1 /*
 2  * Copyright (c) 2002, 2018, 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 
29 // Signalling operations on native threads
30 
31 public class NativeThread {
32     private static final long VIRTUAL_THREAD_ID = -1L;
33 
34     /**
35      * Returns a token representing the current thread or -1 if called in the
36      * context of a virtual thread
37      */
38     public static long current() {
39         if (Thread.currentThread().isVirtual()) {
40             return VIRTUAL_THREAD_ID;
41         } else {
42             return 0;
43         }
44     }
45 
46     static long currentKernelThread() {
47         return 0;
48     }
49 
50     static void signal(long tid) {
51         throw new UnsupportedOperationException();
52     }
53 
54     /**
55      * Returns true if the token presents a virtual thread
56      */
57     static boolean isVirtualThread(long tid) {
58         return (tid == VIRTUAL_THREAD_ID);
59     }
60 
61     static boolean isKernelThread(long tid) {
62         return false;
63     }
64 }