DBPersistentLockManager.java

/**
* OLAT - Online Learning and Training<br>
* http://www.olat.org
* <p>
* Licensed under the Apache License, Version 2.0 (the "License"); <br>
* you may not use this file except in compliance with the License.<br>
* You may obtain a copy of the License at
* <p>
* http://www.apache.org/licenses/LICENSE-2.0
* <p>
* Unless required by applicable law or agreed to in writing,<br>
* software distributed under the License is distributed on an "AS IS" BASIS, <br>
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. <br>
* See the License for the specific language governing permissions and <br>
* limitations under the License.
* <p>
* Copyright (c) since 2004 at Multimedia- & E-Learning Services (MELS),<br>
* University of Zurich, Switzerland.
* <hr>
* <a href="http://www.openolat.org">
* OpenOLAT - Online Learning and Training</a><br>
* This file has been modified by the OpenOLAT community. Changes are licensed
* under the Apache 2.0 license as the original file.
*/
package org.olat.core.util.coordinate;

import java.io.File;

import org.hibernate.type.StandardBasicTypes;
import org.hibernate.type.Type;
import org.olat.basesecurity.BaseSecurityManager;
import org.olat.core.commons.persistence.DBFactory;
import org.olat.core.id.Identity;
import org.olat.core.id.OLATResourceable;
import org.olat.core.logging.AssertException;
import org.olat.core.logging.OLog;
import org.olat.core.logging.Tracing;
import org.olat.core.util.resource.OresHelper;
import org.olat.properties.Property;
import org.olat.properties.PropertyManager;
import org.olat.user.UserDataDeletable;

/**
 * Description:<br>
 * TODO: patrickb Class Description for DBPersistentLockManager
 * <P>
 * Initial Date: 21.06.2006 <br>
 * 
 * @author patrickb
 */
public class DBPersistentLockManager implements PersistentLockManager, UserDataDeletable {
	
	private static final OLog log = Tracing.createLoggerFor(DBPersistentLockManager.class);
	private static final String CATEGORY_PERSISTENTLOCK = "o_lock";
	

	/**
	 * @see org.olat.core.util.locks.PersistentLockManager#aquirePersistentLock(org.olat.core.id.OLATResourceable,
	 *      org.olat.core.id.Identity, java.lang.String)
	 */
	@Override
	public LockResult aquirePersistentLock(OLATResourceable ores, Identity ident, String locksubkey) {
		//synchronisation is solved in the LockManager
		LockResult lres;
		PropertyManager pm = PropertyManager.getInstance();
		String derivedLockString = OresHelper.createStringRepresenting(ores, locksubkey);
		long aqTime;
		Identity lockOwner;
		boolean success;
		Property p;

		p = pm.findProperty(null, null, null, CATEGORY_PERSISTENTLOCK, derivedLockString);
		if (p == null) {
			// no persistent lock acquired yet
			// save a property: cat = o_lock, key = derivedLockString, Longvalue = key
			// of identity acquiring the lock
			Property newp = pm.createPropertyInstance(null, null, null, CATEGORY_PERSISTENTLOCK, derivedLockString, null, ident.getKey(), null,
					null);
			pm.saveProperty(newp);
			aqTime = System.currentTimeMillis();
			lockOwner = ident;
			success = true;
		} else {
			// already acquired, but check on reaquiring
			aqTime = p.getLastModified().getTime();
			Long lockOwnerKey = p.getLongValue();
			if (ident.getKey().equals(lockOwnerKey)) {
				// reaquire ok
				success = true;
			} else {
				// already locked by an other person
				success = false;
			}
			// FIXME:fj:c find a better way to retrieve information about the
			// lock-holder
			lockOwner = BaseSecurityManager.getInstance().loadIdentityByKey(lockOwnerKey);
		}
		
		LockEntry le = new LockEntry(derivedLockString, aqTime, lockOwner);
		lres = new LockResultImpl(success, le);
		return lres;
		
	}

	/**
	 * @see org.olat.core.util.locks.PersistentLockManager#releasePersistentLock(org.olat.core.util.locks.LockEntry)
	 */
	@Override
	public void releasePersistentLock(LockResult le) {
		//synchronisation is solved in the LockManager
		String derivedLockString = ((LockResultImpl)le).getLockEntry().getKey();
		PropertyManager pm = PropertyManager.getInstance();
		Property p = pm.findProperty(null, null, null, CATEGORY_PERSISTENTLOCK, derivedLockString);
		if (p == null) throw new AssertException("could not release lock: no lock in db, " + derivedLockString);
		Identity ident = le.getOwner();
		Long ownerKey = p.getLongValue();
		if (!ownerKey.equals(ident.getKey())) throw new AssertException("user " + ident.getName()
				+ " cannot release lock belonging to user with key " + ownerKey + " on resourcestring " + derivedLockString);
		pm.deleteProperty(p);
	}

	/**
	 * Delete all persisting-locks for certain identity.
	 * @see org.olat.user.UserDataDeletable#deleteUserData(org.olat.core.id.Identity)
	 */
	@Override
	public void deleteUserData(Identity identity, String newDeletedUserName, File archivePath) {		
		String query = "from v in class org.olat.properties.Property where v.category = ? and v.longValue = ?";
		DBFactory.getInstance().delete(query, new Object[] { CATEGORY_PERSISTENTLOCK, identity.getKey() },
				new Type[] { StandardBasicTypes.STRING, StandardBasicTypes.LONG });
		log.debug("All db-persisting-locks deleted for identity=" + identity);
	}

}