org.xmlBlaster.engine.query.plugins
Class QueueQueryPlugin

java.lang.Object
  org.xmlBlaster.engine.query.plugins.QueueQueryPlugin

All Implemented Interfaces:

I_Query, I_StorageSizeListener

public class QueueQueryPlugin
extends java.lang.Object
implements I_Query, I_StorageSizeListener

Each TopicHandler/SessionInfo or SubjectInfo instance creates its own instance of this plugin.

Author:

Michele Laghi

See Also:

The engine.qos.queryspec requirement, The engine.qos.queryspec.QueueQuery requirement

Nested Class Summary

(package private) class

QueueQueryPlugin.WaitingQuery Helper container

Field Summary

private Global	global
private static java.util.logging.Logger	log
private static java.lang.String	ME
private java.util.Set	waitingThreads

Constructor Summary

QueueQueryPlugin(Global global)

Method Summary

void	changed(I_Storage storage, long numEntries, long numBytes, boolean isShutdown) We register for queue size changes and our blocking thread returns if we are done.
private boolean	checkIfNeedsWaiting(int entriesInQueue, long bytesInQueue, QueueQueryPlugin.WaitingQuery wq) If no restriction is given, i.e.
private QueueQueryPlugin.WaitingQuery[]	getWaitingQueries()
MsgUnit[]	query(java.lang.Object source, java.lang.String query) The query to the queue.

Methods inherited from class java.lang.Object

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

Field Detail

ME

private static final java.lang.String ME

See Also:

Constant Field Values

global

private Global global

log

private static java.util.logging.Logger log

waitingThreads

private java.util.Set waitingThreads

Constructor Detail

QueueQueryPlugin

public QueueQueryPlugin(Global global)

Method Detail

getWaitingQueries

private QueueQueryPlugin.WaitingQuery[] getWaitingQueries()

checkIfNeedsWaiting

private final boolean checkIfNeedsWaiting(int entriesInQueue,
                                          long bytesInQueue,
                                          QueueQueryPlugin.WaitingQuery wq)

If no restriction is given, i.e. if both maxEntries and maxBytes is negative, then it will wait.

Returns:

true if it has to wait, false if there are already sufficently entries in the queue.

query

public MsgUnit[] query(java.lang.Object source,
                       java.lang.String query)
                throws XmlBlasterException

The query to the queue. The parameters specifying which kind of query it is are specified in the qos, and more precisely in the QuerySpecQos.

Specified by:

query in interface I_Query

Parameters:

source - must be an I_Queue implementation (can not be null).

query - must not be null, e.g. "maxEntries=3&maxSize=1000&consumable=true&waitingDelay=1000" for example from qosData.getQuerySpecArr()[0].getQuery().getQuery()

Returns:

a MsgUnit[] containing all entries which match the query

Throws:

XmlBlasterException - if something is wrong in the query (for example if the type of the object specified as the source is wrong)

changed

public void changed(I_Storage storage,
                    long numEntries,
                    long numBytes,
                    boolean isShutdown)

We register for queue size changes and our blocking thread returns if we are done. Enforced by I_StorageSizeListener

Specified by:

changed in interface I_StorageSizeListener

Parameters:

storage - The queue which fires the change event

numEntries - the number of entries in the queue after the change has taken place

numBytes - number of bytes in the queue after the change has taken change.

isShutdown - Is set to true if queue.shutdown() was executed