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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.txn;
import org.apache.log4j.Logger;
import org.apache.qpid.AMQException;
import org.apache.qpid.server.store.MessageStore;
import java.util.ArrayList;
import java.util.List;
/**
* Holds a list of TxnOp instance representing transactional
* operations.
*/
public class TxnBuffer
{
private boolean _containsPersistentChanges = false;
private final MessageStore _store;
private final List<TxnOp> _ops = new ArrayList<TxnOp>();
private static final Logger _log = Logger.getLogger(TxnBuffer.class);
public TxnBuffer(MessageStore store)
{
_store = store;
}
public void containsPersistentChanges()
{
_containsPersistentChanges = true;
}
public void commit() throws AMQException
{
if (_containsPersistentChanges)
{
_log.debug("Begin Transaction.");
_store.beginTran();
if(prepare())
{
_log.debug("Transaction Succeeded");
_store.commitTran();
for (TxnOp op : _ops)
{
op.commit();
}
}
else
{
_log.debug("Transaction Failed");
_store.abortTran();
}
}else{
if(prepare())
{
for (TxnOp op : _ops)
{
op.commit();
}
}
}
_ops.clear();
}
private boolean prepare()
{
for (int i = 0; i < _ops.size(); i++)
{
TxnOp op = _ops.get(i);
try
{
op.prepare();
}
catch(Exception e)
{
//compensate previously prepared ops
for(int j = 0; j < i; j++)
{
_ops.get(j).undoPrepare();
}
return false;
}
}
return true;
}
public void rollback() throws AMQException
{
for (TxnOp op : _ops)
{
op.rollback();
}
_ops.clear();
}
public void enlist(TxnOp op)
{
_ops.add(op);
}
public void cancel(TxnOp op)
{
_ops.remove(op);
}
}
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