m4/ac_rwlock.m4

   1 # TODO(csilvers): it would be better to actually try to link against
   2 # -pthreads, to make sure it defines these methods, but that may be
   3 # too hard, since pthread support is really tricky.
   4
   5 # Check for support for pthread_rwlock_init() etc.
   6 # These aren't posix, but are widely supported.  To get them on linux,
   7 # you need to define _XOPEN_SOURCE first, so this check assumes your
   8 # application does that.
   9 #
  10 # Note: OS X (as of 6/1/06) seems to support pthread_rwlock, but
  11 # doesn't define PTHREAD_RWLOCK_INITIALIZER.  Therefore, we don't test
  12 # that particularly macro.  It's probably best if you don't use that
  13 # macro in your code either.
  14
  15 AC_DEFUN([AC_RWLOCK],
  16 [AC_CACHE_CHECK(support for pthread_rwlock_* functions,
  17 ac_cv_rwlock,
  18 [AC_LANG_SAVE
  19  AC_LANG_C
  20  AC_TRY_COMPILE([#define _XOPEN_SOURCE 500
  21                  #include <pthread.h>],
  22                 [pthread_rwlock_t l; pthread_rwlock_init(&l, NULL);
  23                  pthread_rwlock_rdlock(&l);
  24                  return 0;],
  25                 ac_cv_rwlock=yes, ac_cv_rwlock=no)
  26  AC_LANG_RESTORE
  27 ])
  28 if test "$ac_cv_rwlock" = yes; then
  29   AC_DEFINE(HAVE_RWLOCK,1,[define if the compiler implements pthread_rwlock_*])
  30 fi
  31 ])