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/*
 * Hibernate, Relational Persistence for Idiomatic Java
 *
 * Copyright (c) 2008, Red Hat Middleware LLC or third-party contributors as
 * indicated by the @author tags or express copyright attribution
 * statements applied by the authors.  All third-party contributions are
 * distributed under license by Red Hat Middleware LLC.
 *
 * This copyrighted material is made available to anyone wishing to use, modify,
 * copy, or redistribute it subject to the terms and conditions of the GNU
 * Lesser General Public License, as published by the Free Software Foundation.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
 * or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU Lesser General Public License
 * for more details.
 *
 * You should have received a copy of the GNU Lesser General Public License
 * along with this distribution; if not, write to:
 * Free Software Foundation, Inc.
 * 51 Franklin Street, Fifth Floor
 * Boston, MA  02110-1301  USA
 *
 */
package org.hibernate.jdbc;

import java.io.IOException;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;
import java.io.Serializable;
import java.sql.Connection;
import java.sql.SQLException;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.hibernate.ConnectionReleaseMode;
import org.hibernate.HibernateException;
import org.hibernate.Interceptor;
import org.hibernate.engine.SessionFactoryImplementor;
import org.hibernate.exception.JDBCExceptionHelper;
import org.hibernate.util.JDBCExceptionReporter;

/**
 * Encapsulates JDBC Connection management logic needed by Hibernate.
 * 

* The lifecycle is intended to span a logical series of interactions with the * database. Internally, this means the the lifecycle of the Session. * * @author Steve Ebersole */ public class ConnectionManager implements Serializable { private static final Logger log = LoggerFactory.getLogger( ConnectionManager.class ); public static interface Callback { public void connectionOpened(); public void connectionCleanedUp(); public boolean isTransactionInProgress(); } private transient SessionFactoryImplementor factory; private final Callback callback; private final ConnectionReleaseMode releaseMode; private transient Connection connection; private transient Connection borrowedConnection; private final boolean wasConnectionSupplied; private transient Batcher batcher; private transient Interceptor interceptor; private boolean isClosed; private transient boolean isFlushing; /** * Constructs a ConnectionManager. *

* This is the form used internally. * * @param factory The SessionFactory. * @param callback An observer for internal state change. * @param releaseMode The mode by which to release JDBC connections. * @param connection An externally supplied connection. */ public ConnectionManager( SessionFactoryImplementor factory, Callback callback, ConnectionReleaseMode releaseMode, Connection connection, Interceptor interceptor) { this.factory = factory; this.callback = callback; this.interceptor = interceptor; this.batcher = factory.getSettings().getBatcherFactory().createBatcher( this, interceptor ); this.connection = connection; wasConnectionSupplied = ( connection != null ); this.releaseMode = wasConnectionSupplied ? ConnectionReleaseMode.ON_CLOSE : releaseMode; } /** * Private constructor used exclusively from custom serialization */ private ConnectionManager( SessionFactoryImplementor factory, Callback callback, ConnectionReleaseMode releaseMode, Interceptor interceptor, boolean wasConnectionSupplied, boolean isClosed) { this.factory = factory; this.callback = callback; this.interceptor = interceptor; this.batcher = factory.getSettings().getBatcherFactory().createBatcher( this, interceptor ); this.wasConnectionSupplied = wasConnectionSupplied; this.isClosed = isClosed; this.releaseMode = wasConnectionSupplied ? ConnectionReleaseMode.ON_CLOSE : releaseMode; } /** * The session factory. * * @return the session factory. */ public SessionFactoryImplementor getFactory() { return factory; } /** * The batcher managed by this ConnectionManager. * * @return The batcher. */ public Batcher getBatcher() { return batcher; } /** * Was the connection being used here supplied by the user? * * @return True if the user supplied the JDBC connection; false otherwise */ public boolean isSuppliedConnection() { return wasConnectionSupplied; } /** * Retrieves the connection currently managed by this ConnectionManager. *

* Note, that we may need to obtain a connection to return here if a * connection has either not yet been obtained (non-UserSuppliedConnectionProvider) * or has previously been aggressively released (if supported in this environment). * * @return The current Connection. * * @throws HibernateException Indicates a connection is currently not * available (we are currently manually disconnected). */ public Connection getConnection() throws HibernateException { if ( isClosed ) { throw new HibernateException( "connection manager has been closed" ); } if ( connection == null ) { openConnection(); } return connection; } public boolean hasBorrowedConnection() { // used from testsuite return borrowedConnection != null; } public Connection borrowConnection() { if ( isClosed ) { throw new HibernateException( "connection manager has been closed" ); } if ( isSuppliedConnection() ) { return connection; } else { if ( borrowedConnection == null ) { borrowedConnection = BorrowedConnectionProxy.generateProxy( this ); } return borrowedConnection; } } public void releaseBorrowedConnection() { if ( borrowedConnection != null ) { try { BorrowedConnectionProxy.renderUnuseable( borrowedConnection ); } finally { borrowedConnection = null; } } } /** * Is the connection considered "auto-commit"? * * @return True if we either do not have a connection, or the connection * really is in auto-commit mode. * * @throws SQLException Can be thrown by the Connection.isAutoCommit() check. */ public boolean isAutoCommit() throws SQLException { return connection == null || connection.isClosed() || connection.getAutoCommit(); } /** * Will connections be released after each statement execution? *

* Connections will be released after each statement if either:

    *
  • the defined release-mode is {@link ConnectionReleaseMode#AFTER_STATEMENT}; or *
  • the defined release-mode is {@link ConnectionReleaseMode#AFTER_TRANSACTION} but * we are in auto-commit mode. *

    * release-mode = {@link ConnectionReleaseMode#ON_CLOSE} should [b]never[/b] release * a connection. * * @return True if the connections will be released after each statement; false otherwise. */ public boolean isAggressiveRelease() { if ( releaseMode == ConnectionReleaseMode.AFTER_STATEMENT ) { return true; } else if ( releaseMode == ConnectionReleaseMode.AFTER_TRANSACTION ) { boolean inAutoCommitState; try { inAutoCommitState = isAutoCommit()&& !callback.isTransactionInProgress(); } catch( SQLException e ) { // assume we are in an auto-commit state inAutoCommitState = true; } return inAutoCommitState; } return false; } /** * Modified version of {@link #isAggressiveRelease} which does not force a * transaction check. This is solely used from our {@link #afterTransaction} * callback, so no need to do the check; plus it seems to cause problems on * websphere (god i love websphere ;) *

    * It uses this information to decide if an aggressive release was skipped * do to open resources, and if so forces a release. * * @return True if the connections will be released after each statement; false otherwise. */ private boolean isAggressiveReleaseNoTransactionCheck() { if ( releaseMode == ConnectionReleaseMode.AFTER_STATEMENT ) { return true; } else { boolean inAutoCommitState; try { inAutoCommitState = isAutoCommit(); } catch( SQLException e ) { // assume we are in an auto-commit state inAutoCommitState = true; } return releaseMode == ConnectionReleaseMode.AFTER_TRANSACTION && inAutoCommitState; } } /** * Is this ConnectionManager instance "logically" connected. Meaning * do we either have a cached connection available or do we have the * ability to obtain a connection on demand. * * @return True if logically connected; false otherwise. */ public boolean isCurrentlyConnected() { return wasConnectionSupplied ? connection != null : !isClosed; } /** * To be called after execution of each JDBC statement. Used to * conditionally release the JDBC connection aggressively if * the configured release mode indicates. */ public void afterStatement() { if ( isAggressiveRelease() ) { if ( isFlushing ) { log.debug( "skipping aggressive-release due to flush cycle" ); } else if ( batcher.hasOpenResources() ) { log.debug( "skipping aggresive-release due to open resources on batcher" ); } else if ( borrowedConnection != null ) { log.debug( "skipping aggresive-release due to borrowed connection" ); } else { aggressiveRelease(); } } } /** * To be called after local transaction completion. Used to conditionally * release the JDBC connection aggressively if the configured release mode * indicates. */ public void afterTransaction() { if ( isAfterTransactionRelease() ) { aggressiveRelease(); } else if ( isAggressiveReleaseNoTransactionCheck() && batcher.hasOpenResources() ) { log.info( "forcing batcher resource cleanup on transaction completion; forgot to close ScrollableResults/Iterator?" ); batcher.closeStatements(); aggressiveRelease(); } else if ( isOnCloseRelease() ) { // log a message about potential connection leaks log.debug( "transaction completed on session with on_close connection release mode; be sure to close the session to release JDBC resources!" ); } batcher.unsetTransactionTimeout(); } private boolean isAfterTransactionRelease() { return releaseMode == ConnectionReleaseMode.AFTER_TRANSACTION; } private boolean isOnCloseRelease() { return releaseMode == ConnectionReleaseMode.ON_CLOSE; } /** * To be called after Session completion. Used to release the JDBC * connection. * * @return The connection mantained here at time of close. Null if * there was no connection cached internally. */ public Connection close() { try { return cleanup(); } finally { isClosed = true; } } /** * Manually disconnect the underlying JDBC Connection. The assumption here * is that the manager will be reconnected at a later point in time. * * @return The connection mantained here at time of disconnect. Null if * there was no connection cached internally. */ public Connection manualDisconnect() { return cleanup(); } /** * Manually reconnect the underlying JDBC Connection. Should be called at * some point after manualDisconnect(). *

    * This form is used for ConnectionProvider-supplied connections. */ public void manualReconnect() { } /** * Manually reconnect the underlying JDBC Connection. Should be called at * some point after manualDisconnect(). *

    * This form is used for user-supplied connections. */ public void manualReconnect(Connection suppliedConnection) { this.connection = suppliedConnection; } /** * Releases the Connection and cleans up any resources associated with * that Connection. This is intended for use: * 1) at the end of the session * 2) on a manual disconnect of the session * 3) from afterTransaction(), in the case of skipped aggressive releasing * * @return The released connection. * @throws HibernateException */ private Connection cleanup() throws HibernateException { releaseBorrowedConnection(); if ( connection == null ) { log.trace( "connection already null in cleanup : no action"); return null; } try { log.trace( "performing cleanup" ); batcher.closeStatements(); Connection c = null; if ( !wasConnectionSupplied ) { closeConnection(); } else { c = connection; } connection = null; return c; } finally { callback.connectionCleanedUp(); } } /** * Performs actions required to perform an aggressive release of the * JDBC Connection. */ private void aggressiveRelease() { if ( !wasConnectionSupplied ) { log.debug( "aggressively releasing JDBC connection" ); if ( connection != null ) { closeConnection(); } } } /** * Pysically opens a JDBC Connection. * * @throws HibernateException */ private void openConnection() throws HibernateException { if ( connection != null ) { return; } log.debug("opening JDBC connection"); try { connection = factory.getConnectionProvider().getConnection(); } catch (SQLException sqle) { throw JDBCExceptionHelper.convert( factory.getSQLExceptionConverter(), sqle, "Cannot open connection" ); } callback.connectionOpened(); // register synch; stats.connect() } /** * Physically closes the JDBC Connection. */ private void closeConnection() { if ( log.isDebugEnabled() ) { log.debug( "releasing JDBC connection [" + batcher.openResourceStatsAsString() + "]" ); } try { if ( !connection.isClosed() ) { JDBCExceptionReporter.logAndClearWarnings( connection ); } factory.getConnectionProvider().closeConnection( connection ); connection = null; } catch (SQLException sqle) { throw JDBCExceptionHelper.convert( factory.getSQLExceptionConverter(), sqle, "Cannot release connection" ); } } /** * Callback to let us know that a flush is beginning. We use this fact * to temporarily circumvent aggressive connection releasing until after * the flush cycle is complete {@link #flushEnding()} */ public void flushBeginning() { log.trace( "registering flush begin" ); isFlushing = true; } /** * Callback to let us know that a flush is ending. We use this fact to * stop circumventing aggressive releasing connections. */ public void flushEnding() { log.trace( "registering flush end" ); isFlushing = false; afterStatement(); } public boolean isReadyForSerialization() { return wasConnectionSupplied ? connection == null : !batcher.hasOpenResources(); } /** * Used during serialization. * * @param oos The stream to which we are being written. * @throws IOException Indicates an I/O error writing to the stream */ private void writeObject(ObjectOutputStream oos) throws IOException { if ( !isReadyForSerialization() ) { throw new IllegalStateException( "Cannot serialize a ConnectionManager while connected" ); } oos.writeObject( factory ); oos.writeObject( interceptor ); oos.defaultWriteObject(); } /** * Used during deserialization. * * @param ois The stream from which we are being read. * @throws IOException Indicates an I/O error reading the stream * @throws ClassNotFoundException Indicates resource class resolution. */ private void readObject(ObjectInputStream ois) throws IOException, ClassNotFoundException { factory = (SessionFactoryImplementor) ois.readObject(); interceptor = (Interceptor) ois.readObject(); ois.defaultReadObject(); this.batcher = factory.getSettings().getBatcherFactory().createBatcher( this, interceptor ); } public void serialize(ObjectOutputStream oos) throws IOException { oos.writeBoolean( wasConnectionSupplied ); oos.writeBoolean( isClosed ); } public static ConnectionManager deserialize( ObjectInputStream ois, SessionFactoryImplementor factory, Interceptor interceptor, ConnectionReleaseMode connectionReleaseMode, JDBCContext jdbcContext) throws IOException { return new ConnectionManager( factory, jdbcContext, connectionReleaseMode, interceptor, ois.readBoolean(), ois.readBoolean() ); } }





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