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/*******************************************************************************
* Copyright (c) 2004, 2007 Boeing.
* All rights reserved. This program and the accompanying materials
* are made available under the terms of the Eclipse Public License v1.0
* which accompanies this distribution, and is available at
* http://www.eclipse.org/legal/epl-v10.html
*
* Contributors:
* Boeing - initial API and implementation
*******************************************************************************/
package org.eclipse.osee.framework.jini.lease;
import java.lang.ref.WeakReference;
import java.rmi.RemoteException;
import java.rmi.server.ExportException;
import java.util.Collections;
import java.util.HashMap;
import java.util.Iterator;
import java.util.Map;
import java.util.Map.Entry;
import java.util.Set;
import java.util.Timer;
import java.util.TimerTask;
import net.jini.core.lease.Lease;
import net.jini.core.lease.LeaseDeniedException;
import net.jini.core.lease.UnknownLeaseException;
import org.eclipse.osee.framework.jini.util.OseeJini;
/**
* This class manages tasks associated with being a lease grantor. It generates leases, handles renewal & cancelation of
* the leases, and checks the existing leases to determine if any have expired. Provides a callback by way of the
* ILeasee interface to the leasing service to notify it when a lease is canceled or expired.
*
* @author David Diepenbrock
*/
public class OseeLeaseGrantor implements ILeaseGrantor {
public static final long maxDuration = 10 * 60 * 1000; /* 10 minutes */
public static final long minDuration = 2 * 60 * 1000; /* 2 minutes */
private ILeaseGrantor thisRemoteReference;
private final Map<Object, LeaseData> leaseStore;
private final WeakReference<ILeasee> leasee;
private final LeaseChecker leaseChecker;
private final Timer myTimer;
private boolean cancelTimer;
/**
* Use of this constructor will generate a new timer thread for lease checks
*
* @param leasee The "parent" object to be notified when a lease expires or is canceled.
*/
public OseeLeaseGrantor(ILeasee leasee) {
this(leasee, new Timer());
// debug = new Debug(false, true, this.getClass().getName());
cancelTimer = true; // We will need to cancel the timer on shutdown.
}
/**
* @param leasee The "parent" object to be notified when a lease expires or is canceled
* @param timer An existing Timer thread to schedule lease checks
*/
public OseeLeaseGrantor(ILeasee leasee, Timer timer) {
this.leasee = new WeakReference<ILeasee>(leasee);
myTimer = timer;
cancelTimer = false; // If a timer was provided we don't need to cancel it on shutdown
leaseStore = Collections.synchronizedMap(new HashMap<Object, LeaseData>());
try {
thisRemoteReference = (ILeaseGrantor) OseeJini.getRemoteReference(this);
} catch (ExportException ex) {
ex.printStackTrace();
}
long leaseCheckFrequency = minDuration / 2;
leaseChecker = new LeaseChecker();
timer.schedule(leaseChecker, leaseCheckFrequency, leaseCheckFrequency);
}
/**
* Call this to notify the grantor that we are shutting down. We need to clean up the task for checking the leases.
*/
public void shutdown() {
leaseChecker.cancel();
if (cancelTimer) {
myTimer.cancel();
}
}
/**
* Returns a new lease
*
* @return Return lease reference.
*/
public OseeLease newLease(Object consumer, long duration) throws LeaseDeniedException, ExportException {
// debug.report("New Lease:" + consumer + " @" + new Date());
long actualDuration = checkDuration(duration);
OseeLease lease = new OseeLease(thisRemoteReference, consumer, actualDuration);
leaseStore.put(consumer, new LeaseData(actualDuration));
return lease;
}
/**
* Note that the consumer must reset their start timer on the lease. The Grantor cannot set the time since the system
* clocks may differ.
*
* @see org.eclipse.osee.framework.jini.lease.ILeaseGrantor#renewRequest
*/
@Override
public void renewRequest(Lease lease, Object consumer, long duration) throws LeaseDeniedException, UnknownLeaseException, RemoteException {
// debug.report("Lease renewRequest: " + consumer + " @" + new Date());
synchronized (leaseStore) {
LeaseData leaseData = leaseStore.get(consumer);
if (leaseData == null) {
throw new LeaseDeniedException("Consumer does not currently hold a lease");
}
if (lease instanceof OseeLease) {
long actualDuration = checkDuration(duration);
leaseData.setDuration(actualDuration);
leaseData.setStartTime();
((OseeLease) lease).setDuration(actualDuration);
} else {
throw new UnknownLeaseException("Unknown Lease Type");
}
}
}
@Override
public void cancelRequest(Lease lease, Object consumer) throws UnknownLeaseException, RemoteException {
// debug.report("Lease cancelRequest: " + consumer + " @" + new Date());
if (leaseStore.remove(consumer) != null) {
leasee.get().onLeaseCompleted(consumer);
}
}
public boolean isLeaseExpired(Object consumer) {
LeaseData leaseData = leaseStore.get(consumer);
if (leaseData != null) {
return leaseData.isExpired();
}
return true;
}
private long checkDuration(long duration) throws LeaseDeniedException {
long actualDuration;
if (duration > maxDuration) {
actualDuration = maxDuration;
} else if (duration >= minDuration) {
actualDuration = duration;
} else if (duration == Lease.ANY) {
actualDuration = maxDuration;
} else {
throw new LeaseDeniedException("Duration too short - must be at least " + minDuration + " milliseconds.");
}
return actualDuration;
}
private class LeaseChecker extends TimerTask {
@Override
public void run() {
synchronized (leaseStore) {
Set<Entry<Object, LeaseData>> set = leaseStore.entrySet();
Iterator<Entry<Object, LeaseData>> iter = set.iterator();
while (iter.hasNext()) {
Entry<Object, LeaseData> entry = iter.next();
if (entry.getValue().isExpired()) {
leasee.get().onLeaseCompleted(entry.getKey());
iter.remove();
}
}
}
}
}
}
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