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Diffstat (limited to 'gcc-4.4.3/libjava/classpath/gnu/java/rmi/dgc/DGCImpl.java')
| -rw-r--r-- | gcc-4.4.3/libjava/classpath/gnu/java/rmi/dgc/DGCImpl.java | 182 |
1 files changed, 182 insertions, 0 deletions
diff --git a/gcc-4.4.3/libjava/classpath/gnu/java/rmi/dgc/DGCImpl.java b/gcc-4.4.3/libjava/classpath/gnu/java/rmi/dgc/DGCImpl.java new file mode 100644 index 000000000..a5c036e7b --- /dev/null +++ b/gcc-4.4.3/libjava/classpath/gnu/java/rmi/dgc/DGCImpl.java @@ -0,0 +1,182 @@ +/* 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 |