| /* |
| * Copyright (c) 2021, Oracle and/or its affiliates. All rights reserved. |
| * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. |
| * |
| * This code is free software; you can redistribute it and/or modify it |
| * under the terms of the GNU General Public License version 2 only, as |
| * published by the Free Software Foundation. |
| * |
| * This code is distributed in the hope that it will be useful, but WITHOUT |
| * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or |
| * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License |
| * version 2 for more details (a copy is included in the LICENSE file that |
| * accompanied this code). |
| * |
| * You should have received a copy of the GNU General Public License version |
| * 2 along with this work; if not, write to the Free Software Foundation, |
| * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. |
| * |
| * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA |
| * or visit www.oracle.com if you need additional information or have any |
| * questions. |
| */ |
| |
| import java.io.*; |
| import jdk.test.lib.classloader.ClassUnloadCommon; |
| |
| // This class loader will deadlock where one thread has a lock for A, trying to get a lock for B |
| // and the other thread has a lock for B, trying to get a lock for A in the case of |
| // A extends B extends A. It should throw ClassCircularityError from both threads. |
| |
| class MyLoader extends ClassLoader { |
| static { |
| registerAsParallelCapable(); |
| } |
| |
| private static boolean first = true; |
| |
| public Class loadClass(String name) throws ClassNotFoundException { |
| // Wait before getting B lock. |
| if (name.equals("B") && first) { |
| first = false; |
| makeThreadWait(); |
| } |
| synchronized(getClassLoadingLock(name)) { |
| Class<?> c = findLoadedClass(name); |
| if (c != null) return c; |
| |
| if (name.equals("B") && !first) { |
| wakeUpThread(); |
| } |
| |
| byte[] b = loadClassData(name); |
| if (b != null) { |
| return defineClass(name, b, 0, b.length); |
| } else { |
| return super.loadClass(name); |
| } |
| } |
| } |
| |
| private static boolean parallel = false; |
| private Object sync = new Object(); |
| private Object thread_sync = new Object(); |
| private static volatile boolean waiting = false; |
| |
| private void makeThreadWait() { |
| if (!parallel) { return; } |
| |
| // Wake up the second thread here. |
| synchronized (thread_sync) { |
| thread_sync.notify(); |
| } |
| if (isRegisteredAsParallelCapable()) { |
| synchronized(sync) { |
| try { |
| ThreadPrint.println("t1 waits parallelCapable loader"); |
| waiting = true; |
| sync.wait(); // Give up lock before request to load B |
| } catch (InterruptedException e) {} |
| } |
| } else { |
| try { |
| ThreadPrint.println("t1 waits non-parallelCapable loader"); |
| wait(); // Give up lock before request to load B |
| } catch (InterruptedException e) {} |
| } |
| } |
| |
| // Parallel capable loader should wake up the first thread. |
| // Non-parallelCapable class loader thread will be woken up by the jvm. |
| private void wakeUpThread() { |
| if (isRegisteredAsParallelCapable()) { |
| while (!waiting) { |
| try { |
| Thread.sleep(1); |
| } catch (InterruptedException e) {} |
| } |
| synchronized(sync) { |
| sync.notify(); |
| } |
| } |
| } |
| |
| private byte[] loadClassData(String name) { |
| if (name.equals("A")) { |
| ThreadPrint.println("loading A extends B"); |
| return ClassUnloadCommon.getClassData("A"); |
| } else if (name.equals("B")) { |
| ThreadPrint.println("loading B extends A"); |
| try { |
| return AsmClasses.dumpB(); |
| } catch (Exception e) { |
| e.printStackTrace(); |
| return null; |
| } |
| } else if (!name.startsWith("java")) { |
| return ClassUnloadCommon.getClassData(name); |
| } |
| return null; |
| } |
| |
| |
| ClassLoadingThread[] threads = new ClassLoadingThread[2]; |
| private boolean success = true; |
| |
| public boolean report_success() { |
| for (int i = 0; i < 2; i++) { |
| try { |
| threads[i].join(); |
| if (!threads[i].report_success()) success = false; |
| } catch (InterruptedException e) {} |
| } |
| return success; |
| } |
| |
| void startLoading() { |
| |
| for (int i = 0; i < 2; i++) { |
| threads[i] = new ClassLoadingThread(this, thread_sync); |
| threads[i].setName("Loading Thread #" + (i + 1)); |
| threads[i].start(); |
| System.out.println("Thread " + (i + 1) + " was started..."); |
| // wait to start the second thread if not concurrent |
| if (i == 0) { |
| synchronized(thread_sync) { |
| try { |
| ThreadPrint.println("t2 waits"); |
| thread_sync.wait(); |
| } catch (InterruptedException e) {} |
| } |
| } |
| } |
| } |
| |
| MyLoader(boolean load_in_parallel) { |
| parallel = load_in_parallel; |
| } |
| } |