001: /*
002: * ====================================================================
003: * JAFFA - Java Application Framework For All
004: *
005: * Copyright (C) 2002 JAFFA Development Group
006: *
007: * This library is free software; you can redistribute it and/or
008: * modify it under the terms of the GNU Lesser General Public
009: * License as published by the Free Software Foundation; either
010: * version 2.1 of the License, or (at your option) any later version.
011: *
012: * This library is distributed in the hope that it will be useful,
013: * but WITHOUT ANY WARRANTY; without even the implied warranty of
014: * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
015: * Lesser General Public License for more details.
016: *
017: * You should have received a copy of the GNU Lesser General Public
018: * License along with this library; if not, write to the Free Software
019: * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
020: *
021: * Redistribution and use of this software and associated documentation ("Software"),
022: * with or without modification, are permitted provided that the following conditions are met:
023: * 1. Redistributions of source code must retain copyright statements and notices.
024: * Redistributions must also contain a copy of this document.
025: * 2. Redistributions in binary form must reproduce the above copyright notice,
026: * this list of conditions and the following disclaimer in the documentation
027: * and/or other materials provided with the distribution.
028: * 3. The name "JAFFA" must not be used to endorse or promote products derived from
029: * this Software without prior written permission. For written permission,
030: * please contact mail to: jaffagroup@yahoo.com.
031: * 4. Products derived from this Software may not be called "JAFFA" nor may "JAFFA"
032: * appear in their names without prior written permission.
033: * 5. Due credit should be given to the JAFFA Project (http://jaffa.sourceforge.net).
034: *
035: * THIS SOFTWARE IS PROVIDED "AS IS" AND ANY EXPRESSED OR IMPLIED
036: * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
037: * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
038: * DISCLAIMED. IN NO EVENT SHALL THE APACHE SOFTWARE FOUNDATION OR
039: * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
040: * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
041: * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
042: * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
043: * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
044: * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
045: * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
046: * SUCH DAMAGE.
047: * ====================================================================
048: */
049:
050: package org.jaffa.persistence.engines.jdbcengine.interceptor;
051:
052: import java.util.*;
053: import org.apache.log4j.Logger;
054: import org.jaffa.persistence.engines.jdbcengine.datasource.PersistentTransaction;
055: import org.jaffa.persistence.engines.jdbcengine.querygenerator.JdbcBridge;
056: import org.jaffa.persistence.IPersistent;
057: import org.jaffa.persistence.exceptions.UOWException;
058: import org.jaffa.persistence.exceptions.AlreadyLockedObjectException;
059:
060: /** This is the Interceptor which locks the Persistent objects in the database.
061: */
062: public class LockInterceptor extends AbstractInterceptor {
063:
064: private static final Logger log = Logger
065: .getLogger(LockInterceptor.class);
066:
067: /**Performs the logic associated with locking Persistent objects in the database.
068: * This will lock each object in the PersistentTransaction's UPDATE + DELETE collection in the database, utilising the JdbcBridge.
069: * It will then pass on the control to the next Interceptor in the chain.
070: * @param pt The PersistentTransaction object, on which the Interceptor is to be executed.
071: * @throws UOWException if any error occurs.
072: * @return the output from the next Interceptor in the chain.
073: */
074: public Object invoke(PersistentTransaction pt) throws UOWException {
075: lockObjects(pt, pt.getUpdates());
076: lockObjects(pt, pt.getDeletes());
077:
078: // pass control to the next interceptor in the chain
079: if (getNextInterceptor() != null) {
080: if (log.isDebugEnabled())
081: log.debug("Invoking the next Interceptor in the chain "
082: + getNextInterceptor().getClass().getName());
083: return getNextInterceptor().invoke(pt);
084: } else {
085: if (log.isDebugEnabled())
086: log.debug("This is the end of the Interceptor chain");
087: return null;
088: }
089: }
090:
091: private void lockObjects(PersistentTransaction pt,
092: Collection objects) throws AlreadyLockedObjectException {
093: if (objects != null) {
094: // locks the objects in the database
095: for (Iterator i = objects.iterator(); i.hasNext();) {
096: IPersistent object = (IPersistent) i.next();
097: try {
098: if (object.isLocked()) {
099: if (log.isDebugEnabled())
100: log
101: .debug("Already locked object "
102: + object);
103: } else {
104: if (log.isDebugEnabled())
105: log
106: .debug("Invoking JdbcBridge.executeLock() for the object "
107: + object);
108: JdbcBridge.executeLock(object, pt
109: .getDataSource());
110: }
111: } catch (Exception e) {
112: String str = "Error while locking the Persistent object in the database: "
113: + object;
114: log.error(str, e);
115: throw new AlreadyLockedObjectException(null, e);
116: }
117: }
118: }
119: }
120: }
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