edu.mit.csail.aeolus.api
Class AeolusQueue<T extends java.io.Serializable>

java.lang.Object
  edu.mit.csail.aeolus.api.AeolusShared
      edu.mit.csail.aeolus.api.AeolusQueue<T>

Type Parameters:

T -

All Implemented Interfaces:

AeolusSafe

public final class AeolusQueue<T extends java.io.Serializable>
extends AeolusShared

This behaves like the AeolusBox class but is a queue of objects instead.

Field Summary

Fields inherited from class edu.mit.csail.aeolus.api.AeolusShared

sharedLastEid

Constructor Summary

AeolusQueue()
Construct an empty AeolusQueue with the current thread's labels.

AeolusQueue(AeolusLabel sLabel, AeolusLabel iLabel)
Construct an empty AeolusQueue with the specified labels.

Method Summary

T	dequeue() This method returns the object at the head of the queue.
T	dequeueNoWait() This call will wait for the lock on the queue before trying to remove a potentially empty head (it will not block if the queue is empty, though).
void	enqueue(T obj) Adds a copy of obj to the shared queue.

Methods inherited from class edu.mit.csail.aeolus.api.AeolusShared

getIntegrityLabel, getSecrecyLabel

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

AeolusQueue

public AeolusQueue()

Construct an empty AeolusQueue with the current thread's labels.

AeolusQueue

public AeolusQueue(AeolusLabel sLabel,
                   AeolusLabel iLabel)
            throws InfoFlowControlException

Construct an empty AeolusQueue with the specified labels.

Throws:

InfoFlowControlException - if thread's labels are more constraining than those provided.

Method Detail

dequeue

public T dequeue()
                                       throws InfoFlowControlException

This method returns the object at the head of the queue. (no copying is needed!) It will block until an object is available.

Returns:

dequeued element

Throws:

InfoFlowControlException - if thread's labels are not equal to the queue's labels.

dequeueNoWait

public T dequeueNoWait()
                                             throws InfoFlowControlException

This call will wait for the lock on the queue before trying to remove a potentially empty head (it will not block if the queue is empty, though).

Returns:

the object at the head of the shared queue or null if there is no head. (no copying is needed!)

Throws:

InfoFlowControlException - if thread's labels are not equal to the queue's labels.

enqueue

public void enqueue(T obj)
             throws InfoFlowControlException,
                    java.lang.NullPointerException

Adds a copy of obj to the shared queue. requires obj != null

Throws:

java.lang.NullPointerException - - if obj is null

InfoFlowControlException - if queue's labels are more constrained that the thread's.