/*
* Copyright 1999-2004 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.
*/
/*
* $Id: DefaultConnectionPool.java,v 1.22 2005/08/06 20:21:41 mcnamara Exp $
*/
package org.apache.xalan.lib.sql;
import java.sql.Connection;
import java.sql.DatabaseMetaData;
import java.sql.Driver;
import java.sql.DriverManager;
import java.sql.SQLException;
import java.util.Enumeration;
import java.util.Iterator;
import java.util.Properties;
import java.util.Vector;
import org.apache.xalan.res.XSLMessages;
import org.apache.xalan.res.XSLTErrorResources;
/**
* For internal connectiones, i.e. Connection information supplies in the
* Stylesheet. The Default Connection Pool will be used.
*/
public class DefaultConnectionPool implements ConnectionPool
{
/**
* A placeholder thast will keep the driver loaded
* between calls.
*/
private Driver m_Driver = null;
/**
*/
private static final boolean DEBUG = false;
/**
* The basic information to make a JDBC Connection
*/
private String m_driver = new String("");
/**
*/
private String m_url = new String("");
/**
* The mimimum size of the connection pool, if the
* number of available connections falls below this
* mark, min connections will be allocated. The Connection
* Pool will always be somewhere between MinSize and MinSize*2
*/
private int m_PoolMinSize = 1;
/**
* Always implement the properties mechinism, if the Password
* or Username is set seperatly then we will add them to the
* property manually.
*/
private Properties m_ConnectionProtocol = new Properties();
/**
* Storage for the PooledConnections
*/
private Vector m_pool = new Vector();
/**
* Are we active ??
*/
private boolean m_IsActive = false;
/**
*/
public DefaultConnectionPool( ) {}
/**
* Return our current Active state
*
*/
public boolean isEnabled( )
{
return m_IsActive;
}
/**
* Set the driver call to be used to create connections
* @param d
*
*/
public void setDriver( String d )
{
m_driver = d;
}
/**
* Set the url used to connect to the database
* @param url
*
*/
public void setURL( String url )
{
m_url = url;
}
/**
* Go through the connection pool and release any connections
* that are not InUse;
*
*/
public void freeUnused( )
{
// Iterate over the entire pool closing the
// JDBC Connections.
Iterator i = m_pool.iterator();
while(i.hasNext())
{
PooledConnection pcon =
(PooledConnection) i.next();
// If the PooledConnection is not in use, close it
if ( pcon.inUse() == false )
{
if (DEBUG)
{
System.err.println("Closing JDBC Connection ");
}
pcon.close();
i.remove();
}
}
}
/**
* Is our ConnectionPool have any connections that are still in Use ??
*
*/
public boolean hasActiveConnections( )
{
return (m_pool.size() > 0);
}
/**
* Set the password in the property set.
* @param p
*
*/
public void setPassword( String p )
{
m_ConnectionProtocol.put("password", p);
}
/**
* Set the user name in the property set
* @param u
*
*/
public void setUser( String u )
{
m_ConnectionProtocol.put("user", u);
}
/**
* The Protocol string is used to pass in other connection
* properties. A properties file is a general purpose container
*
* @param p
*
*/
public void setProtocol( Properties p )
{
Enumeration e = p.keys();
while (e.hasMoreElements())
{
String key = (String) e.nextElement();
m_ConnectionProtocol.put(key, p.getProperty(key));
}
}
/**
* Override the current number of connections to keep in the pool. This
* setting will only have effect on a new pool or when a new connection
* is requested and there is less connections that this setting.
* @param n
*
*/
public void setMinConnections( int n )
{
m_PoolMinSize = n;
}
/**
* Try to aquire a new connection, if it succeeds then return
* true, else return false.
* Note: This method will cause the connection pool to be built.
*
*/
public boolean testConnection( )
{
try
{
if (DEBUG)
{
System.out.println("Testing Connection");
}
Connection conn = getConnection();
if (DEBUG)
{
DatabaseMetaData dma = conn.getMetaData();
System.out.println("\nConnected to " + dma.getURL());
System.out.println("Driver " + dma.getDriverName());
System.out.println("Version " + dma.getDriverVersion());
System.out.println("");
}
if (conn == null) return false;
releaseConnection(conn);
if (DEBUG)
{
System.out.println("Testing Connection, SUCCESS");
}
return true;
}
catch(Exception e)
{
if (DEBUG)
{
System.out.println("Testing Connection, FAILED");
e.printStackTrace();
}
return false;
}
}
// Find an available connection
/**
* @return Connection
* @throws java.sql.SQLException
* @throws IllegalArgumentException
*/
public synchronized Connection getConnection( )throws IllegalArgumentException, SQLException
{
PooledConnection pcon = null;
// We will fill up the pool any time it is less than the
// Minimum. THis could be cause by the enableing and disabling
// or the pool.
//
if ( m_pool.size() < m_PoolMinSize ) { initializePool(); }
// find a connection not in use
for ( int x = 0; x < m_pool.size(); x++ )
{
pcon = (PooledConnection) m_pool.elementAt(x);
// Check to see if the Connection is in use
if ( pcon.inUse() == false )
{
// Mark it as in use
pcon.setInUse(true);
// return the JDBC Connection stored in the
// PooledConnection object
return pcon.getConnection();
}
}
// Could not find a free connection,
// create and add a new one
// Create a new JDBC Connection
Connection con = createConnection();
// Create a new PooledConnection, passing it the JDBC
// Connection
pcon = new PooledConnection(con);
// Mark the connection as in use
pcon.setInUse(true);
// Add the new PooledConnection object to the pool
m_pool.addElement(pcon);
// return the new Connection
return pcon.getConnection();
}
/**
* @param con
*
* @throws java.sql.SQLException
*/
public synchronized void releaseConnection( Connection con )throws SQLException
{
// find the PooledConnection Object
for ( int x = 0; x < m_pool.size(); x++ )
{
PooledConnection pcon =
(PooledConnection) m_pool.elementAt(x);
// Check for correct Connection
if ( pcon.getConnection() == con )
{
if (DEBUG)
{
System.out.println("Releasing Connection " + x);
}
if (! isEnabled())
{
con.close();
m_pool.removeElementAt(x);
if (DEBUG)
{
System.out.println("-->Inactive Pool, Closing connection");
}
}
else
{
// Set it's inuse attribute to false, which
// releases it for use
pcon.setInUse(false);
}
break;
}
}
}
/**
* @param con
*
* @throws java.sql.SQLException
*/
public synchronized void releaseConnectionOnError( Connection con )throws SQLException
{
// find the PooledConnection Object
for ( int x = 0; x < m_pool.size(); x++ )
{
PooledConnection pcon =
(PooledConnection) m_pool.elementAt(x);
// Check for correct Connection
if ( pcon.getConnection() == con )
{
if (DEBUG)
{
System.out.println("Releasing Connection On Error" + x);
}
con.close();
m_pool.removeElementAt(x);
if (DEBUG)
{
System.out.println("-->Inactive Pool, Closing connection");
}
break;
}
}
}
/**
*
* @throws java.sql.SQLException
*/
private Connection createConnection( )throws SQLException
{
Connection con = null;
// Create a Connection directly from the Driver that was loaded
// with the context class loader. This is to support JDK1.4
con = m_Driver.connect(m_url, m_ConnectionProtocol );
return con;
}
// Initialize the pool
/**
*
* @throws IllegalArgumentException
* @throws java.sql.SQLException
*/
public synchronized void initializePool( )throws IllegalArgumentException, SQLException
{
// Check our initial values
if ( m_driver == null )
{
throw new IllegalArgumentException(XSLMessages.createMessage(XSLTErrorResources.ER_NO_DRIVER_NAME_SPECIFIED, null));
// "No Driver Name Specified!");
}
if ( m_url == null )
{
throw new IllegalArgumentException(XSLMessages.createMessage(XSLTErrorResources.ER_NO_URL_SPECIFIED, null));
// "No URL Specified!");
}
if ( m_PoolMinSize < 1 )
{
throw new IllegalArgumentException(XSLMessages.createMessage(XSLTErrorResources.ER_POOLSIZE_LESS_THAN_ONE, null));
// "Pool size is less than 1!");
}
// Create the Connections
// Load the Driver class file
try
{
// We have also had problems with drivers unloading
// load an instance that will get freed with the class.
m_Driver = (Driver) ObjectFactory.newInstance(
m_driver, ObjectFactory.findClassLoader(), true);
// Register the Driver that was loaded with the Context Classloader
// but we will ask for connections directly from the Driver
// instance
DriverManager.registerDriver(m_Driver);
}
catch(ObjectFactory.ConfigurationError e)
{
throw new IllegalArgumentException(XSLMessages.createMessage(XSLTErrorResources.ER_INVALID_DRIVER_NAME, null));
// "Invalid Driver Name Specified!");
}
catch(Exception e)
{
throw new IllegalArgumentException(XSLMessages.createMessage(XSLTErrorResources.ER_INVALID_DRIVER_NAME, null));
}
// IF we are not active, don't actuall build a pool yet
// Just set up the driver and periphal items.
if ( !m_IsActive) return;
// Create Connections based on the size member
do
{
Connection con = createConnection();
if ( con != null )
{
// Create a PooledConnection to encapsulate the
// real JDBC Connection
PooledConnection pcon = new PooledConnection(con);
// Add the Connection the pool.
addConnection(pcon);
if (DEBUG) System.out.println("Adding DB Connection to the Pool");
}
}
while (m_pool.size() < m_PoolMinSize);
}
// Adds the PooledConnection to the pool
/**
* @param value
*
*/
private void addConnection( PooledConnection value )
{
// Add the PooledConnection Object to the vector
m_pool.addElement(value);
}
/**
*
* @throws Throwable
*/
protected void finalize( )throws Throwable
{
if (DEBUG)
{
System.out.println("In Default Connection Pool, Finalize");
}
// Iterate over the entire pool closing the
// JDBC Connections.
for ( int x = 0; x < m_pool.size(); x++ )
{
if (DEBUG)
{
System.out.println("Closing JDBC Connection " + x);
}
PooledConnection pcon =
(PooledConnection) m_pool.elementAt(x);
// If the PooledConnection is not in use, close it
if ( pcon.inUse() == false ) { pcon.close(); }
else
{
if (DEBUG)
{
System.out.println("--> Force close");
}
// If it still in use, sleep for 30 seconds and
// force close.
try
{
Thread.sleep(30000);
pcon.close();
}
catch (InterruptedException ie)
{
if (DEBUG) System.err.println(ie.getMessage());
}
}
}
if (DEBUG)
{
System.out.println("Exit Default Connection Pool, Finalize");
}
super.finalize();
}
/**
* The Pool can be Enabled and Disabled. Disabling the pool
* closes all the outstanding Unused connections and any new
* connections will be closed upon release.
*
* @param flag Control the Connection Pool.
* If it is enabled then Connections will actuall be held
* around. If disabled then all unused connections will be instantly
* closed and as connections are released they are closed and removed
* from the pool.
*
*
*/
public void setPoolEnabled( boolean flag )
{
m_IsActive = flag;
if ( ! flag )
freeUnused();
}
}