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| 1 | +/* |
| 2 | + * Copyright (c) 2021, 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 | +import java.io.*; |
| 25 | +import jdk.test.lib.classloader.ClassUnloadCommon; |
| 26 | + |
| 27 | +// This class loader will deadlock where one thread has a lock for A, trying to get a lock for B |
| 28 | +// and the other thread has a lock for B, trying to get a lock for A in the case of |
| 29 | +// A extends B extends A. It should throw ClassCircularityError from both threads. |
| 30 | + |
| 31 | +class MyLoader extends ClassLoader { |
| 32 | + static { |
| 33 | + registerAsParallelCapable(); |
| 34 | + } |
| 35 | + |
| 36 | + private static boolean first = true; |
| 37 | + |
| 38 | + public Class loadClass(String name) throws ClassNotFoundException { |
| 39 | + // Wait before getting B lock. |
| 40 | + if (name.equals("B") && first) { |
| 41 | + first = false; |
| 42 | + makeThreadWait(); |
| 43 | + } |
| 44 | + synchronized(getClassLoadingLock(name)) { |
| 45 | + Class<?> c = findLoadedClass(name); |
| 46 | + if (c != null) return c; |
| 47 | + |
| 48 | + if (name.equals("B") && !first) { |
| 49 | + wakeUpThread(); |
| 50 | + } |
| 51 | + |
| 52 | + byte[] b = loadClassData(name); |
| 53 | + if (b != null) { |
| 54 | + return defineClass(name, b, 0, b.length); |
| 55 | + } else { |
| 56 | + return super.loadClass(name); |
| 57 | + } |
| 58 | + } |
| 59 | + } |
| 60 | + |
| 61 | + private static boolean parallel = false; |
| 62 | + private Object sync = new Object(); |
| 63 | + private Object thread_sync = new Object(); |
| 64 | + |
| 65 | + private void makeThreadWait() { |
| 66 | + if (!parallel) { return; } |
| 67 | + |
| 68 | + // Wake up the second thread here. |
| 69 | + synchronized (thread_sync) { |
| 70 | + thread_sync.notify(); |
| 71 | + } |
| 72 | + if (isRegisteredAsParallelCapable()) { |
| 73 | + synchronized(sync) { |
| 74 | + try { |
| 75 | + ThreadPrint.println("t1 waits parallelCapable loader"); |
| 76 | + sync.wait(); // Give up lock before request to load B |
| 77 | + } catch (InterruptedException e) {} |
| 78 | + } |
| 79 | + } else { |
| 80 | + try { |
| 81 | + ThreadPrint.println("t1 waits non-parallelCapable loader"); |
| 82 | + wait(); // Give up lock before request to load B |
| 83 | + } catch (InterruptedException e) {} |
| 84 | + } |
| 85 | + } |
| 86 | + |
| 87 | + // Parallel capable loader should wake up the first thread. |
| 88 | + // Non-parallelCapable class loader thread will be woken up by the jvm. |
| 89 | + private void wakeUpThread() { |
| 90 | + if (isRegisteredAsParallelCapable()) { |
| 91 | + synchronized(sync) { |
| 92 | + sync.notify(); |
| 93 | + } |
| 94 | + } |
| 95 | + } |
| 96 | + |
| 97 | + private byte[] loadClassData(String name) { |
| 98 | + if (name.equals("A")) { |
| 99 | + ThreadPrint.println("loading A extends B"); |
| 100 | + return ClassUnloadCommon.getClassData("A"); |
| 101 | + } else if (name.equals("B")) { |
| 102 | + ThreadPrint.println("loading B extends A"); |
| 103 | + try { |
| 104 | + return AsmClasses.dumpB(); |
| 105 | + } catch (Exception e) { |
| 106 | + e.printStackTrace(); |
| 107 | + return null; |
| 108 | + } |
| 109 | + } else if (!name.startsWith("java")) { |
| 110 | + return ClassUnloadCommon.getClassData(name); |
| 111 | + } |
| 112 | + return null; |
| 113 | + } |
| 114 | + |
| 115 | + |
| 116 | + ClassLoadingThread[] threads = new ClassLoadingThread[2]; |
| 117 | + private boolean success = true; |
| 118 | + |
| 119 | + public boolean report_success() { |
| 120 | + for (int i = 0; i < 2; i++) { |
| 121 | + try { |
| 122 | + threads[i].join(); |
| 123 | + if (!threads[i].report_success()) success = false; |
| 124 | + } catch (InterruptedException e) {} |
| 125 | + } |
| 126 | + return success; |
| 127 | + } |
| 128 | + |
| 129 | + void startLoading() { |
| 130 | + |
| 131 | + for (int i = 0; i < 2; i++) { |
| 132 | + threads[i] = new ClassLoadingThread(this, thread_sync); |
| 133 | + threads[i].setName("Loading Thread #" + (i + 1)); |
| 134 | + threads[i].start(); |
| 135 | + System.out.println("Thread " + (i + 1) + " was started..."); |
| 136 | + // wait to start the second thread if not concurrent |
| 137 | + if (i == 0) { |
| 138 | + synchronized(thread_sync) { |
| 139 | + try { |
| 140 | + ThreadPrint.println("t2 waits"); |
| 141 | + thread_sync.wait(); |
| 142 | + } catch (InterruptedException e) {} |
| 143 | + } |
| 144 | + } |
| 145 | + } |
| 146 | + } |
| 147 | + |
| 148 | + MyLoader(boolean load_in_parallel) { |
| 149 | + parallel = load_in_parallel; |
| 150 | + } |
| 151 | +} |
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