Commit 853609a2 authored by Bruno Haible's avatar Bruno Haible
Browse files

threadlib: Improve code structure.

* m4/threadlib.m4: Reorder macros. Add comments.
parent 7ccef84b
2019-12-21 Bruno Haible <bruno@clisp.org>
threadlib: Improve code structure.
* m4/threadlib.m4: Reorder macros. Add comments.
2019-12-21 Bruno Haible <bruno@clisp.org>
 
threadlib: Fix LIBMULTITHREAD on FreeBSD with --enable-threads=isoc.
# threadlib.m4 serial 25
# threadlib.m4 serial 26
dnl Copyright (C) 2005-2019 Free Software Foundation, Inc.
dnl This file is free software; the Free Software Foundation
dnl gives unlimited permission to copy and/or distribute it,
......@@ -8,57 +8,48 @@ dnl From Bruno Haible.
AC_PREREQ([2.60])
dnl gl_PTHREADLIB
dnl -------------
dnl Tests for the libraries needs for using the POSIX threads API.
dnl Sets the variable LIBPTHREAD to the linker options for use in a Makefile.
dnl Sets the variable LIBPMULTITHREAD, for programs that really need
dnl multithread functionality. The difference between LIBPTHREAD and
dnl LIBPMULTITHREAD is that on platforms supporting weak symbols, typically
dnl LIBPTHREAD is empty whereas LIBPMULTITHREAD is not.
dnl Sets the variable LIB_SCHED_YIELD to the linker options needed to use the
dnl sched_yield() function.
dnl Adds to CPPFLAGS the flag -D_REENTRANT or -D_THREAD_SAFE if needed for
dnl multithread-safe programs.
dnl Defines the C macro HAVE_PTHREAD_API if (at least parts of) the POSIX
dnl threads API is available.
dnl gl_STDTHREADLIB
dnl ---------------
dnl Tests for the libraries needs for using the ISO C threads API.
dnl Sets the variable LIBSTDTHREAD to the linker options for use in a Makefile.
dnl Adds to CPPFLAGS the flag -D_REENTRANT or -D_THREAD_SAFE if needed for
dnl multithread-safe programs.
dnl Defines the C macro HAVE_THREADS_H if (at least parts of) the ISO C threads
dnl API is available.
dnl The general structure of the multithreading modules in gnulib is that we
dnl have three set of modules:
dnl
dnl * POSIX API:
dnl pthread, which combines
dnl pthread-h
dnl pthread-thread
dnl pthread-once
dnl pthread-mutex
dnl pthread-rwlock
dnl pthread-cond
dnl pthread-tss
dnl pthread-spin
dnl sched_yield
dnl
dnl * ISO C API:
dnl threads, which combines
dnl threads-h
dnl thrd
dnl mtx
dnl cnd
dnl tss
dnl
dnl * Gnulib API, with an implementation that can be chosen at configure
dnl time through the option --enable-threads=...
dnl thread
dnl lock
dnl cond
dnl tls
dnl yield
dnl
dnl They are independent, except for the fact that
dnl - the implementation of the ISO C API may use the POSIX (or some other
dnl platform dependent) API,
dnl - the implementation of the Gnulib API may use the POSIX or ISO C or
dnl some other platform dependent API, depending on the --enable-threads
dnl option.
dnl
dnl This file contains macros for all of these APIs!
dnl gl_THREADLIB
dnl ------------
dnl Tests for a multithreading library to be used.
dnl If the configure.ac contains a definition of the gl_THREADLIB_DEFAULT_NO
dnl (it must be placed before the invocation of gl_THREADLIB_EARLY!), then the
dnl default is 'no', otherwise it is system dependent. In both cases, the user
dnl can change the choice through the options --enable-threads=choice or
dnl --disable-threads.
dnl Defines at most one of the macros USE_ISOC_THREADS, USE_POSIX_THREADS,
dnl USE_ISOC_AND_POSIX_THREADS, USE_WINDOWS_THREADS.
dnl The choice --enable-threads=isoc+posix is available only on platforms that
dnl have both the ISO C and the POSIX threads APIs. It has the effect of using
dnl the ISO C API for most things and the POSIX API only for creating and
dnl controlling threads (because there is no equivalent to pthread_atfork in
dnl the ISO C API).
dnl Sets the variables LIBTHREAD and LTLIBTHREAD to the linker options for use
dnl in a Makefile (LIBTHREAD for use without libtool, LTLIBTHREAD for use with
dnl libtool).
dnl Sets the variables LIBMULTITHREAD and LTLIBMULTITHREAD similarly, for
dnl programs that really need multithread functionality. The difference
dnl between LIBTHREAD and LIBMULTITHREAD is that on platforms supporting weak
dnl symbols, typically LIBTHREAD is empty whereas LIBMULTITHREAD is not.
dnl Adds to CPPFLAGS the flag -D_REENTRANT or -D_THREAD_SAFE if needed for
dnl multithread-safe programs.
dnl Since support for GNU pth was removed, $LTLIBTHREAD and $LIBTHREAD have the
dnl same value, and similarly $LTLIBMULTITHREAD and $LIBMULTITHREAD have the
dnl same value. Only system libraries are needed.
dnl ============================================================================
dnl Macros for all thread APIs
AC_DEFUN([gl_ANYTHREADLIB_EARLY],
[
......@@ -86,73 +77,6 @@ AC_DEFUN([gl_ANYTHREADLIB_EARLY],
fi
])
AC_DEFUN([gl_THREADLIB_EARLY],
[
AC_REQUIRE([gl_THREADLIB_EARLY_BODY])
])
dnl The guts of gl_THREADLIB_EARLY. Needs to be expanded only once.
AC_DEFUN([gl_THREADLIB_EARLY_BODY],
[
dnl Ordering constraints: This macro modifies CPPFLAGS in a way that
dnl influences the result of the autoconf tests that test for *_unlocked
dnl declarations, on AIX 5 at least. Therefore it must come early.
AC_BEFORE([$0], [gl_FUNC_GLIBC_UNLOCKED_IO])dnl
AC_BEFORE([$0], [gl_ARGP])dnl
AC_REQUIRE([AC_CANONICAL_HOST])
dnl _GNU_SOURCE is needed for pthread_rwlock_t on glibc systems.
AC_REQUIRE([AC_USE_SYSTEM_EXTENSIONS])
dnl Check for multithreading.
m4_ifdef([gl_THREADLIB_DEFAULT_NO],
[m4_divert_text([DEFAULTS], [gl_use_threads_default=no])],
[m4_divert_text([DEFAULTS], [gl_use_threads_default=])])
m4_divert_text([DEFAULTS], [gl_use_winpthreads_default=])
AC_ARG_ENABLE([threads],
AC_HELP_STRING([--enable-threads={isoc|posix|isoc+posix|windows}], [specify multithreading API])m4_ifdef([gl_THREADLIB_DEFAULT_NO], [], [
AC_HELP_STRING([--disable-threads], [build without multithread safety])]),
[gl_use_threads=$enableval],
[if test -n "$gl_use_threads_default"; then
gl_use_threads="$gl_use_threads_default"
else
changequote(,)dnl
case "$host_os" in
dnl Disable multithreading by default on OSF/1, because it interferes
dnl with fork()/exec(): When msgexec is linked with -lpthread, its
dnl child process gets an endless segmentation fault inside execvp().
osf*) gl_use_threads=no ;;
dnl Disable multithreading by default on Cygwin 1.5.x, because it has
dnl bugs that lead to endless loops or crashes. See
dnl <https://cygwin.com/ml/cygwin/2009-08/msg00283.html>.
cygwin*)
case `uname -r` in
1.[0-5].*) gl_use_threads=no ;;
*) gl_use_threads=yes ;;
esac
;;
dnl Obey gl_AVOID_WINPTHREAD on mingw.
mingw*)
case "$gl_use_winpthreads_default" in
yes) gl_use_threads=posix ;;
no) gl_use_threads=windows ;;
*) gl_use_threads=yes ;;
esac
;;
*) gl_use_threads=yes ;;
esac
changequote([,])dnl
fi
])
if test "$gl_use_threads" = yes \
|| test "$gl_use_threads" = isoc \
|| test "$gl_use_threads" = posix \
|| test "$gl_use_threads" = isoc+posix; then
# For using <threads.h> or <pthread.h>:
gl_ANYTHREADLIB_EARLY
fi
])
dnl Checks whether the compiler and linker support weak declarations of symbols.
AC_DEFUN([gl_WEAK_SYMBOLS],
......@@ -204,6 +128,24 @@ int main ()
esac
])
dnl ============================================================================
dnl Macros for the POSIX API
dnl gl_PTHREADLIB
dnl -------------
dnl Tests for the libraries needs for using the POSIX threads API.
dnl Sets the variable LIBPTHREAD to the linker options for use in a Makefile.
dnl Sets the variable LIBPMULTITHREAD, for programs that really need
dnl multithread functionality. The difference between LIBPTHREAD and
dnl LIBPMULTITHREAD is that on platforms supporting weak symbols, typically
dnl LIBPTHREAD is empty whereas LIBPMULTITHREAD is not.
dnl Sets the variable LIB_SCHED_YIELD to the linker options needed to use the
dnl sched_yield() function.
dnl Adds to CPPFLAGS the flag -D_REENTRANT or -D_THREAD_SAFE if needed for
dnl multithread-safe programs.
dnl Defines the C macro HAVE_PTHREAD_API if (at least parts of) the POSIX
dnl threads API is available.
dnl The guts of gl_PTHREADLIB. Needs to be expanded only once.
AC_DEFUN([gl_PTHREADLIB_BODY],
......@@ -307,6 +249,24 @@ AC_DEFUN([gl_PTHREADLIB_BODY],
fi
])
AC_DEFUN([gl_PTHREADLIB],
[
AC_REQUIRE([gl_ANYTHREADLIB_EARLY])
gl_PTHREADLIB_BODY
])
dnl ============================================================================
dnl Macros for the ISO C API
dnl gl_STDTHREADLIB
dnl ---------------
dnl Tests for the libraries needs for using the ISO C threads API.
dnl Sets the variable LIBSTDTHREAD to the linker options for use in a Makefile.
dnl Adds to CPPFLAGS the flag -D_REENTRANT or -D_THREAD_SAFE if needed for
dnl multithread-safe programs.
dnl Defines the C macro HAVE_THREADS_H if (at least parts of) the ISO C threads
dnl API is available.
dnl The guts of gl_STDTHREADLIB. Needs to be expanded only once.
AC_DEFUN([gl_STDTHREADLIB_BODY],
......@@ -352,6 +312,110 @@ AC_DEFUN([gl_STDTHREADLIB_BODY],
fi
])
AC_DEFUN([gl_STDTHREADLIB],
[
AC_REQUIRE([gl_ANYTHREADLIB_EARLY])
gl_STDTHREADLIB_BODY
])
dnl ============================================================================
dnl Macros for the Gnulib API
dnl gl_THREADLIB
dnl ------------
dnl Tests for a multithreading library to be used.
dnl If the configure.ac contains a definition of the gl_THREADLIB_DEFAULT_NO
dnl (it must be placed before the invocation of gl_THREADLIB_EARLY!), then the
dnl default is 'no', otherwise it is system dependent. In both cases, the user
dnl can change the choice through the options --enable-threads=choice or
dnl --disable-threads.
dnl Defines at most one of the macros USE_ISOC_THREADS, USE_POSIX_THREADS,
dnl USE_ISOC_AND_POSIX_THREADS, USE_WINDOWS_THREADS.
dnl The choice --enable-threads=isoc+posix is available only on platforms that
dnl have both the ISO C and the POSIX threads APIs. It has the effect of using
dnl the ISO C API for most things and the POSIX API only for creating and
dnl controlling threads (because there is no equivalent to pthread_atfork in
dnl the ISO C API).
dnl Sets the variables LIBTHREAD and LTLIBTHREAD to the linker options for use
dnl in a Makefile (LIBTHREAD for use without libtool, LTLIBTHREAD for use with
dnl libtool).
dnl Sets the variables LIBMULTITHREAD and LTLIBMULTITHREAD similarly, for
dnl programs that really need multithread functionality. The difference
dnl between LIBTHREAD and LIBMULTITHREAD is that on platforms supporting weak
dnl symbols, typically LIBTHREAD is empty whereas LIBMULTITHREAD is not.
dnl Adds to CPPFLAGS the flag -D_REENTRANT or -D_THREAD_SAFE if needed for
dnl multithread-safe programs.
dnl Since support for GNU pth was removed, $LTLIBTHREAD and $LIBTHREAD have the
dnl same value, and similarly $LTLIBMULTITHREAD and $LIBMULTITHREAD have the
dnl same value. Only system libraries are needed.
AC_DEFUN([gl_THREADLIB_EARLY],
[
AC_REQUIRE([gl_THREADLIB_EARLY_BODY])
])
dnl The guts of gl_THREADLIB_EARLY. Needs to be expanded only once.
AC_DEFUN([gl_THREADLIB_EARLY_BODY],
[
dnl Ordering constraints: This macro modifies CPPFLAGS in a way that
dnl influences the result of the autoconf tests that test for *_unlocked
dnl declarations, on AIX 5 at least. Therefore it must come early.
AC_BEFORE([$0], [gl_FUNC_GLIBC_UNLOCKED_IO])dnl
AC_BEFORE([$0], [gl_ARGP])dnl
AC_REQUIRE([AC_CANONICAL_HOST])
dnl _GNU_SOURCE is needed for pthread_rwlock_t on glibc systems.
AC_REQUIRE([AC_USE_SYSTEM_EXTENSIONS])
dnl Check for multithreading.
m4_ifdef([gl_THREADLIB_DEFAULT_NO],
[m4_divert_text([DEFAULTS], [gl_use_threads_default=no])],
[m4_divert_text([DEFAULTS], [gl_use_threads_default=])])
m4_divert_text([DEFAULTS], [gl_use_winpthreads_default=])
AC_ARG_ENABLE([threads],
AC_HELP_STRING([--enable-threads={isoc|posix|isoc+posix|windows}], [specify multithreading API])m4_ifdef([gl_THREADLIB_DEFAULT_NO], [], [
AC_HELP_STRING([--disable-threads], [build without multithread safety])]),
[gl_use_threads=$enableval],
[if test -n "$gl_use_threads_default"; then
gl_use_threads="$gl_use_threads_default"
else
changequote(,)dnl
case "$host_os" in
dnl Disable multithreading by default on OSF/1, because it interferes
dnl with fork()/exec(): When msgexec is linked with -lpthread, its
dnl child process gets an endless segmentation fault inside execvp().
osf*) gl_use_threads=no ;;
dnl Disable multithreading by default on Cygwin 1.5.x, because it has
dnl bugs that lead to endless loops or crashes. See
dnl <https://cygwin.com/ml/cygwin/2009-08/msg00283.html>.
cygwin*)
case `uname -r` in
1.[0-5].*) gl_use_threads=no ;;
*) gl_use_threads=yes ;;
esac
;;
dnl Obey gl_AVOID_WINPTHREAD on mingw.
mingw*)
case "$gl_use_winpthreads_default" in
yes) gl_use_threads=posix ;;
no) gl_use_threads=windows ;;
*) gl_use_threads=yes ;;
esac
;;
*) gl_use_threads=yes ;;
esac
changequote([,])dnl
fi
])
if test "$gl_use_threads" = yes \
|| test "$gl_use_threads" = isoc \
|| test "$gl_use_threads" = posix \
|| test "$gl_use_threads" = isoc+posix; then
# For using <threads.h> or <pthread.h>:
gl_ANYTHREADLIB_EARLY
fi
])
dnl The guts of gl_THREADLIB. Needs to be expanded only once.
AC_DEFUN([gl_THREADLIB_BODY],
......@@ -436,18 +500,6 @@ AC_DEFUN([gl_THREADLIB_BODY],
AC_SUBST([LTLIBMULTITHREAD])
])
AC_DEFUN([gl_PTHREADLIB],
[
AC_REQUIRE([gl_ANYTHREADLIB_EARLY])
gl_PTHREADLIB_BODY
])
AC_DEFUN([gl_STDTHREADLIB],
[
AC_REQUIRE([gl_ANYTHREADLIB_EARLY])
gl_STDTHREADLIB_BODY
])
AC_DEFUN([gl_THREADLIB],
[
AC_REQUIRE([gl_THREADLIB_EARLY])
......@@ -478,6 +530,9 @@ AC_DEFUN([gl_AVOID_WINPTHREAD], [
])
dnl ============================================================================
dnl Survey of platforms:
dnl
dnl Platform Available Compiler Supports test-lock
......
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