alfresco-community-repo/source/java/org/alfresco/filesys/repo/FilesystemTransactionAdvice.java

/*
 * Copyright (C) 2005-2010 Alfresco Software Limited.
 *
 * This file is part of Alfresco
 *
 * Alfresco is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Lesser General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * Alfresco is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public License
 * along with Alfresco. If not, see <http://www.gnu.org/licenses/>.
 */
package org.alfresco.filesys.repo;

import java.io.IOException;

import org.alfresco.jlan.server.core.DeviceContextException;
import org.alfresco.jlan.server.filesys.IOControlNotImplementedException;
import org.alfresco.jlan.smb.SMBException;
import org.alfresco.repo.transaction.RetryingTransactionHelper;
import org.alfresco.repo.transaction.RetryingTransactionHelper.RetryingTransactionCallback;
import org.alfresco.service.transaction.TransactionService;
import org.aopalliance.intercept.MethodInterceptor;
import org.aopalliance.intercept.MethodInvocation;

/**
 * An advice wrapper for an AlfrescoDiskDriver.   Wraps the method call with a 
 * RetryingTransactionHandler.
 * <p>
 * Needs to let the checked exceptions that are specified on the JLAN interfaces through.  
 * In particular must avoid wrapping JLAN's checked exceptions with an AlfrescoRuntimeException 
 * (so must throw IOException etc)
 * <p>
 * @See DiskInterface
 * @See IOControlHandler
 * 
 */
public class FilesystemTransactionAdvice implements MethodInterceptor
{
    private boolean readOnly;
    
//    private AlfrescoDiskDriver driver;
    
    private TransactionService transactionService;

    public FilesystemTransactionAdvice()
    {
        readOnly = false;
    }
    
    public void setReadOnly(boolean readOnly)
    {
        this.readOnly = readOnly;
    }

    public Object invoke(final MethodInvocation methodInvocation) throws IOException, SMBException, Throwable
    {
        
        RetryingTransactionHelper tran = transactionService.getRetryingTransactionHelper();
        
        RetryingTransactionCallback<Object> callback = new RetryingTransactionHelper.RetryingTransactionCallback<Object>()
        {
            public Object execute() throws Throwable
            {
                try
                {
                    return methodInvocation.proceed();
                }
                catch (SMBException e)
                {
                    throw new PropagatingException(e);
                }
                catch (IOControlNotImplementedException e)
                {
                    throw new PropagatingException(e);
                }
                catch (IOException e)
                {
                    // Ensure original checked IOExceptions get propagated
                    throw new PropagatingException(e);
                }
                catch (DeviceContextException e)
                {
                    throw new PropagatingException(e);
                }
            }
        };

        if(readOnly)
        {
            // read only transaction
            try
            {
                return tran.doInTransaction(callback, true);
            }
            catch(PropagatingException pe)
            {
                Throwable t = pe.getCause();
                if(t != null)
                {
                    if(t instanceof IOException)
                    {
                        throw (IOException) pe.getCause();
                    }
                    if(t instanceof SMBException)
                    {
                        throw pe.getCause();
                    }
                    if(t instanceof DeviceContextException)
                    {
                        throw pe.getCause();
                    }
                    throw t;
                }
                throw pe;
            }
        }
        else
        {
            // read/write only transaction
            try
            {
               return tran.doInTransaction(callback);  
            }
            catch(PropagatingException pe)
            {  
                Throwable t = pe.getCause();
                if(t != null)
                {
                    if(t instanceof IOException)
                    {
                        // Unwrap checked exceptions
                        throw pe.getCause();
                    }
                    if(t instanceof SMBException)
                    {
                        throw pe.getCause();
                    }
                    if(t instanceof DeviceContextException)
                    {
                        throw pe.getCause();
                    }
                    throw t;
                }
                throw pe;
            }            
        }
    }

    public void setTransactionService(TransactionService transactionService)
    {
        this.transactionService = transactionService;
    }

    public TransactionService getTransactionService()
    {
        return transactionService;
    }
    
    /**
     * A wrapper for checked exceptions to be passed through the retrying transaction handler.
     */
    protected static class PropagatingException extends RuntimeException
    {
        private static final long serialVersionUID = 1L;

        /**
         * @param cause
         */
        public PropagatingException(Throwable cause)
        {
            super(cause);
        }        
    }
}