it, and the implmentation matches the POSIX spec.
> 
> Case 3 is not being considered. In my original patch this was handled
> by the pqGetpwuid etc functions simply being defined to getpwuid_r
> (except for pqStrerror).

I believe what we did was that there was no way to test for #3 (at the
time), so we just went with the normal function and the POSIX one, and
were going to see what happened to see if anyone needed the non-POSIX
one.  Do we have any platforms that need it?

> I remember discussing with you that the implementation of pqStrerror
> didn't really need the distinction between the two _r
> versions. However I think the others do, and the native/correct _r
> calls should be #defined in if they match the POSIX spec.
> 
> It's also worth considering that when the _r function is available AND
> the normal function is also thread-safe then the _r version should
> still be used since it has a clean API which removes unneeded locking
> within the old function.

We have that already. Have you looked in the template files.  There you
control whether you should use _r functions.

Also, I doubt that the locking really has any performance hit to it.

> I've still got the latest (and earlier with some configure work)
> patches I submitted up at:

I just looked at this --- I have not seem them before.

Seems theading requires four things, potentially:
compile flagslink flagslink librariesspecial functions

While your configure checks can detect the existance of the last one,
they don't tell us what to do if they don't exist --- are the normal
ones thread-safe.

So, the big question is whether we gain by having detection of non-posix
functions or whether it is better to just have template control it.

--  Bruce Momjian                        |  http://candle.pha.pa.us pgman@candle.pha.pa.us               |  (610)
359-1001+  If your life is a hard drive,     |  13 Roberts Road +  Christ can be your backup.        |  Newtown Square,
Pennsylvania19073