postgresql/config/acx_pthread.m4

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dnl This is based on an old macro from the GNU Autoconf Macro Archive at:
dnl http://www.gnu.org/software/ac-archive/htmldoc/acx_pthread.html
dnl but it's been rather heavily hacked --- beware of blindly dropping in
dnl upstream changes!
dnl
AC_DEFUN([ACX_PTHREAD], [
AC_REQUIRE([AC_CANONICAL_HOST])
AC_LANG_SAVE
AC_LANG_C
acx_pthread_ok=no
# We used to check for pthread.h first, but this fails if pthread.h
# requires special compiler flags (e.g. on True64 or Sequent).
# It gets checked for in the link test anyway.
# First of all, check if the user has set any of the PTHREAD_LIBS,
# etcetera environment variables, and if threads linking works using
# them:
if test x"$PTHREAD_LIBS$PTHREAD_CFLAGS" != x; then
save_CFLAGS="$CFLAGS"
CFLAGS="$CFLAGS $PTHREAD_CFLAGS"
save_LIBS="$LIBS"
LIBS="$PTHREAD_LIBS $LIBS"
AC_MSG_CHECKING([for pthread_join in LIBS=$PTHREAD_LIBS with CFLAGS=$PTHREAD_CFLAGS])
AC_TRY_LINK_FUNC(pthread_join, acx_pthread_ok=yes)
AC_MSG_RESULT($acx_pthread_ok)
if test x"$acx_pthread_ok" = xno; then
PTHREAD_LIBS=""
PTHREAD_CFLAGS=""
fi
LIBS="$save_LIBS"
CFLAGS="$save_CFLAGS"
fi
# We must check for the threads library under a number of different
# names; the ordering is very important because some systems
# (e.g. DEC) have both -lpthread and -lpthreads, where one of the
# libraries is broken (non-POSIX).
# Create a list of thread flags to try. Items starting with a "-" are
# C compiler flags, and other items are library names, except for "none"
# which indicates that we try without any flags at all, and "pthread-config"
# which is a program returning the flags for the Pth emulation library.
acx_pthread_flags="pthreads none -Kthread -kthread lthread -pthread -pthreads -mthreads pthread --thread-safe -mt pthread-config pthreadGC2"
# The ordering *is* (sometimes) important. Some notes on the
# individual items follow:
# pthreads: AIX (must check this before -lpthread)
# none: in case threads are in libc; should be tried before -Kthread and
# other compiler flags to prevent continual compiler warnings
# -Kthread: Sequent (threads in libc, but -Kthread needed for pthread.h)
# -kthread: FreeBSD kernel threads (preferred to -pthread since SMP-able)
# lthread: LinuxThreads port on FreeBSD (also preferred to -pthread)
# -pthread: Linux/gcc (kernel threads), BSD/gcc (userland threads)
# -pthreads: Solaris/gcc
# -mthreads: Mingw32/gcc, Lynx/gcc
# -mt: Sun Workshop C (may only link SunOS threads [-lthread], but it
# doesn't hurt to check since this sometimes defines pthreads too;
# also defines -D_REENTRANT)
# pthread: Linux, etcetera
# --thread-safe: KAI C++
# pthread-config: use pthread-config program (for GNU Pth library)
case "${host_cpu}-${host_os}" in
*solaris*)
# On Solaris (at least, for some versions), libc contains stubbed
# (non-functional) versions of the pthreads routines, so link-based
# tests will erroneously succeed. (We need to link with -pthread or
# -lpthread.) (The stubs are missing pthread_cleanup_push, or rather
# a function called by this macro, so we could check for that, but
# who knows whether they'll stub that too in a future libc.) So,
# we'll just look for -pthreads and -lpthread first:
acx_pthread_flags="-pthread -pthreads pthread -mt $acx_pthread_flags"
;;
esac
if test x"$acx_pthread_ok" = xno; then
for flag in $acx_pthread_flags; do
tryPTHREAD_CFLAGS=""
tryPTHREAD_LIBS=""
case $flag in
none)
AC_MSG_CHECKING([whether pthreads work without any flags])
;;
-*)
AC_MSG_CHECKING([whether pthreads work with $flag])
tryPTHREAD_CFLAGS="$flag"
;;
pthread-config)
# skip this if we already have flags defined, for PostgreSQL
if test x"$PTHREAD_CFLAGS" != x -o x"$PTHREAD_LIBS" != x; then continue; fi
AC_CHECK_PROG(acx_pthread_config, pthread-config, yes, no)
if test x"$acx_pthread_config" = xno; then continue; fi
tryPTHREAD_CFLAGS="`pthread-config --cflags`"
tryPTHREAD_LIBS="`pthread-config --ldflags` `pthread-config --libs`"
;;
*)
AC_MSG_CHECKING([for the pthreads library -l$flag])
tryPTHREAD_LIBS="-l$flag"
;;
esac
save_LIBS="$LIBS"
save_CFLAGS="$CFLAGS"
LIBS="$tryPTHREAD_LIBS $PTHREAD_LIBS $LIBS"
CFLAGS="$CFLAGS $PTHREAD_CFLAGS $tryPTHREAD_CFLAGS"
# Check for various functions. We must include pthread.h,
# since some functions may be macros. (On the Sequent, we
# need a special flag -Kthread to make this header compile.)
# We check for pthread_join because it is in -lpthread on IRIX
# while pthread_create is in libc. We check for pthread_attr_init
# due to DEC craziness with -lpthreads. We check for
# pthread_cleanup_push because it is one of the few pthread
# functions on Solaris that doesn't have a non-functional libc stub.
# We try pthread_create on general principles.
AC_TRY_LINK([#include <pthread.h>],
[pthread_t th; pthread_join(th, 0);
pthread_attr_init(0); pthread_cleanup_push(0, 0);
pthread_create(0,0,0,0); pthread_cleanup_pop(0); ],
[acx_pthread_ok=yes], [acx_pthread_ok=no])
if test "x$acx_pthread_ok" = xyes; then
# Don't use options that are ignored by the compiler.
# We find them by checking stderror.
cat >conftest.$ac_ext <<_ACEOF
int
main (int argc, char **argv)
{
(void) argc;
(void) argv;
return 0;
}
_ACEOF
rm -f conftest.$ac_objext conftest$ac_exeext
# Check both linking and compiling, because they might tolerate different options.
if test "`(eval $ac_link 2>&1 1>&5)`" = "" && test "`(eval $ac_compile 2>&1 1>&5)`" = ""; then
# The original macro breaks out of the loop at this point,
# but we continue trying flags because Linux needs -lpthread
# too to build libpq successfully. The test above only
# tests for building binaries, not shared libraries.
PTHREAD_LIBS=" $tryPTHREAD_LIBS $PTHREAD_LIBS"
PTHREAD_CFLAGS="$PTHREAD_CFLAGS $tryPTHREAD_CFLAGS"
else acx_pthread_ok=no
fi
fi
LIBS="$save_LIBS"
CFLAGS="$save_CFLAGS"
AC_MSG_RESULT($acx_pthread_ok)
done
fi
# The original macro has a bunch of other tests here, which we have removed
# because (a) Postgres doesn't need them, and (b) $acx_pthread_ok is not
# meaningful at this point.
AC_SUBST(PTHREAD_LIBS)
AC_SUBST(PTHREAD_CFLAGS)
AC_LANG_RESTORE
])dnl ACX_PTHREAD