117 lines
3.7 KiB
Java
117 lines
3.7 KiB
Java
/*
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* Copyright (c) 2015, 2016, Oracle and/or its affiliates. All rights reserved.
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* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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*
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* This code is free software; you can redistribute it and/or modify it
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* under the terms of the GNU General Public License version 2 only, as
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* published by the Free Software Foundation.
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*
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* This code is distributed in the hope that it will be useful, but WITHOUT
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* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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* version 2 for more details (a copy is included in the LICENSE file that
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* accompanied this code).
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*
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* You should have received a copy of the GNU General Public License version
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* 2 along with this work; if not, write to the Free Software Foundation,
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* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
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*
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* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
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* or visit www.oracle.com if you need additional information or have any
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* questions.
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*/
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/**
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* @test
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* @summary Calculates Fibonacci numbers "recursively" via threads and compares
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* the result with the classical calculation.
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* This test is skipped on 32-bit Windows: limited virtual space on Win-32
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* make this test inherently unstable on Windows with 32-bit VM data model.
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* @requires !(os.family == "windows" & sun.arch.data.model == "32")
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* @requires !(os.family == "linux" & os.maxMemory < 512M)
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* @modules java.base/jdk.internal.misc
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* @library /test/lib
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* @run main/othervm Fibonacci 15
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*/
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import jdk.test.lib.Asserts;
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public class Fibonacci extends Thread {
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private int index;
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private int value;
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private Fibonacci left;
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private Fibonacci right;
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public Fibonacci(int i) {
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index = i;
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}
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private int getValue() {
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return value;
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}
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@Override
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public void run() {
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if (index == 0 || index == 1) {
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// base cases, 0 Fibonacci number = 0, 1 Fibonacci number = 1
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value = index;
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} else {
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// inductive cases
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left = new Fibonacci(index - 2);
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right = new Fibonacci(index - 1);
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left.start();
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right.start();
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try {
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left.join();
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right.join();
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} catch (InterruptedException e) {
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throw new Error("InterruptedException for index " + index, e);
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}
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// compute and terminate
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value = left.getValue() + right.getValue();
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}
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}
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public static int traditionalFibonacci(int n) {
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int n1 = 0, n2 = 1, nn = 0;
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if (n == 0 || n == 1) {
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nn = n;
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}
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for (int i = 1; i < n; ++i) {
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nn = n2 + n1;
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n1 = n2;
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n2 = nn;
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}
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return nn;
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}
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public static void main(String[] args) throws Error,AssertionError {
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int expected;
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int number;
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Fibonacci recursiveFibonacci;
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if (args.length != 1) {
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throw new Error("Error: args.length must be 1");
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}
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number = Integer.parseInt(args[0]);
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recursiveFibonacci = new Fibonacci(number);
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recursiveFibonacci.start();
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try {
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recursiveFibonacci.join();
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} catch (InterruptedException e) {
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throw new Error("InterruptedException in main thread", e);
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}
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expected = traditionalFibonacci(number);
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System.out.println("Fibonacci[" + number + "] = " + expected);
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Asserts.assertEQ(recursiveFibonacci.getValue(), expected,
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"Unexpected calculated value: " + recursiveFibonacci.getValue() + " expected " + expected );
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}
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}
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