/*-------------------------------------------------------------------------
*
* Copyright (c) 2004-2008, PostgreSQL Global Development Group
*
* IDENTIFICATION
* $PostgreSQL: pgjdbc/org/postgresql/ds/jdbc23/AbstractJdbc23PooledConnection.java,v 1.4 2008/01/08 06:56:27 jurka Exp $
*
*-------------------------------------------------------------------------
*/
package org.postgresql.ds.jdbc23;
import javax.sql.*;
import java.sql.*;
import java.util.*;
import java.lang.reflect.*;
import org.postgresql.PGConnection;
import org.postgresql.util.GT;
import org.postgresql.util.PSQLException;
import org.postgresql.util.PSQLState;
/**
* PostgreSQL implementation of the PooledConnection interface. This shouldn't
* be used directly, as the pooling client should just interact with the
* ConnectionPool instead.
* @see org.postgresql.ds.PGConnectionPoolDataSource
*
* @author Aaron Mulder (ammulder@chariotsolutions.com)
* @author Csaba Nagy (ncsaba@yahoo.com)
*/
public abstract class AbstractJdbc23PooledConnection
{
private List listeners = new LinkedList();
private Connection con;
private ConnectionHandler last;
private final boolean autoCommit;
private final boolean isXA;
/**
* Creates a new PooledConnection representing the specified physical
* connection.
*/
public AbstractJdbc23PooledConnection(Connection con, boolean autoCommit, boolean isXA)
{
this.con = con;
this.autoCommit = autoCommit;
this.isXA = isXA;
}
/**
* Adds a listener for close or fatal error events on the connection
* handed out to a client.
*/
public void addConnectionEventListener(ConnectionEventListener connectionEventListener)
{
listeners.add(connectionEventListener);
}
/**
* Removes a listener for close or fatal error events on the connection
* handed out to a client.
*/
public void removeConnectionEventListener(ConnectionEventListener connectionEventListener)
{
listeners.remove(connectionEventListener);
}
/**
* Closes the physical database connection represented by this
* PooledConnection. If any client has a connection based on
* this PooledConnection, it is forcibly closed as well.
*/
public void close() throws SQLException
{
if (last != null)
{
last.close();
if (!con.getAutoCommit())
{
try
{
con.rollback();
}
catch (SQLException e)
{
}
}
}
try
{
con.close();
}
finally
{
con = null;
}
}
/**
* Gets a handle for a client to use. This is a wrapper around the
* physical connection, so the client can call close and it will just
* return the connection to the pool without really closing the
* pgysical connection.
*
* <p>According to the JDBC 2.0 Optional Package spec (6.2.3), only one
* client may have an active handle to the connection at a time, so if
* there is a previous handle active when this is called, the previous
* one is forcibly closed and its work rolled back.</p>
*/
public Connection getConnection() throws SQLException
{
if (con == null)
{
// Before throwing the exception, let's notify the registered listeners about the error
PSQLException sqlException = new PSQLException(GT.tr("This PooledConnection has already been closed."),
PSQLState.CONNECTION_DOES_NOT_EXIST);
fireConnectionFatalError(sqlException);
throw sqlException;
}
// If any error occures while opening a new connection, the listeners
// have to be notified. This gives a chance to connection pools to
// elliminate bad pooled connections.
try
{
// Only one connection can be open at a time from this PooledConnection. See JDBC 2.0 Optional Package spec section 6.2.3
if (last != null)
{
last.close();
if (!con.getAutoCommit())
{
try
{
con.rollback();
}
catch (SQLException e)
{
}
}
con.clearWarnings();
}
/*
* In XA-mode, autocommit is handled in PGXAConnection,
* because it depends on whether an XA-transaction is open
* or not
*/
if (!isXA)
con.setAutoCommit(autoCommit);
}
catch (SQLException sqlException)
{
fireConnectionFatalError(sqlException);
throw (SQLException)sqlException.fillInStackTrace();
}
ConnectionHandler handler = new ConnectionHandler(con);
last = handler;
Connection proxyCon = (Connection)Proxy.newProxyInstance(getClass().getClassLoader(), new Class[]{Connection.class, PGConnection.class}, handler);
last.setProxy(proxyCon);
return proxyCon;
}
/**
* Used to fire a connection closed event to all listeners.
*/
void fireConnectionClosed()
{
ConnectionEvent evt = null;
// Copy the listener list so the listener can remove itself during this method call
ConnectionEventListener[] local = (ConnectionEventListener[]) listeners.toArray(new ConnectionEventListener[listeners.size()]);
for (int i = 0; i < local.length; i++)
{
ConnectionEventListener listener = local[i];
if (evt == null)
{
evt = createConnectionEvent(null);
}
listener.connectionClosed(evt);
}
}
/**
* Used to fire a connection error event to all listeners.
*/
void fireConnectionFatalError(SQLException e)
{
ConnectionEvent evt = null;
// Copy the listener list so the listener can remove itself during this method call
ConnectionEventListener[] local = (ConnectionEventListener[])listeners.toArray(new ConnectionEventListener[listeners.size()]);
for (int i = 0; i < local.length; i++)
{
ConnectionEventListener listener = local[i];
if (evt == null)
{
evt = createConnectionEvent(e);
}
listener.connectionErrorOccurred(evt);
}
}
protected abstract ConnectionEvent createConnectionEvent(SQLException e);
// Classes we consider fatal.
private static String[] fatalClasses = {
"08", // connection error
"53", // insufficient resources
// nb: not just "57" as that includes query cancel which is nonfatal
"57P01", // admin shutdown
"57P02", // crash shutdown
"57P03", // cannot connect now
"58", // system error (backend)
"60", // system error (driver)
"99", // unexpected error
"F0", // configuration file error (backend)
"XX", // internal error (backend)
};
private static boolean isFatalState(String state) {
if (state == null) // no info, assume fatal
return true;
if (state.length() < 2) // no class info, assume fatal
return true;
for (int i = 0; i < fatalClasses.length; ++i)
if (state.startsWith(fatalClasses[i]))
return true; // fatal
return false;
}
/**
* Fires a connection error event, but only if we
* think the exception is fatal.
*
* @param e the SQLException to consider
*/
private void fireConnectionError(SQLException e)
{
if (!isFatalState(e.getSQLState()))
return;
fireConnectionFatalError(e);
}
/**
* Instead of declaring a class implementing Connection, which would have
* to be updated for every JDK rev, use a dynamic proxy to handle all
* calls through the Connection interface. This is the part that
* requires JDK 1.3 or higher, though JDK 1.2 could be supported with a
* 3rd-party proxy package.
*/
private class ConnectionHandler implements InvocationHandler
{
private Connection con;
private Connection proxy; // the Connection the client is currently using, which is a proxy
private boolean automatic = false;
public ConnectionHandler(Connection con)
{
this.con = con;
}
public Object invoke(Object proxy, Method method, Object[] args)
throws Throwable
{
// From Object
if (method.getDeclaringClass().getName().equals("java.lang.Object"))
{
if (method.getName().equals("toString"))
{
return "Pooled connection wrapping physical connection " + con;
}
if (method.getName().equals("hashCode"))
{
return new Integer(con.hashCode());
}
if (method.getName().equals("equals"))
{
if (args[0] == null)
{
return Boolean.FALSE;
}
try
{
return Proxy.isProxyClass(args[0].getClass()) && ((ConnectionHandler) Proxy.getInvocationHandler(args[0])).con == con ? Boolean.TRUE : Boolean.FALSE;
}
catch (ClassCastException e)
{
return Boolean.FALSE;
}
}
try
{
return method.invoke(con, args);
}
catch (InvocationTargetException e)
{
throw e.getTargetException();
}
}
// All the rest is from the Connection or PGConnection interface
if (method.getName().equals("isClosed"))
{
return con == null ? Boolean.TRUE : Boolean.FALSE;
}
if (con == null && !method.getName().equals("close"))
{
throw new PSQLException(automatic ? GT.tr("Connection has been closed automatically because a new connection was opened for the same PooledConnection or the PooledConnection has been closed.") : GT.tr("Connection has been closed."),
PSQLState.CONNECTION_DOES_NOT_EXIST);
}
if (method.getName().equals("close"))
{
// we are already closed and a double close
// is not an error.
if (con == null)
return null;
SQLException ex = null;
if (!isXA && !con.getAutoCommit())
{
try
{
con.rollback();
}
catch (SQLException e)
{
ex = e;
}
}
con.clearWarnings();
con = null;
this.proxy = null;
last = null;
fireConnectionClosed();
if (ex != null)
{
throw ex;
}
return null;
}
// From here on in, we invoke via reflection, catch exceptions,
// and check if they're fatal before rethrowing.
try {
if (method.getName().equals("createStatement"))
{
Statement st = (Statement)method.invoke(con, args);
return Proxy.newProxyInstance(getClass().getClassLoader(), new Class[]{Statement.class, org.postgresql.PGStatement.class}, new StatementHandler(this, st));
}
else if (method.getName().equals("prepareCall"))
{
Statement st = (Statement)method.invoke(con, args);
return Proxy.newProxyInstance(getClass().getClassLoader(), new Class[]{CallableStatement.class, org.postgresql.PGStatement.class}, new StatementHandler(this, st));
}
else if (method.getName().equals("prepareStatement"))
{
Statement st = (Statement)method.invoke(con, args);
return Proxy.newProxyInstance(getClass().getClassLoader(), new Class[]{PreparedStatement.class, org.postgresql.PGStatement.class}, new StatementHandler(this, st));
}
else
{
return method.invoke(con, args);
}
} catch (InvocationTargetException e) {
Throwable te = e.getTargetException();
if (te instanceof SQLException)
fireConnectionError((SQLException)te); // Tell listeners about exception if it's fatal
throw te;
}
}
Connection getProxy() {
return proxy;
}
void setProxy(Connection proxy) {
this.proxy = proxy;
}
public void close()
{
if (con != null)
{
automatic = true;
}
con = null;
proxy = null;
// No close event fired here: see JDBC 2.0 Optional Package spec section 6.3
}
public boolean isClosed() {
return con == null;
}
}
/**
* Instead of declaring classes implementing Statement, PreparedStatement,
* and CallableStatement, which would have to be updated for every JDK rev,
* use a dynamic proxy to handle all calls through the Statement
* interfaces. This is the part that requires JDK 1.3 or higher, though
* JDK 1.2 could be supported with a 3rd-party proxy package.
*
* The StatementHandler is required in order to return the proper
* Connection proxy for the getConnection method.
*/
private class StatementHandler implements InvocationHandler {
private AbstractJdbc23PooledConnection.ConnectionHandler con;
private Statement st;
public StatementHandler(AbstractJdbc23PooledConnection.ConnectionHandler con, Statement st) {
this.con = con;
this.st = st;
}
public Object invoke(Object proxy, Method method, Object[] args)
throws Throwable
{
// From Object
if (method.getDeclaringClass().getName().equals("java.lang.Object"))
{
if (method.getName().equals("toString"))
{
return "Pooled statement wrapping physical statement " + st;
}
if (method.getName().equals("hashCode"))
{
return new Integer(st.hashCode());
}
if (method.getName().equals("equals"))
{
if (args[0] == null)
{
return Boolean.FALSE;
}
try
{
return Proxy.isProxyClass(args[0].getClass()) && ((StatementHandler) Proxy.getInvocationHandler(args[0])).st == st ? Boolean.TRUE : Boolean.FALSE;
}
catch (ClassCastException e)
{
return Boolean.FALSE;
}
}
return method.invoke(st, args);
}
// All the rest is from the Statement interface
if (method.getName().equals("close"))
{
// closing an already closed object is a no-op
if (st == null || con.isClosed())
return null;
try
{
st.close();
}
finally
{
con = null;
st = null;
}
return null;
}
if (st == null || con.isClosed())
{
throw new PSQLException(GT.tr("Statement has been closed."),
PSQLState.OBJECT_NOT_IN_STATE);
}
if (method.getName().equals("getConnection"))
{
return con.getProxy(); // the proxied connection, not a physical connection
}
try
{
return method.invoke(st, args);
} catch (InvocationTargetException e) {
Throwable te = e.getTargetException();
if (te instanceof SQLException)
fireConnectionError((SQLException)te); // Tell listeners about exception if it's fatal
throw te;
}
}
}
}