Source for gnu.java.rmi.dgc.DGCImpl

   1: /* DGCImpl.java --
   2:    Copyright (c) 1996, 1997, 1998, 1999, 2002, 2005
   3:    Free Software Foundation, Inc.
   4: 
   5: This file is part of GNU Classpath.
   6: 
   7: GNU Classpath is free software; you can redistribute it and/or modify
   8: it under the terms of the GNU General Public License as published by
   9: the Free Software Foundation; either version 2, or (at your option)
  10: any later version.
  11:  
  12: GNU Classpath is distributed in the hope that it will be useful, but
  13: WITHOUT ANY WARRANTY; without even the implied warranty of
  14: MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  15: General Public License for more details.
  16: 
  17: You should have received a copy of the GNU General Public License
  18: along with GNU Classpath; see the file COPYING.  If not, write to the
  19: Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
  20: 02110-1301 USA.
  21: 
  22: Linking this library statically or dynamically with other modules is
  23: making a combined work based on this library.  Thus, the terms and
  24: conditions of the GNU General Public License cover the whole
  25: combination.
  26: 
  27: As a special exception, the copyright holders of this library give you
  28: permission to link this library with independent modules to produce an
  29: executable, regardless of the license terms of these independent
  30: modules, and to copy and distribute the resulting executable under
  31: terms of your choice, provided that you also meet, for each linked
  32: independent module, the terms and conditions of the license of that
  33: module.  An independent module is a module which is not derived from
  34: or based on this library.  If you modify this library, you may extend
  35: this exception to your version of the library, but you are not
  36: obligated to do so.  If you do not wish to do so, delete this
  37: exception statement from your version. */
  38: 
  39: package gnu.java.rmi.dgc;
  40: 
  41: import gnu.java.rmi.server.UnicastServerRef;
  42: 
  43: import java.rmi.RemoteException;
  44: import java.rmi.dgc.DGC;
  45: import java.rmi.dgc.Lease;
  46: import java.rmi.dgc.VMID;
  47: import java.rmi.server.ObjID;
  48: import java.rmi.server.RMISocketFactory;
  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