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Java JDBC 4.2 (JRE 8+) driver for PostgreSQL database
/*
* Copyright (c) 2004, PostgreSQL Global Development Group.
* See the LICENSE file in the project root for more information.
*/
package org.postgresql.ds;
import org.postgresql.PGConnection;
import org.postgresql.util.GT;
import org.postgresql.util.PSQLException;
import org.postgresql.util.PSQLState;
import java.lang.reflect.InvocationHandler;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
import java.lang.reflect.Proxy;
import java.sql.CallableStatement;
import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.SQLException;
import java.sql.Statement;
import java.util.LinkedList;
import java.util.List;
import javax.sql.ConnectionEvent;
import javax.sql.ConnectionEventListener;
import javax.sql.PooledConnection;
import javax.sql.StatementEventListener;
/**
* PostgreSQL implementation of the PooledConnection interface. This shouldn't be used directly, as
* the pooling client should just interact with the ConnectionPool instead.
*
* @author Aaron Mulder ([email protected])
* @author Csaba Nagy ([email protected])
* @see org.postgresql.ds.PGConnectionPoolDataSource
*/
public class PGPooledConnection implements PooledConnection {
private final 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.
*
* @param con connection
* @param autoCommit whether to autocommit
* @param isXA whether connection is a XA connection
*/
public PGPooledConnection(Connection con, boolean autoCommit, boolean isXA) {
this.con = con;
this.autoCommit = autoCommit;
this.isXA = isXA;
}
public PGPooledConnection(Connection con, boolean autoCommit) {
this(con, autoCommit, false);
}
/**
* Adds a listener for close or fatal error events on the connection handed out to a client.
*/
@Override
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.
*/
@Override
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.
*/
@Override
public void close() throws SQLException {
if (last != null) {
last.close();
if (!con.isClosed()) {
if (!con.getAutoCommit()) {
try {
con.rollback();
} catch (SQLException ignored) {
}
}
}
}
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.
*
*
* 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.
*
*/
@Override
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 occurs while opening a new connection, the listeners
// have to be notified. This gives a chance to connection pools to
// eliminate 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 ignored) {
}
}
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 =
listeners.toArray(new ConnectionEventListener[listeners.size()]);
for (ConnectionEventListener listener : local) {
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 =
listeners.toArray(new ConnectionEventListener[listeners.size()]);
for (ConnectionEventListener listener : local) {
if (evt == null) {
evt = createConnectionEvent(e);
}
listener.connectionErrorOccurred(evt);
}
}
protected ConnectionEvent createConnectionEvent(SQLException e) {
return new ConnectionEvent(this, 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 (String fatalClass : fatalClasses) {
if (state.startsWith(fatalClass)) {
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;
ConnectionHandler(Connection con) {
this.con = con;
}
@Override
public Object invoke(Object proxy, Method method, Object[] args) throws Throwable {
final String methodName = method.getName();
// From Object
if (method.getDeclaringClass() == Object.class) {
if (methodName.equals("toString")) {
return "Pooled connection wrapping physical connection " + con;
}
if (methodName.equals("equals")) {
return proxy == args[0];
}
if (methodName.equals("hashCode")) {
return System.identityHashCode(proxy);
}
try {
return method.invoke(con, args);
} catch (InvocationTargetException e) {
throw e.getTargetException();
}
}
// All the rest is from the Connection or PGConnection interface
if (methodName.equals("isClosed")) {
return con == null || con.isClosed();
}
if (methodName.equals("close")) {
// we are already closed and a double close
// is not an error.
if (con == null) {
return null;
}
SQLException ex = null;
if (!con.isClosed()) {
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;
}
if (con == null || con.isClosed()) {
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);
}
// From here on in, we invoke via reflection, catch exceptions,
// and check if they're fatal before rethrowing.
try {
if (methodName.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 (methodName.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 (methodName.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 (final InvocationTargetException ite) {
final Throwable te = ite.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 ConnectionHandler con;
private Statement st;
StatementHandler(ConnectionHandler con, Statement st) {
this.con = con;
this.st = st;
}
@Override
public Object invoke(Object proxy, Method method, Object[] args) throws Throwable {
final String methodName = method.getName();
// From Object
if (method.getDeclaringClass() == Object.class) {
if (methodName.equals("toString")) {
return "Pooled statement wrapping physical statement " + st;
}
if (methodName.equals("hashCode")) {
return System.identityHashCode(proxy);
}
if (methodName.equals("equals")) {
return proxy == args[0];
}
return method.invoke(st, args);
}
// All the rest is from the Statement interface
if (methodName.equals("isClosed")) {
return st == null || st.isClosed();
}
if (methodName.equals("close")) {
if (st == null || st.isClosed()) {
return null;
}
con = null;
final Statement oldSt = st;
st = null;
oldSt.close();
return null;
}
if (st == null || st.isClosed()) {
throw new PSQLException(GT.tr("Statement has been closed."), PSQLState.OBJECT_NOT_IN_STATE);
}
if (methodName.equals("getConnection")) {
return con.getProxy(); // the proxied connection, not a physical connection
}
// Delegate the call to the proxied Statement.
try {
return method.invoke(st, args);
} catch (final InvocationTargetException ite) {
final Throwable te = ite.getTargetException();
if (te instanceof SQLException) {
fireConnectionError((SQLException) te); // Tell listeners about exception if it's fatal
}
throw te;
}
}
}
@Override
public void removeStatementEventListener(StatementEventListener listener) {
}
@Override
public void addStatementEventListener(StatementEventListener listener) {
}
}