94 lines
3.1 KiB
Java
94 lines
3.1 KiB
Java
/*
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* Copyright (c) 1994, 2005, Oracle and/or its affiliates. All rights reserved.
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* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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*
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* This code is free software; you can redistribute it and/or modify it
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* under the terms of the GNU General Public License version 2 only, as
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* published by the Free Software Foundation. Oracle designates this
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* particular file as subject to the "Classpath" exception as provided
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* by Oracle in the LICENSE file that accompanied this code.
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*
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* This code is distributed in the hope that it will be useful, but WITHOUT
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* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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* version 2 for more details (a copy is included in the LICENSE file that
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* accompanied this code).
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*
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* You should have received a copy of the GNU General Public License version
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* 2 along with this work; if not, write to the Free Software Foundation,
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* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
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*
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* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
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* or visit www.oracle.com if you need additional information or have any
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* questions.
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*/
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package sun.misc;
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/**
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* The Lock class provides a simple, useful interface to a lock.
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* Unlike monitors which synchronize access to an object, locks
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* synchronize access to an arbitrary set of resources (objects,
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* methods, variables, etc.). <p>
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*
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* The programmer using locks must be responsible for clearly defining
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* the semantics of their use and should handle deadlock avoidance in
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* the face of exceptions. <p>
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*
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* For example, if you want to protect a set of method invocations with
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* a lock, and one of the methods may throw an exception, you must be
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* prepared to release the lock similarly to the following example:
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* <pre>
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* class SomeClass {
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* Lock myLock = new Lock();
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* void someMethod() {
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* myLock.lock();
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* try {
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* StartOperation();
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* ContinueOperation();
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* EndOperation();
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* } finally {
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* myLock.unlock();
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* }
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* }
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* }
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* </pre>
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*
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* @author Peter King
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*/
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public
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class Lock {
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private boolean locked = false;
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/**
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* Create a lock, which is initially not locked.
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*/
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public Lock () {
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}
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/**
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* Acquire the lock. If someone else has the lock, wait until it
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* has been freed, and then try to acquire it again. This method
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* will not return until the lock has been acquired.
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*
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* @exception java.lang.InterruptedException if any thread has
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* interrupted this thread.
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*/
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public final synchronized void lock() throws InterruptedException {
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while (locked) {
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wait();
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}
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locked = true;
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}
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/**
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* Release the lock. If someone else is waiting for the lock, the
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* will be notitified so they can try to acquire the lock again.
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*/
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public final synchronized void unlock() {
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locked = false;
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notifyAll();
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}
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}
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