shared_rwlock_lock
error = shared_rwlock_lock(rwlp, NULL, READ_LOCK_TRY);
error = shared_rwlock_lock(rwlp, NULL, WRITE_LOCK_TRY);
error = shared_rwlock_lock(rwlp, tsp, READ_LOCK);
error = shared_rwlock_lock(rwlp, tsp, WRITE_LOCK);