/**
* 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.
* <p>
*/
package org.olat.commons.coordinate.singlevm;
import java.util.ArrayList;
import java.util.Collections;
import java.util.HashMap;
import java.util.Iterator;
import java.util.List;
import java.util.Map;
import java.util.Map.Entry;
import org.olat.core.CoreSpringFactory;
import org.olat.core.gui.control.Event;
import org.olat.core.id.Identity;
import org.olat.core.id.OLATResourceable;
import org.olat.core.logging.OLog;
import org.olat.core.logging.Tracing;
import org.olat.core.util.SignOnOffEvent;
import org.olat.core.util.UserSession;
import org.olat.core.util.coordinate.LockEntry;
import org.olat.core.util.coordinate.LockResult;
import org.olat.core.util.coordinate.LockResultImpl;
import org.olat.core.util.coordinate.Locker;
import org.olat.core.util.coordinate.PersistentLockManager;
import org.olat.core.util.event.EventBus;
import org.olat.core.util.event.GenericEventListener;
import org.olat.core.util.resource.OresHelper;
/**
* Description:<br>
* implementation of the olat system bus within one vm
*
* <P>
* Initial Date: 19.09.2007 <br>
*
* @author Felix Jost, http://www.goodsolutions.ch
*/
public class SingleVMLocker implements Locker, GenericEventListener {
private static final OLog log = Tracing.createLoggerFor(SingleVMLocker.class);
private PersistentLockManager plm = null;
// lock for the persistent lock manager
private final Object PERS_LOCK = new Object();
private Map<String, LockEntry> locks = new HashMap<String, LockEntry>(); // key, lockentry
private EventBus eventBus;
SingleVMLocker() { // singleton
}
/**
* [used by spring]
*/
public void init() {
eventBus.registerFor(this, null,
OresHelper.createOLATResourceableType(UserSession.class));
}
/**
* [used by spring]
* @param eventBus
*/
public void setEventBus(EventBus eventBus) {
this.eventBus = eventBus;
}
/**
* @param ores the OLATResourceable to lock upon, e.g a repositoryentry or such
* @param identity the identity who tries to acquire the lock
* @param locksubkey null or any string to lock finer upon the resource (e.g. "authors", or "write", ...)
* @return lock result
*/
public LockResult acquireLock(OLATResourceable ores, Identity identity, String locksubkey) {
String derivedLockString = OresHelper.createStringRepresenting(ores, locksubkey);
return acquireLock(derivedLockString, identity);
}
/**
* releases the lock. can also be called if the lock was not sucessfully
* acquired
*
* @param le the LockResult received when locking
*/
public void releaseLock(LockResult lockResult) {
// if the lock has not been acquired, then nothing is to be released -
// return silently to make cleaning up easier
if (!lockResult.isSuccess()) {
return;
}
LockEntry le = ((LockResultImpl) lockResult).getLockEntry();
releaseLock(le);
}
/**
* @param ores
* @param locksubkey
* @return if the olatresourceable with the subkey is already locked by
* someone (returns true even if locked by "myself")
*/
public boolean isLocked(OLATResourceable ores, String locksubkey) {
String derivedLockString = OresHelper.createStringRepresenting(ores, locksubkey);
return isLocked(derivedLockString);
}
private boolean isLocked(Object key) {
synchronized (locks) { //o_clusterOK by:fj, by definition we are in singleVM mode
return locks.get(key) != null;
}
}
/**
* aquires a lock
*
* @param identity
* the identity who wishes to obtain the lock
* @return the lockresult
*/
private LockResult acquireLock(String key, Identity identity) {
LockResult lockResult;
boolean logDebug = log.isDebug();
synchronized (locks) { //o_clusterOK by:fj, by definition we are in singleVM mode
LockEntry oldLockEntry = locks.get(key);
if (oldLockEntry == null || identity.getName().equals(oldLockEntry.getOwner().getName())) {
// no one has the lock aquired yet - or user reacquired its own
// lock (e.g. in case of browser crash or such)
LockEntry lockEntry = new LockEntry(key, System.currentTimeMillis(), identity);
locks.put(key, lockEntry);
lockResult = new LockResultImpl(true, lockEntry);
if (logDebug) {
String msg;
if (oldLockEntry == null) {
msg = "identity '" + identity.getName() + "' acquired lock on " + key;
} else {
msg = "identity '" + identity.getName() + "' re-acquired lock on " + key;
}
log.audit(msg);
}
} else {
// already locked
lockResult = new LockResultImpl(false, oldLockEntry);
}
}
return lockResult;
}
private void releaseLock(LockEntry lockEntry) {
synchronized (locks) { //o_clusterOK by:fj, by definition we are in singleVM mode
boolean removed = locks.values().remove(lockEntry);
if (removed) {
log.audit("identity '" + lockEntry.getOwner().getName() + "' released lock on " + lockEntry.getKey());
} else {
log.warn("identity '" + lockEntry.getOwner().getName() + "' tried to release lock a non-existing lock on "+ lockEntry.getKey());
}
}
}
/**
* receives all sign on / sign off events so it can release locks of users
* which have or are logged off
*
* @see org.olat.core.util.event.GenericEventListener#event(org.olat.core.gui.control.Event)
*/
public void event(Event event) {
SignOnOffEvent se = (SignOnOffEvent) event;
if (!se.isSignOn()) { // it is a "logout" event - we are only interested in logout events
String name = se.getIdentityName();
// release all locks hold by the identity that has just logged out.
synchronized (locks) { //o_clusterOK by:fj, by definition we are in singleVM mode
for (Iterator<Entry<String, LockEntry>> iter = locks.entrySet().iterator(); iter.hasNext();) {
Map.Entry<String, LockEntry> entry = iter.next();
String key = entry.getKey();
LockEntry le = entry.getValue();
Identity owner = le.getOwner();
if (owner.getName().equals(name)) {
iter.remove();
log.audit("identity '" + name + "' signed off and thus released lock on " + key);
}
}
}
}
}
/**
* @see java.lang.Object#toString()
*/
public String toString() {
return "Lockmanager locks:" + locks.entrySet().toString();
}
public LockResult aquirePersistentLock(OLATResourceable ores, Identity ident, String locksubkey) {
synchronized (PERS_LOCK) { //o_clusterOK by:fj, by definition we are in singleVM mode
if (plm == null) { // lazy init because the impl is not defined in the core spring config
plm = (PersistentLockManager) CoreSpringFactory.getBean(PersistentLockManager.class);
}
// delegate
return plm.aquirePersistentLock(ores, ident, locksubkey);
}
}
/**
*
* @see org.olat.core.util.coordinate.PersistentLockManager#releasePersistentLock(org.olat.core.util.coordinate.LockResult)
*/
public void releasePersistentLock(LockResult lockResult) {
// if the lock has not been acquired, do nothing
if (!lockResult.isSuccess())
return;
synchronized (PERS_LOCK) { //o_clusterOK by:fj, by definition we are in singleVM mode
if (plm == null) { // lazy init because the impl is not defined in the core spring config
plm = (PersistentLockManager) CoreSpringFactory.getBean(PersistentLockManager.class);
}
// delegate
plm.releasePersistentLock(lockResult);
}
}
/* (non-Javadoc)
* @see org.olat.core.util.coordinate.Locker#adminOnlyGetLockEntries()
*/
public List<LockEntry> adminOnlyGetLockEntries() {
return Collections.unmodifiableList(new ArrayList<LockEntry>(locks.values()));
}
}