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/*
*
* Copyright (c) 2006 The Apache Software Foundation
*
* Licensed 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.client.failover;
import org.apache.log4j.Logger;
import org.apache.qpid.client.AMQConnection;
import org.apache.qpid.client.failover.FailoverException;
import javax.jms.JMSException;
public abstract class FailoverSupport
{
private static final Logger _log = Logger.getLogger(FailoverSupport.class);
public Object execute(AMQConnection con) throws JMSException
{
// We wait until we are not in the middle of failover before acquiring the mutex and then proceeding.
// Any method that can potentially block for any reason should use this class so that deadlock will not
// occur. The FailoverException is propagated by the AMQProtocolHandler to any listeners (e.g. frame listeners)
// that might be causing a block. When that happens, the exception is caught here and the mutex is released
// before waiting for the failover to complete (either successfully or unsuccessfully).
while (true)
{
try
{
con.blockUntilNotFailingOver();
}
catch (InterruptedException e)
{
_log.info("Interrupted: " + e, e);
return null;
}
synchronized (con.getFailoverMutex())
{
try
{
return operation();
}
catch (FailoverException e)
{
_log.info("Failover exception caught during operation");
}
}
}
}
protected abstract Object operation() throws JMSException;
}
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