# 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.
# Note: Cygwin (as of 12/1/08) has a bug in pthread_rwlock, where
# if you try to acquire a read-lock twice, you get EDEADLCK, where
# it should succeed. It would be nice to test for that, but we
# can't do runtime checks here. So we just manually fail for CYGWIN.
# TODO(csilvers): do better.
[AC_CACHE_CHECK(support for pthread_rwlock_* functions,
AC_TRY_COMPILE([#define _XOPEN_SOURCE 500
# error Cygwin has a bug in pthread_rwlock; disabling
[pthread_rwlock_t l; pthread_rwlock_init(&l, NULL);
if test "$ac_cv_rwlock" = yes; then
AC_DEFINE(HAVE_RWLOCK,1,[define if the compiler implements pthread_rwlock_*])