| /* |
| * Copyright (c) 2007, 2018, 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. |
| */ |
| |
| package nsk.share.gc.lock; |
| |
| import nsk.share.TestBug; |
| import nsk.share.gc.lock.Locker; |
| |
| /** |
| * CriticalSectionLocker represents a way to lock a resource |
| * by entering some critical section. |
| */ |
| public abstract class CriticalSectionLocker<T> implements Locker<T> { |
| private transient boolean enabled = false; |
| private transient boolean locked = false; |
| private Object sync = new Object(); |
| private Thread thread; |
| private Throwable exception; |
| |
| private final Runnable runnable = new Runnable() { |
| public void run() { |
| //System.out.println("Running"); |
| try { |
| do { |
| synchronized (sync) { |
| while (enabled && !locked) { |
| try { |
| sync.wait(); |
| } catch (InterruptedException e) { |
| } |
| } |
| if (!enabled) |
| break; |
| } |
| do { |
| criticalSection(); |
| } while (locked); |
| } while (enabled); |
| // System.out.println("Exiting"); |
| } catch (RuntimeException t) { |
| t.printStackTrace(); |
| exception = t; |
| throw t; |
| } |
| } |
| }; |
| |
| public CriticalSectionLocker() { |
| } |
| |
| /** |
| * Enter critical section. |
| * |
| */ |
| protected abstract void criticalSection(); |
| |
| public void enable() { |
| synchronized (sync) { |
| if (enabled) |
| throw new TestBug("Locker already enabled."); |
| // System.out.println("Enabling " + this); |
| enabled = true; |
| thread = new Thread(runnable, "Locker: " + runnable); |
| thread.setDaemon(true); |
| thread.start(); |
| } |
| } |
| |
| public void lock() { |
| synchronized (sync) { |
| if (locked) |
| throw new TestBug("Locker already locked."); |
| // System.out.println("Locking " + this); |
| locked = true; |
| sync.notifyAll(); |
| } |
| } |
| |
| public void unlock() { |
| synchronized (sync) { |
| if (!locked) |
| throw new TestBug("Locker not locked."); |
| // System.out.println("Unocking " + this); |
| locked = false; |
| sync.notifyAll(); |
| } |
| } |
| |
| public void disable() { |
| synchronized (sync) { |
| if (!enabled) |
| throw new TestBug("Locker not enabled."); |
| // System.out.println("Disabling " + this); |
| enabled = false; |
| sync.notifyAll(); |
| } |
| try { |
| thread.join(); |
| } catch (InterruptedException e) { |
| throw new TestBug(e); |
| } |
| } |
| |
| public Throwable getException() { |
| return exception; |
| } |
| } |