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- Synopsis
ACX_PTHREAD([ACTION-IF-FOUND[, ACTION-IF-NOT-FOUND]])
- Version
1.3 (2002/12/12) Installed_Packages @ ac-archive-0.5.39
- Author
Steven G. Johnson <stevenj@alum.mit.edu> and Alejandro Forero Cuervo <bachue@bachue.com>
- Description
This macro figures out how to build C programs using POSIX
threads. It sets the PTHREAD_LIBS output variable to the threads
library and linker flags, and the PTHREAD_CFLAGS output variable
to any special C compiler flags that are needed. (The user can also
force certain compiler flags/libs to be tested by setting these
environment variables.)
Also sets PTHREAD_CC to any special C compiler that is needed for
multi-threaded programs (defaults to the value of CC otherwise).
(This is necessary on AIX to use the special cc_r compiler alias.)
If you are only building threads programs, you may wish to
use these variables in your default LIBS, CFLAGS, and CC:
LIBS="$PTHREAD_LIBS $LIBS"
CFLAGS="$CFLAGS $PTHREAD_CFLAGS"
CC="$PTHREAD_CC"
In addition, if the PTHREAD_CREATE_JOINABLE thread-attribute
constant has a nonstandard name, defines PTHREAD_CREATE_JOINABLE
to that name (e.g. PTHREAD_CREATE_UNDETACHED on AIX).
ACTION-IF-FOUND is a list of shell commands to run if a threads
library is found, and ACTION-IF-NOT-FOUND is a list of commands
to run it if it is not found. If ACTION-IF-FOUND is not specified,
the default action will define HAVE_PTHREAD.
Please let the authors know if this macro fails on any platform,
or if you have any other suggestions or comments. This macro was
based on work by SGJ on autoconf scripts for FFTW (www.fftw.org)
(with help from M. Frigo), as well as ac_pthread and hb_pthread
macros posted by AFC to the autoconf macro repository. We are also
grateful for the helpful feedback of numerous users.
- M4 Source Code
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="$save_CFLAGS"
fi
# We must check for the threads library under a number of different
# names; the ordering is very important because some systems
# (e.g. DEC) have both -lpthread and -lpthreads, where one of the
# libraries is broken (non-POSIX).
# Create a list of thread flags to try. Items starting with a "-" are
# C compiler flags, and other items are library names, except for "none"
# which indicates that we try without any flags at all.
acx_pthread_flags="pthreads none -Kthread -kthread lthread -pthread -pthreads -mthreads pthread --thread-safe -mt"
# The ordering *is* (sometimes) important. Some notes on the
# individual items follow:
# pthreads: AIX (must check this before -lpthread)
# none: in case threads are in libc; should be tried before -Kthread and
# other compiler flags to prevent continual compiler warnings
# -Kthread: Sequent (threads in libc, but -Kthread needed for pthread.h)
# -kthread: FreeBSD kernel threads (preferred to -pthread since SMP-able)
# lthread: LinuxThreads port on FreeBSD (also preferred to -pthread)
# -pthread: Linux/gcc (kernel threads), BSD/gcc (userland threads)
# -pthreads: Solaris/gcc
# -mthreads: Mingw32/gcc, Lynx/gcc
# -mt: Sun Workshop C (may only link SunOS threads [-lthread], but it
# doesn't hurt to check since this sometimes defines pthreads too;
# also defines -D_REENTRANT)
# pthread: Linux, etcetera
# --thread-safe: KAI C++
case "${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
case $flag in
none)
AC_MSG_CHECKING([whether pthreads work without any flags])
;;
-*)
AC_MSG_CHECKING([whether pthreads work with $flag])
PTHREAD_CFLAGS="$flag"
;;
*)
AC_MSG_CHECKING([for the pthreads library -l$flag])
PTHREAD_LIBS="-l$flag"
;;
esac
save_LIBS="$LIBS"
save_CFLAGS="$CFLAGS"
LIBS="$PTHREAD_LIBS $LIBS"
CFLAGS="$CFLAGS $PTHREAD_CFLAGS"
# Check for various functions. We must include pthread.h,
# since some functions may be macros. (On the Sequent, we
# need a special flag -Kthread to make this header compile.)
# We check for pthread_join because it is in -lpthread on IRIX
# while pthread_create is in libc. We check for pthread_attr_init
# due to DEC craziness with -lpthreads. We check for
# pthread_cleanup_push because it is one of the few pthread
# functions on Solaris that doesn't have a non-functional libc stub.
# We try pthread_create on general principles.
AC_TRY_LINK([#include <pthread.h>],
[pthread_t th; pthread_join(th, 0);
pthread_attr_init(0); pthread_cleanup_push(0, 0);
pthread_create(0,0,0,0); pthread_cleanup_pop(0); ],
[acx_pthread_ok=yes])
LIBS="$save_LIBS"
CFLAGS="$save_CFLAGS"
AC_MSG_RESULT($acx_pthread_ok)
if test "x$acx_pthread_ok" = xyes; then
break;
fi
PTHREAD_LIBS=""
PTHREAD_CFLAGS=""
done
fi
# Various other checks:
if test "x$acx_pthread_ok" = xyes; then
save_LIBS="$LIBS"
LIBS="$PTHREAD_LIBS $LIBS"
save_CFLAGS="$CFLAGS"
CFLAGS="$CFLAGS $PTHREAD_CFLAGS"
# Detect AIX lossage: threads are created detached by default
# and the JOINABLE attribute has a nonstandard name (UNDETACHED).
AC_MSG_CHECKING([for joinable pthread attribute])
AC_TRY_LINK([#include <pthread.h>],
[int attr=PTHREAD_CREATE_JOINABLE;],
ok=PTHREAD_CREATE_JOINABLE, ok=unknown)
if test x"$ok" = xunknown; then
AC_TRY_LINK([#include <pthread.h>],
[int attr=PTHREAD_CREATE_UNDETACHED;],
ok=PTHREAD_CREATE_UNDETACHED, ok=unknown)
fi
if test x"$ok" != xPTHREAD_CREATE_JOINABLE; then
AC_DEFINE(PTHREAD_CREATE_JOINABLE, $ok,
[Define to the necessary symbol if this constant
uses a non-standard name on your system.])
fi
AC_MSG_RESULT(${ok})
if test x"$ok" = xunknown; then
AC_MSG_WARN([we do not know how to create joinable pthreads])
fi
AC_MSG_CHECKING([if more special flags are required for pthreads])
flag=no
case "${host_cpu}-${host_os}" in
*-aix* | *-freebsd*) flag="-D_THREAD_SAFE";;
*solaris* | *-osf* | *-hpux*) flag="-D_REENTRANT";;
esac
AC_MSG_RESULT(${flag})
if test "x$flag" != xno; then
PTHREAD_CFLAGS="$flag $PTHREAD_CFLAGS"
fi
LIBS="$save_LIBS"
CFLAGS="$save_CFLAGS"
# More AIX lossage: must compile with cc_r
AC_CHECK_PROG(PTHREAD_CC, cc_r, cc_r, ${CC})
else
PTHREAD_CC="$CC"
fi
AC_SUBST(PTHREAD_LIBS)
AC_SUBST(PTHREAD_CFLAGS)
AC_SUBST(PTHREAD_CC)
# Finally, execute ACTION-IF-FOUND/ACTION-IF-NOT-FOUND:
if test x"$acx_pthread_ok" = xyes; then
ifelse([$1],,AC_DEFINE(HAVE_PTHREAD,1,[Define if you have POSIX threads libraries and header files.]),[$1])
:
else
acx_pthread_ok=no
$2
fi
AC_LANG_RESTORE
])dnl ACX_PTHREAD
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