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

#        http://www.gnu.org/software/autoconf-archive/ax_pthread.html

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

#

# SYNOPSIS

#

#   AX_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).

#

#   Also HAVE_PTHREAD_PRIO_INHERIT is defined if pthread is found and the

#   PTHREAD_PRIO_INHERIT symbol is defined when compiling with

#   PTHREAD_CFLAGS.

#

#   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.

#

#   Updated for Autoconf 2.68 by Daniel Richard G.

#

# LICENSE

#

#   Copyright (c) 2008 Steven G. Johnson <stevenj@alum.mit.edu>

#   Copyright (c) 2011 Daniel Richard G. <skunk@iSKUNK.ORG>

#

#   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 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.

#serial 21

AU_ALIAS([ACX_PTHREAD], [AX_PTHREAD])

AC_DEFUN([AX_PTHREAD], [

AC_REQUIRE([AC_CANONICAL_HOST])

AC_LANG_PUSH([C])

ax_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], [ax_pthread_ok=yes])

        AC_MSG_RESULT([$ax_pthread_ok])

        if test x"$ax_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.

ax_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_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:

        ax_pthread_flags="-pthreads pthread -mt -pthread $ax_pthread_flags"

        ;;

        darwin*)

        ax_pthread_flags="-pthread $ax_pthread_flags"

        ;;

	netbsd*)

	# use libc stubs, don't link against libpthread, to allow

	# dynamic loading

	ax_pthread_flags=""

	;;

esac

# Clang doesn't consider unrecognized options an error unless we specify

# -Werror. We throw in some extra Clang-specific options to ensure that

# this doesn't happen for GCC, which also accepts -Werror.

AC_MSG_CHECKING([if compiler needs -Werror to reject unknown flags])

save_CFLAGS="$CFLAGS"

ax_pthread_extra_flags="-Werror"

CFLAGS="$CFLAGS $ax_pthread_extra_flags -Wunknown-warning-option -Wsizeof-array-argument"

AC_COMPILE_IFELSE([AC_LANG_PROGRAM([int foo(void);],[foo()])],

                  [AC_MSG_RESULT([yes])],

                  [ax_pthread_extra_flags=

                   AC_MSG_RESULT([no])])

CFLAGS="$save_CFLAGS"

if test x"$ax_pthread_ok" = xno; then

for flag in $ax_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([ax_pthread_config], [pthread-config], [yes], [no])

                if test x"$ax_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 $ax_pthread_extra_flags"

        # 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_LINK_IFELSE([AC_LANG_PROGRAM([#include <pthread.h>

                        static void routine(void *a) { a = 0; }

                        static void *start_routine(void *a) { return a; }],

                       [pthread_t th; pthread_attr_t attr;

                        pthread_create(&th, 0, start_routine, 0);

                        pthread_join(th, 0);

                        pthread_attr_init(&attr);

                        pthread_cleanup_push(routine, 0);

                        pthread_cleanup_pop(0) /* ; */])],

                [ax_pthread_ok=yes],

                [])

        LIBS="$save_LIBS"

        CFLAGS="$save_CFLAGS"

        AC_MSG_RESULT([$ax_pthread_ok])

        if test "x$ax_pthread_ok" = xyes; then

                break;

        fi

        PTHREAD_LIBS=""

        PTHREAD_CFLAGS=""

done

fi

# Various other checks:

if test "x$ax_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_LINK_IFELSE([AC_LANG_PROGRAM([#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_os} in

            aix* | freebsd* | darwin*) flag="-D_THREAD_SAFE";;

            osf* | hpux*) flag="-D_REENTRANT";;

            solaris*)

            if test "$GCC" = "yes"; then

                flag="-D_REENTRANT"

            else

                # TODO: What about Clang on Solaris?

                flag="-mt -D_REENTRANT"

            fi

            ;;

        esac

        AC_MSG_RESULT([$flag])

        if test "x$flag" != xno; then

            PTHREAD_CFLAGS="$flag $PTHREAD_CFLAGS"

        fi

        AC_CACHE_CHECK([for PTHREAD_PRIO_INHERIT],

            [ax_cv_PTHREAD_PRIO_INHERIT], [

                AC_LINK_IFELSE([AC_LANG_PROGRAM([[#include <pthread.h>]],

                                                [[int i = PTHREAD_PRIO_INHERIT;]])],

                    [ax_cv_PTHREAD_PRIO_INHERIT=yes],

                    [ax_cv_PTHREAD_PRIO_INHERIT=no])

            ])

        AS_IF([test "x$ax_cv_PTHREAD_PRIO_INHERIT" = "xyes"],

            [AC_DEFINE([HAVE_PTHREAD_PRIO_INHERIT], [1], [Have PTHREAD_PRIO_INHERIT.])])

        LIBS="$save_LIBS"

        CFLAGS="$save_CFLAGS"

        # More AIX lossage: compile with *_r variant

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

            case $host_os in

                aix*)

                AS_CASE(["x/$CC"],

                  [x*/c89|x*/c89_128|x*/c99|x*/c99_128|x*/cc|x*/cc128|x*/xlc|x*/xlc_v6|x*/xlc128|x*/xlc128_v6],

                  [#handle absolute path differently from PATH based program lookup

                   AS_CASE(["x$CC"],

                     [x/*],

                     [AS_IF([AS_EXECUTABLE_P([${CC}_r])],[PTHREAD_CC="${CC}_r"])],

                     [AC_CHECK_PROGS([PTHREAD_CC],[${CC}_r],[$CC])])])

                ;;

            esac

        fi

fi

test -n "$PTHREAD_CC" || PTHREAD_CC="$CC"

AC_SUBST([PTHREAD_LIBS])

AC_SUBST([PTHREAD_CFLAGS])

AC_SUBST([PTHREAD_CC])

# Finally, execute ACTION-IF-FOUND/ACTION-IF-NOT-FOUND:

if test x"$ax_pthread_ok" = xyes; then

        ifelse([$1],,[AC_DEFINE([HAVE_PTHREAD],[1],[Define if you have POSIX threads libraries and header files.])],[$1])

        :

else

        ax_pthread_ok=no

        $2

fi

AC_LANG_POP

])dnl AX_PTHREAD