[PATCH] Add autoconf tests for pthreads

[PATCH] Add autoconf tests for pthreads

[david.syzdek]

From: David M. Syzdek <david.syzdek@acsalaska.net>

Sets the value of PTHREAD_LIBS to the correct flags for linking pthreads on
the current environment.  If the correct flags can be determined then
THREADED_DELTA_SEARCH is set.  If the correct flags cannot be determined,
then THREADED_DELTA_SEARCH is unset.

Signed-off-by: David M. Syzdek <david.syzdek@acsalaska.net>
---
 config.mak.in |    2 ++
 configure.ac  |   20 ++++++++++++++++++++
 2 files changed, 22 insertions(+), 0 deletions(-)

diff --git a/config.mak.in b/config.mak.in
index 7170729..3d3fbcd 100644
--- a/config.mak.in
+++ b/config.mak.in
@@ -51,3 +51,5 @@ OLD_ICONV=@OLD_ICONV@
 NO_DEFLATE_BOUND=@NO_DEFLATE_BOUND@
 FREAD_READS_DIRECTORIES=@FREAD_READS_DIRECTORIES@
 SNPRINTF_RETURNS_BOGUS=@SNPRINTF_RETURNS_BOGUS@
+THREADED_DELTA_SEARCH=@THREADED_DELTA_SEARCH@
+PTHREAD_LIBS=@PTHREAD_LIBS@
diff --git a/configure.ac b/configure.ac
index 9dfc0d3..3bf5d15 100644
--- a/configure.ac
+++ b/configure.ac
@@ -489,6 +489,26 @@ AC_SUBST(NO_MKDTEMP)
 #
 # Define NO_SYMLINK_HEAD if you never want .git/HEAD to be a symbolic link.
 # Enable it on Windows.  By default, symrefs are still used.
+#
+# Define PTHREAD_LIBS to the linker flag used for Pthread support and define
+# THREADED_DELTA_SEARCH if Pthreads are available.
+AC_LANG_CONFTEST([AC_LANG_PROGRAM(
+  [[#include <pthread.h>]],
+  [[pthread_mutex_t test_mutex;]]
+)])
+${CC} -pthread conftest.c -o conftest.o > /dev/null 2>&1
+if test $? -eq 0;then
+ PTHREAD_LIBS="-pthread"
+ THREADED_DELTA_SEARCH=YesPlease
+else
+ ${CC} -lpthread conftest.c -o conftest.o > /dev/null 2>&1
+ if test $? -eq 0;then
+  PTHREAD_LIBS="-lpthread"
+  THREADED_DELTA_SEARCH=YesPlease
+ fi
+fi
+AC_SUBST(PTHREAD_LIBS)
+AC_SUBST(THREADED_DELTA_SEARCH)
 
 ## Site configuration (override autodetection)
 ## --with-PACKAGE[=ARG] and --without-PACKAGE
-- 
1.6.0.2.GIT

Re: [PATCH] Add autoconf tests for pthreads

[Junio C Hamano]

david.syzdek@acsalaska.net writes:

> +# Define PTHREAD_LIBS to the linker flag used for Pthread support and define
> +# THREADED_DELTA_SEARCH if Pthreads are available.

This may affect platforms that do have pthread library but choose not to
use threaded delta search for whatever reason by suddenly turning it on.

Which arguably may be a good thing to do, but it is a change unrelated to
porting to FreeBSD.

> +AC_LANG_CONFTEST([AC_LANG_PROGRAM(
> +  [[#include <pthread.h>]],
> +  [[pthread_mutex_t test_mutex;]]
> +)])
> +${CC} -pthread conftest.c -o conftest.o > /dev/null 2>&1
> +if test $? -eq 0;then
> + PTHREAD_LIBS="-pthread"
> + THREADED_DELTA_SEARCH=YesPlease
> +else
> + ${CC} -lpthread conftest.c -o conftest.o > /dev/null 2>&1

Maybe I am old fashioned, but having "-library" very near the beginning of
the command line and naming the final link product (i.e. not with -c) *.o
makes me go "Huh?"  If it were written like this,

	$CC -o conftest$ac_exeext conftest.c -lpthread

it might have been easier to swallow.  I dunno.