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/*
* File: QueueSubscriber.java
*
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS HEADER.
*
* The contents of this file are subject to the terms and conditions of
* the Common Development and Distribution License 1.0 (the "License").
*
* You may not use this file except in compliance with the License.
*
* You can obtain a copy of the License by consulting the LICENSE.txt file
* distributed with this file, or by consulting
* or https://oss.oracle.com/licenses/CDDL
*
* See the License for the specific language governing permissions
* and limitations under the License.
*
* When distributing the software, include this License Header Notice in each
* file and include the License file LICENSE.txt.
*
* MODIFICATIONS:
* If applicable, add the following below the License Header, with the fields
* enclosed by brackets [] replaced by your own identifying information:
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*/
package com.oracle.coherence.patterns.messaging;
import com.oracle.coherence.patterns.messaging.entryprocessors.AcknowledgeMessageProcessor;
import com.oracle.coherence.patterns.messaging.entryprocessors.AcknowledgeSubscriptionMessagesProcessor;
import com.oracle.coherence.patterns.messaging.entryprocessors.RequestMessageFromQueueProcessor;
import com.oracle.coherence.patterns.messaging.entryprocessors.RequestMessageProcessor;
import com.oracle.coherence.patterns.messaging.entryprocessors.RollbackMessageProcessor;
import com.oracle.coherence.patterns.messaging.entryprocessors.SubscriptionRollbackProcessor;
import com.tangosol.net.CacheFactory;
import com.tangosol.net.NamedCache;
import com.tangosol.util.processor.ExtractorProcessor;
import java.util.ArrayList;
import java.util.logging.Level;
import java.util.logging.Logger;
/**
* A specific implementation of {@link Subscriber} for {@link Queue}s.
*
* Copyright (c) 2008. All Rights Reserved. Oracle Corporation.
* Oracle is a registered trademark of Oracle Corporation and/or its affiliates.
*
* @author Brian Oliver
* @author Paul Mackin
*/
class QueueSubscriber extends AbstractSubscriber
{
/**
* Logger
*/
private static Logger logger = Logger.getLogger(QueueSubscriber.class.getName());
/**
* Package Level Constructor.
*
* @param messagingSession messaging session
* @param subscriptionIdentifier subscription identifier
*/
QueueSubscriber(MessagingSession messagingSession,
SubscriptionIdentifier subscriptionIdentifier)
{
super(messagingSession, subscriptionIdentifier);
}
/**
* {@inheritDoc}
*/
public Object getMessage()
{
// ensure that the subscriber is still active
ensureActive();
// ensure that we have a subscription from which we can retrieve
// messages
ensureSubscription();
// Request a message from the {@link Queue}
NamedCache destinationCache = CacheFactory.getCache(Destination.CACHENAME);
destinationCache.invoke(getDestinationIdentifier(),
new RequestMessageFromQueueProcessor(getSubscriptionIdentifier()));
// wait for the message to arrive
QueueSubscription subscription = getNextSubscriptionUpdate();
// ensure the subscription has not been removed/shutdown
ensureSubscription();
MessageIdentifier messageIdentifier = subscription.getVisibleMessageTracker().getLast();
if (messageIdentifier == null)
{
logger.log(Level.SEVERE,
"Queue Subscriber.getMessage got null messageIdentifier for subscription {0}",
subscription.getIdentifier());
return null;
}
// get the message
int partitionId = messageIdentifier.getPartitionId();
long messageSequenceNumber = messageIdentifier.getMessageSequenceNumber();
Message message;
if (isAutoCommitting())
{
// retrieve and acknowledge the message on behalf of this subscriber
message =
(Message) CacheFactory.getCache(Message.CACHENAME)
.invoke(Message.getKey(getDestinationIdentifier(), partitionId, messageSequenceNumber),
new AcknowledgeMessageProcessor(getSubscriptionIdentifier()));
if (message == null)
{
logger.log(Level.SEVERE,
"AcknowledgeMessageProcessor returned null message for subscription {0}",
subscription.getIdentifier());
return null;
}
if (!verifyMessageSequence(message))
{
// verifyMessageSequence will log an error
return null;
}
// let the subscriber know that we've acknowledged the message
MessageTracker messageTracker = new DefaultMessageTracker();
messageTracker.add(messageIdentifier);
CacheFactory.getCache(Subscription.CACHENAME).invoke(getSubscriptionIdentifier(),
new AcknowledgeSubscriptionMessagesProcessor(messageTracker));
}
else
{
// retrieve the message
message =
(Message) CacheFactory.getCache(Message.CACHENAME)
.invoke(Message.getKey(getDestinationIdentifier(), partitionId, messageSequenceNumber),
new RequestMessageProcessor(getSubscriptionIdentifier()));
if (message == null)
{
logger.log(Level.SEVERE,
"RequestMessageProcessor returned null message for subscription {0}",
subscription.getIdentifier());
return null;
}
if (!verifyMessageSequence(message))
{
// verifyMessageSequence will log an error
return null;
}
}
return message.getPayload();
}
/**
* {@inheritDoc}
*/
public void commit()
{
ensureActive();
if (!isAutoCommitting())
{
// ensure that we have a subscription from which we can retrieve
// messages
ensureSubscription();
// determine the range of messages that are visible
// (these are the ones we must acknowledge)
MessageTracker messageTracker =
(MessageTracker) CacheFactory.getCache(Subscription.CACHENAME).invoke(getSubscriptionIdentifier(),
new ExtractorProcessor("getVisibleMessageTracker"));
// send the AcknowledgeMessageProcessor to all of the visible
// messages
ArrayList messageKeys = messageTracker.getMessageKeys(getDestinationIdentifier());
CacheFactory.getCache(Message.CACHENAME).invokeAll(messageKeys,
new AcknowledgeMessageProcessor(getSubscriptionIdentifier()));
// let the subscriber know that we've acknowledged all messages
CacheFactory.getCache(Subscription.CACHENAME).invoke(getSubscriptionIdentifier(),
new AcknowledgeSubscriptionMessagesProcessor(messageTracker));
}
}
/**
* {@inheritDoc}
*/
public void rollback()
{
ensureActive();
resetMessageSequenceVerification();
if (!isAutoCommitting())
{
// ensure that we have a subscription from which we can retrieve
// messages
ensureSubscription();
// determine the range of messages that are visible
// (these are the ones we must rollback)
MessageTracker messageTracker =
(MessageTracker) CacheFactory.getCache(Subscription.CACHENAME).invoke(getSubscriptionIdentifier(),
new ExtractorProcessor("getVisibleMessageTracker"));
NamedCache destinationCache = CacheFactory.getCache(Destination.CACHENAME);
destinationCache.invoke(getDestinationIdentifier(),
new RollbackMessageProcessor(getSubscriptionIdentifier(), messageTracker));
// clear the delivered list for the subscription
CacheFactory.getCache(Subscription.CACHENAME).invoke(getSubscriptionIdentifier(),
new SubscriptionRollbackProcessor());
}
}
/**
* {@inheritDoc}
*/
public void release()
{
unsubscribe();
}
}