jdk/test/java/rmi/transport/dgcDeadLock/TestImpl.java

/* 
 * Copyright 1998-2005 Sun Microsystems, Inc.  All Rights Reserved.
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 *
 * This code is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2 only, as
 * published by the Free Software Foundation.
 *
 * This code 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
 * version 2 for more details (a copy is included in the LICENSE file that
 * accompanied this code).
 *
 * You should have received a copy of the GNU General Public License version
 * 2 along with this work; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
 *
 * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
 * CA 95054 USA or visit www.sun.com if you need additional information or
 * have any questions.
 */

/*
 */

import java.rmi.*;
import sun.rmi.transport.*;
import sun.rmi.*;
import java.io.*;
import java.lang.reflect.*;
import java.rmi.dgc.*;
import java.util.*;
import java.rmi.registry.*;
import java.rmi.server.*;

public class TestImpl extends UnicastRemoteObject 
    implements Test {

    static Thread locker = null;
    static TestImpl foo = null;
    static TestImpl bar = null;

    TestImpl() throws RemoteException {
    }

    public String echo(String msg) throws RemoteException {

	if (locker == null) {
	    // hold the target if not already held
	    locker = lockTargetExpireLeases(foo, DGCDeadLock.HOLD_TARGET_TIME);
	}
        return "Message received: " + msg;
    }

    static public void main(String[] args) {
	Registry registry = null;

        try {
	    registry = java.rmi.registry.LocateRegistry.
		createRegistry(TestLibrary.REGISTRY_PORT);

	    //export "Foo"
	    foo = new TestImpl();
            Naming.rebind("rmi://:" + 
			  TestLibrary.REGISTRY_PORT
			  + "/Foo", foo);  

	    try {
		//export "Bar" after leases have been expired.
		bar = new TestImpl();
		Naming.rebind("rmi://localhost:" + 
			      TestLibrary.REGISTRY_PORT
			      + "/Bar", bar);  
	    } catch (Exception e) {
		throw new RemoteException(e.getMessage());
	    }
	    Thread.sleep(DGCDeadLock.TEST_FAIL_TIME);
	    System.err.println("object vm exiting...");
	    System.exit(0);

        } catch (Exception e) {
	    System.err.println(e.getMessage());
	    e.printStackTrace();
        } finally {
	    TestLibrary.unexport(registry);
	    registry = null;
	}
    }

    static Thread lockTargetExpireLeases(Remote toLock, int timeOut) {
	Thread t = new Thread((Runnable) new TargetLocker(toLock, timeOut));
	t.start();
	return t;
    }

    static class TargetLocker implements Runnable {

	Remote toLock = null;
	int timeOut = 0;

	TargetLocker(Remote toLock, int timeOut) {
	    this.toLock = toLock;
	    this.timeOut = timeOut;
	}

	public void run() {
	    try {
		// give dgc dirty calls time to finish.
		Thread.currentThread().sleep(4000);

		java.security.AccessController.
		    doPrivileged(new LockTargetCheckLeases(toLock, 
							   timeOut));

	    } catch (Exception e) {
		System.err.println(e.getMessage());
		e.printStackTrace();
		System.exit(1);
	    }
	}
    }

    static class LockTargetCheckLeases 
	implements java.security.PrivilegedAction {

	Remote toLock = null;
	int timeOut = 0;

	LockTargetCheckLeases(Remote toLock, int timeOut) {
	    this.toLock = toLock;
	    this.timeOut = timeOut;
	}

	public Object run() {
	    try {
		
		Class args[] = new Class[1];
		
		Class objTableClass = Class.forName
		    ("sun.rmi.transport.ObjectTable");
		
		/* get the Target that corresponds to toLock from the
		 * ObjectTable 
		 */
		args[0] = Class.forName("java.rmi.Remote");
		Method objTableGetTarget = 
		    objTableClass.getDeclaredMethod("getTarget", args );
		objTableGetTarget.setAccessible(true);
		
		Target lockTarget = 
		    ((Target) objTableGetTarget.invoke
		     (null , new Object [] {toLock} ));
		
		// make sure the lease on this object has expired.
		expireLeases(lockTarget);
		
		// stop other threads from using the target for toLock.
		synchronized (lockTarget) {
		    System.err.println("Locked the relevant target, sleeping " + 
				       timeOut/1000 + " seconds");
		    Thread.currentThread().sleep(timeOut);
		    System.err.println("Target unlocked");
		}

	    } catch (Exception e) {
		System.err.println(e.getMessage());
		e.printStackTrace();
		System.exit(1);
	    }
	    return null;
	}
    }

    /* leases have long values, so no dirty calls which would lock out
     * a clean call, but the leases need to expire anyway, so we do it
     * explicitly. 
     */
    static void expireLeases(Target t) throws Exception {

	final Target target = t;

	java.security.AccessController.doPrivileged(

	    //  put this into another class?
	    new java.security.PrivilegedAction() {
	    public Object run() {
		try {

		    Class DGCClass = Class.forName("sun.rmi.transport.DGCImpl");
		    Method getDGCImpl = 
			DGCClass.getDeclaredMethod("getDGCImpl", null );
		    getDGCImpl.setAccessible(true);
		    
		    // make sure the lease on this object has expired.
		    DGC dgcImpl = ((DGC) getDGCImpl.invoke(null, null));
		    
		    /* Get the lease table from the DGCImpl. */
		    Field reflectedLeaseTable = 
			dgcImpl.getClass().getDeclaredField("leaseTable");
		    reflectedLeaseTable.setAccessible(true);
		    
		    Map leaseTable = (Map) reflectedLeaseTable.get(dgcImpl);
		    
		    // dont really need this synchronization...
		    synchronized (leaseTable) {
			Iterator en = leaseTable.values().iterator();
			while (en.hasNext()) {
			    Object info = en.next();
			    
			    /* Get the notifySet in the leaseInfo object. */
			    Field notifySetField = 
				info.getClass().getDeclaredField("notifySet");
			    notifySetField.setAccessible(true);
			    HashSet notifySet = (HashSet) notifySetField.get(info);
			    
			    Iterator iter = notifySet.iterator();
			    while (iter.hasNext()) {
				Target notified = (Target) iter.next();
				
				if (notified == target) {
				    
				/* Get and set the expiration field from the info object. */
				    Field expirationField = info.getClass().
					getDeclaredField("expiration");
				    expirationField.setAccessible(true);
				    expirationField.setLong(info, 0);
				}
			    }
			}
		    }
		} catch (Exception e) {
		    System.err.println(e.getMessage());
		    e.printStackTrace();
		    System.exit(1);
		}
		// no interesting return value for this privileged action
		return null;
	    }
	});
    }
}