1 /* 2 * Copyright (c) 2024, 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. 8 * 9 * This code is distributed in the hope that it will be useful, but WITHOUT 10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or 11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 12 * version 2 for more details (a copy is included in the LICENSE file that 13 * accompanied this code). 14 * 15 * You should have received a copy of the GNU General Public License version 16 * 2 along with this work; if not, write to the Free Software Foundation, 17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. 18 * 19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA 20 * or visit www.oracle.com if you need additional information or have any 21 * questions. 22 */ 23 24 /* 25 * @test 26 * @summary Test ThreadMXBean.getLockedMonitors returns information about an object 27 * monitor lock entered with a synchronized native method or JNI MonitorEnter 28 * @run junit/othervm LockedMonitorInNative 29 */ 30 31 import java.lang.management.ManagementFactory; 32 import java.lang.management.ThreadInfo; 33 import java.lang.management.ThreadMXBean; 34 import java.util.Arrays; 35 36 import org.junit.jupiter.api.Test; 37 import org.junit.jupiter.api.BeforeAll; 38 import static org.junit.jupiter.api.Assertions.*; 39 40 public class LockedMonitorInNative { 41 42 @BeforeAll 43 static void setup() throws Exception { 44 System.loadLibrary("LockedMonitorInNative"); 45 } 46 47 /** 48 * Test ThreadMXBean.getLockedMonitors returns information about an object 49 * monitor lock entered with a synchronized native method. 50 */ 51 @Test 52 void testSynchronizedNative() { 53 Object lock = this; 54 runWithSynchronizedNative(() -> { 55 assertTrue(holdsLock(lock), "Thread does not hold lock"); 56 }); 57 } 58 59 /** 60 * Test ThreadMXBean.getLockedMonitors returns information about an object 61 * monitor lock entered with JNI MonitorEnter. 62 */ 63 @Test 64 void testMonitorEnteredInNative() { 65 var lock = new Object(); 66 runWithMonitorEnteredInNative(lock, () -> { 67 assertTrue(holdsLock(lock), "Thread does not hold lock"); 68 }); 69 } 70 71 private boolean holdsLock(Object lock) { 72 int hc = System.identityHashCode(lock); 73 long tid = Thread.currentThread().threadId(); 74 ThreadInfo ti = ManagementFactory.getPlatformMXBean(ThreadMXBean.class) 75 .getThreadInfo(new long[] { tid }, true, true)[0]; 76 return Arrays.stream(ti.getLockedMonitors()) 77 .anyMatch(mi -> mi.getIdentityHashCode() == hc); 78 } 79 80 /** 81 * Invokes the given task's run method while holding the monitor for "this". 82 */ 83 private synchronized native void runWithSynchronizedNative(Runnable task); 84 85 /** 86 * Invokes the given task's run method while holding the monitor for the given 87 * object. The monitor is entered with JNI MonitorEnter, and exited with JNI MonitorExit. 88 */ 89 private native void runWithMonitorEnteredInNative(Object lock, Runnable task); 90 91 /** 92 * Called from native methods to run the given task. 93 */ 94 private void run(Runnable task) { 95 task.run(); 96 } 97 }