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/*
* Copyright (c) 2004, 2024, 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 collection views
* @author Martin Buchholz
*/
import java.util.List;
import java.util.concurrent.CompletableFuture;
import java.util.concurrent.ConcurrentHashMap;
import java.util.concurrent.Executors;
import java.util.concurrent.ThreadLocalRandom;
import java.util.stream.Collectors;
import java.util.stream.IntStream;
public class ToArray {
public static void main(String[] args) throws Throwable {
final int runsPerTest = Integer.getInteger("jsr166.runsPerTest", 1);
final int reps = 10 * runsPerTest;
for (int i = reps; i--> 0; )
executeTest();
}
static void executeTest() throws Throwable {
try (var executor = Executors.newCachedThreadPool()) {
final ConcurrentHashMap<Integer, Integer> m = new ConcurrentHashMap<>();
final ThreadLocalRandom rnd = ThreadLocalRandom.current();
final int nCPU = Runtime.getRuntime().availableProcessors();
final int minWorkers = 2;
final int maxWorkers = Math.max(minWorkers, Math.min(32, nCPU));
final int nWorkers = rnd.nextInt(minWorkers, maxWorkers + 1);
final int sizePerWorker = 1024;
final int maxSize = nWorkers * sizePerWorker;
// The foreman busy-checks that the size of the arrays obtained
// from the keys and values views grows monotonically until it
// reaches 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 || size > maxSize)
throw new AssertionError(
String.format("prevSize=%d size=%d maxSize=%d",
prevSize, size, maxSize));
prevSize = size;
return size == maxSize;
}
public void run() {
Integer[] empty = new Integer[0];
for (; ; )
if (checkProgress(m.values().toArray())
& checkProgress(m.keySet().toArray())
& checkProgress(m.values().toArray(empty))
& checkProgress(m.keySet().toArray(empty)))
return;
}
}, executor);
// Each worker puts globally unique keys into the map
List<CompletableFuture<?>> workers =
IntStream.range(0, nWorkers)
.mapToObj(w -> (Runnable) () -> {
for (int i = 0, o = w * sizePerWorker; i < sizePerWorker; i++)
m.put(o + i, i);
})
.map(r -> CompletableFuture.runAsync(r, executor))
.collect(Collectors.toList());
// Wait for workers and foreman to complete
workers.forEach(CompletableFuture<?>::join);
foreman.join();
}
}
}
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