xadatasourceimpl.java

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/**
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 * 1. Redistributions of source code must retain copyright
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 * 2. Redistributions in binary form must reproduce the
 *    above copyright notice, this list of conditions and the
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 *    please contact [e-mail].
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 * 4. Products derived from this Software may not be called "Exolab"
 *    nor may "Exolab" appear in their names without prior written
 *    permission of Exoffice Technologies. Exolab is a registered
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 *
 * 5. Due credit should be given to the Exolab Project
 *    (http://www.exolab.org/).
 *
 * THIS SOFTWARE IS PROVIDED BY EXOFFICE TECHNOLOGIES AND CONTRIBUTORS
 * ``AS IS'' AND ANY EXPRESSED OR IMPLIED WARRANTIES, INCLUDING, BUT
 * NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND
 * FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL
 * EXOFFICE TECHNOLOGIES OR ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT,
 * INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
 * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
 * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
 * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
 * OF THE POSSIBILITY OF SUCH DAMAGE.
 *
 * Copyright 1999 (C) Exoffice Technologies Inc. All Rights Reserved.
 *
 * $Id: XADataSourceImpl.java,v 1.2 2002/04/21 03:03:46 mark_matthews Exp $
 */

package com.mysql.jdbc.xa;

import java.io.Serializable;
import java.io.PrintWriter;
import java.util.Hashtable;
import java.util.Vector;
import java.util.ArrayList;
import java.util.Enumeration;
import java.util.Iterator;
import java.sql.Connection;
import java.sql.SQLException;

import javax.sql.DataSource;
import javax.sql.PooledConnection;
import javax.sql.ConnectionPoolDataSource;
import javax.sql.XAConnection;
import javax.sql.XADataSource;
import javax.transaction.xa.Xid;

/**
 * Implements a JDBC 2.0 {@link XADataSource} for any JDBC driver
 * with JNDI persistance support. The base implementation is actually
 * provided by a different {@link DataSource} class; although this is
 * the super class, it only provides the pooling and XA specific
 * implementation.
 *
 *
 * @author <a href="[e-mail]">Assaf Arkin</a>
 * @version 1.0
 */
public abstract class XADataSourceImpl
	implements DataSource, Serializable, Runnable {

	/**
	 * Maps underlying JDBC connections into global transaction Xids.
	 */
	private transient Hashtable _txConnections = new Hashtable();

	/**
	 * This is a pool of free underlying JDBC connections. If two
	 * XA connections are used in the same transaction, the second
	 * one will make its underlying JDBC connection available to
	 * the pool. This is not a real connection pool, only a marginal
	 * efficiency solution for dealing with shared transactions.
	 */
	private transient ArrayList _pool = new ArrayList();

	/**
	 * A background deamon thread terminating connections that have
	 * timed out.
	 */
	private transient Thread _background;

	/**
	 * The default timeout for all new transactions.
	 */
	private int _txTimeout = DEFAULT_TX_TIMEOUT;

	/**
	 * The default timeout for all new transactions is 10 seconds.
	 */
	public final static int DEFAULT_TX_TIMEOUT = 10;

	/**
	 * Implementation details:
	 *   If two XAConnections are associated with the same transaction
	 *   (one with a start the other with a join) they must use the
	 *   same underlying JDBC connection. They lookup the underlying
	 *   JDBC connection based on the transaction's Xid in the
	 *   originating XADataSource.
	 *
	 *   Currently the XADataSource must be the exact same object,
	 *   this should be changed so all XADataSources that are equal
	 *   share a table of all enlisted connections
	 *
	 *   To test is two connections should fall under the same
	 *   transaction we match the resource managers by comparing the
	 *   database/user they fall under using a comparison of the
	 *   XADataSource properties.
	 */

	public XADataSourceImpl() {
		super();

		// Create a background thread that will track transactions
		// that timeout, abort them and release the underlying
		// connections to the pool.
		_background = new Thread(this, "XADataSource Timeout Daemon");
		_background.setPriority(Thread.MIN_PRIORITY);
		_background.setDaemon(true);
		_background.start();
	}

	public XAConnection getXAConnection() throws SQLException {
		// Construct a new XAConnection with no underlying connection.
		// When a JDBC method requires an underlying connection, one
		// will be created. We don't create the underlying connection
		// beforehand, as it might be coming from an existing
		// transaction.
		return getXAConnection(null, null);
	}

	public XAConnection getXAConnection(String user, String password)
		throws SQLException {
		// Since we create the connection on-demand with newConnection
		// or obtain it from a transaction, we cannot support XA
		// connections with a caller specified user name.
		//throw new SQLException( "XAConnection does not support connections with caller specified user name" );
		return new XAConnectionImpl(
			this,
			newConnection(user, password),
			user,
			password);
	}

	public PooledConnection getPooledConnection() throws SQLException {
		// Construct a new pooled connection and an underlying JDBC
		// connection to go along with it.
		return getPooledConnection(null, null);

	}

	public PooledConnection getPooledConnection(String user, String password)
		throws SQLException {
		// Construct a new pooled connection and an underlying JDBC
		// connection to go along with it.
		return new XAConnectionImpl(
			this,
			newConnection(user, password),
			user,
			password);
	}

	/**
	 * Returns the default timeout for all transactions.
	 */
	public int getTransactionTimeout() {
		return _txTimeout;
	}

	/**
	 * This method is defined in the interface and implemented in the
	 * derived class, we re-define it just to make sure it does not
	 * throw an {@link SQLException} and that we do not need to
	 * catch one.
	 */
	public abstract java.io.PrintWriter getLogWriter();

	/**
	 * Sets the default timeout for all transactions. The timeout is
	 * specified in seconds. Use zero for the default timeout. Calling
	 * this method does not affect transactions in progress.
	 *
	 * @param seconds The timeout in seconds
	 */
	public void setTransactionTimeout(int seconds) {
		if (seconds <= 0)
			_txTimeout = DEFAULT_TX_TIMEOUT;
		else
			_txTimeout = seconds;
		_background.interrupt();
	}

	/**
	 * Returns an underlying connection for the global transaction,
	 * if one has been associated before.
	 *
	 * @param xid The transaction Xid
	 * @return A connection associated with that transaction, or null
	 */
	TxConnection getTxConnection(Xid xid) {
		return (TxConnection) _txConnections.get(xid);
	}

	/**
	 * Associates the global transaction with an underlying connection,
	 * or dissociate it when null is passed.
	 *
	 * @param xid The transaction Xid
	 * @param conn The connection to associate, null to dissociate
	 */
	TxConnection setTxConnection(Xid xid, TxConnection txConn) {
		if (txConn == null)
			return (TxConnection) _txConnections.remove(xid);
		else
			return (TxConnection) _txConnections.put(xid, txConn);
	}

	/**
	 * Release an unused connection back to the pool. If an XA
	 * connection has been asked to join an existing transaction,
	 * it will no longer use it's own connection and make it available
	 * to newly created connections.
	 *
	 * @param conn An open connection that is no longer in use
	 * @param userName the user name for the connection
	 * @param password the password for the connection
	 */
	void releaseConnection(Connection conn, String userName, String password) {
		if (null != conn) {
			// make sure the connection has no work
			synchronized (_pool) {
				_pool.add(new ConnectionEntry(conn, getAccount(userName, password)));
			}
		}
	}

	/**
	 * In order to deal with connections opened for a specific
	 * account, we record the account name in the pool.
	 * Given the user and password used to open the account,
	 * we get a unique account identifier that combines the two.
	 * The returned account can be encrypted for added security.
	 * 
	 * @param user The user name for creating the connection
	 * @param password The password for creating the connection
	 * @return A unique account name matching the user name
	 *   and password, null if <tt>user</tt> is null
	 */
	private String getAccount(String user, String password) {
		if (user == null)
			return "";