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Revision **1.4** -
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*Fri Jul 26 16:36:21 2013 UTC*
(4 years, 6 months ago)
by *jsr166*

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Changes since**1.3: +1 -1 lines**

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make compute() protected

/* * Written by Doug Lea with assistance from members of JCP JSR-166 * Expert Group and released to the public domain, as explained at * http://creativecommons.org/publicdomain/zero/1.0/ */ package jsr166e; /** * A recursive result-bearing {@link ForkJoinTask}. * * <p>For a classic example, here is a task computing Fibonacci numbers: * * <pre> {@code * class Fibonacci extends RecursiveTask<Integer> { * final int n; * Fibonacci(int n) { this.n = n; } * protected Integer compute() { * if (n <= 1) * return n; * Fibonacci f1 = new Fibonacci(n - 1); * f1.fork(); * Fibonacci f2 = new Fibonacci(n - 2); * return f2.compute() + f1.join(); * } * }}</pre> * * However, besides being a dumb way to compute Fibonacci functions * (there is a simple fast linear algorithm that you'd use in * practice), this is likely to perform poorly because the smallest * subtasks are too small to be worthwhile splitting up. Instead, as * is the case for nearly all fork/join applications, you'd pick some * minimum granularity size (for example 10 here) for which you always * sequentially solve rather than subdividing. * * @since 1.7 * @author Doug Lea */ public abstract class RecursiveTask<V> extends ForkJoinTask<V> { private static final long serialVersionUID = 5232453952276485270L; /** * The result of the computation. */ V result; /** * The main computation performed by this task. * @return the result of the computation */ protected abstract V compute(); public final V getRawResult() { return result; } protected final void setRawResult(V value) { result = value; } /** * Implements execution conventions for RecursiveTask. */ protected final boolean exec() { result = compute(); return true; } }

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