void lock_init(int write_locks);
int lock_request(int clientid,int num);
int lock_request_multiple(int clientid,int n,int *nums);
int lock_release(int clientid,int num);
int lock_release_wait(int clientid);
int lock_get_next_client();
int lockedQ(int num);

// debugging only:
void dump_lock(int n);