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1 /* |
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2 * Copyright (c) 2015, Oracle and/or its affiliates. All rights reserved. |
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3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. |
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4 * |
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5 * This code is free software; you can redistribute it and/or modify it |
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6 * under the terms of the GNU General Public License version 2 only, as |
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7 * published by the Free Software Foundation. |
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8 * |
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9 * This code is distributed in the hope that it will be useful, but WITHOUT |
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10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or |
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11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License |
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12 * version 2 for more details (a copy is included in the LICENSE file that |
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13 * accompanied this code). |
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14 * |
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15 * You should have received a copy of the GNU General Public License version |
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16 * 2 along with this work; if not, write to the Free Software Foundation, |
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17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. |
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18 * |
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19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA |
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20 * or visit www.oracle.com if you need additional information or have any |
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21 * questions. |
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22 */ |
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23 |
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24 /** |
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25 * @test |
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26 * @summary Calculates Fibonacci numbers "recursively" via threads and compares |
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27 * the result with the classical calculation. |
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28 * This test is skipped on 32-bit Windows: limited virtual space on Win-32 |
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29 * make this test inherently unstable on Windows with 32-bit VM data model. |
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30 * @requires !(os.family == "windows" & sun.arch.data.model == "32") |
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31 * @library /testlibrary |
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32 * @run main Fibonacci 15 |
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33 */ |
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34 |
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35 import com.oracle.java.testlibrary.Asserts; |
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36 |
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37 public class Fibonacci extends Thread { |
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38 private int index; |
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39 private int value; |
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40 private Fibonacci left; |
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41 private Fibonacci right; |
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42 |
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43 public Fibonacci(int i) { |
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44 index = i; |
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45 } |
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46 |
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47 private int getValue() { |
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48 return value; |
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49 } |
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50 |
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51 @Override |
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52 public void run() { |
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53 if (index == 0 || index == 1) { |
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54 // base cases, 0 Fibonacci number = 0, 1 Fibonacci number = 1 |
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55 value = index; |
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56 } else { |
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57 // inductive cases |
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58 left = new Fibonacci(index - 2); |
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59 right = new Fibonacci(index - 1); |
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60 left.start(); |
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61 right.start(); |
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62 try { |
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63 left.join(); |
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64 right.join(); |
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65 } catch (InterruptedException e) { |
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66 throw new Error("InterruptedException for index " + index, e); |
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67 } |
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68 // compute and terminate |
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69 value = left.getValue() + right.getValue(); |
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70 } |
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71 } |
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72 |
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73 public static int traditionalFibonacci(int n) { |
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74 int n1 = 0, n2 = 1, nn = 0; |
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75 |
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76 if (n == 0 || n == 1) { |
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77 nn = n; |
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78 } |
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79 |
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80 for (int i = 1; i < n; ++i) { |
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81 nn = n2 + n1; |
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82 n1 = n2; |
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83 n2 = nn; |
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84 } |
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85 return nn; |
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86 } |
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87 |
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88 public static void main(String[] args) throws Error,AssertionError { |
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89 int expected; |
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90 int number; |
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91 Fibonacci recursiveFibonacci; |
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92 |
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93 if (args.length != 1) { |
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94 throw new Error("Error: args.length must be 1"); |
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95 } |
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96 |
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97 number = Integer.parseInt(args[0]); |
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98 recursiveFibonacci = new Fibonacci(number); |
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99 |
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100 recursiveFibonacci.start(); |
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101 try { |
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102 recursiveFibonacci.join(); |
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103 } catch (InterruptedException e) { |
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104 throw new Error("InterruptedException in main thread", e); |
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105 } |
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106 |
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107 expected = traditionalFibonacci(number); |
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108 |
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109 System.out.println("Fibonacci[" + number + "] = " + expected); |
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110 |
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111 Asserts.assertEQ(recursiveFibonacci.getValue(), expected, |
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112 "Unexpected calculated value: " + recursiveFibonacci.getValue() + " expected " + expected ); |
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113 } |
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114 } |