__nisdb_wlock_trylock
return (__nisdb_wlock_trylock(rw, 0));
#define TRYWLOCK(var) __nisdb_wlock_trylock(&var ## _rwlock, 1)
#define TRYWLOCK(var) __nisdb_wlock_trylock(&var ## _rwlock, 1)
extern int __nisdb_wlock_trylock(__nisdb_rwlock_t *, int);