1dnl @synopsis ACX_PTHREAD([ACTION-IF-FOUND[, ACTION-IF-NOT-FOUND]])
2dnl
3dnl This macro figures out how to build C programs using POSIX threads.
4dnl It sets the PTHREAD_LIBS output variable to the threads library and
5dnl linker flags, and the PTHREAD_CFLAGS output variable to any special
6dnl C compiler flags that are needed. (The user can also force certain
7dnl compiler flags/libs to be tested by setting these environment
8dnl variables.)
9dnl
10dnl Also sets PTHREAD_CC to any special C compiler that is needed for
11dnl multi-threaded programs (defaults to the value of CC otherwise).
12dnl (This is necessary on AIX to use the special cc_r compiler alias.)
13dnl
14dnl NOTE: You are assumed to not only compile your program with these
15dnl flags, but also link it with them as well. e.g. you should link
16dnl with $PTHREAD_CC $CFLAGS $PTHREAD_CFLAGS $LDFLAGS ... $PTHREAD_LIBS
17dnl $LIBS
18dnl
19dnl If you are only building threads programs, you may wish to use
20dnl these variables in your default LIBS, CFLAGS, and CC:
21dnl
22dnl        LIBS="$PTHREAD_LIBS $LIBS"
23dnl        CFLAGS="$CFLAGS $PTHREAD_CFLAGS"
24dnl        CC="$PTHREAD_CC"
25dnl
26dnl In addition, if the PTHREAD_CREATE_JOINABLE thread-attribute
27dnl constant has a nonstandard name, defines PTHREAD_CREATE_JOINABLE to
28dnl that name (e.g. PTHREAD_CREATE_UNDETACHED on AIX).
29dnl
30dnl ACTION-IF-FOUND is a list of shell commands to run if a threads
31dnl library is found, and ACTION-IF-NOT-FOUND is a list of commands to
32dnl run it if it is not found. If ACTION-IF-FOUND is not specified, the
33dnl default action will define HAVE_PTHREAD.
34dnl
35dnl Please let the authors know if this macro fails on any platform, or
36dnl if you have any other suggestions or comments. This macro was based
37dnl on work by SGJ on autoconf scripts for FFTW (www.fftw.org) (with
38dnl help from M. Frigo), as well as ac_pthread and hb_pthread macros
39dnl posted by Alejandro Forero Cuervo to the autoconf macro repository.
40dnl We are also grateful for the helpful feedback of numerous users.
41dnl
42dnl @category InstalledPackages
43dnl @author Steven G. Johnson <stevenj@alum.mit.edu>
44dnl @version 2005-01-14
45dnl @license GPLWithACException
46
47AC_DEFUN([ACX_PTHREAD], [
48AC_REQUIRE([AC_CANONICAL_HOST])
49AC_LANG_SAVE
50AC_LANG_C
51acx_pthread_ok=no
52
53# We used to check for pthread.h first, but this fails if pthread.h
54# requires special compiler flags (e.g. on True64 or Sequent).
55# It gets checked for in the link test anyway.
56
57# First of all, check if the user has set any of the PTHREAD_LIBS,
58# etcetera environment variables, and if threads linking works using
59# them:
60if test x"$PTHREAD_LIBS$PTHREAD_CFLAGS" != x; then
61        save_CFLAGS="$CFLAGS"
62        CFLAGS="$CFLAGS $PTHREAD_CFLAGS"
63        save_LIBS="$LIBS"
64        LIBS="$PTHREAD_LIBS $LIBS"
65        AC_MSG_CHECKING([for pthread_join in LIBS=$PTHREAD_LIBS with CFLAGS=$PTHREAD_CFLAGS])
66        AC_TRY_LINK_FUNC(pthread_join, acx_pthread_ok=yes)
67        AC_MSG_RESULT($acx_pthread_ok)
68        if test x"$acx_pthread_ok" = xno; then
69                PTHREAD_LIBS=""
70                PTHREAD_CFLAGS=""
71        fi
72        LIBS="$save_LIBS"
73        CFLAGS="$save_CFLAGS"
74fi
75
76# We must check for the threads library under a number of different
77# names; the ordering is very important because some systems
78# (e.g. DEC) have both -lpthread and -lpthreads, where one of the
79# libraries is broken (non-POSIX).
80
81# Create a list of thread flags to try.  Items starting with a "-" are
82# C compiler flags, and other items are library names, except for "none"
83# which indicates that we try without any flags at all, and "pthread-config"
84# which is a program returning the flags for the Pth emulation library.
85
86acx_pthread_flags="pthreads none -Kthread -kthread lthread -pthread -pthreads -mthreads pthread --thread-safe -mt pthread-config"
87
88# The ordering *is* (sometimes) important.  Some notes on the
89# individual items follow:
90
91# pthreads: AIX (must check this before -lpthread)
92# none: in case threads are in libc; should be tried before -Kthread and
93#       other compiler flags to prevent continual compiler warnings
94# -Kthread: Sequent (threads in libc, but -Kthread needed for pthread.h)
95# -kthread: FreeBSD kernel threads (preferred to -pthread since SMP-able)
96# lthread: LinuxThreads port on FreeBSD (also preferred to -pthread)
97# -pthread: Linux/gcc (kernel threads), BSD/gcc (userland threads)
98# -pthreads: Solaris/gcc
99# -mthreads: Mingw32/gcc, Lynx/gcc
100# -mt: Sun Workshop C (may only link SunOS threads [-lthread], but it
101#      doesn't hurt to check since this sometimes defines pthreads too;
102#      also defines -D_REENTRANT)
103# pthread: Linux, etcetera
104# --thread-safe: KAI C++
105# pthread-config: use pthread-config program (for GNU Pth library)
106
107case "${host_cpu}-${host_os}" in
108        *solaris*)
109
110        # On Solaris (at least, for some versions), libc contains stubbed
111        # (non-functional) versions of the pthreads routines, so link-based
112        # tests will erroneously succeed.  (We need to link with -pthread or
113        # -lpthread.)  (The stubs are missing pthread_cleanup_push, or rather
114        # a function called by this macro, so we could check for that, but
115        # who knows whether they'll stub that too in a future libc.)  So,
116        # we'll just look for -pthreads and -lpthread first:
117
118        acx_pthread_flags="-pthread -pthreads pthread -mt $acx_pthread_flags"
119        ;;
120esac
121
122if test x"$acx_pthread_ok" = xno; then
123for flag in $acx_pthread_flags; do
124
125        case $flag in
126                none)
127                AC_MSG_CHECKING([whether pthreads work without any flags])
128                ;;
129
130                -*)
131                AC_MSG_CHECKING([whether pthreads work with $flag])
132                PTHREAD_CFLAGS="$flag"
133                ;;
134
135		pthread-config)
136		AC_CHECK_PROG(acx_pthread_config, pthread-config, yes, no)
137		if test x"$acx_pthread_config" = xno; then continue; fi
138		PTHREAD_CFLAGS="`pthread-config --cflags`"
139		PTHREAD_LIBS="`pthread-config --ldflags` `pthread-config --libs`"
140		;;
141
142                *)
143                AC_MSG_CHECKING([for the pthreads library -l$flag])
144                PTHREAD_LIBS="-l$flag"
145                ;;
146        esac
147
148        save_LIBS="$LIBS"
149        save_CFLAGS="$CFLAGS"
150        LIBS="$PTHREAD_LIBS $LIBS"
151        CFLAGS="$CFLAGS $PTHREAD_CFLAGS"
152
153        # Check for various functions.  We must include pthread.h,
154        # since some functions may be macros.  (On the Sequent, we
155        # need a special flag -Kthread to make this header compile.)
156        # We check for pthread_join because it is in -lpthread on IRIX
157        # while pthread_create is in libc.  We check for pthread_attr_init
158        # due to DEC craziness with -lpthreads.  We check for
159        # pthread_cleanup_push because it is one of the few pthread
160        # functions on Solaris that doesn't have a non-functional libc stub.
161        # We try pthread_create on general principles.
162        AC_TRY_LINK([#include <pthread.h>],
163                    [pthread_t th; pthread_join(th, 0);
164                     pthread_attr_init(0); pthread_cleanup_push(0, 0);
165                     pthread_create(0,0,0,0); pthread_cleanup_pop(0); ],
166                    [acx_pthread_ok=yes])
167
168        LIBS="$save_LIBS"
169        CFLAGS="$save_CFLAGS"
170
171        AC_MSG_RESULT($acx_pthread_ok)
172        if test "x$acx_pthread_ok" = xyes; then
173                break;
174        fi
175
176        PTHREAD_LIBS=""
177        PTHREAD_CFLAGS=""
178done
179fi
180
181# Various other checks:
182if test "x$acx_pthread_ok" = xyes; then
183        save_LIBS="$LIBS"
184        LIBS="$PTHREAD_LIBS $LIBS"
185        save_CFLAGS="$CFLAGS"
186        CFLAGS="$CFLAGS $PTHREAD_CFLAGS"
187
188        # Detect AIX lossage: JOINABLE attribute is called UNDETACHED.
189	AC_MSG_CHECKING([for joinable pthread attribute])
190	attr_name=unknown
191	for attr in PTHREAD_CREATE_JOINABLE PTHREAD_CREATE_UNDETACHED; do
192	    AC_TRY_LINK([#include <pthread.h>], [int attr=$attr;],
193                        [attr_name=$attr; break])
194	done
195        AC_MSG_RESULT($attr_name)
196        if test "$attr_name" != PTHREAD_CREATE_JOINABLE; then
197            AC_DEFINE_UNQUOTED(PTHREAD_CREATE_JOINABLE, $attr_name,
198                               [Define to necessary symbol if this constant
199                                uses a non-standard name on your system.])
200        fi
201
202        AC_MSG_CHECKING([if more special flags are required for pthreads])
203        flag=no
204        case "${host_cpu}-${host_os}" in
205            *-aix* | *-freebsd* | *-darwin*) flag="-D_THREAD_SAFE";;
206            *solaris* | *-osf* | *-hpux*) flag="-D_REENTRANT";;
207        esac
208        AC_MSG_RESULT(${flag})
209        if test "x$flag" != xno; then
210            PTHREAD_CFLAGS="$flag $PTHREAD_CFLAGS"
211        fi
212
213        LIBS="$save_LIBS"
214        CFLAGS="$save_CFLAGS"
215
216        # More AIX lossage: must compile with cc_r
217        AC_CHECK_PROG(PTHREAD_CC, cc_r, cc_r, ${CC})
218else
219        PTHREAD_CC="$CC"
220fi
221
222AC_SUBST(PTHREAD_LIBS)
223AC_SUBST(PTHREAD_CFLAGS)
224AC_SUBST(PTHREAD_CC)
225
226# Finally, execute ACTION-IF-FOUND/ACTION-IF-NOT-FOUND:
227if test x"$acx_pthread_ok" = xyes; then
228        ifelse([$1],,AC_DEFINE(HAVE_PTHREAD,1,[Define if you have POSIX threads libraries and header files.]),[$1])
229        :
230else
231        acx_pthread_ok=no
232        $2
233fi
234AC_LANG_RESTORE
235])dnl ACX_PTHREAD
236