1 /*
 2  * Copyright (c) 2002, 2023, 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 
26 package sun.nio.ch;
27 
28 import java.util.concurrent.locks.LockSupport;
29 
30 public class NativeThread {
31     private NativeThread() { }
32 
33     /**
34      * Returns the Thread to signal the current thread or {@code null} if the current
35      * thread cannot be signalled.
36      */
37     public static Thread threadToSignal() {
38         Thread thread = Thread.currentThread();
39         return thread.isVirtual() ? thread : null;
40     }
41 
42     /**
43      * Signals the given thread.
44      * @throws UnsupportedOperationException is not supported
45      */
46     public static void signal(Thread thread) {
47         if (thread.isVirtual()) {
48             LockSupport.unpark(null);
49         } else {
50             throw new UnsupportedOperationException();
51         }
52     }
53 }