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99 lines
2.0 KiB
99 lines
2.0 KiB
/*
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* ORACLE PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
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*
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*
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*
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*
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*
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*
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*
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*
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*
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*
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*
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*
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*
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*
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*
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*
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*
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*
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*
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*
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*/
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/*
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*
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*
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*
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*
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*
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* Written by Doug Lea with assistance from members of JCP JSR-166
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* Expert Group and released to the public domain, as explained at
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* http://creativecommons.org/publicdomain/zero/1.0/
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*/
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package java.util.concurrent;
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/**
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* A recursive result-bearing {@link ForkJoinTask}.
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*
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* <p>For a classic example, here is a task computing Fibonacci numbers:
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*
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* <pre> {@code
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* class Fibonacci extends RecursiveTask<Integer> {
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* final int n;
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* Fibonacci(int n) { this.n = n; }
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* Integer compute() {
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* if (n <= 1)
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* return n;
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* Fibonacci f1 = new Fibonacci(n - 1);
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* f1.fork();
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* Fibonacci f2 = new Fibonacci(n - 2);
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* return f2.compute() + f1.join();
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* }
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* }}</pre>
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*
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* However, besides being a dumb way to compute Fibonacci functions
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* (there is a simple fast linear algorithm that you'd use in
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* practice), this is likely to perform poorly because the smallest
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* subtasks are too small to be worthwhile splitting up. Instead, as
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* is the case for nearly all fork/join applications, you'd pick some
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* minimum granularity size (for example 10 here) for which you always
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* sequentially solve rather than subdividing.
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*
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* @since 1.7
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* @author Doug Lea
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*/
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public abstract class RecursiveTask<V> extends ForkJoinTask<V> {
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private static final long serialVersionUID = 5232453952276485270L;
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/**
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* The result of the computation.
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*/
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V result;
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/**
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* The main computation performed by this task.
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* @return the result of the computation
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*/
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protected abstract V compute();
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public final V getRawResult() {
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return result;
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}
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protected final void setRawResult(V value) {
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result = value;
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}
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/**
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* Implements execution conventions for RecursiveTask.
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*/
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protected final boolean exec() {
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result = compute();
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return true;
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}
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}
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