Java example source code file (Synch.java)

This example Java source code file (Synch.java) is included in the alvinalexander.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" ^TM.

Learn more about this Java project at its project page.

Java - Java tags/keywords

cn\=alice, cn\=bob, cn\=claire, object, principal, privilegedaction, security, set, subject, synch, thread, util, x500principal

The Synch.java Java example source code

/*
 * Copyright (c) 2003, 2011, Oracle and/or its affiliates. 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 Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
 * or visit www.oracle.com if you need additional information or have any
 * questions.
 */

/*
 * @test
 * @bug 4893489
 * @summary     Subject.doAs not thread-safe against changes to principals
 */

import java.security.Principal;
import java.security.PrivilegedAction;
import java.util.Collections;
import java.util.Set;
import javax.security.auth.Subject;
import javax.security.auth.x500.X500Principal;

public class Synch {
    static volatile boolean finished = false;
    public static void main(String[] args) {
        Subject subject = new Subject();
        final Set principals = subject.getPrincipals();
        principals.add(new X500Principal("CN=Alice"));
        new Thread() {
            public void run() {
                Principal last = new X500Principal("CN=Bob");
                for (int i = 0; !finished; i++) {
                    Principal next = new X500Principal("CN=Bob" + i);
                    principals.add(next);
                    principals.remove(last);
                    last = next;
                }
            }
        }.start();
        for (int i = 0; i < 1000; i++) {
            Subject.doAs(
                subject,
                new PrivilegedAction() {
                    public Object run() {
                        return Subject.doAs(
                            new Subject(true,
                                        Collections.singleton(
                                            new X500Principal("CN=Claire")),
                                        Collections.EMPTY_SET,
                                        Collections.EMPTY_SET),
                            new PrivilegedAction() {
                                public Object run() {
                                    return null;
                                }
                            });
                    }
                });
        }
        finished = true;
    }
}