# TODO(csilvers): it would be better to actually try to link against

# -pthreads, to make sure it defines these methods, but that may be

# too hard, since pthread support is really tricky.

# Check for support for pthread_rwlock_init() etc.

# These aren't posix, but are widely supported.  To get them on linux,

# you need to define _XOPEN_SOURCE first, so this check assumes your

# application does that.

#

# Note: OS X (as of 6/1/06) seems to support pthread_rwlock, but

# doesn't define PTHREAD_RWLOCK_INITIALIZER.  Therefore, we don't test

# that particularly macro.  It's probably best if you don't use that

# macro in your code either.

AC_DEFUN([AC_RWLOCK],

[AC_CACHE_CHECK(support for pthread_rwlock_* functions,

ac_cv_rwlock,

[AC_LANG_SAVE

 AC_LANG_C

 AC_TRY_COMPILE([#define _XOPEN_SOURCE 500

                 #include <pthread.h>],

		[pthread_rwlock_t l; pthread_rwlock_init(&l, NULL);

                 pthread_rwlock_rdlock(&l); 

                 return 0;],

                ac_cv_rwlock=yes, ac_cv_rwlock=no)

 AC_LANG_RESTORE

])

if test "$ac_cv_rwlock" = yes; then

  AC_DEFINE(HAVE_RWLOCK,1,[define if the compiler implements pthread_rwlock_*])

fi

])