github.com/jlmucb/cloudproxy@v0.0.0-20170830161738-b5aa0b619bc4/src/third_party/google-glog/m4/.svn/text-base/ac_rwlock.m4.svn-base (about)

     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  ])