1 files changed, 118 insertions, 0 deletions
diff --git a/src/test/java/org/apache/commons/lang3/builder/ReflectionToStringBuilderConcurrencyTest.java b/src/test/java/org/apache/commons/lang3/builder/ReflectionToStringBuilderConcurrencyTest.java
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+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You under the Apache License, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License.  You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.apache.commons.lang3.builder;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertNotNull;
+
+import java.util.ArrayList;
+import java.util.Collection;
+import java.util.LinkedList;
+import java.util.List;
+import java.util.concurrent.Callable;
+import java.util.concurrent.CopyOnWriteArrayList;
+import java.util.concurrent.ExecutorService;
+import java.util.concurrent.Executors;
+import java.util.concurrent.Future;
+import java.util.concurrent.TimeUnit;
+
+import org.apache.commons.lang3.AbstractLangTest;
+import org.apache.commons.lang3.concurrent.UncheckedFuture;
+import org.junit.jupiter.api.Disabled;
+import org.junit.jupiter.api.Test;
+
+/**
+ * Tests concurrent access for {@link ReflectionToStringBuilder}.
+ * <p>
+ * The {@link ToStringStyle} class includes a registry to avoid infinite loops for objects with circular references. We
+ * want to make sure that we do not get concurrency exceptions accessing this registry.
+ * </p>
+ * <p>
+ * The tests on the non-thread-safe collections do not pass.
+ * </p>
+ *
+ * @see <a href="https://issues.apache.org/jira/browse/LANG-762">[LANG-762] Handle or document ReflectionToStringBuilder
+ *      and ToStringBuilder for collections that are not thread safe</a>
+ * @since 3.1
+ */
+public class ReflectionToStringBuilderConcurrencyTest extends AbstractLangTest {
+
+    static class CollectionHolder<T extends Collection<?>> {
+        T collection;
+
+        CollectionHolder(final T collection) {
+            this.collection = collection;
+        }
+    }
+
+    private static final int DATA_SIZE = 100000;
+    private static final int REPEAT = 100;
+
+    @Test
+    @Disabled
+    public void testLinkedList() throws InterruptedException {
+        this.testConcurrency(new CollectionHolder<>(new LinkedList<>()));
+    }
+
+    @Test
+    @Disabled
+    public void testArrayList() throws InterruptedException {
+        this.testConcurrency(new CollectionHolder<>(new ArrayList<>()));
+    }
+
+    @Test
+    @Disabled
+    public void testCopyOnWriteArrayList() throws InterruptedException {
+        this.testConcurrency(new CollectionHolder<>(new CopyOnWriteArrayList<>()));
+    }
+
+    private void testConcurrency(final CollectionHolder<List<Integer>> holder) throws InterruptedException {
+        final List<Integer> list = holder.collection;
+        // make a big array that takes a long time to toString()
+        for (int i = 0; i < DATA_SIZE; i++) {
+            list.add(Integer.valueOf(i));
+        }
+        // Create a thread pool with two threads to cause the most contention on the underlying resource.
+        final ExecutorService threadPool = Executors.newFixedThreadPool(2);
+        try {
+            // Consumes toStrings
+            final Callable<Integer> consumer = () -> {
+                for (int i = 0; i < REPEAT; i++) {
+                    final String s = ReflectionToStringBuilder.toString(holder);
+                    assertNotNull(s);
+                }
+                return Integer.valueOf(REPEAT);
+            };
+            // Produces changes in the list
+            final Callable<Integer> producer = () -> {
+                for (int i = 0; i < DATA_SIZE; i++) {
+                    list.remove(list.get(0));
+                }
+                return Integer.valueOf(REPEAT);
+            };
+            final Collection<Callable<Integer>> tasks = new ArrayList<>();
+            tasks.add(consumer);
+            tasks.add(producer);
+            final List<Future<Integer>> futures = threadPool.invokeAll(tasks);
+            UncheckedFuture.on(futures).forEach(f -> assertEquals(REPEAT, f.get().intValue()));
+        } finally {
+            threadPool.shutdown();
+            threadPool.awaitTermination(1, TimeUnit.SECONDS);
+        }
+    }
+}