diff --git a/src/changes/changes.xml b/src/changes/changes.xml
index eb6ab2296..8d68c4287 100644
--- a/src/changes/changes.xml
+++ b/src/changes/changes.xml
@@ -75,6 +75,9 @@
Add CollectionUtils containsAny method for primitive array: org.apache.commons.collections4.CollectionUtils.containsAny(Collection<?>, T...).
+
+ Synchronized queue wrapper in QueueUtils.
+
diff --git a/src/main/java/org/apache/commons/collections4/QueueUtils.java b/src/main/java/org/apache/commons/collections4/QueueUtils.java
index 053581cb3..ee4114bea 100644
--- a/src/main/java/org/apache/commons/collections4/QueueUtils.java
+++ b/src/main/java/org/apache/commons/collections4/QueueUtils.java
@@ -20,6 +20,7 @@ import java.util.LinkedList;
import java.util.Queue;
import org.apache.commons.collections4.queue.PredicatedQueue;
+import org.apache.commons.collections4.queue.SynchronizedQueue;
import org.apache.commons.collections4.queue.TransformedQueue;
import org.apache.commons.collections4.queue.UnmodifiableQueue;
@@ -43,6 +44,37 @@ public class QueueUtils {
//-----------------------------------------------------------------------
+ /**
+ * Returns a synchronized (thread-safe) queue backed by the given queue.
+ * In order to guarantee serial access, it is critical that all access to the
+ * backing queue is accomplished through the returned queue.
+ *
+ * It is imperative that the user manually synchronize on the returned queue
+ * when iterating over it:
+ *
+ *
+ * Queue queue = QueueUtils.synchronizedQueue(new CircularFifoQueue());
+ * ...
+ * synchronized(queue) {
+ * Iterator i = queue.iterator(); // Must be in synchronized block
+ * while (i.hasNext())
+ * foo(i.next());
+ * }
+ * }
+ *
+ *
+ * Failure to follow this advice may result in non-deterministic behavior.
+ *
+ * @param the element type
+ * @param queue the queue to synchronize, must not be null
+ * @return a synchronized queue backed by that queue
+ * @throws NullPointerException if the queue is null
+ * @since 4.2
+ */
+ public static Queue synchronizedQueue(final Queue queue) {
+ return SynchronizedQueue.synchronizedQueue(queue);
+ }
+
/**
* Returns an unmodifiable queue backed by the given queue.
*
diff --git a/src/main/java/org/apache/commons/collections4/queue/SynchronizedQueue.java b/src/main/java/org/apache/commons/collections4/queue/SynchronizedQueue.java
new file mode 100644
index 000000000..5eda57fb0
--- /dev/null
+++ b/src/main/java/org/apache/commons/collections4/queue/SynchronizedQueue.java
@@ -0,0 +1,143 @@
+/*
+ * 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.collections4.queue;
+
+import java.util.Queue;
+
+import org.apache.commons.collections4.collection.SynchronizedCollection;
+
+/**
+ * Decorates another {@link Queue} to synchronize its behaviour for a multi-threaded environment.
+ *
+ * Methods are synchronized, then forwarded to the decorated queue. Iterators must be separately synchronized around the
+ * loop.
+ *
+ * @param the type of the elements in the collection
+ * @since 4.2
+ */
+public class SynchronizedQueue extends SynchronizedCollection implements Queue {
+
+ /** Serialization version */
+ private static final long serialVersionUID = 1L;
+
+ /**
+ * Factory method to create a synchronized queue.
+ *
+ * @param
+ * the type of the elements in the queue
+ * @param queue
+ * the queue to decorate, must not be null
+ * @return a new synchronized Queue
+ * @throws NullPointerException
+ * if queue is null
+ */
+ public static SynchronizedQueue synchronizedQueue(final Queue queue) {
+ return new SynchronizedQueue(queue);
+ }
+
+ // -----------------------------------------------------------------------
+ /**
+ * Constructor that wraps (not copies).
+ *
+ * @param queue
+ * the queue to decorate, must not be null
+ * @throws NullPointerException
+ * if queue is null
+ */
+ protected SynchronizedQueue(final Queue queue) {
+ super(queue);
+ }
+
+ /**
+ * Constructor that wraps (not copies).
+ *
+ * @param queue
+ * the queue to decorate, must not be null
+ * @param lock
+ * the lock to use, must not be null
+ * @throws NullPointerException
+ * if queue or lock is null
+ */
+ protected SynchronizedQueue(final Queue queue, final Object lock) {
+ super(queue, lock);
+ }
+
+ /**
+ * Gets the queue being decorated.
+ *
+ * @return the decorated queue
+ */
+ @Override
+ protected Queue decorated() {
+ return (Queue) super.decorated();
+ }
+
+ @Override
+ public E element() {
+ synchronized (lock) {
+ return decorated().element();
+ }
+ }
+
+ @Override
+ public boolean equals(final Object object) {
+ if (object == this) {
+ return true;
+ }
+ synchronized (lock) {
+ return decorated().equals(object);
+ }
+ }
+
+ // -----------------------------------------------------------------------
+
+ @Override
+ public int hashCode() {
+ synchronized (lock) {
+ return decorated().hashCode();
+ }
+ }
+
+ @Override
+ public boolean offer(final E e) {
+ synchronized (lock) {
+ return decorated().offer(e);
+ }
+ }
+
+ @Override
+ public E peek() {
+ synchronized (lock) {
+ return decorated().peek();
+ }
+ }
+
+ @Override
+ public E poll() {
+ synchronized (lock) {
+ return decorated().poll();
+ }
+ }
+
+ @Override
+ public E remove() {
+ synchronized (lock) {
+ return decorated().remove();
+ }
+ }
+
+}
diff --git a/src/test/java/org/apache/commons/collections4/QueueUtilsTest.java b/src/test/java/org/apache/commons/collections4/QueueUtilsTest.java
index 970f9ce55..d75c321cf 100644
--- a/src/test/java/org/apache/commons/collections4/QueueUtilsTest.java
+++ b/src/test/java/org/apache/commons/collections4/QueueUtilsTest.java
@@ -16,13 +16,16 @@
*/
package org.apache.commons.collections4;
-import static org.junit.Assert.*;
+import static org.junit.Assert.assertSame;
+import static org.junit.Assert.assertTrue;
+import static org.junit.Assert.fail;
import java.util.LinkedList;
import java.util.Queue;
import org.apache.commons.collections4.functors.TruePredicate;
import org.apache.commons.collections4.queue.PredicatedQueue;
+import org.apache.commons.collections4.queue.SynchronizedQueue;
import org.apache.commons.collections4.queue.TransformedQueue;
import org.apache.commons.collections4.queue.UnmodifiableQueue;
import org.junit.Test;
@@ -38,6 +41,18 @@ public class QueueUtilsTest {
// ----------------------------------------------------------------------
+ @Test
+ public void testSynchronizedQueue() {
+ Queue