/*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You under the Apache License, Version 2.0
* (the "License"); you may not use this file except in compliance with
* the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
*
* See the License for the specific language governing permissions and
* limitations under the License.
*/
/**
* @author Mikhail A. Markov
*/
package org.apache.harmony.rmi.server;
import java.rmi.RemoteException;
import java.rmi.dgc.DGC;
import java.rmi.dgc.Lease;
import java.rmi.dgc.VMID;
import java.rmi.server.ObjID;
import java.security.AccessController;
import java.util.Collections;
import java.util.Enumeration;
import java.util.HashSet;
import java.util.Hashtable;
import java.util.Iterator;
import java.util.Set;
import org.apache.harmony.rmi.common.CreateThreadAction;
import org.apache.harmony.rmi.common.GetLongPropAction;
import org.apache.harmony.rmi.common.RMILog;
import org.apache.harmony.rmi.common.RMIProperties;
import org.apache.harmony.rmi.internal.nls.Messages;
/**
* Distributed Garbage Collector implementation (Server side).
* It is made package protected for security reasons.
*
* @author Mikhail A. Markov
*/
class DGCImpl implements DGC {
/* Log where to write dgc activity. */
static final RMILog dgcLog = RMILog.getDGCLog();
/*
* Maximum lease duration granted by this DGC.
* Default value is 10 minutes.
*/
static final long maxDuration =
((Long) AccessController.doPrivileged(
new GetLongPropAction(RMIProperties.DGCLEASEVALUE_PROP,
10 * 60 * 1000))).longValue();
/*
* How often we will check DGC leases.
* Default value is half of maxDuration time.
*/
private static final long checkInterval =
((Long) AccessController.doPrivileged(
new GetLongPropAction(RMIProperties.DGCCHECKINTERVAL_PROP,
maxDuration / 2))).longValue();
/*
* Table where VMIDs are keys and HashSets of ObjIDs are the values.
*/
private Hashtable vmidTable = new Hashtable();
// Thread checking leases expirations.
private static Thread expTracker;
/**
* @see DGC.dirty(ObjID[], long, Lease)
*/
public Lease dirty(ObjID[] ids, long seqNum, Lease lease)
throws RemoteException {
VMID vmid = lease.getVMID();
if (vmid == null) {
vmid = new VMID();
if (dgcLog.isLoggable(RMILog.VERBOSE)) {
// rmi.log.10E=Created new VMID: {0}
dgcLog.log(RMILog.VERBOSE, Messages.getString("rmi.log.10E", vmid)); //$NON-NLS-1$
}
}
long duration = lease.getValue();
if (duration > maxDuration || duration < 0) {
duration = maxDuration;
}
Lease l = new Lease(vmid, duration);
synchronized (vmidTable) {
Set s = (Set) vmidTable.get(vmid);
if (s == null) {
if (ids == null || ids.length == 0) {
// Nothing to do: no VM with such VMID registered
return l;
}
s = Collections.synchronizedSet(new HashSet());
vmidTable.put(vmid, s);
}
if (expTracker == null) {
(expTracker = (Thread) AccessController.doPrivileged(
new CreateThreadAction(new ExpirationTracker(),
"ExpirationTracker", true))).start(); //$NON-NLS-1$
}
for (int i = 0; i < ids.length; ++i) {
s.add(ids[i]);
if (dgcLog.isLoggable(RMILog.VERBOSE)) {
// rmi.log.10F=Added {0}, {1}, duration ={2}
dgcLog.log(RMILog.VERBOSE, Messages.getString("rmi.log.10F", //$NON-NLS-1$
new Object[]{ids[i], vmid, duration}));
}
}
for (Iterator allIds = s.iterator(); allIds.hasNext();) {
RMIObjectInfo info = ExportManager.getInfo(
(ObjID) allIds.next());
if (info == null) {
/*
* Object with this id has not been exported or has been
* garbage-collected.
*/
allIds.remove();
continue;
}
info.dgcDirty(vmid, seqNum, duration);
}
}
if (dgcLog.isLoggable(RMILog.VERBOSE)) {
// rmi.log.110=Updated {0}
dgcLog.log(RMILog.VERBOSE, Messages.getString("rmi.log.110", vmid)); //$NON-NLS-1$
}
return l;
}
/**
* @see DGC.clean(ObjID[], long, VMID, boolean)
*/
public void clean(ObjID[] ids, long seqNum, VMID vmid, boolean strong)
throws RemoteException {
synchronized (vmidTable) {
Set s = (Set) vmidTable.get(vmid);
if (s == null) {
return;
}
if (ids != null && ids.length > 0) {
for (int i = 0; i < ids.length; ++i) {
RMIObjectInfo info = ExportManager.getInfo(ids[i]);
if (info == null || info.dgcClean(vmid, seqNum, strong)) {
s.remove(ids[i]);
if (dgcLog.isLoggable(RMILog.VERBOSE)) {
// rmi.log.111=Removed {0},{1}
dgcLog.log(RMILog.VERBOSE, Messages.getString("rmi.log.111", //$NON-NLS-1$
ids[i], vmid));
}
}
}
} else {
for (Iterator allIds = s.iterator(); allIds.hasNext();) {
RMIObjectInfo info = ExportManager.getInfo(
(ObjID) allIds.next());
if (info == null || info.dgcClean(vmid, seqNum, strong)) {
allIds.remove();
}
}
}
if (s.isEmpty()) {
vmidTable.remove(vmid);
if (dgcLog.isLoggable(RMILog.VERBOSE)) {
// rmi.log.112=Removed {0}
dgcLog.log(RMILog.VERBOSE, Messages.getString("rmi.log.112", vmid)); //$NON-NLS-1$
}
}
}
}
/*
* Auxiliary class checking expiration times and removing expired entries
* from the list of active objects.
*/
private class ExpirationTracker implements Runnable {
/**
* Checks expiration times until no objects left in the table.
* Sleeps for a checkInterval period of time between checks.
*/
public void run() {
do {
try {
Thread.sleep(checkInterval);
} catch (InterruptedException ie) {
}
} while (checkExpiration());
expTracker = null;
}
/*
* Checks expiration times and removes expired entries
* from the list of active objects.
*
* @return false if there are no objects in the table left and false
* otherwise
*/
boolean checkExpiration() {
if (vmidTable.size() == 0) {
return false;
}
long curTime = System.currentTimeMillis();
synchronized (vmidTable) {
for (Enumeration en = vmidTable.keys(); en.hasMoreElements();) {
VMID vmid = (VMID) en.nextElement();
Set s = (Set) vmidTable.get(vmid);
for (Iterator iter = s.iterator(); iter.hasNext();) {
RMIObjectInfo info = ExportManager.getInfo(
(ObjID) iter.next());
if (info == null || info.dgcClean(vmid)) {
iter.remove();
if (info != null
&& dgcLog.isLoggable(RMILog.VERBOSE)) {
dgcLog.log(RMILog.VERBOSE, Messages.getString("rmi.log.113", //$NON-NLS-1$
info.id, vmid));
}
}
}
}
}
return true;
}
}
}