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/*
* Copyright (c) 2004, 2013, Oracle and/or its affiliates. All rights reserved.
* 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.
*
* 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.
*/
/*
* @test
* @bug 4486658 8010293
* @summary thread safety of toArray methods of subCollections
* @author Martin Buchholz
*/
import java.util.concurrent.CompletableFuture;
import java.util.concurrent.ConcurrentHashMap;
import java.util.stream.IntStream;
public class ToArray {
public static void main(String[] args) throws Throwable {
// Execute a number of times to increase the probability of
// failure if there is an issue
for (int i = 0; i < 16; i++) {
executeTest();
}
}
static void executeTest() throws Throwable {
final Throwable[] throwable = new Throwable[1];
final ConcurrentHashMap<Integer, Integer> m = new ConcurrentHashMap<>();
// Number of workers equal to the number of processors
// Each worker will put globally unique keys into the map
final int nWorkers = Runtime.getRuntime().availableProcessors();
final int sizePerWorker = 1024;
final int maxSize = nWorkers * sizePerWorker;
// The foreman keeps checking that the size of the arrays
// obtained from the key and value sets is never less than the
// previously observed size and is never greater than the maximum size
// NOTE: these size constraints are not specific to toArray and are
// applicable to any form of traversal of the collection views
CompletableFuture<?> foreman = CompletableFuture.runAsync(new Runnable() {
private int prevSize = 0;
private boolean checkProgress(Object[] a) {
int size = a.length;
if (size < prevSize) throw new RuntimeException("WRONG WAY");
if (size > maxSize) throw new RuntimeException("OVERSHOOT");
if (size == maxSize) return true;
prevSize = size;
return false;
}
@Override
public void run() {
try {
Integer[] empty = new Integer[0];
while (true) {
if (checkProgress(m.values().toArray())) return;
if (checkProgress(m.keySet().toArray())) return;
if (checkProgress(m.values().toArray(empty))) return;
if (checkProgress(m.keySet().toArray(empty))) return;
}
}
catch (Throwable t) {
throwable[0] = t;
}
}
});
// Create workers
// Each worker will put globally unique keys into the map
CompletableFuture<?>[] workers = IntStream.range(0, nWorkers).
mapToObj(w -> CompletableFuture.runAsync(() -> {
for (int i = 0, o = w * sizePerWorker; i < sizePerWorker; i++)
m.put(o + i, i);
})).
toArray(CompletableFuture<?>[]::new);
// Wait for workers and then foreman to complete
CompletableFuture.allOf(workers).join();
foreman.join();
if (throwable[0] != null)
throw throwable[0];
}
}
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