1/*
2 * Copyright (c) 2000, 2005, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.  Oracle designates this
8 * particular file as subject to the "Classpath" exception as provided
9 * by Oracle in the LICENSE file that accompanied this code.
10 *
11 * This code is distributed in the hope that it will be useful, but WITHOUT
12 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
13 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
14 * version 2 for more details (a copy is included in the LICENSE file that
15 * accompanied this code).
16 *
17 * You should have received a copy of the GNU General Public License version
18 * 2 along with this work; if not, write to the Free Software Foundation,
19 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
20 *
21 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
22 * or visit www.oracle.com if you need additional information or have any
23 * questions.
24 */
25
26package sun.rmi.runtime;
27
28import java.security.AccessController;
29import java.security.PrivilegedAction;
30import sun.security.util.SecurityConstants;
31
32/**
33 * A PrivilegedAction for creating a new thread conveniently with an
34 * AccessController.doPrivileged construct.
35 *
36 * All constructors allow the choice of the Runnable for the new
37 * thread to execute, the name of the new thread (which will be
38 * prefixed with "RMI "), and whether or not it will be a daemon
39 * thread.
40 *
41 * The new thread may be created in the system thread group (the root
42 * of the thread group tree) or an internally created non-system
43 * thread group, as specified at construction of this class.
44 *
45 * The new thread will have the system class loader as its initial
46 * context class loader (that is, its context class loader will NOT be
47 * inherited from the current thread).
48 *
49 * @author      Peter Jones
50 **/
51public final class NewThreadAction implements PrivilegedAction<Thread> {
52
53    /** cached reference to the system (root) thread group */
54    static final ThreadGroup systemThreadGroup =
55        AccessController.doPrivileged(new PrivilegedAction<ThreadGroup>() {
56            public ThreadGroup run() {
57                ThreadGroup group = Thread.currentThread().getThreadGroup();
58                ThreadGroup parent;
59                while ((parent = group.getParent()) != null) {
60                    group = parent;
61                }
62                return group;
63            }
64        });
65
66    /**
67     * special child of the system thread group for running tasks that
68     * may execute user code, so that the security policy for threads in
69     * the system thread group will not apply
70     */
71    static final ThreadGroup userThreadGroup =
72        AccessController.doPrivileged(new PrivilegedAction<ThreadGroup>() {
73            public ThreadGroup run() {
74                return new ThreadGroup(systemThreadGroup, "RMI Runtime");
75            }
76        });
77
78    private final ThreadGroup group;
79    private final Runnable runnable;
80    private final String name;
81    private final boolean daemon;
82
83    NewThreadAction(ThreadGroup group, Runnable runnable,
84                    String name, boolean daemon)
85    {
86        this.group = group;
87        this.runnable = runnable;
88        this.name = name;
89        this.daemon = daemon;
90    }
91
92    /**
93     * Creates an action that will create a new thread in the
94     * system thread group.
95     *
96     * @param   runnable the Runnable for the new thread to execute
97     *
98     * @param   name the name of the new thread
99     *
100     * @param   daemon if true, new thread will be a daemon thread;
101     * if false, new thread will not be a daemon thread
102     */
103    public NewThreadAction(Runnable runnable, String name, boolean daemon) {
104        this(systemThreadGroup, runnable, name, daemon);
105    }
106
107    /**
108     * Creates an action that will create a new thread.
109     *
110     * @param   runnable the Runnable for the new thread to execute
111     *
112     * @param   name the name of the new thread
113     *
114     * @param   daemon if true, new thread will be a daemon thread;
115     * if false, new thread will not be a daemon thread
116     *
117     * @param   user if true, thread will be created in a non-system
118     * thread group; if false, thread will be created in the system
119     * thread group
120     */
121    public NewThreadAction(Runnable runnable, String name, boolean daemon,
122                           boolean user)
123    {
124        this(user ? userThreadGroup : systemThreadGroup,
125             runnable, name, daemon);
126    }
127
128    public Thread run() {
129        SecurityManager sm = System.getSecurityManager();
130        if (sm != null) {
131            sm.checkPermission(SecurityConstants.GET_CLASSLOADER_PERMISSION);
132        }
133        Thread t = new Thread(group, runnable, "RMI " + name);
134        t.setContextClassLoader(ClassLoader.getSystemClassLoader());
135        t.setDaemon(daemon);
136        return t;
137    }
138}
139