# ===========================================================================

#              http://autoconf-archive.cryp.to/acx_pthread.html

# ===========================================================================

#

# SYNOPSIS

#

#   ACX_PTHREAD([ACTION-IF-FOUND[, ACTION-IF-NOT-FOUND]])

#

# 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.)

#

#   NOTE: You are assumed to not only compile your program with these flags,

#   but also link it with them as well. e.g. you should link with

#   $PTHREAD_CC $CFLAGS $PTHREAD_CFLAGS $LDFLAGS ... $PTHREAD_LIBS $LIBS

#

#   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 (http://www.fftw.org/) (with help

#   from M. Frigo), as well as ac_pthread and hb_pthread macros posted by

#   Alejandro Forero Cuervo to the autoconf macro repository. We are also

#   grateful for the helpful feedback of numerous users.

#

# LAST MODIFICATION

#

#   2008-04-12

#

# COPYLEFT

#

#   Copyright (c) 2008 Steven G. Johnson <[email protected]>

#

#   This program is free software: you can redistribute it and/or modify it

#   under the terms of the GNU General Public License as published by the

#   Free Software Foundation, either version 3 of the License, or (at your

#   option) any later version.

#

#   This program is distributed in the hope that it will be useful, but

#   WITHOUT ANY WARRANTY; without even the implied warranty of

#   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General

#   Public License for more details.

#

#   You should have received a copy of the GNU General Public License along

#   with this program. If not, see <http://www.gnu.org/licenses/>.

#

#   As a special exception, the respective Autoconf Macro's copyright owner

#   gives unlimited permission to copy, distribute and modify the configure

#   scripts that are the output of Autoconf when processing the Macro. You

#   need not follow the terms of the GNU General Public License when using

#   or distributing such scripts, even though portions of the text of the

#   Macro appear in them. The GNU General Public License (GPL) does govern

#   all other use of the material that constitutes the Autoconf Macro.

#

#   This special exception to the GPL applies to versions of the Autoconf

#   Macro released by the Autoconf Macro Archive. When you make and

#   distribute a modified version of the Autoconf Macro, you may extend this

#   special exception to the GPL to apply to your modified version as well.

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"

# 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)

#      ... -mt is also the pthreads flag for HP/aCC

# 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 -pthreads/-mt/

        # -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="-pthreads pthread -mt -pthread $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"

                ;;

		pthread-config)

		AC_CHECK_PROG(acx_pthread_config, pthread-config, yes, no)

		if test x"$acx_pthread_config" = xno; then continue; fi

		PTHREAD_CFLAGS="`pthread-config --cflags`"

		PTHREAD_LIBS="`pthread-config --ldflags` `pthread-config --libs`"

		;;

                *)

                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: JOINABLE attribute is called UNDETACHED.

	AC_MSG_CHECKING([for joinable pthread attribute])

	attr_name=unknown

	for attr in PTHREAD_CREATE_JOINABLE PTHREAD_CREATE_UNDETACHED; do

	    AC_TRY_LINK([#include <pthread.h>], [int attr=$attr; return attr;],

                        [attr_name=$attr; break])

	done

        AC_MSG_RESULT($attr_name)

        if test "$attr_name" != PTHREAD_CREATE_JOINABLE; then

            AC_DEFINE_UNQUOTED(PTHREAD_CREATE_JOINABLE, $attr_name,

                               [Define to necessary symbol if this constant

                                uses a non-standard name on your system.])

        fi

        AC_MSG_CHECKING([if more special flags are required for pthreads])

        flag=no

        case "${host_cpu}-${host_os}" in

            *-aix* | *-freebsd* | *-darwin*) 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 xlc_r or cc_r

	if test x"$GCC" != xyes; then

          AC_CHECK_PROGS(PTHREAD_CC, xlc_r cc_r, ${CC})

        else

          PTHREAD_CC=$CC

	fi

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