/*

 * Copyright (c) 2000, 2005, 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.  Oracle designates this

 * particular file as subject to the "Classpath" exception as provided

 * by Oracle in the LICENSE file that accompanied this code.

 *

 * 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.

 */

package sun.rmi.runtime;

import java.security.AccessController;

import java.security.PrivilegedAction;

import sun.security.util.SecurityConstants;

/**

 * A PrivilegedAction for creating a new thread conveniently with an

 * AccessController.doPrivileged construct.

 *

 * All constructors allow the choice of the Runnable for the new

 * thread to execute, the name of the new thread (which will be

 * prefixed with "RMI "), and whether or not it will be a daemon

 * thread.

 *

 * The new thread may be created in the system thread group (the root

 * of the thread group tree) or an internally created non-system

 * thread group, as specified at construction of this class.

 *

 * The new thread will have the system class loader as its initial

 * context class loader (that is, its context class loader will NOT be

 * inherited from the current thread).

 *

 * @author      Peter Jones

 **/

public final class NewThreadAction implements PrivilegedAction<Thread> {

    /** cached reference to the system (root) thread group */

    static final ThreadGroup systemThreadGroup =

        AccessController.doPrivileged(new PrivilegedAction<ThreadGroup>() {

            public ThreadGroup run() {

                ThreadGroup group = Thread.currentThread().getThreadGroup();

                ThreadGroup parent;

                while ((parent = group.getParent()) != null) {

                    group = parent;

                }

                return group;

            }

        });

    /**

     * special child of the system thread group for running tasks that

     * may execute user code, so that the security policy for threads in

     * the system thread group will not apply

     */

    static final ThreadGroup userThreadGroup =

        AccessController.doPrivileged(new PrivilegedAction<ThreadGroup>() {

            public ThreadGroup run() {

                return new ThreadGroup(systemThreadGroup, "RMI Runtime");

            }

        });

    private final ThreadGroup group;

    private final Runnable runnable;

    private final String name;

    private final boolean daemon;

    NewThreadAction(ThreadGroup group, Runnable runnable,

                    String name, boolean daemon)

    {

        this.group = group;

        this.runnable = runnable;

        this.name = name;

        this.daemon = daemon;

    }

    /**

     * Creates an action that will create a new thread in the

     * system thread group.

     *

     * @param   runnable the Runnable for the new thread to execute

     *

     * @param   name the name of the new thread

     *

     * @param   daemon if true, new thread will be a daemon thread;

     * if false, new thread will not be a daemon thread

     */

    public NewThreadAction(Runnable runnable, String name, boolean daemon) {

        this(systemThreadGroup, runnable, name, daemon);

    }

    /**

     * Creates an action that will create a new thread.

     *

     * @param   runnable the Runnable for the new thread to execute

     *

     * @param   name the name of the new thread

     *

     * @param   daemon if true, new thread will be a daemon thread;

     * if false, new thread will not be a daemon thread

     *

     * @param   user if true, thread will be created in a non-system

     * thread group; if false, thread will be created in the system

     * thread group

     */

    public NewThreadAction(Runnable runnable, String name, boolean daemon,

                           boolean user)

    {

        this(user ? userThreadGroup : systemThreadGroup,

             runnable, name, daemon);

    }

    public Thread run() {

        SecurityManager sm = System.getSecurityManager();

        if (sm != null) {

            sm.checkPermission(SecurityConstants.GET_CLASSLOADER_PERMISSION);

        }

        Thread t = new Thread(group, runnable, "RMI " + name);

        t.setContextClassLoader(ClassLoader.getSystemClassLoader());

        t.setDaemon(daemon);

        return t;

    }

}