/*
 * ORACLE PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
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/*
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 * 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 java.util.concurrent;

/**
 * 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;
 }

}