org.apache.qpid.jms.util

Class PriorityMessageQueue

java.lang.Object

org.apache.qpid.jms.util.PriorityMessageQueue

All Implemented Interfaces:

MessageQueue

public final class PriorityMessageQueue
extends Object
implements MessageQueue

Simple Message Priority ordered Queue. Message envelopes are stored in the Queue based on their priority value, except where enqueueFirst(org.apache.qpid.jms.message.JmsInboundMessageDispatch) is used.

Field Summary

Fields

Modifier and Type	Field and Description
protected static int	CLOSED
protected Object	lock
protected static int	RUNNING
protected static AtomicIntegerFieldUpdater<PriorityMessageQueue>	STATE_FIELD_UPDATER
protected static int	STOPPED

Constructor Summary

Constructors

Constructor and Description
PriorityMessageQueue()

Method Summary

Modifier and Type	Method and Description
void	clear() Clears the Queue of any Messages.
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.
void	enqueue(JmsInboundMessageDispatch envelope) Adds the given message envelope to the end of the Message queue.
void	enqueueFirst(JmsInboundMessageDispatch envelope) Adds the given message envelope to the front of the Message queue.
boolean	isClosed()
boolean	isEmpty()
boolean	isRunning()
int	size() Returns the number of Messages currently in the 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

Field Detail

STATE_FIELD_UPDATER

protected static final AtomicIntegerFieldUpdater<PriorityMessageQueue> STATE_FIELD_UPDATER

CLOSED

protected static final int CLOSED

See Also:

Constant Field Values

STOPPED

protected static final int STOPPED

See Also:

Constant Field Values

RUNNING

protected static final int RUNNING

See Also:

Constant Field Values

lock

protected final Object lock

Constructor Detail

PriorityMessageQueue

public PriorityMessageQueue()

Method Detail

enqueue

public void enqueue(JmsInboundMessageDispatch envelope)

Description copied from interface: MessageQueue

Adds the given message envelope to the end of the Message queue.

Specified by:

enqueue in interface MessageQueue

Parameters:

envelope - The in-bound Message envelope to enqueue.

enqueueFirst

public void enqueueFirst(JmsInboundMessageDispatch envelope)

Description copied from interface: MessageQueue

Adds the given message envelope to the front of the Message queue.

Specified by:

enqueueFirst in interface MessageQueue

Parameters:

envelope - The in-bound Message envelope to enqueue.

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 woken.

Specified by:

stop in interface MessageQueue

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

isRunning

public final boolean isRunning()

Specified by:

isRunning in interface MessageQueue

Returns:

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

isClosed

public final boolean isClosed()

Specified by:

isClosed in interface MessageQueue

Returns:

true if the Queue has been closed.

isEmpty

public boolean isEmpty()

Specified by:

isEmpty in interface MessageQueue

Returns:

true if there are no messages in the queue.

size

public int size()

Description copied from interface: MessageQueue

Returns the number of Messages currently in the Queue. This value is only meaningful at the time of the call as the size of the Queue changes rapidly as Messages arrive and are consumed.

Specified by:

size in interface MessageQueue

Returns:

the current number of Messages in the Queue.

clear

public void clear()

Description copied from interface: MessageQueue

Clears the Queue of any Messages.

Specified by:

clear in interface MessageQueue