1 /* 2 * Copyright (c) 2004, 2013, Oracle and/or its affiliates. All rights reserved. 3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. 4 * 5 * This code is free software; you can redistribute it and/or modify it 6 * under the terms of the GNU General Public License version 2 only, as 7 * published by the Free Software Foundation. 8 * 9 * This code is distributed in the hope that it will be useful, but WITHOUT 10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or 11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 12 * version 2 for more details (a copy is included in the LICENSE file that 13 * accompanied this code). 14 * 15 * You should have received a copy of the GNU General Public License version 16 * 2 along with this work; if not, write to the Free Software Foundation, 17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. 18 * 19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA 20 * or visit www.oracle.com if you need additional information or have any 21 * questions. 22 */ 23 24 /* 25 * @test 26 * @bug 4486658 8010293 27 * @summary thread safety of toArray methods of subCollections 28 * @author Martin Buchholz 29 */ 30 31 import java.util.concurrent.CompletableFuture; 32 import java.util.concurrent.ConcurrentHashMap; 33 import java.util.stream.IntStream; 34 35 public class ToArray { 36 37 public static void main(String[] args) throws Throwable { 38 // Execute a number of times to increase the probability of 39 // failure if there is an issue 40 for (int i = 0; i < 16; i++) { 41 executeTest(); 42 } 43 } 44 45 static void executeTest() throws Throwable { 46 final Throwable[] throwable = new Throwable[1]; 47 final ConcurrentHashMap<Integer, Integer> m = new ConcurrentHashMap<>(); 48 49 // Number of workers equal to the number of processors 50 // Each worker will put globally unique keys into the map 51 final int nWorkers = Runtime.getRuntime().availableProcessors(); 52 final int sizePerWorker = 1024; 53 final int maxSize = nWorkers * sizePerWorker; 54 55 // The foreman keeps checking that the size of the arrays 56 // obtained from the key and value sets is never less than the 57 // previously observed size and is never greater than the maximum size 58 // NOTE: these size constraints are not specific to toArray and are 59 // applicable to any form of traversal of the collection views 60 CompletableFuture<?> foreman = CompletableFuture.runAsync(new Runnable() { 61 private int prevSize = 0; 62 63 private boolean checkProgress(Object[] a) { 64 int size = a.length; 65 if (size < prevSize) throw new RuntimeException("WRONG WAY"); 66 if (size > maxSize) throw new RuntimeException("OVERSHOOT"); 67 if (size == maxSize) return true; 68 prevSize = size; 69 return false; 70 } 71 72 @Override 73 public void run() { 74 try { 75 Integer[] empty = new Integer[0]; 76 while (true) { 77 if (checkProgress(m.values().toArray())) return; 78 if (checkProgress(m.keySet().toArray())) return; 79 if (checkProgress(m.values().toArray(empty))) return; 80 if (checkProgress(m.keySet().toArray(empty))) return; 81 } 82 } 83 catch (Throwable t) { 84 throwable[0] = t; 85 } 86 } 87 }); 88 89 // Create workers 90 // Each worker will put globally unique keys into the map 91 CompletableFuture<?>[] workers = IntStream.range(0, nWorkers). 92 mapToObj(w -> CompletableFuture.runAsync(() -> { 93 for (int i = 0, o = w * sizePerWorker; i < sizePerWorker; i++) 94 m.put(o + i, i); 95 })). 96 toArray(CompletableFuture<?>[]::new); 97 98 // Wait for workers and then foreman to complete 99 CompletableFuture.allOf(workers).join(); 100 foreman.join(); 101 102 if (throwable[0] != null) 103 throw throwable[0]; 104 } 105 }