Justin Erenkrantz <[EMAIL PROTECTED]> writes:
> Can someone enlighten me as to why we have --with-pthread-cross and we
> aren't telling anyone? If we have pthread.h, PTHREAD_PROCESS_SHARED,
> and pthread_mutexattr_setpshared, it seems reasonable enough to
> define USE_PROC_PTHREAD_SERIALIZE to 1. Or, are pthread_mutex_t not
> suitable for cross-process locks for some other reason that we have to
> have a manual override?
>
> Unless someone says otherwise, I'll commit this tonight/tomorrow.
Please don't commit just yet.
That piece of code decides not what kind of interprocess lock
mechanism APR *has* support for on the platform but what kind of
interprocess lock mechanism APR will *use* by default.
I suspect that you misunderstood what that code is doing... otherwise,
you'd try to explain why you want to change the [usual] default
mechanism from fcntl() to interprocess pthread mutex.
Let's back up now. What is the problem you want to solve?
a) you really think we should default to interprocess pthread mutex
whenever the platform supports it?
I don't feel too comfortable with that for several reasons
i) the current APR code doesn't support all platforms which have
interprocess pthread mutex support
the current logic relies on mmap-ed /dev/zero for the shared
memory where the mutex lives; this doesn't work everywhere
This should be remedied, but with your patch we go downhill on
some platforms.
ii) it means we pick a different default lock depending upon
whether or not we have thread support
iii) historically, fcntl()-based locking is something that works
pretty darn well overall across supported platforms. There are
platform and config-specific situations where something else is
more appropriate, but historically it has been the safest bet
for a system-independent default.
b) you don't like the way APR let's the builder tell APR "yes
indeed it is okay to use interprocess pthread mutex by default"
c) something else
> Index: configure.in
> ===================================================================
> RCS file: /home/cvs/apr/configure.in,v
> retrieving revision 1.321
> diff -u -r1.321 configure.in
> --- configure.in 2001/06/28 01:57:02 1.321
> +++ configure.in 2001/06/30 19:52:34
> @@ -955,7 +955,7 @@
> APR_IFALLYES(header:fcntl.h define:F_SETLK,
> APR_DECIDE(USE_FCNTL_SERIALIZE, [SVR4-style fcntl()]))
> APR_IFALLYES(header:pthread.h define:PTHREAD_PROCESS_SHARED dnl
> - func:pthread_mutexattr_setpshared custom:with_pthread_cross,
> + func:pthread_mutexattr_setpshared,
> APR_DECIDE(USE_PROC_PTHREAD_SERIALIZE, [pthread mutex]))
> if test "x$apr_lock_method" != "x"; then
> APR_DECISION_FORCE($apr_lock_method)
(Sorry for the delay... We've been moving over the last week and
things are pretty crazy.)
--
Jeff Trawick | [EMAIL PROTECTED] | PGP public key at web site:
http://www.geocities.com/SiliconValley/Park/9289/
Born in Roswell... married an alien...
