Re: --enable-thread-safety broken + patch regressions

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 flags
link flags
link libraries
special 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(at)candle(dot)pha(dot)pa(dot)us | (610) 359-1001
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