Re: UPDATED UnixWare Threads Patch. - Mailing list pgsql-patches

what about the pieces of src/port/unixware to allow the threads stuff?



--On Thursday, August 14, 2003 01:25:48 -0400 Bruce Momjian
<pgman@candle.pha.pa.us> wrote:

>
> OK, I have applied the attached patch.
>
> Here is the comment I have added to the thread.c file:
>
> /*
>  *    Threading sometimes requires specially-named versions of functions
>  *    that return data in static buffers, like strerror_r() instead of
>  *    strerror().  Other operating systems use pthread_setspecific()
>  *    and pthread_getspecific() internally to allow standard library
>  *    functions to return static data to threaded applications.
>  *
>  *    Additional confusion exists because many operating systems that
>  *    use pthread_setspecific/pthread_getspecific() also have *_r versions
>  *    of standard library functions for compatibility with operating
> systems  *    that require them.  However, internally, these *_r
> functions merely  *    call the thread-safe standard library functions.
>  *
>  *    For example, BSD/OS 4.3 uses Bind 8.2.3 for getpwuid().  Internally,
>  *    getpwuid() calls pthread_setspecific/pthread_getspecific() to return
>  *    static data to the caller in a thread-safe manner.  However, BSD/OS
>  *    also has getpwuid_r(), which merely calls getpwuid() and shifts
>  *    around the arguments to match the getpwuid_r() function declaration.
>  *    Therefore, while BSD/OS has getpwuid_r(), it isn't required.  It
> also  *    doesn't have strerror_r(), so we can't fall back to only using
> *_r  *    functions for threaded programs.
>  *
>  *    The current setup is to assume either all standard functions are
>  *    thread-safe (NEED_REENTRANT_FUNC_NAMES=no), or the operating system
>  *    requires reentrant function names (NEED_REENTRANT_FUNC_NAMES=yes).
>  */
>
> As an additional data point, here is a README comment from Bind 8.2.3:
>
>   Thread Safety:
>
>           It is possible for a thread safe program to be altered to call
> the   underlying interface (rather than the standard getXbyY() stubs) and
> get some   reentrance capabilities.  Note that the underlying libraries
> (which we call)   are not all thread-safe, for example, the YP and DNS
> resolvers.  A lot more   work will need to be done before we have full
> thread safety.  But we believe   that the native API for this system does
> not impose any reentrancy problems.   We don't use global or static
> variables anywhere except in the getXbyY() stubs.
>
> Here is Bind's gethostbyname_r:
>
>     HOST_R_RETURN
>     gethostbyname_r(const char *name,  struct hostent *hptr, HOST_R_ARGS) {
>         struct hostent *he = gethostbyname(name);
>
>         HOST_R_ERRNO;
>
>         if (he == NULL)
>             return (HOST_R_BAD);
>
>         return (copy_hostent(he, hptr, HOST_R_COPY));
>     }
>
> As you can see, it merely calls gethostbyname() and adjusts to return
> the proper values.
>
> I removed the pre-POSIX getpwuid_r function call and added the POSIX
> one.  If we need the pre-POSIX one, we can add it with a configure
> test, but I would rather find out if someone needs it first.  The
> original thread patch that was posted had only the pre-POSIX version of
> the function, and I am not sure why the didn't include the POSIX one
> too, or use that instead of the pre-POSIX one.
>
> There are also a few stylistic function declaration cleanups.
>
> The unixware optimizer changes have already been applied.
>
>
> -------------------------------------------------------------------------
> --
>
> Larry Rosenman wrote:
>>
>>
>> --On Friday, August 08, 2003 18:56:45 -0500 Larry Rosenman
>> <ler@lerctr.org>  wrote:
>>
>> >
>> >
>> > Here is the updated UnixWare threads patch.  I need some help to set
>> > the HAVE_POSIX_GETPWUID_R define from configure, but this will suffice
>> > for now.
>> >
>> > This also includes my recommendation for the Compiler Bug issue.
>> >
>> > Please Apply, and if one of the configure guru's can help here, I'd be
>> > most appreciative.
>> Grr.  I'm an idiot, the following is a CORRECTED version, basically
>> s/#elsif/#elif/
>>
>> Index: src/port/thread.c
>> ===================================================================
>> RCS file: /projects/cvsroot/pgsql-server/src/port/thread.c,v
>> retrieving revision 1.2
>> diff -u -r1.2 thread.c
>> --- src/port/thread.c    8 Aug 2003 03:09:56 -0000    1.2
>> +++ src/port/thread.c    9 Aug 2003 00:47:00 -0000
>> @@ -40,13 +40,18 @@
>>  pqGetpwuid(uid_t uid, struct passwd * resultbuf, char *buffer,
>>             size_t buflen, struct passwd ** result)
>>  {
>> -#if defined(USE_THREADS) && defined(HAVE_GETPWUID_R)
>> +#if defined(USE_THREADS) && defined(HAVE_GETPWUID_R) &&
>> !defined(HAVE_POSIX_GETPWUID_R)
>>
>>      /*
>>       * broken (well early POSIX draft) getpwuid_r() which returns 'struct
>>       * passwd *'
>>       */
>>      *result = getpwuid_r(uid, resultbuf, buffer, buflen);
>> +#elif defined(USE_THREADS) && defined(HAVE_GETPWUID_R) &&
>> defined(HAVE_POSIX_GETPWUID_R)
>> +    /*
>> +     * SUSv2/POSIX getpwuid_r
>> +     */
>> +    return getpwuid_r(uid, resultbuf, buffer, buflen, result);
>>  # else
>>      /* no getpwuid_r() available, just use getpwuid() */
>>      *result = getpwuid(uid);
>> Index: src/template/unixware
>> ===================================================================
>> RCS file: /projects/cvsroot/pgsql-server/src/template/unixware,v
>> retrieving revision 1.11
>> diff -u -r1.11 unixware
>> --- src/template/unixware    4 Sep 2002 22:54:18 -0000    1.11
>> +++ src/template/unixware    9 Aug 2003 00:47:00 -0000
>> @@ -1,5 +1,13 @@
>> +SUPPORTS_THREADS=yes
>>  if test "$GCC" = yes; then
>> -  CFLAGS=-O2
>> +  CFLAGS="-O2 -DHAVE_POSIX_GETPWUID_R"
>> +  THREAD_CFLAGS="-pthread -D_REENTRANT"
>> +  NEED_REENTRANT_FUNC_NAMES=yes
>>  else
>> -  CFLAGS='-O -K inline'
>> +# the -Kno_host is temporary for a bug in the compiler.  See -hackers
>> +# discussion on 7-8/Aug/2003.
>> +# when the 7.1.3UP3 or later compiler is out, we can do a version check.
>> +  CFLAGS='-O -Kinline,no_host  -DHAVE_POSIX_GETPWUID_R'
>> +  THREAD_CFLAGS="-D_REENTRANT -K pthread -DHAVE_POSIX_GETPWUID_R"
>> +  NEED_REENTRANT_FUNC_NAMES=yes
>>  fi
>>
>> --
>> Larry Rosenman                     http://www.lerctr.org/~ler
>> Phone: +1 972-414-9812                 E-Mail: ler@lerctr.org
>> US Mail: 1905 Steamboat Springs Drive, Garland, TX 75044-6749
>
> [ Attachment, skipping... ]
>
>>
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--
Larry Rosenman                     http://www.lerctr.org/~ler
Phone: +1 972-414-9812                 E-Mail: ler@lerctr.org
US Mail: 1905 Steamboat Springs Drive, Garland, TX 75044-6749