import java.rmi.*;
import java.rmi.server.*;

//// Distributed mutex implementation


// Every remote call to a method on a RemoteObject will spin off a new
// thread, which may need to be synchronized.  The distributed concurrency
// is thus mirrored by local thread-concurrency on the server.

public class dmuteximpl extends UnicastRemoteObject implements dmutex
{
    boolean lock = false;
    String name;
    
    // even default constructor must throw RemoteException
    public dmuteximpl() throws RemoteException
    {}


    public synchronized void lock()
    {
      try 
      {
	if (lock) wait();
	lock = true;
      }
      catch (InterruptedException ie) {System.out.println(ie);}
    } // lock
   
    public synchronized void unlock()
    {
	lock = false;
	notify();
    }

    public boolean getState() 
    { return lock; }


    // main method to initiate RMI engine:
    public static void main(String[] args) throws Exception
    {
	dmuteximpl server = new dmuteximpl();
	Naming.rebind("dmutex0",server); // register with rmiregistry
    }//main

} //dmuteximpl