org.olat.core.util.coordinate.DBPersistentLockManager.java Source code

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Here is the source code for org.olat.core.util.coordinate.DBPersistentLockManager.java

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/**
* 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 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";

    /**
     * [used by spring]
     * @param userDeletionManager
     */
    private DBPersistentLockManager() {
        //
    }

    /**
     * @see org.olat.core.util.locks.PersistentLockManager#aquirePersistentLock(org.olat.core.id.OLATResourceable,
     *      org.olat.core.id.Identity, java.lang.String)
     */
    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)
     */
    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)
     */
    public void deleteUserData(Identity identity, String newDeletedUserName) {
        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);
    }

}