org.apache.qpid.jms.util

Class AbstractMessageQueue

java.lang.Object

org.apache.qpid.jms.util.AbstractMessageQueue

All Implemented Interfaces:

MessageQueue

Direct Known Subclasses:

FifoMessageQueue, PriorityMessageQueue

public abstract class AbstractMessageQueue
extends Object
implements MessageQueue

Abstract Message Queue class used to implement the common functions of a Message Queue instance.

Constructor Summary

Constructors

Constructor and Description
AbstractMessageQueue()

Method Summary

Methods

Modifier and Type	Method and Description
void	close() Closes the Message Queue.
JmsInboundMessageDispatch	dequeue(long timeout) Used to get an enqueued message.
JmsInboundMessageDispatch	dequeueNoWait() Used to get an enqueued Message if on exists, otherwise returns null.
Object	getLock()
boolean	isClosed()
boolean	isRunning()
JmsInboundMessageDispatch	peek() Return but do not remove the first element in the Message queue.
protected abstract JmsInboundMessageDispatch	peekFirst() Returns but does not remove the first entry in the implementation queue.
protected abstract JmsInboundMessageDispatch	removeFirst() Removes and returns the first entry in the implementation queue.
void	start() Starts the Message Queue.
void	stop() Stops the Message Queue.

Methods inherited from class java.lang.Object

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

Methods inherited from interface org.apache.qpid.jms.util.MessageQueue

clear, enqueue, enqueueFirst, isEmpty, removeAll, size

Constructor Detail

AbstractMessageQueue

public AbstractMessageQueue()

Method Detail

peek

public final JmsInboundMessageDispatch peek()

Description copied from interface: MessageQueue

Return but do not remove the first element in the Message queue.

Specified by:

peek in interface MessageQueue

Returns:

the first element in the Queue or null if empty.

dequeue

public final JmsInboundMessageDispatch dequeue(long timeout)
                                        throws InterruptedException

Description copied from interface: MessageQueue

Used to get an enqueued message. The amount of time this method blocks is based on the timeout value. - if timeout==-1 then it blocks until a message is received. - if timeout==0 then it it tries to not block at all, it returns a message if it is available - if timeout > 0 then it blocks up to timeout amount of time. Expired messages will consumed by this method.

Specified by:

dequeue in interface MessageQueue

Parameters:

timeout - The amount of time to wait for an entry to be added before returning null.

Returns:

null if we timeout or if the consumer is closed.

Throws:

InterruptedException - if the wait is interrupted.

dequeueNoWait

public final JmsInboundMessageDispatch dequeueNoWait()

Description copied from interface: MessageQueue

Used to get an enqueued Message if on exists, otherwise returns null.

Specified by:

dequeueNoWait in interface MessageQueue

Returns:

the next Message in the Queue if one exists, otherwise null.

start

public final void start()

Description copied from interface: MessageQueue

Starts the Message Queue. An non-started Queue will always return null for any of the Queue methods.

Specified by:

start in interface MessageQueue

stop

public final void stop()

Description copied from interface: MessageQueue

Stops the Message Queue. Messages cannot be read from the Queue when it is in the stopped state and any waiters will be awoken.

Specified by:

stop in interface MessageQueue

isRunning

public final boolean isRunning()

Specified by:

isRunning in interface MessageQueue

Returns:

true if the Queue is not in the stopped or closed state.

close

public final void close()

Description copied from interface: MessageQueue

Closes the Message Queue. No messages can be added or removed from the Queue once it has entered the closed state.

Specified by:

close in interface MessageQueue

isClosed

public final boolean isClosed()

Specified by:

isClosed in interface MessageQueue

Returns:

true if the Queue has been closed.

getLock

public final Object getLock()

Specified by:

getLock in interface MessageQueue

Returns:

the lock object used to protect against concurrent access.

removeFirst

protected abstract JmsInboundMessageDispatch removeFirst()

Removes and returns the first entry in the implementation queue. This method is always called under lock and does not need to protect itself or check running state etc.

Returns:

the first message queued in the implemented queue.

peekFirst

protected abstract JmsInboundMessageDispatch peekFirst()

Returns but does not remove the first entry in the implementation queue. This method is always called under lock and does not need to protect itself or check running state etc.

Returns:

the first message queued in the implemented queue.