88 lines
2.3 KiB
Java
88 lines
2.3 KiB
Java
// concurrency/ExplicitCriticalSection.java
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// ©2016 MindView LLC: see Copyright.txt
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// We make no guarantees that this code is fit for any purpose.
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// Visit http://mindviewinc.com/Books/OnJava/ for more book information.
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// {ThrowsException} on a multiprocessor machine
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// Using explicit Lock objects to create
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// critical sections.
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package concurrency;
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import java.util.concurrent.locks.*;
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// Synchronize the entire method:
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class ExplicitPairManager1 extends PairManager {
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private Lock lock = new ReentrantLock();
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@Override
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public void increment() {
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lock.lock();
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try {
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p.incrementX();
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p.incrementY();
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store(getPair());
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} finally {
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lock.unlock();
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}
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}
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}
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// Use a critical section:
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class ExplicitPairManager2 extends PairManager {
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private Lock lock = new ReentrantLock();
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@Override
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public void increment() {
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Pair temp;
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lock.lock();
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try {
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p.incrementX();
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p.incrementY();
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temp = getPair();
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} finally {
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lock.unlock();
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}
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store(temp);
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}
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}
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public class ExplicitCriticalSection {
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public static void
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main(String[] args) throws Exception {
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PairManager
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pman1 = new ExplicitPairManager1(),
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pman2 = new ExplicitPairManager2();
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CriticalSection.testApproaches(pman1, pman2);
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}
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}
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/* Output:
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pm1: Pair: x: 10, y: 10 checkCounter = 68453
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pm2: Pair: x: 11, y: 11 checkCounter = 663407
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___[ Error Output ]___
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Exception in thread "pool-1-thread-3"
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concurrency.Pair$PairValuesNotEqualException: Pair values
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not equal: x: 1, y: 0
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at
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concurrency.Pair.checkState(CriticalSection.java:36)
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at
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concurrency.PairChecker.run(CriticalSection.java:110)
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at
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java.util.concurrent.ThreadPoolExecutor.runWorker(Unknown
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Source)
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at
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java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown
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Source)
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at java.lang.Thread.run(Unknown Source)
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Exception in thread "pool-1-thread-4"
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concurrency.Pair$PairValuesNotEqualException: Pair values
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not equal: x: 2, y: 1
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at
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concurrency.Pair.checkState(CriticalSection.java:36)
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at
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concurrency.PairChecker.run(CriticalSection.java:110)
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at
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java.util.concurrent.ThreadPoolExecutor.runWorker(Unknown
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Source)
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at
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java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown
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Source)
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at java.lang.Thread.run(Unknown Source)
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___[ Exception is Expected ]___
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*/
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