/**
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You under the Apache License, Version 2.0
* (the "License"); you may not use this file except in compliance with
* the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.apache.activemq.broker.region;
import java.io.IOException;
import javax.jms.InvalidSelectorException;
import javax.jms.JMSException;
import org.apache.activemq.broker.Broker;
import org.apache.activemq.broker.ConnectionContext;
import org.apache.activemq.broker.region.group.MessageGroupMap;
import org.apache.activemq.command.ActiveMQMessage;
import org.apache.activemq.command.ConsumerId;
import org.apache.activemq.command.ConsumerInfo;
import org.apache.activemq.command.Message;
import org.apache.activemq.command.MessageAck;
import org.apache.activemq.transaction.Synchronization;
import org.apache.activemq.usage.SystemUsage;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
public class QueueSubscription extends PrefetchSubscription implements LockOwner {
private static final Log LOG = LogFactory.getLog(QueueSubscription.class);
public QueueSubscription(Broker broker, SystemUsage usageManager, ConnectionContext context, ConsumerInfo info) throws InvalidSelectorException {
super(broker,usageManager, context, info);
}
/**
* In the queue case, mark the node as dropped and then a gc cycle will
* remove it from the queue.
*
* @throws IOException
*/
protected void acknowledge(ConnectionContext context, final MessageAck ack, final MessageReference n) throws IOException {
final Destination q = n.getRegionDestination();
q.acknowledge(context, this, ack, n);
final QueueMessageReference node = (QueueMessageReference)n;
final Queue queue = (Queue)q;
if (!ack.isInTransaction()) {
node.drop();
queue.dropEvent();
} else {
node.setAcked(true);
context.getTransaction().addSynchronization(new Synchronization() {
public void afterCommit() throws Exception {
node.drop();
queue.dropEvent();
}
public void afterRollback() throws Exception {
node.setAcked(false);
}
});
}
}
protected boolean canDispatch(MessageReference n) throws IOException {
QueueMessageReference node = (QueueMessageReference)n;
if (node.isAcked()) {
return false;
}
// Keep message groups together.
String groupId = node.getGroupID();
int sequence = node.getGroupSequence();
if (groupId != null) {
MessageGroupMap messageGroupOwners = ((Queue)node.getRegionDestination()).getMessageGroupOwners();
// If we can own the first, then no-one else should own the rest.
if (sequence == 1) {
if (node.lock(this)) {
assignGroupToMe(messageGroupOwners, n, groupId);
return true;
} else {
return false;
}
}
// Make sure that the previous owner is still valid, we may
// need to become the new owner.
ConsumerId groupOwner;
synchronized (node) {
groupOwner = messageGroupOwners.get(groupId);
if (groupOwner == null) {
if (node.lock(this)) {
assignGroupToMe(messageGroupOwners, n, groupId);
return true;
} else {
return false;
}
}
}
if (groupOwner.equals(info.getConsumerId())) {
// A group sequence < 1 is an end of group signal.
if (sequence < 0) {
messageGroupOwners.removeGroup(groupId);
}
return true;
}
return false;
} else {
return node.lock(this);
}
}
/**
* Assigns the message group to this subscription and set the flag on the
* message that it is the first message to be dispatched.
*/
protected void assignGroupToMe(MessageGroupMap messageGroupOwners, MessageReference n, String groupId) throws IOException {
messageGroupOwners.put(groupId, info.getConsumerId());
Message message = n.getMessage();
if (message instanceof ActiveMQMessage) {
ActiveMQMessage activeMessage = (ActiveMQMessage)message;
try {
activeMessage.setBooleanProperty("JMSXGroupFirstForConsumer", true, false);
} catch (JMSException e) {
LOG.warn("Failed to set boolean header: " + e, e);
}
}
}
public synchronized String toString() {
return "QueueSubscription:" + " consumer=" + info.getConsumerId() + ", destinations=" + destinations.size() + ", dispatched=" + dispatched.size() + ", delivered="
+ this.prefetchExtension + ", pending=" + getPendingQueueSize();
}
public int getLockPriority() {
return info.getPriority();
}
public boolean isLockExclusive() {
return info.isExclusive();
}
/**
* Override so that the message ref count is > 0 only when the message is
* being dispatched to a client. Keeping it at 0 when it is in the pending
* list allows the message to be swapped out to disk.
*
* @return true if the message was dispatched.
*/
protected boolean dispatch(MessageReference node) throws IOException {
boolean rc = false;
// This brings the message into memory if it was swapped out.
node.incrementReferenceCount();
try {
rc = super.dispatch(node);
} finally {
// If the message was dispatched, it could be getting dispatched
// async, so we
// can only drop the reference count when that completes @see
// onDispatch
if (!rc) {
node.decrementReferenceCount();
}
}
return rc;
}
/**
* OK Message was transmitted, we can now drop the reference count.
*
* @see org.apache.activemq.broker.region.PrefetchSubscription#onDispatch(org.apache.activemq.broker.region.MessageReference,
* org.apache.activemq.command.Message)
*/
protected void onDispatch(MessageReference node, Message message) {
// Now that the message has been sent over the wire to the client,
// we can let it get swapped out.
node.decrementReferenceCount();
super.onDispatch(node, message);
}
/**
* Sending a message to the DQL will require us to increment the ref count
* so we can get at the content.
*/
protected void sendToDLQ(ConnectionContext context, MessageReference node) throws IOException, Exception {
// This brings the message into memory if it was swapped out.
node.incrementReferenceCount();
try {
super.sendToDLQ(context, node);
} finally {
// This let's the message be swapped out of needed.
node.decrementReferenceCount();
}
}
/**
*/
public void destroy() {
}
}