1dnl @synopsis ACX_PTHREAD([ACTION-IF-FOUND[, ACTION-IF-NOT-FOUND]])
2dnl
3dnl @summary figure out how to build C programs using POSIX threads
4dnl
5dnl This macro figures out how to build C programs using POSIX threads.
6dnl It sets the PTHREAD_LIBS output variable to the threads library and
7dnl linker flags, and the PTHREAD_CFLAGS output variable to any special
8dnl C compiler flags that are needed. (The user can also force certain
9dnl compiler flags/libs to be tested by setting these environment
10dnl variables.)
11dnl
12dnl Also sets PTHREAD_CC to any special C compiler that is needed for
13dnl multi-threaded programs (defaults to the value of CC otherwise).
14dnl (This is necessary on AIX to use the special cc_r compiler alias.)
15dnl
16dnl NOTE: You are assumed to not only compile your program with these
17dnl flags, but also link it with them as well. e.g. you should link
18dnl with $PTHREAD_CC $CFLAGS $PTHREAD_CFLAGS $LDFLAGS ... $PTHREAD_LIBS
19dnl $LIBS
20dnl
21dnl If you are only building threads programs, you may wish to use
22dnl these variables in your default LIBS, CFLAGS, and CC:
23dnl
24dnl        LIBS="$PTHREAD_LIBS $LIBS"
25dnl        CFLAGS="$CFLAGS $PTHREAD_CFLAGS"
26dnl        CC="$PTHREAD_CC"
27dnl
28dnl In addition, if the PTHREAD_CREATE_JOINABLE thread-attribute
29dnl constant has a nonstandard name, defines PTHREAD_CREATE_JOINABLE to
30dnl that name (e.g. PTHREAD_CREATE_UNDETACHED on AIX).
31dnl
32dnl ACTION-IF-FOUND is a list of shell commands to run if a threads
33dnl library is found, and ACTION-IF-NOT-FOUND is a list of commands to
34dnl run it if it is not found. If ACTION-IF-FOUND is not specified, the
35dnl default action will define HAVE_PTHREAD.
36dnl
37dnl Please let the authors know if this macro fails on any platform, or
38dnl if you have any other suggestions or comments. This macro was based
39dnl on work by SGJ on autoconf scripts for FFTW (www.fftw.org) (with
40dnl help from M. Frigo), as well as ac_pthread and hb_pthread macros
41dnl posted by Alejandro Forero Cuervo to the autoconf macro repository.
42dnl We are also grateful for the helpful feedback of numerous users.
43dnl
44dnl @category InstalledPackages
45dnl @author Steven G. Johnson <stevenj@alum.mit.edu>
46dnl @version 2006-05-29
47dnl @license GPLWithACException
48
49AC_DEFUN([ACX_PTHREAD], [
50AC_REQUIRE([AC_CANONICAL_HOST])
51AC_LANG_SAVE
52AC_LANG_C
53acx_pthread_ok=no
54
55# We used to check for pthread.h first, but this fails if pthread.h
56# requires special compiler flags (e.g. on True64 or Sequent).
57# It gets checked for in the link test anyway.
58
59# First of all, check if the user has set any of the PTHREAD_LIBS,
60# etcetera environment variables, and if threads linking works using
61# them:
62if test x"$PTHREAD_LIBS$PTHREAD_CFLAGS" != x; then
63        save_CFLAGS="$CFLAGS"
64        CFLAGS="$CFLAGS $PTHREAD_CFLAGS"
65        save_LIBS="$LIBS"
66        LIBS="$PTHREAD_LIBS $LIBS"
67        AC_MSG_CHECKING([for pthread_join in LIBS=$PTHREAD_LIBS with CFLAGS=$PTHREAD_CFLAGS])
68        AC_TRY_LINK_FUNC(pthread_join, acx_pthread_ok=yes)
69        AC_MSG_RESULT($acx_pthread_ok)
70        if test x"$acx_pthread_ok" = xno; then
71                PTHREAD_LIBS=""
72                PTHREAD_CFLAGS=""
73        fi
74        LIBS="$save_LIBS"
75        CFLAGS="$save_CFLAGS"
76fi
77
78# We must check for the threads library under a number of different
79# names; the ordering is very important because some systems
80# (e.g. DEC) have both -lpthread and -lpthreads, where one of the
81# libraries is broken (non-POSIX).
82
83# Create a list of thread flags to try.  Items starting with a "-" are
84# C compiler flags, and other items are library names, except for "none"
85# which indicates that we try without any flags at all, and "pthread-config"
86# which is a program returning the flags for the Pth emulation library.
87
88acx_pthread_flags="pthreads none -Kthread -kthread lthread -pthread -pthreads -mthreads pthread --thread-safe -mt pthread-config"
89
90# The ordering *is* (sometimes) important.  Some notes on the
91# individual items follow:
92
93# pthreads: AIX (must check this before -lpthread)
94# none: in case threads are in libc; should be tried before -Kthread and
95#       other compiler flags to prevent continual compiler warnings
96# -Kthread: Sequent (threads in libc, but -Kthread needed for pthread.h)
97# -kthread: FreeBSD kernel threads (preferred to -pthread since SMP-able)
98# lthread: LinuxThreads port on FreeBSD (also preferred to -pthread)
99# -pthread: Linux/gcc (kernel threads), BSD/gcc (userland threads)
100# -pthreads: Solaris/gcc
101# -mthreads: Mingw32/gcc, Lynx/gcc
102# -mt: Sun Workshop C (may only link SunOS threads [-lthread], but it
103#      doesn't hurt to check since this sometimes defines pthreads too;
104#      also defines -D_REENTRANT)
105#      ... -mt is also the pthreads flag for HP/aCC
106# pthread: Linux, etcetera
107# --thread-safe: KAI C++
108# pthread-config: use pthread-config program (for GNU Pth library)
109
110case "${host_cpu}-${host_os}" in
111        *solaris*)
112
113        # On Solaris (at least, for some versions), libc contains stubbed
114        # (non-functional) versions of the pthreads routines, so link-based
115        # tests will erroneously succeed.  (We need to link with -pthreads/-mt/
116        # -lpthread.)  (The stubs are missing pthread_cleanup_push, or rather
117        # a function called by this macro, so we could check for that, but
118        # who knows whether they'll stub that too in a future libc.)  So,
119        # we'll just look for -pthreads and -lpthread first:
120
121        acx_pthread_flags="-pthreads pthread -mt -pthread $acx_pthread_flags"
122        ;;
123esac
124
125if test x"$acx_pthread_ok" = xno; then
126for flag in $acx_pthread_flags; do
127
128        case $flag in
129                none)
130                AC_MSG_CHECKING([whether pthreads work without any flags])
131                ;;
132
133                -*)
134                AC_MSG_CHECKING([whether pthreads work with $flag])
135                PTHREAD_CFLAGS="$flag"
136                ;;
137
138		pthread-config)
139		AC_CHECK_PROG(acx_pthread_config, pthread-config, yes, no)
140		if test x"$acx_pthread_config" = xno; then continue; fi
141		PTHREAD_CFLAGS="`pthread-config --cflags`"
142		PTHREAD_LIBS="`pthread-config --ldflags` `pthread-config --libs`"
143		;;
144
145                *)
146                AC_MSG_CHECKING([for the pthreads library -l$flag])
147                PTHREAD_LIBS="-l$flag"
148                ;;
149        esac
150
151        save_LIBS="$LIBS"
152        save_CFLAGS="$CFLAGS"
153        LIBS="$PTHREAD_LIBS $LIBS"
154        CFLAGS="$CFLAGS $PTHREAD_CFLAGS"
155
156        # Check for various functions.  We must include pthread.h,
157        # since some functions may be macros.  (On the Sequent, we
158        # need a special flag -Kthread to make this header compile.)
159        # We check for pthread_join because it is in -lpthread on IRIX
160        # while pthread_create is in libc.  We check for pthread_attr_init
161        # due to DEC craziness with -lpthreads.  We check for
162        # pthread_cleanup_push because it is one of the few pthread
163        # functions on Solaris that doesn't have a non-functional libc stub.
164        # We try pthread_create on general principles.
165        AC_TRY_LINK([#include <pthread.h>],
166                    [pthread_t th; pthread_join(th, 0);
167                     pthread_attr_init(0); pthread_cleanup_push(0, 0);
168                     pthread_create(0,0,0,0); pthread_cleanup_pop(0); ],
169                    [acx_pthread_ok=yes])
170
171        LIBS="$save_LIBS"
172        CFLAGS="$save_CFLAGS"
173
174        AC_MSG_RESULT($acx_pthread_ok)
175        if test "x$acx_pthread_ok" = xyes; then
176                break;
177        fi
178
179        PTHREAD_LIBS=""
180        PTHREAD_CFLAGS=""
181done
182fi
183
184# Various other checks:
185if test "x$acx_pthread_ok" = xyes; then
186        save_LIBS="$LIBS"
187        LIBS="$PTHREAD_LIBS $LIBS"
188        save_CFLAGS="$CFLAGS"
189        CFLAGS="$CFLAGS $PTHREAD_CFLAGS"
190
191        # Detect AIX lossage: JOINABLE attribute is called UNDETACHED.
192	AC_MSG_CHECKING([for joinable pthread attribute])
193	attr_name=unknown
194	for attr in PTHREAD_CREATE_JOINABLE PTHREAD_CREATE_UNDETACHED; do
195	    AC_TRY_LINK([#include <pthread.h>], [int attr=$attr; return attr;],
196                        [attr_name=$attr; break])
197	done
198        AC_MSG_RESULT($attr_name)
199        if test "$attr_name" != PTHREAD_CREATE_JOINABLE; then
200            AC_DEFINE_UNQUOTED(PTHREAD_CREATE_JOINABLE, $attr_name,
201                               [Define to necessary symbol if this constant
202                                uses a non-standard name on your system.])
203        fi
204
205        AC_MSG_CHECKING([if more special flags are required for pthreads])
206        flag=no
207        case "${host_cpu}-${host_os}" in
208            *-aix* | *-freebsd* | *-darwin*) flag="-D_THREAD_SAFE";;
209            *solaris* | *-osf* | *-hpux*) flag="-D_REENTRANT";;
210        esac
211        AC_MSG_RESULT(${flag})
212        if test "x$flag" != xno; then
213            PTHREAD_CFLAGS="$flag $PTHREAD_CFLAGS"
214        fi
215
216        LIBS="$save_LIBS"
217        CFLAGS="$save_CFLAGS"
218
219        # More AIX lossage: must compile with xlc_r or cc_r
220	if test x"$GCC" != xyes; then
221          AC_CHECK_PROGS(PTHREAD_CC, xlc_r cc_r, ${CC})
222        else
223          PTHREAD_CC=$CC
224	fi
225else
226        PTHREAD_CC="$CC"
227fi
228
229AC_SUBST(PTHREAD_LIBS)
230AC_SUBST(PTHREAD_CFLAGS)
231AC_SUBST(PTHREAD_CC)
232
233# Finally, execute ACTION-IF-FOUND/ACTION-IF-NOT-FOUND:
234if test x"$acx_pthread_ok" = xyes; then
235        ifelse([$1],,AC_DEFINE(HAVE_PTHREAD,1,[Define if you have POSIX threads libraries and header files.]),[$1])
236        :
237else
238        acx_pthread_ok=no
239        $2
240fi
241AC_LANG_RESTORE
242])dnl ACX_PTHREAD
243