diff -r 000000000000 -r 212417b74b72 rt/emul/compact/src/main/java/java/util/concurrent/RecursiveTask.java --- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/rt/emul/compact/src/main/java/java/util/concurrent/RecursiveTask.java Sat Mar 19 10:46:31 2016 +0100 @@ -0,0 +1,97 @@ +/* + * 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}. + * + *
For a classic example, here is a task computing Fibonacci numbers: + * + *
{@code + * class Fibonacci extends RecursiveTask+ * + * 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{ + * final int n; + * Fibonacci(int n) { this.n = n; } + * 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(); + * } + * }}