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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.qpid.server.transactionlog.TransactionLog;
import java.util.concurrent.atomic.AtomicLong;
public class MessageFactory
{
private AtomicLong _messageId;
private static MessageFactory INSTANCE;
private enum State
{
RECOVER,
OPEN
}
private State _state = State.RECOVER;
private MessageFactory()
{
_messageId = new AtomicLong(0L);
}
public void recoveryComplete()
{
_state = State.OPEN;
}
/**
* Only to be used by tests as this will cause violate the principal that message IDs should not be reused.
*/
public void reset()
{
_state = State.RECOVER;
_messageId = new AtomicLong(0L);
}
/**
* Normal message creation path
* @param transactionLog
* @param persistent
* @return
*/
public AMQMessage createMessage(TransactionLog transactionLog, boolean persistent)
{
if (_state != State.OPEN)
{
_state = State.OPEN;
}
return createNextMessage(_messageId.incrementAndGet(), transactionLog, persistent);
}
/**
* Used for message recovery only and so only creates persistent messages.
* @param messageId the id that this message must have
* @param transactionLog
* @return
*/
public AMQMessage createMessage(Long messageId, TransactionLog transactionLog)
{
if (_state != State.RECOVER)
{
throw new RuntimeException("Unable to create message by ID when not recovering");
}
long currentID = _messageId.get();
if (messageId <= currentID)
{
throw new RuntimeException("Message IDs can only increase current id is:"
+ currentID + ". Requested:" + messageId);
}
else
{
_messageId.set(messageId);
}
return createNextMessage(messageId, transactionLog, true);
}
private AMQMessage createNextMessage(Long messageId, TransactionLog transactionLog, boolean persistent)
{
if (persistent)
{
return new PersistentAMQMessage(messageId, transactionLog);
}
else
{
return new TransientAMQMessage(messageId);
}
}
public static MessageFactory getInstance()
{
if (INSTANCE == null)
{
INSTANCE = new MessageFactory();
}
return INSTANCE;
}
}
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