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Another attempt at 7.0

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This commit is contained in:
Peter Mount
2000-04-17 20:07:56 +00:00
parent aafff4af16
commit 25dadc8514
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src/interfaces/jdbc/org/postgresql/xa/XADataSourceImpl.java Normal file
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/**
* Redistribution and use of this software and associated documentation
* ("Software"), with or without modification, are permitted provided
* that the following conditions are met:
*
* 1. Redistributions of source code must retain copyright
* statements and notices. Redistributions must also contain a
* copy of this document.
*
* 2. Redistributions in binary form must reproduce the
* above copyright notice, this list of conditions and the
* following disclaimer in the documentation and/or other
* materials provided with the distribution.
*
* 3. The name "Exolab" must not be used to endorse or promote
* products derived from this Software without prior written
* permission of Exoffice Technologies. For written permission,
* please contact info@exolab.org.
*
* 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
* trademark of Exoffice Technologies.
*
* 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 1.1 2000/04/17 20:07:56 peter Exp $
*/
package org.postgresql.xa;
import java.io.Serializable;
import java.io.PrintWriter;
import java.util.Hashtable;
import java.util.Vector;
import java.util.Stack;
import java.util.Enumeration;
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="arkin@exoffice.com">Assaf Arkin</a>
* @version 1.0
*/
public abstract class XADataSourceImpl
implements DataSource, ConnectionPoolDataSource,
XADataSource, 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 Stack _pool = new Stack();
/**
* 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 new XAConnectionImpl( this, 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" );
}
public PooledConnection getPooledConnection()
throws SQLException
{
// Construct a new pooled connection and an underlying JDBC
// connection to go along with it.
return new XAConnectionImpl( this, getConnection() );
}
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, getConnection( 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
*/
void releaseConnection( Connection conn )
{
_pool.push( conn );
}
/**
* Creates a new underlying connection. Used by XA connection
* that lost it's underlying connection when joining a
* transaction and is now asked to produce a new connection.
*
* @return An open connection ready for use
* @throws SQLException An error occured trying to open
* a connection
*/
Connection newConnection()
throws SQLException
{
Connection conn;
// Check in the pool first.
if ( ! _pool.empty() ) {
conn = (Connection) _pool.pop();
return conn;
}
return getConnection();
}
/**
* XXX Not fully implemented yet and no code to really
* test it.
*/
Xid[] getTxRecover()
{
Vector list;
Enumeration enum;
TxConnection txConn;
list = new Vector();
enum = _txConnections.elements();
while ( enum.hasMoreElements() ) {
txConn = (TxConnection) enum.nextElement();
if ( txConn.conn != null && txConn.prepared )
list.add( txConn.xid );
}
return (Xid[]) list.toArray();
}
/**
* Returns the transaction isolation level to use with all newly
* created transactions, or {@link Connection#TRANSACTION_NONE}
* if using the driver's default isolation level.
*/
public int isolationLevel()
{
return Connection.TRANSACTION_NONE;
}
public void run()
{
Enumeration enum;
int reduce;
long timeout;
TxConnection txConn;
while ( true ) {
// Go to sleep for the duration of a transaction
// timeout. This mean transactions will timeout on average
// at _txTimeout * 1.5.
try {
Thread.sleep( _txTimeout * 1000 );
} catch ( InterruptedException except ) {
}
try {
// Check to see if there are any pooled connections
// we can release. We release 10% of the pooled
// connections each time, so in a heavy loaded
// environment we don't get to release that many, but
// as load goes down we do. These are not actually
// pooled connections, but connections that happen to
// get in and out of a transaction, not that many.
reduce = _pool.size() - ( _pool.size() / 10 ) - 1;
if ( reduce >= 0 && _pool.size() > reduce ) {
if ( getLogWriter() != null )
getLogWriter().println( "DataSource " + toString() +
": Reducing internal connection pool size from " +
_pool.size() + " to " + reduce );
while ( _pool.size() > reduce ) {
try {
( (Connection) _pool.pop() ).close();
} catch ( SQLException except ) { }
}
}
} catch ( Exception except ) { }
// Look for all connections inside a transaction that
// should have timed out by now.
timeout = System.currentTimeMillis();
enum = _txConnections.elements();
while ( enum.hasMoreElements() ) {
txConn = (TxConnection) enum.nextElement();
// If the transaction timed out, we roll it back and
// invalidate it, but do not remove it from the transaction
// list yet. We wait for the next iteration, minimizing the
// chance of a NOTA exception.
if ( txConn.conn == null ) {
_txConnections.remove( txConn.xid );
// Chose not to use an iterator so we must
// re-enumerate the list after removing
// an element from it.
enum = _txConnections.elements();
} else if ( txConn.timeout < timeout ) {
try {
Connection underlying;
synchronized ( txConn ) {
if ( txConn.conn == null )
continue;
if ( getLogWriter() != null )
getLogWriter().println( "DataSource " + toString() +
": Transaction timed out and being aborted: " +
txConn.xid );
// Remove the connection from the transaction
// association. XAConnection will now have
// no underlying connection and attempt to
// create a new one.
underlying = txConn.conn;
txConn.conn = null;
txConn.timedOut = true;
// Rollback the underlying connection to
// abort the transaction and release the
// underlying connection to the pool.
try {
underlying.rollback();
releaseConnection( underlying );
} catch ( SQLException except ) {
if ( getLogWriter() != null )
getLogWriter().println( "DataSource " + toString() +
": Error aborting timed out transaction: " + except );
try {
underlying.close();
} catch ( SQLException e2 ) { }
}
}
} catch ( Exception except ) { }
}
}
}
}
public void debug( PrintWriter writer )
{
Enumeration enum;
TxConnection txConn;
StringBuffer buffer;
writer.println( "Debug info for XADataSource:" );
enum = _txConnections.elements();
if ( ! enum.hasMoreElements() )
writer.println( "Empty" );
while ( enum.hasMoreElements() ) {
buffer = new StringBuffer();
txConn = (TxConnection) enum.nextElement();
buffer.append( "TxConnection " );
if ( txConn.xid != null )
buffer.append( txConn.xid );
if ( txConn.conn != null )
buffer.append( ' ' ).append( txConn.conn );
buffer.append( " count: " ).append( txConn.count );
if ( txConn.prepared )
buffer.append( " prepared" );
if ( txConn.timedOut )
buffer.append( " timed-out" );
if ( txConn.readOnly )
buffer.append( " read-only" );
writer.println( buffer.toString() );
}
enum = _pool.elements();
while ( enum.hasMoreElements() )
writer.println( "Pooled underlying: " + enum.nextElement().toString() );
}
}