| /* DGCImpl.java -- |
| Copyright (c) 1996, 1997, 1998, 1999, 2002, 2005 |
| Free Software Foundation, Inc. |
| |
| This file is part of GNU Classpath. |
| |
| GNU Classpath is free software; you can redistribute it and/or modify |
| it under the terms of the GNU General Public License as published by |
| the Free Software Foundation; either version 2, or (at your option) |
| any later version. |
| |
| GNU Classpath is distributed in the hope that it will be useful, but |
| WITHOUT ANY WARRANTY; without even the implied warranty of |
| MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
| General Public License for more details. |
| |
| You should have received a copy of the GNU General Public License |
| along with GNU Classpath; see the file COPYING. If not, write to the |
| Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA |
| 02110-1301 USA. |
| |
| Linking this library statically or dynamically with other modules is |
| making a combined work based on this library. Thus, the terms and |
| conditions of the GNU General Public License cover the whole |
| combination. |
| |
| As a special exception, the copyright holders of this library give you |
| permission to link this library with independent modules to produce an |
| executable, regardless of the license terms of these independent |
| modules, and to copy and distribute the resulting executable under |
| terms of your choice, provided that you also meet, for each linked |
| independent module, the terms and conditions of the license of that |
| module. An independent module is a module which is not derived from |
| or based on this library. If you modify this library, you may extend |
| this exception to your version of the library, but you are not |
| obligated to do so. If you do not wish to do so, delete this |
| exception statement from your version. */ |
| |
| package gnu.java.rmi.dgc; |
| |
| import gnu.java.rmi.server.UnicastServer; |
| import gnu.java.rmi.server.UnicastServerRef; |
| |
| 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.rmi.server.RMISocketFactory; |
| import java.util.Collection; |
| import java.util.TimerTask; |
| |
| /** |
| * The DGC implementation is used for the server side during the distributed |
| * garbage collection. This interface contains the two methods: dirty and clean. |
| * A dirty call is made when a remote reference is unmarshaled in a client. A |
| * corresponding clean call is made by client it no longer uses that remote |
| * reference. A reference to a remote object is also automatically released |
| * after so called lease period that starts after the dirty call is received. It |
| * is the client's responsibility to renew the leases, by making additional |
| * dirty calls before such leases expire. |
| */ |
| public class DGCImpl |
| extends UnicastServerRef |
| implements DGC |
| { |
| /* |
| * The DGCImpl extends UnicastServerRef and not UnicastRemoteObject, because |
| * UnicastRemoteObject must exportObject automatically. |
| */ |
| |
| /** |
| * Use the serial version UID for interoperability. |
| */ |
| private static final long serialVersionUID = 1; |
| |
| /** |
| * Protects the array of object Id's for the scheduled period of time |
| * (lease). After the time expires, the protector is automatically discarded, |
| * making the references unprotected and hence applicable for the garbage |
| * collection. |
| */ |
| class RefProtector extends TimerTask |
| { |
| /** |
| * The corresponding server references to protect. Each Id may contain |
| * multiple references that are stored to collection. |
| */ |
| Collection[] references; |
| |
| /** |
| * Create the new instance of the reference protector that protects the |
| * given array of ids and exists for the given period of time. |
| * |
| * @param ids the ids to protect. |
| */ |
| RefProtector(ObjID[] ids, long timeToLive) |
| { |
| references = new Collection[ids.length]; |
| for (int i = 0; i < ids.length; i++) |
| { |
| references[i] = UnicastServer.getExported(ids[i]); |
| } |
| |
| // Schedule the existence. |
| LeaseRenewingTask.timer.schedule(this, timeToLive); |
| } |
| |
| /** |
| * Break all links, ensuring easy collection of the references by the gc. |
| */ |
| public void run() |
| { |
| for (int i = 0; i < references.length; i++) |
| { |
| references[i].clear(); |
| references[i] = null; |
| } |
| } |
| } |
| |
| /** |
| * This defauld lease value is used if the lease value, passed to the |
| * {@link #dirty} is equal to zero. |
| */ |
| static final long LEASE_VALUE = 600000L; |
| |
| /** |
| * Create the new DGC implementation. |
| * |
| * @throws RemoteException if the super constructor throws or the |
| * socket factory fails. |
| */ |
| public DGCImpl() throws RemoteException |
| { |
| super(new ObjID(ObjID.DGC_ID), 0, RMISocketFactory.getSocketFactory()); |
| } |
| |
| /** |
| * Mark the given objects referecnes as used on the client side. |
| * |
| * @param ids the ids of the used objects. |
| * @param sequenceNum the number of the call (used to detect and discard late |
| * calls). |
| * @param lease the requested lease |
| * @return the granted lease |
| */ |
| public Lease dirty(ObjID[] ids, long sequenceNum, Lease lease) |
| throws RemoteException |
| { |
| // We do not fill in VMID because in this implementation it is not used. |
| long leaseValue = lease.getValue(); |
| |
| // Grant the maximal default lease time if the passed value is zero. |
| if (leaseValue <= 0) |
| leaseValue = LEASE_VALUE; |
| |
| // Create (and shedule of the given existence) the new reference |
| // protector. |
| new RefProtector(ids, leaseValue); |
| |
| lease = new Lease(lease.getVMID(), leaseValue); |
| return lease; |
| } |
| |
| /** |
| * Mark the given objects as no longer used on the client side. |
| * |
| * @param ids the ids of the objects that are no longer used. |
| * @param sequenceNum the number of the call (used to detect and discard late |
| * calls) |
| * @param vmid the VMID of the client. |
| * @param strong make the "strong" clean call. |
| */ |
| public void clean(ObjID[] ids, long sequenceNum, VMID vmid, boolean strong) |
| throws RemoteException |
| { |
| // Not implemented |
| // TODO implement |
| } |
| |
| } // End of DGCImpl |