package locklib.mutex;
   
   import locklib.LockPolicy;
   import ensure.Ensure;
   
   /**
    * Locking policy for mutex locking. In a mutex locking policy, locking a
    * child requires locking its parent.
    */
  public class MutexLockPolicy implements LockPolicy<MutexLockType> {
  	/**
  	 * Creates a new mutex locking policy.
  	 */
  	public MutexLockPolicy() {
  	}
  
  	@Override
  	public boolean is_compatible(MutexLockType lock_type_1,
  			MutexLockType lock_type_2) {
  		Ensure.not_null(lock_type_1, "lock_type_1 == null");
  		Ensure.not_null(lock_type_2, "lock_type_2 == null");
  		
  		return false;
  	}
  
  	@Override
  	public MutexLockType parent_lock(MutexLockType lock_type) {
  		Ensure.not_null(lock_type, "lock_type == null");
  		
  		return lock_type;
  	}
  	
  	@Override
  	public boolean starvation_allowed() {
  		return false;
  	}
  }