source: trunk/gcc/libjava/gnu/java/rmi/dgc/DGCImpl.java

/*
  Copyright (c) 1996, 1997, 1998, 1999, 2002 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.
 
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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.

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Free Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
02111-1307 USA.

Linking this library statically or dynamically with other modules is
making a combined work based on this library.  Thus, the terms and
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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
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terms of your choice, provided that you also meet, for each linked
independent module, the terms and conditions of the license of that
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this exception to your version of the library, but you are not
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exception statement from your version. */

package gnu.java.rmi.dgc;

import java.rmi.dgc.DGC;
import java.rmi.dgc.Lease;
import java.rmi.dgc.VMID;
import java.rmi.server.ObjID;
import java.rmi.RemoteException;
import java.rmi.server.UnicastRemoteObject;
import java.rmi.server.RMISocketFactory;
import gnu.java.rmi.server.UnicastServerRef;

import java.util.Hashtable;

/**
  * I let DGCImpl to extend UnicastServerRef, but not 
  * UnicastRemoteObject, because UnicastRemoteObject must
  * exportObject automatically.
  */
public class DGCImpl
    extends UnicastServerRef implements DGC {

    private static final long LEASE_VALUE = 600000L;
    // leaseCache caches a LeaseRecord associated with a vmid
    private Hashtable leaseCache = new Hashtable();

public DGCImpl() throws RemoteException {
        super(new ObjID(ObjID.DGC_ID), 0, RMISocketFactory.getSocketFactory());
}

public Lease dirty(ObjID[] ids, long sequenceNum, Lease lease) throws RemoteException {
        VMID vmid = lease.getVMID();
        if (vmid == null)
            vmid = new VMID();
        long leaseValue = LEASE_VALUE;
        //long leaseValue = lease.getValue();
    lease = new Lease(vmid, leaseValue);
        synchronized(leaseCache){
            LeaseRecord lr = (LeaseRecord)leaseCache.get(vmid);
            if (lr != null)
                lr.reset(leaseValue);
            else{
                lr = new LeaseRecord(vmid, leaseValue);
                leaseCache.put(vmid, lr);
            }
        }
        
        return (lease);
}

public void clean(ObjID[] ids, long sequenceNum, VMID vmid, boolean strong) throws RemoteException {
  // Not implemented
}
    
  /**
   * LeaseRecord associates a vmid to expireTime.
   */
  private static class LeaseRecord{
    private VMID vmid;
    private long expireTime;
    
    LeaseRecord(VMID vmid, long leaseValue){
      this.vmid = vmid;
      reset(leaseValue);
    }
    
    // reset expireTime
    void reset(long leaseValue){
      long l = System.currentTimeMillis();
      expireTime = l + leaseValue;
    }

    boolean isExpired(){
      long l = System.currentTimeMillis();
      if ( l > expireTime)
        return true;
      return false;
    }
        
  } //End of LeaseRecord

} //End of DGCImpl