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/*
*
* 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.qpid.server.queue;
import org.apache.log4j.Logger;
import org.apache.mina.common.ByteBuffer;
import org.apache.qpid.AMQException;
import org.apache.qpid.framing.AMQDataBlock;
import org.apache.qpid.framing.AMQFrame;
import org.apache.qpid.framing.BasicDeliverBody;
import org.apache.qpid.server.AMQChannel;
import org.apache.qpid.server.protocol.AMQProtocolSession;
/**
* Encapsulation of a supscription to a queue.
* <p/>
* Ties together the protocol session of a subscriber, the consumer tag that
* was given out by the broker and the channel id.
* <p/>
*/
public class SubscriptionImpl implements Subscription
{
private static final Logger _logger = Logger.getLogger(SubscriptionImpl.class);
public final AMQChannel channel;
public final AMQProtocolSession protocolSession;
public final String consumerTag;
private final Object sessionKey;
/**
* True if messages need to be acknowledged
*/
private final boolean _acks;
public static class Factory implements SubscriptionFactory
{
public SubscriptionImpl createSubscription(int channel, AMQProtocolSession protocolSession, String consumerTag, boolean acks)
throws AMQException
{
return new SubscriptionImpl(channel, protocolSession, consumerTag, acks);
}
public SubscriptionImpl createSubscription(int channel, AMQProtocolSession protocolSession, String consumerTag)
throws AMQException
{
return new SubscriptionImpl(channel, protocolSession, consumerTag);
}
}
public SubscriptionImpl(int channelId, AMQProtocolSession protocolSession,
String consumerTag, boolean acks)
throws AMQException
{
AMQChannel channel = protocolSession.getChannel(channelId);
if (channel == null)
{
throw new NullPointerException("channel not found in protocol session");
}
this.channel = channel;
this.protocolSession = protocolSession;
this.consumerTag = consumerTag;
sessionKey = protocolSession.getKey();
_acks = acks;
}
public SubscriptionImpl(int channel, AMQProtocolSession protocolSession,
String consumerTag)
throws AMQException
{
this(channel, protocolSession, consumerTag, false);
}
public boolean equals(Object o)
{
return (o instanceof SubscriptionImpl) && equals((SubscriptionImpl) o);
}
/**
* Equality holds if the session matches and the channel and consumer tag are the same.
*/
private boolean equals(SubscriptionImpl psc)
{
return sessionKey.equals(psc.sessionKey)
&& psc.channel == channel
&& psc.consumerTag.equals(consumerTag);
}
public int hashCode()
{
return sessionKey.hashCode();
}
public String toString()
{
return "[channel=" + channel + ", consumerTag=" + consumerTag + ", session=" + protocolSession.getKey() + "]";
}
/**
* This method can be called by each of the publisher threads.
* As a result all changes to the channel object must be thread safe.
*
* @param msg
* @param queue
* @throws AMQException
*/
public void send(AMQMessage msg, AMQQueue queue) throws FailedDequeueException
{
if (msg != null)
{
// if we do not need to wait for client acknowledgements
// we can decrement the reference count immediately.
// By doing this _before_ the send we ensure that it
// doesn't get sent if it can't be dequeued, preventing
// duplicate delivery on recovery.
// The send may of course still fail, in which case, as
// the message is unacked, it will be lost.
if (!_acks)
{
queue.dequeue(msg);
}
synchronized(channel)
{
long deliveryTag = channel.getNextDeliveryTag();
if (_acks)
{
channel.addUnacknowledgedMessage(msg, deliveryTag, consumerTag, queue);
}
ByteBuffer deliver = createEncodedDeliverFrame(deliveryTag, msg.getRoutingKey(), msg.getExchangeName());
AMQDataBlock frame = msg.getDataBlock(deliver, channel.getChannelId());
protocolSession.writeFrame(frame);
}
}
else
{
_logger.error("Attempt to send Null message", new NullPointerException());
}
}
public boolean isSuspended()
{
return channel.isSuspended();
}
/**
* Callback indicating that a queue has been deleted.
*
* @param queue
*/
public void queueDeleted(AMQQueue queue)
{
channel.queueDeleted(queue);
}
private ByteBuffer createEncodedDeliverFrame(long deliveryTag, String routingKey, String exchange)
{
AMQFrame deliverFrame = BasicDeliverBody.createAMQFrame(channel.getChannelId(), consumerTag,
deliveryTag, false, exchange,
routingKey);
ByteBuffer buf = ByteBuffer.allocate((int) deliverFrame.getSize()); // XXX: Could cast be a problem?
deliverFrame.writePayload(buf);
buf.flip();
return buf;
}
}
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