libjava/gnu/java/rmi/dgc/DGCImpl.java

   1 /*
   2   Copyright (c) 1996, 1997, 1998, 1999, 2002 Free Software Foundation, Inc.
   3
   4 This file is part of GNU Classpath.
   5
   6 GNU Classpath is free software; you can redistribute it and/or modify
   7 it under the terms of the GNU General Public License as published by
   8 the Free Software Foundation; either version 2, or (at your option)
   9 any later version.
  10
  11 GNU Classpath is distributed in the hope that it will be useful, but
  12 WITHOUT ANY WARRANTY; without even the implied warranty of
  13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  14 General Public License for more details.
  15
  16 You should have received a copy of the GNU General Public License
  17 along with GNU Classpath; see the file COPYING.  If not, write to the
  18 Free Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
  19 02111-1307 USA.
  20
  21 Linking this library statically or dynamically with other modules is
  22 making a combined work based on this library.  Thus, the terms and
  23 conditions of the GNU General Public License cover the whole
  24 combination.
  25
  26 As a special exception, the copyright holders of this library give you
  27 permission to link this library with independent modules to produce an
  28 executable, regardless of the license terms of these independent
  29 modules, and to copy and distribute the resulting executable under
  30 terms of your choice, provided that you also meet, for each linked
  31 independent module, the terms and conditions of the license of that
  32 module.  An independent module is a module which is not derived from
  33 or based on this library.  If you modify this library, you may extend
  34 this exception to your version of the library, but you are not
  35 obligated to do so.  If you do not wish to do so, delete this
  36 exception statement from your version. */
  37
  38 package gnu.java.rmi.dgc;
  39
  40 import java.rmi.dgc.DGC;
  41 import java.rmi.dgc.Lease;
  42 import java.rmi.dgc.VMID;
  43 import java.rmi.server.ObjID;
  44 import java.rmi.RemoteException;
  45 import java.rmi.server.UnicastRemoteObject;
  46 import java.rmi.server.RMISocketFactory;
  47 import gnu.java.rmi.server.UnicastServerRef;
  48
  49 import java.util.Hashtable;
  50
  51 /**
  52   * I let DGCImpl to extend UnicastServerRef, but not
  53   * UnicastRemoteObject, because UnicastRemoteObject must
  54   * exportObject automatically.
  55   */
  56 public class DGCImpl
  57     extends UnicastServerRef implements DGC {
  58
  59     private static final long LEASE_VALUE = 600000L;
  60     // leaseCache caches a LeaseRecord associated with a vmid
  61     private Hashtable leaseCache = new Hashtable();
  62
  63 public DGCImpl() throws RemoteException {
  64         super(new ObjID(ObjID.DGC_ID), 0, RMISocketFactory.getSocketFactory());
  65 }
  66
  67 public Lease dirty(ObjID[] ids, long sequenceNum, Lease lease) throws RemoteException {
  68         VMID vmid = lease.getVMID();
  69         if (vmid == null)
  70             vmid = new VMID();
  71         long leaseValue = LEASE_VALUE;
  72         //long leaseValue = lease.getValue();
  73     lease = new Lease(vmid, leaseValue);
  74         synchronized(leaseCache){
  75             LeaseRecord lr = (LeaseRecord)leaseCache.get(vmid);
  76             if (lr != null)
  77                 lr.reset(leaseValue);
  78             else{
  79                 lr = new LeaseRecord(vmid, leaseValue);
  80                 leaseCache.put(vmid, lr);
  81             }
  82         }
  83
  84         return (lease);
  85 }
  86
  87 public void clean(ObjID[] ids, long sequenceNum, VMID vmid, boolean strong) throws RemoteException {
  88   // Not implemented
  89 }
  90
  91   /**
  92    * LeaseRecord associates a vmid to expireTime.
  93    */
  94   private static class LeaseRecord{
  95     private VMID vmid;
  96     private long expireTime;
  97
  98     LeaseRecord(VMID vmid, long leaseValue){
  99       this.vmid = vmid;
 100       reset(leaseValue);
 101     }
 102
 103     // reset expireTime
 104     void reset(long leaseValue){
 105       long l = System.currentTimeMillis();
 106       expireTime = l + leaseValue;
 107     }
 108
 109     boolean isExpired(){
 110       long l = System.currentTimeMillis();
 111       if ( l > expireTime)
 112         return true;
 113       return false;
 114     }
 115
 116   } //End of LeaseRecord
 117
 118 } //End of DGCImpl