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/*
 * $Id: AbstractSingleResourceTransaction.java 19191 2010-08-25 21:05:23Z tcarlson $
 * --------------------------------------------------------------------------------------
 * Copyright (c) MuleSoft, Inc.  All rights reserved.  http://www.mulesoft.com
 *
 * The software in this package is published under the terms of the CPAL v1.0
 * license, a copy of which has been included with this distribution in the
 * LICENSE.txt file.
 */

package org.mule.transaction;

import org.mule.api.MuleContext;
import org.mule.api.transaction.TransactionException;
import org.mule.config.i18n.CoreMessages;

import java.lang.reflect.Field;
import java.util.Collections;
import java.util.HashMap;
import java.util.Map;

import javax.transaction.Status;

import edu.emory.mathcs.backport.java.util.concurrent.atomic.AtomicBoolean;

/**
 * This abstract class can be used as a base class for transactions that can enlist
 * only one resource (such as a JMS session or JDBC connection).
 */
public abstract class AbstractSingleResourceTransaction extends AbstractTransaction
{

    /**
     * TX status code to human-readable string mappings.
     *
     * @see javax.transaction.Status
     */
    protected static Map txStatusMappings = new HashMap(10); // populated later

    protected volatile Object key;
    protected volatile Object resource;

    protected final AtomicBoolean started = new AtomicBoolean(false);
    protected final AtomicBoolean committed = new AtomicBoolean(false);
    protected final AtomicBoolean rolledBack = new AtomicBoolean(false);
    protected final AtomicBoolean rollbackOnly = new AtomicBoolean(false);

    static
    {
        Field[] fields = Status.class.getFields();
        for (Field field : fields)
        {
            try
            {
                txStatusMappings.put(field.getInt(Status.class), field.getName());
            }
            catch (IllegalAccessException e)
            {
                // ignore
            }
        }

        txStatusMappings = Collections.unmodifiableMap(txStatusMappings);
    }

    protected AbstractSingleResourceTransaction(MuleContext muleContext)
    {
        super(muleContext);
    }

    public void begin() throws TransactionException
    {
        super.begin();
        started.compareAndSet(false, true);
    }

    public void commit() throws TransactionException
    {
        super.commit();
        committed.compareAndSet(false, true);
    }

    public void rollback() throws TransactionException
    {
        super.rollback();
        rolledBack.compareAndSet(false, true);
    }

    public int getStatus() throws TransactionStatusException
    {
        if (rolledBack.get())
        {
            return STATUS_ROLLEDBACK;
        }
        if (committed.get())
        {
            return STATUS_COMMITTED;
        }
        if (rollbackOnly.get())
        {
            return STATUS_MARKED_ROLLBACK;
        }
        if (started.get())
        {
            return STATUS_ACTIVE;
        }
        return STATUS_NO_TRANSACTION;
    }

    public Object getResource(Object key)
    {
        return key != null && this.key == key ? this.resource : null;
    }

    public boolean hasResource(Object key)
    {
        return key != null && this.key == key;
    }

    public void bindResource(Object key, Object resource) throws TransactionException
    {
        if (key == null)
        {
            throw new IllegalTransactionStateException(CoreMessages.transactionCannotBindToNullKey());
        }
        if (resource == null)
        {
            throw new IllegalTransactionStateException(CoreMessages.transactionCannotBindNullResource());
        }
        if (this.key != null)
        {
            throw new IllegalTransactionStateException(CoreMessages.transactionSingleResourceOnly());
        }
        
        if (logger.isDebugEnabled())
        {
            logger.debug("Binding " + resource + " to " + key);
        }
        
        this.key = key;
        this.resource = resource;
    }

    public void setRollbackOnly()
    {
        rollbackOnly.set(true);
    }

    @Override
    public String toString()
    {
        int status;
        try
        {
            status = getStatus();
        }
        catch (TransactionException e)
        {
            status = -1;
        }

        // map status to a human-readable string

        String statusName = txStatusMappings.get(status);
        if (statusName == null)
        {
            statusName = "*undefined*";
        }

        return new StringBuilder().append(getClass().getName())
                .append('@').append(id)
                .append("[status=").append(statusName)
                .append(", key=").append(key)
                .append(", resource=").append(resource)
                .append("]").toString();
    }
}