content: /*
   * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   *
   * This code is free software; you can redistribute it and/or modify it
   * under the terms of the GNU General Public License version 2 only, as
   * published by the Free Software Foundation.  Oracle designates this
   * particular file as subject to the "Classpath" exception as provided
   * by Oracle in the LICENSE file that accompanied this code.
   *
   * This code is distributed in the hope that it will be useful, but WITHOUT
   * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
   * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
   * version 2 for more details (a copy is included in the LICENSE file that
   * accompanied this code).
   *
   * You should have received a copy of the GNU General Public License version
   * 2 along with this work; if not, write to the Free Software Foundation,
   * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
   *
   * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
   * or visit www.oracle.com if you need additional information or have any
   * questions.
   */
  
  /*
   * This file is available under and governed by the GNU General Public
   * License version 2 only, as published by the Free Software Foundation.
   * However, the following notice accompanied the original version of this
   * file:
   *
   * 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;
      }
  
  }
  