Adapt RedisList to API changes in Java 21 SequencedCollections.

Closes #2602
Original pull request: #2608

src/main/java/org/springframework/data/redis/support/collections/DefaultRedisList.java

@@ -17,6 +17,7 @@ package org.springframework.data.redis.support.collections;
 
 import java.util.Collection;
 import java.util.Collections;
+import java.util.ConcurrentModificationException;
 import java.util.Iterator;
 import java.util.List;
 import java.util.ListIterator;
@@ -39,42 +40,32 @@ import org.springframework.util.Assert;
  * @author Costin Leau
  * @author Christoph Strobl
  * @author Mark Paluch
+ * @author John Blum
  */
 public class DefaultRedisList<E> extends AbstractRedisCollection<E> implements RedisList<E> {
 
-	private final BoundListOperations<String, E> listOps;
-
-	private volatile int maxSize = 0;
 	private volatile boolean capped = false;
 
-	private class DefaultRedisListIterator extends RedisIterator<E> {
+	private volatile int maxSize = 0;
 
-		public DefaultRedisListIterator(Iterator<E> delegate) {
-			super(delegate);
-		}
-
-		@Override
-		protected void removeFromRedisStorage(E item) {
-			DefaultRedisList.this.remove(item);
-		}
-	}
+	private final BoundListOperations<String, E> listOps;
 
 	/**
 	 * Constructs a new, uncapped {@link DefaultRedisList} instance.
 	 *
 	 * @param key Redis key of this list.
-	 * @param operations {@link RedisOperations} for the value type of this list.
+	 * @param operations {@link RedisOperations} used to retrieve values of the declared {@link E type} from this list.
 	 */
 	public DefaultRedisList(String key, RedisOperations<String, E> operations) {
 		this(operations.boundListOps(key));
 	}
 
 	/**
-	 * Constructs a new {@link DefaultRedisList} instance.
+	 * Constructs a new {@link DefaultRedisList} instance constrained to the given {@link Integer max size}.
 	 *
 	 * @param key Redis key of this list.
-	 * @param operations {@link RedisOperations} for the value type of this list.
-	 * @param maxSize
+	 * @param operations {@link RedisOperations} used to retrieve values of the declared {@link E type} from this list.
+	 * @param maxSize {@link Integer maximum number of elements} allowed to be stored in this list.
 	 * @since 2.6
 	 */
 	public DefaultRedisList(String key, RedisOperations<String, E> operations, int maxSize) {
@@ -91,10 +82,10 @@ public class DefaultRedisList<E> extends AbstractRedisCollection<E> implements R
 	}
 
 	/**
-	 * Constructs a new {@link DefaultRedisList} instance.
+	 * Constructs a new {@link DefaultRedisList} instance constrained to the given {@link Integer max size}.
 	 *
 	 * @param boundOps {@link BoundListOperations} for the value type of this list.
-	 * @param maxSize
+	 * @param maxSize {@link Integer maximum number of elements} allowed to be stored in this list.
 	 */
 	public DefaultRedisList(BoundListOperations<String, E> boundOps, int maxSize) {
 
@@ -165,6 +156,7 @@ public class DefaultRedisList<E> extends AbstractRedisCollection<E> implements R
 		return result;
 	}
 
+	@SuppressWarnings("unchecked")
 	private void potentiallyCap(RedisList<E> destination) {
 		if (destination instanceof DefaultRedisList) {
 			((DefaultRedisList<Object>) destination).cap();
@@ -217,11 +209,12 @@ public class DefaultRedisList<E> extends AbstractRedisCollection<E> implements R
 	@Override
 	public boolean remove(Object o) {
 		Long result = listOps.remove(1, o);
-		return (result != null && result.longValue() > 0);
+		return result != null && result > 0L;
 	}
 
 	@Override
 	public void add(int index, E element) {
+
 		if (index == 0) {
 			listOps.leftPush(element);
 			cap();
@@ -244,23 +237,26 @@ public class DefaultRedisList<E> extends AbstractRedisCollection<E> implements R
 	}
 
 	@Override
-	public boolean addAll(int index, Collection<? extends E> c) {
+	public boolean addAll(int index, Collection<? extends E> collection) {
+
 		// insert collection in reverse
 		if (index == 0) {
-			Collection<? extends E> reverseC = CollectionUtils.reverse(c);
 
-			for (E e : reverseC) {
-				listOps.leftPush(e);
+			Collection<? extends E> reverseCollection = CollectionUtils.reverse(collection);
+
+			for (E element : reverseCollection) {
+				listOps.leftPush(element);
 				cap();
 			}
+
 			return true;
 		}
 
 		int size = size();
 
 		if (index == size()) {
-			for (E e : c) {
-				listOps.rightPush(e);
+			for (E element : collection) {
+				listOps.rightPush(element);
 				cap();
 			}
 			return true;
@@ -275,34 +271,40 @@ public class DefaultRedisList<E> extends AbstractRedisCollection<E> implements R
 
 	@Override
 	public E get(int index) {
+
 		if (index < 0 || index > size()) {
 			throw new IndexOutOfBoundsException();
 		}
+
 		return listOps.index(index);
 	}
 
 	@Override
-	public int indexOf(Object o) {
+	@SuppressWarnings("unchecked")
+	public int indexOf(Object element) {
+
+		Long index = listOps.indexOf((E) element);
 
-		Long index = listOps.indexOf((E) o);
 		return index != null ? index.intValue() : -1;
 	}
 
 	@Override
-	public int lastIndexOf(Object o) {
+	@SuppressWarnings("unchecked")
+	public int lastIndexOf(Object element) {
+
+		Long index = listOps.lastIndexOf((E) element);
 
-		Long index = listOps.lastIndexOf((E) o);
 		return index != null ? index.intValue() : -1;
 	}
 
 	@Override
 	public ListIterator<E> listIterator() {
-		throw new UnsupportedOperationException();
+		return listIterator(0);
 	}
 
 	@Override
 	public ListIterator<E> listIterator(int index) {
-		throw new UnsupportedOperationException();
+		return new ListItr(index);
 	}
 
 	@Override
@@ -311,10 +313,10 @@ public class DefaultRedisList<E> extends AbstractRedisCollection<E> implements R
 	}
 
 	@Override
-	public E set(int index, E e) {
+	public E set(int index, E element) {
 
 		E object = get(index);
-		listOps.set(index, e);
+		listOps.set(index, element);
 		return object;
 	}
 
@@ -338,8 +340,8 @@ public class DefaultRedisList<E> extends AbstractRedisCollection<E> implements R
 	}
 
 	@Override
-	public boolean offer(E e) {
-		listOps.rightPush(e);
+	public boolean offer(E element) {
+		listOps.rightPush(element);
 		cap();
 		return true;
 	}
@@ -372,14 +374,14 @@ public class DefaultRedisList<E> extends AbstractRedisCollection<E> implements R
 	//
 
 	@Override
-	public void addFirst(E e) {
-		listOps.leftPush(e);
+	public void addFirst(E element) {
+		listOps.leftPush(element);
 		cap();
 	}
 
 	@Override
-	public void addLast(E e) {
-		add(e);
+	public void addLast(E element) {
+		add(element);
 	}
 
 	@Override
@@ -396,22 +398,22 @@ public class DefaultRedisList<E> extends AbstractRedisCollection<E> implements R
 
 	@Override
 	public E getLast() {
-		E e = peekLast();
-		if (e == null) {
+		E element = peekLast();
+		if (element == null) {
 			throw new NoSuchElementException();
 		}
-		return e;
+		return element;
 	}
 
 	@Override
-	public boolean offerFirst(E e) {
-		addFirst(e);
+	public boolean offerFirst(E element) {
+		addFirst(element);
 		return true;
 	}
 
 	@Override
-	public boolean offerLast(E e) {
-		addLast(e);
+	public boolean offerLast(E element) {
+		addLast(element);
 		return true;
 	}
 
@@ -442,16 +444,16 @@ public class DefaultRedisList<E> extends AbstractRedisCollection<E> implements R
 	@Override
 	public E pop() {
 
-		E e = poll();
-		if (e == null) {
+		E element = poll();
+		if (element == null) {
 			throw new NoSuchElementException();
 		}
-		return e;
+		return element;
 	}
 
 	@Override
-	public void push(E e) {
-		addFirst(e);
+	public void push(E element) {
+		addFirst(element);
 	}
 
 	@Override
@@ -460,52 +462,52 @@ public class DefaultRedisList<E> extends AbstractRedisCollection<E> implements R
 	}
 
 	@Override
-	public boolean removeFirstOccurrence(Object o) {
-		return remove(o);
+	public boolean removeFirstOccurrence(Object element) {
+		return remove(element);
 	}
 
 	@Override
 	public E removeLast() {
-		E e = pollLast();
-		if (e == null) {
+		E element = pollLast();
+		if (element == null) {
 			throw new NoSuchElementException();
 		}
-		return e;
+		return element;
 	}
 
 	@Override
-	public boolean removeLastOccurrence(Object o) {
-		Long result = listOps.remove(-1, o);
-		return (result != null && result.longValue() > 0);
+	public boolean removeLastOccurrence(Object element) {
+		Long result = listOps.remove(-1, element);
+		return result != null && result > 0L;
 	}
 
 	//
 	// BlockingQueue
 	//
 	@Override
-	public int drainTo(Collection<? super E> c, int maxElements) {
-		if (this.equals(c)) {
+	public int drainTo(Collection<? super E> collection, int maxElements) {
+
+		if (this.equals(collection)) {
 			throw new IllegalArgumentException("Cannot drain a queue to itself");
 		}
 
-		int size = size();
-		int loop = (size >= maxElements ? maxElements : size);
+		int loop = (Math.min(size(), maxElements));
 
 		for (int index = 0; index < loop; index++) {
-			c.add(poll());
+			collection.add(poll());
 		}
 
 		return loop;
 	}
 
 	@Override
-	public int drainTo(Collection<? super E> c) {
-		return drainTo(c, size());
+	public int drainTo(Collection<? super E> collection) {
+		return drainTo(collection, size());
 	}
 
 	@Override
-	public boolean offer(E e, long timeout, TimeUnit unit) throws InterruptedException {
-		return offer(e);
+	public boolean offer(E element, long timeout, TimeUnit unit) throws InterruptedException {
+		return offer(element);
 	}
 
 	@Override
@@ -515,8 +517,8 @@ public class DefaultRedisList<E> extends AbstractRedisCollection<E> implements R
 	}
 
 	@Override
-	public void put(E e) throws InterruptedException {
-		offer(e);
+	public void put(E element) throws InterruptedException {
+		offer(element);
 	}
 
 	@Override
@@ -535,13 +537,13 @@ public class DefaultRedisList<E> extends AbstractRedisCollection<E> implements R
 	//
 
 	@Override
-	public boolean offerFirst(E e, long timeout, TimeUnit unit) throws InterruptedException {
-		return offerFirst(e);
+	public boolean offerFirst(E element, long timeout, TimeUnit unit) {
+		return offerFirst(element);
 	}
 
 	@Override
-	public boolean offerLast(E e, long timeout, TimeUnit unit) throws InterruptedException {
-		return offerLast(e);
+	public boolean offerLast(E element, long timeout, TimeUnit unit) {
+		return offerLast(element);
 	}
 
 	@Override
@@ -552,18 +554,18 @@ public class DefaultRedisList<E> extends AbstractRedisCollection<E> implements R
 
 	@Override
 	@Nullable
-	public E pollLast(long timeout, TimeUnit unit) throws InterruptedException {
+	public E pollLast(long timeout, TimeUnit unit) {
 		return listOps.rightPop(timeout, unit);
 	}
 
 	@Override
-	public void putFirst(E e) throws InterruptedException {
-		add(e);
+	public void putFirst(E element) {
+		add(element);
 	}
 
 	@Override
-	public void putLast(E e) throws InterruptedException {
-		put(e);
+	public void putLast(E element) throws InterruptedException {
+		put(element);
 	}
 
 	@Override
@@ -574,7 +576,7 @@ public class DefaultRedisList<E> extends AbstractRedisCollection<E> implements R
 
 	@Override
 	@Nullable
-	public E takeLast() throws InterruptedException {
+	public E takeLast() {
 		return pollLast(0, TimeUnit.SECONDS);
 	}
 
@@ -592,4 +594,131 @@ public class DefaultRedisList<E> extends AbstractRedisCollection<E> implements R
 			listOps.trim(0, maxSize - 1);
 		}
 	}
+
+	private class DefaultRedisListIterator extends RedisIterator<E> {
+
+		public DefaultRedisListIterator(Iterator<E> delegate) {
+			super(delegate);
+		}
+
+		@Override
+		protected void removeFromRedisStorage(E item) {
+			DefaultRedisList.this.remove(item);
+		}
+	}
+
+	private class Itr implements Iterator<E> {
+
+		/**
+		 * Index of the {@link E element} in this iteration to be returned by subsequent call to {@link #next()}.
+		 */
+		int cursor = 0;
+
+		/**
+		 * Index of the {@link E element} in this iteration last returned by a call to {@link #next()}.
+		 */
+		int lastReturnedElementIndex = -1;
+
+		@Nullable
+		E lastReturnedElement;
+
+		@Override
+		public boolean hasNext() {
+			return this.cursor < size();
+		}
+
+		@Override
+		public E next() {
+
+			try {
+				int index = this.cursor;
+				this.lastReturnedElement = get(index);
+				this.cursor = index + 1;
+				this.lastReturnedElementIndex = index;
+				return this.lastReturnedElement;
+			} catch (IndexOutOfBoundsException cause) {
+				throw new NoSuchElementException(cause);
+			}
+		}
+
+		@Override
+		@SuppressWarnings("all")
+		public void remove() {
+
+			Assert.state(this.lastReturnedElement != null,
+				"Next must be called before remove");
+
+			if (!DefaultRedisList.this.remove(this.lastReturnedElement)) {
+				throw new ConcurrentModificationException();
+			}
+
+			this.lastReturnedElementIndex = -1;
+			this.lastReturnedElement = null;
+			this.cursor--;
+		}
+	}
+
+	private class ListItr extends Itr implements ListIterator<E> {
+
+		ListItr(int index) {
+			this.cursor = index;
+		}
+
+		@Override
+		public boolean hasPrevious() {
+			return this.cursor > 0;
+		}
+
+		@Override
+		public int nextIndex() {
+			return this.cursor;
+		}
+
+		@Override
+		public int previousIndex() {
+			return this.cursor - 1;
+		}
+
+		@Override
+		public void add(E element) {
+
+			try {
+				int index = this.cursor;
+				DefaultRedisList.this.add(index, element);
+				this.lastReturnedElementIndex = -1;
+				this.lastReturnedElement = null;
+				this.cursor = index + 1;
+			} catch (IndexOutOfBoundsException cause) {
+				throw new ConcurrentModificationException();
+			}
+		}
+
+		@Override
+		public E previous() {
+
+			try {
+				int index = this.cursor - 1;
+				this.lastReturnedElement = get(index);
+				this.lastReturnedElementIndex = index;
+				this.cursor = index;
+				return this.lastReturnedElement;
+			} catch (IndexOutOfBoundsException cause) {
+				throw new NoSuchElementException();
+			}
+		}
+
+		@Override
+
+		public void set(E element) {
+
+			Assert.state(this.lastReturnedElement != null,
+				"next() or previous() must be called before set(:E)");
+
+			try {
+				DefaultRedisList.this.set(this.lastReturnedElementIndex, element);
+			} catch (IndexOutOfBoundsException cause) {
+				throw new ConcurrentModificationException();
+			}
+		}
+	}
 }

src/main/java/org/springframework/data/redis/support/collections/RedisList.java

@@ -15,7 +15,7 @@
  */
 package org.springframework.data.redis.support.collections;
 
-import static org.springframework.data.redis.connection.RedisListCommands.*;
+import static org.springframework.data.redis.connection.RedisListCommands.Direction;
 
 import java.time.Duration;
 import java.util.Deque;
@@ -36,6 +36,7 @@ import org.springframework.util.Assert;
  *
  * @author Costin Leau
  * @author Mark Paluch
+ * @author John Blum
  */
 public interface RedisList<E> extends RedisCollection<E>, List<E>, BlockingDeque<E> {
 
@@ -51,11 +52,12 @@ public interface RedisList<E> extends RedisCollection<E>, List<E>, BlockingDeque
 	}
 
 	/**
-	 * Constructs a new {@link RedisList} instance.
+	 * Factory method used to construct a new {@link RedisList} from a Redis list reference by the given {@link String
+	 * key}.
 	 *
 	 * @param key Redis key of this list.
 	 * @param operations {@link RedisOperations} for the value type of this list.
-	 * @param maxSize
+	 * @param maxSize {@link Integer} used to constrain the size of the list.
 	 * @since 2.6
 	 */
 	static <E> RedisList<E> create(String key, RedisOperations<String, E> operations, int maxSize) {
@@ -73,10 +75,10 @@ public interface RedisList<E> extends RedisCollection<E>, List<E>, BlockingDeque
 	}
 
 	/**
-	 * Constructs a new {@link DefaultRedisList} instance.
+	 * Constructs a new {@link DefaultRedisList}.
 	 *
 	 * @param boundOps {@link BoundListOperations} for the value type of this list.
-	 * @param maxSize
+	 * @param maxSize {@link Integer} constraining the size of the list.
 	 * @since 2.6
 	 */
 	static <E> RedisList<E> create(BoundListOperations<String, E> boundOps, int maxSize) {
@@ -98,6 +100,25 @@ public interface RedisList<E> extends RedisCollection<E>, List<E>, BlockingDeque
 	@Nullable
 	E moveFirstTo(RedisList<E> destination, Direction destinationPosition);
 
+	/**
+	 * Atomically returns and removes the first element of the list stored at the bound key, and pushes the element at the
+	 * first/last element (head/tail depending on the {@link Direction destinationPosition} argument) of the list stored
+	 * at {@link RedisList destination}.
+	 * <p>
+	 * <b>Blocks connection</b> until element available or {@code timeout} reached.
+	 *
+	 * @param destination must not be {@literal null}.
+	 * @param destinationPosition must not be {@literal null}.
+	 * @param timeout
+	 * @param unit must not be {@literal null}.
+	 * @return
+	 * @since 2.6
+	 * @see Direction#first()
+	 * @see Direction#last()
+	 */
+	@Nullable
+	E moveFirstTo(RedisList<E> destination, Direction destinationPosition, long timeout, TimeUnit unit);
+
 	/**
 	 * Atomically returns and removes the first element of the list stored at the bound key, and pushes the element at the
 	 * first/last element (head/tail depending on the {@link Direction destinationPosition} argument) of the list stored
@@ -123,25 +144,6 @@ public interface RedisList<E> extends RedisCollection<E>, List<E>, BlockingDeque
 				TimeoutUtils.toMillis(timeout.toMillis(), TimeUnit.MILLISECONDS), TimeUnit.MILLISECONDS);
 	}
 
-	/**
-	 * Atomically returns and removes the first element of the list stored at the bound key, and pushes the element at the
-	 * first/last element (head/tail depending on the {@link Direction destinationPosition} argument) of the list stored
-	 * at {@link RedisList destination}.
-	 * <p>
-	 * <b>Blocks connection</b> until element available or {@code timeout} reached.
-	 *
-	 * @param destination must not be {@literal null}.
-	 * @param destinationPosition must not be {@literal null}.
-	 * @param timeout
-	 * @param unit must not be {@literal null}.
-	 * @return
-	 * @since 2.6
-	 * @see Direction#first()
-	 * @see Direction#last()
-	 */
-	@Nullable
-	E moveFirstTo(RedisList<E> destination, Direction destinationPosition, long timeout, TimeUnit unit);
-
 	/**
 	 * Atomically returns and removes the last element of the list stored at the bound key, and pushes the element at the
 	 * first/last element (head/tail depending on the {@link Direction destinationPosition} argument) of the list stored
@@ -157,6 +159,25 @@ public interface RedisList<E> extends RedisCollection<E>, List<E>, BlockingDeque
 	@Nullable
 	E moveLastTo(RedisList<E> destination, Direction destinationPosition);
 
+	/**
+	 * Atomically returns and removes the last element of the list stored at the bound key, and pushes the element at the
+	 * first/last element (head/tail depending on the {@link Direction destinationPosition} argument) of the list stored
+	 * at {@link RedisList destination}.
+	 * <p>
+	 * <b>Blocks connection</b> until element available or {@code timeout} reached.
+	 *
+	 * @param destination must not be {@literal null}.
+	 * @param destinationPosition must not be {@literal null}.
+	 * @param timeout
+	 * @param unit must not be {@literal null}.
+	 * @return
+	 * @since 2.6
+	 * @see Direction#first()
+	 * @see Direction#last()
+	 */
+	@Nullable
+	E moveLastTo(RedisList<E> destination, Direction destinationPosition, long timeout, TimeUnit unit);
+
 	/**
 	 * Atomically returns and removes the last element of the list stored at the bound key, and pushes the element at the
 	 * first/last element (head/tail depending on the {@link Direction destinationPosition} argument) of the list stored
@@ -182,25 +203,6 @@ public interface RedisList<E> extends RedisCollection<E>, List<E>, BlockingDeque
 				TimeoutUtils.toMillis(timeout.toMillis(), TimeUnit.MILLISECONDS), TimeUnit.MILLISECONDS);
 	}
 
-	/**
-	 * Atomically returns and removes the last element of the list stored at the bound key, and pushes the element at the
-	 * first/last element (head/tail depending on the {@link Direction destinationPosition} argument) of the list stored
-	 * at {@link RedisList destination}.
-	 * <p>
-	 * <b>Blocks connection</b> until element available or {@code timeout} reached.
-	 *
-	 * @param destination must not be {@literal null}.
-	 * @param destinationPosition must not be {@literal null}.
-	 * @param timeout
-	 * @param unit must not be {@literal null}.
-	 * @return
-	 * @since 2.6
-	 * @see Direction#first()
-	 * @see Direction#last()
-	 */
-	@Nullable
-	E moveLastTo(RedisList<E> destination, Direction destinationPosition, long timeout, TimeUnit unit);
-
 	/**
 	 * Get elements between {@code start} and {@code end} from list at the bound key.
 	 *
@@ -229,4 +231,92 @@ public interface RedisList<E> extends RedisCollection<E>, List<E>, BlockingDeque
 	 * @see <a href="https://redis.io/commands/ltrim">Redis Documentation: LTRIM</a>
 	 */
 	RedisList<E> trim(long start, long end);
+
+	/**
+	 * {@inheritDoc}
+	 * <p>
+	 * This method is forward-compatible with Java 21 {@literal SequencedCollections}.
+	 *
+	 * @param element element to be added to the head of the collection.
+	 */
+	@Override
+	default void addFirst(E element) {
+		add(0, element);
+	}
+
+	/**
+	 * {@inheritDoc}
+	 * <p>
+	 * This method is forward-compatible with Java 21 {@literal SequencedCollections}.
+	 *
+	 * @param element element to be added to be added the end of the collection.
+	 */
+	default void addLast(E element) {
+		add(element);
+	}
+
+	/**
+	 * {@inheritDoc}
+	 * <p>
+	 * This method is forward-compatible with Java 21 {@literal SequencedCollections}.
+	 *
+	 * @return the head of this {@link Deque}.
+	 */
+	@Nullable
+	default E getFirst() {
+		return peekFirst();
+	}
+
+	/**
+	 * {@inheritDoc}
+	 * <p>
+	 * This method is forward-compatible with Java 21 {@literal SequencedCollections}.
+	 *
+	 * @return the tail of this {@link Deque}.
+	 */
+	@Nullable
+	default E getLast() {
+		return peekLast();
+	}
+
+	/**
+	 * {@inheritDoc}
+	 * <p>
+	 * This method is forward-compatible with Java 21 {@literal SequencedCollections}.
+	 *
+	 * @return the head of this {@link Deque}.
+	 */
+	@Nullable
+	default E removeFirst() {
+		return pollFirst();
+	}
+
+	/**
+	 * {@inheritDoc}
+	 * <p>
+	 * This method is forward-compatible with Java 21 {@literal SequencedCollections}.
+	 *
+	 * @return the tail of this {@link Deque}.
+	 */
+	@Nullable
+	default E removeLast() {
+		return pollLast();
+	}
+
+	/**
+	 * Returns a reverse-ordered view of this collection.
+	 * <p>
+	 * The encounter order of elements returned by the view is the inverse of the encounter order of the elements
+	 * stored in this collection. The reverse ordering affects all order-sensitive operations, including any operations
+	 * on further views of the returned view. If the collection implementation permits modifications to this view,
+	 * the modifications "write-through" to the underlying collection. Changes to the underlying collection might
+	 * or might not be visible in this reversed view, depending upon the implementation.
+	 * <p>
+	 * This method is forward-compatible with Java 21 {@literal SequencedCollections}.
+	 *
+	 * @return a reverse-ordered view of this collection.
+	 */
+	default RedisList<E> reversed() {
+		return new ReversedRedisListView<>(this);
+	}
 }

src/main/java/org/springframework/data/redis/support/collections/ReversedRedisListView.java

@@ -0,0 +1,739 @@
+/*
+ * Copyright 2023 the original author or authors.
+ *
+ * Licensed 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
+ *
+ *      https://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.springframework.data.redis.support.collections;
+
+import java.util.Arrays;
+import java.util.Collection;
+import java.util.Collections;
+import java.util.Comparator;
+import java.util.Date;
+import java.util.Iterator;
+import java.util.List;
+import java.util.ListIterator;
+import java.util.NoSuchElementException;
+import java.util.Objects;
+import java.util.Spliterator;
+import java.util.Spliterators;
+import java.util.concurrent.TimeUnit;
+import java.util.function.Consumer;
+import java.util.function.IntFunction;
+import java.util.function.Predicate;
+import java.util.function.UnaryOperator;
+import java.util.stream.Stream;
+import java.util.stream.StreamSupport;
+
+import org.springframework.data.redis.connection.DataType;
+import org.springframework.data.redis.connection.RedisListCommands.Direction;
+import org.springframework.data.redis.core.RedisOperations;
+import org.springframework.lang.Nullable;
+
+/**
+ * Implementation and view of an existing {@link RedisList} where the elements in the list (deque) are returned in
+ * reverse order.
+ *
+ * @author John Blum
+ * @author Mark Paluch
+ * @param <E> {@link Class type} of the {@link Object elements} contained in the underlying, wrapped {@link RedisList}.
+ * @since 3.2
+ */
+class ReversedRedisListView<E> implements RedisList<E> {
+
+	private final RedisList<E> base;
+
+	ReversedRedisListView(RedisList<E> list) {
+		this.base = list;
+	}
+
+	// ========== RedisCollection ==========
+
+	@Override
+	public String getKey() {
+		return this.base.getKey();
+	}
+
+	@Nullable
+	@Override
+	public Long getExpire() {
+		return this.base.getExpire();
+	}
+
+	@Override
+	public RedisOperations<String, ?> getOperations() {
+		return this.base.getOperations();
+	}
+
+	@Nullable
+	@Override
+	public DataType getType() {
+		return this.base.getType();
+	}
+
+	@Nullable
+	@Override
+	public Boolean expire(long timeout, TimeUnit unit) {
+		return this.base.expire(timeout, unit);
+	}
+
+	@Nullable
+	@Override
+	public Boolean expireAt(Date date) {
+		return this.base.expireAt(date);
+	}
+
+	@Nullable
+	@Override
+	public Boolean persist() {
+		return this.base.persist();
+	}
+
+	@Nullable
+	@Override
+	public E moveFirstTo(RedisList<E> destination, Direction destinationPosition) {
+		return this.base.moveLastTo(destination, destinationPosition);
+	}
+
+	@Nullable
+	@Override
+	public E moveFirstTo(RedisList<E> destination, Direction destinationPosition, long timeout, TimeUnit unit) {
+		return base.moveLastTo(destination, destinationPosition, timeout, unit);
+	}
+
+	@Nullable
+	@Override
+	public E moveLastTo(RedisList<E> destination, Direction destinationPosition) {
+		return base.moveFirstTo(destination, destinationPosition);
+	}
+
+	@Nullable
+	@Override
+	public E moveLastTo(RedisList<E> destination, Direction destinationPosition, long timeout, TimeUnit unit) {
+		return base.moveFirstTo(destination, destinationPosition, timeout, unit);
+	}
+
+	@Override
+	public List<E> range(long start, long end) {
+		return this.base.range(end, start);
+	}
+
+	@Override
+	public void rename(String newKey) {
+		this.base.rename(newKey);
+	}
+
+	@Override
+	public RedisList<E> trim(int start, int end) {
+		this.base.trim(end, start);
+		return this;
+	}
+
+	@Override
+	public RedisList<E> trim(long start, long end) {
+		this.base.trim(end, start);
+		return this;
+	}
+
+	// ========== Iterable ==========
+
+	@Override
+	public void forEach(Consumer<? super E> action) {
+		for (E e : this)
+			action.accept(e);
+	}
+
+	@Override
+	public Iterator<E> iterator() {
+		return new DescendingIterator();
+	}
+
+	@Override
+	public Spliterator<E> spliterator() {
+		return Spliterators.spliteratorUnknownSize(new DescendingIterator(), 0);
+	}
+
+	// ========== Collection ==========
+
+	@Override
+	public boolean add(E element) {
+		this.base.add(0, element);
+		return true;
+	}
+
+	@Override
+	@SuppressWarnings("unchecked")
+	public boolean addAll(Collection<? extends E> collection) {
+
+		return !org.springframework.util.CollectionUtils.isEmpty(collection)
+			&& this.base.addAll(0, Arrays.asList(reverse((E[]) collection.toArray())));
+	}
+
+	@Override
+	public void clear() {
+		this.base.clear();
+	}
+
+	@Override
+	public boolean contains(Object element) {
+		return this.base.contains(element);
+	}
+
+	@Override
+	public boolean containsAll(Collection<?> collection) {
+		return this.base.containsAll(collection);
+	}
+
+	public boolean equals(Object obj) {
+
+		if (this == obj) {
+			return true;
+		}
+
+		if (!(obj instanceof List<?> that)) {
+			return false;
+		}
+
+		ListIterator<E> thisListIterator = this.listIterator();
+		ListIterator<?> thatListIterator = that.listIterator();
+
+		while (thisListIterator.hasNext() && thatListIterator.hasNext()) {
+			if (!(Objects.equals(thisListIterator.next(), thatListIterator.next()))) {
+				return false;
+			}
+		}
+
+		return !(thisListIterator.hasNext() || thatListIterator.hasNext());
+	}
+
+	public int hashCode() {
+		int hashCode = 1;
+		for (E element : this) {
+			hashCode = 31 * hashCode + Objects.hashCode(element);
+		}
+		return hashCode;
+	}
+
+	@Override
+	public boolean isEmpty() {
+		return this.base.isEmpty();
+	}
+
+	@Override
+	public Stream<E> parallelStream() {
+		return StreamSupport.stream(spliterator(), true);
+	}
+
+	@Override
+	public boolean remove(Object element) {
+
+		Iterator<E> it = iterator();
+
+		while (it.hasNext()) {
+			if (Objects.equals(element, it.next())) {
+				it.remove();
+				return true;
+			}
+		}
+
+		return false;
+	}
+
+	@Override
+	public boolean removeAll(Collection<?> collection) {
+
+		Objects.requireNonNull(collection);
+
+		Iterator<?> it = iterator();
+		boolean modified = false;
+
+		while (it.hasNext()) {
+			if (collection.contains(it.next())) {
+				it.remove();
+				modified = true;
+			}
+		}
+
+		return modified;
+	}
+
+	@Override
+	public boolean retainAll(Collection<?> collection) {
+
+		Objects.requireNonNull(collection);
+
+		Iterator<E> it = iterator();
+		boolean modified = false;
+
+		while (it.hasNext()) {
+			if (!collection.contains(it.next())) {
+				it.remove();
+				modified = true;
+			}
+		}
+
+		return modified;
+	}
+
+	@Override
+	public int size() {
+		return this.base.size();
+	}
+
+	@Override
+	public Stream<E> stream() {
+		return StreamSupport.stream(spliterator(), false);
+	}
+
+	@Override
+	public Object[] toArray() {
+		return reverse(this.base.toArray());
+	}
+
+	@Override
+	public <T> T[] toArray(T[] array) {
+		return toArrayReversed(this.base, array);
+	}
+
+	@Override
+	public <T> T[] toArray(IntFunction<T[]> generator) {
+		return reverse(this.base.toArray(generator));
+	}
+
+	public String toString() {
+
+		Iterator<E> it = iterator();
+
+		if (!it.hasNext()) {
+			return "[]";
+		}
+
+		StringBuilder stringBuilder = new StringBuilder("[");
+
+		for (;;) {
+			E element = it.next();
+			stringBuilder.append(element == this ? "(this Collection)" : element);
+			if (!it.hasNext()) {
+				return stringBuilder.append(']').toString();
+			}
+			stringBuilder.append(',').append(' ');
+		}
+	}
+
+	// ========== List ==========
+
+	@Override
+	public void add(int index, E element) {
+
+		int size = this.base.size();
+
+		checkClosedRange(index, size);
+		this.base.add(size - index, element);
+	}
+
+	@Override
+	public boolean addAll(int index, Collection<? extends E> c) {
+
+		int size = base.size();
+
+		checkClosedRange(index, size);
+
+		@SuppressWarnings("unchecked")
+		E[] adds = (E[]) c.toArray();
+
+		if (adds.length == 0) {
+			return false;
+		} else {
+			base.addAll(size - index, Arrays.asList(reverse(adds)));
+			return true;
+		}
+	}
+
+	@Override
+	public E get(int index) {
+		int size = base.size();
+		Objects.checkIndex(index, size);
+		return this.base.get(size - index - 1);
+	}
+
+	@Override
+	@SuppressWarnings("all")
+	public int indexOf(Object element) {
+		int lastIndex = this.base.lastIndexOf(element);
+		return lastIndex == -1 ? -1 : this.base.size() - lastIndex - 1;
+	}
+
+	@Override
+	@SuppressWarnings("all")
+	public int lastIndexOf(Object element) {
+		int index = this.base.indexOf(element);
+		return index == -1 ? -1 : this.base.size() - index - 1;
+	}
+
+	@Override
+	public ListIterator<E> listIterator() {
+		return new DescendingListIterator(base.size(), 0);
+	}
+
+	@Override
+	public ListIterator<E> listIterator(int index) {
+		int size = this.base.size();
+		checkClosedRange(index, size);
+		return new DescendingListIterator(size, index);
+	}
+
+	@Override
+	public E remove(int index) {
+		int size = this.base.size();
+		Objects.checkIndex(index, size);
+		return this.base.remove(size - index - 1);
+	}
+
+	@Override
+	public boolean removeIf(Predicate<? super E> filter) {
+		return this.base.removeIf(filter);
+	}
+
+	@Override
+	public void replaceAll(UnaryOperator<E> operator) {
+		this.base.replaceAll(operator);
+	}
+
+	@Override
+	public void sort(Comparator<? super E> comparator) {
+		this.base.sort(Collections.reverseOrder(comparator));
+	}
+
+	@Override
+	public E set(int index, E element) {
+		int size = this.base.size();
+		Objects.checkIndex(index, size);
+		return this.base.set(size - index - 1, element);
+	}
+
+	@Override
+	public List<E> subList(int fromIndex, int toIndex) {
+		throw new UnsupportedOperationException();
+	}
+
+	// ========== BlockingDeque ==========
+
+	@Override
+	public E element() {
+		return peekLast();
+	}
+
+	@Override
+	public boolean offer(E element) {
+		return this.base.offerFirst(element);
+	}
+
+	@Override
+	public boolean offer(E element, long timeout, TimeUnit unit) throws InterruptedException {
+		return this.base.offerFirst(element, timeout, unit);
+	}
+
+	@Override
+	public boolean offerFirst(E element) {
+		return this.base.offerLast(element);
+	}
+
+	@Override
+	public boolean offerFirst(E element, long timeout, TimeUnit unit) throws InterruptedException {
+		return this.base.offerLast(element, timeout, unit);
+	}
+
+	@Override
+	public boolean offerLast(E element) {
+		return this.base.offerFirst(element);
+	}
+
+	@Override
+	public boolean offerLast(E element, long timeout, TimeUnit unit) throws InterruptedException {
+		return this.base.offerFirst(element, timeout, unit);
+	}
+
+	@Override
+	public void putFirst(E element) throws InterruptedException {
+		this.base.putLast(element);
+	}
+
+	@Override
+	public void putLast(E element) throws InterruptedException {
+		this.base.putFirst(element);
+	}
+
+	@Nullable
+	@Override
+	public E pollFirst(long timeout, TimeUnit unit) throws InterruptedException {
+		return this.base.pollLast(timeout, unit);
+	}
+
+	@Nullable
+	@Override
+	public E pollLast(long timeout, TimeUnit unit) throws InterruptedException {
+		return this.base.pollFirst(timeout, unit);
+	}
+
+	@Override
+	public void put(E element) throws InterruptedException {
+		this.base.offerFirst(element);
+	}
+
+	@Override
+	public boolean removeFirstOccurrence(Object element) {
+		return this.base.removeLastOccurrence(element);
+	}
+
+	@Override
+	public boolean removeLastOccurrence(Object element) {
+		return this.base.removeFirstOccurrence(element);
+	}
+
+	@Override
+	public E take() throws InterruptedException {
+		return takeFirst();
+	}
+
+	@Override
+	public E takeFirst() throws InterruptedException {
+		return this.base.takeLast();
+	}
+
+	@Override
+	public E takeLast() throws InterruptedException {
+		return this.base.takeFirst();
+	}
+
+	// ========== Deque ==========
+
+	@Override
+	public Iterator<E> descendingIterator() {
+		return this.base.iterator();
+	}
+
+	@Override
+	public int drainTo(Collection<? super E> collection) {
+		return drainTo(collection, size());
+	}
+
+	@Override
+	public int drainTo(Collection<? super E> collection, int maxElements) {
+
+		if (this.equals(collection)) {
+			throw new IllegalArgumentException("Cannot drain a queue to itself");
+		}
+
+		int loop = Math.min(size(), maxElements);
+
+		for (int index = 0; index < loop; index++) {
+			collection.add(poll());
+		}
+
+		return loop;
+	}
+
+	@Override
+	public E peek() {
+		return peekLast();
+	}
+
+	@Override
+	public E peekFirst() {
+		return this.base.peekLast();
+	}
+
+	@Override
+	public E peekLast() {
+		return this.base.peekFirst();
+	}
+
+	@Override
+	public E poll() {
+		return pollLast();
+	}
+
+	@Nullable
+	@Override
+	public E poll(long timeout, TimeUnit unit) throws InterruptedException {
+		return pollLast(0, TimeUnit.SECONDS);
+	}
+
+	@Override
+	public E pollFirst() {
+		return this.base.pollLast();
+	}
+
+	@Override
+	public E pollLast() {
+		return this.base.pollFirst();
+	}
+
+	@Override
+	public E pop() {
+
+		E element = poll();
+
+		if (element == null) {
+			throw new NoSuchElementException();
+		}
+
+		return element;
+	}
+
+	@Override
+	public void push(E element) {
+		this.base.addLast(element);
+	}
+
+	@Override
+	public int remainingCapacity() {
+		return this.base.remainingCapacity();
+	}
+
+	@Override
+	public E remove() {
+		return pollLast();
+	}
+
+	@Override
+	public RedisList<E> reversed() {
+		return this.base;
+	}
+
+	class DescendingIterator implements Iterator<E> {
+
+		final ListIterator<E> it = base.listIterator(base.size());
+
+		@Override
+		public boolean hasNext() {
+			return this.it.hasPrevious();
+		}
+
+		@Override
+		public E next() {
+			return this.it.previous();
+		}
+
+		@Override
+		public void remove() {
+			this.it.remove();
+		}
+	}
+
+	class DescendingListIterator implements ListIterator<E> {
+
+		final ListIterator<E> it;
+
+		DescendingListIterator(int size, int position) {
+
+			if (position < 0 || position > size) {
+				String message = String.format("Position [%d] is out of bounds: [0, %d]", position, size);
+				throw new IndexOutOfBoundsException(message);
+			}
+
+			this.it = base.listIterator(size - position);
+		}
+
+		@Override
+		public boolean hasNext() {
+			return it.hasPrevious();
+		}
+
+		@Override
+		public E next() {
+			return it.previous();
+		}
+
+		@Override
+		public boolean hasPrevious() {
+			return it.hasNext();
+		}
+
+		@Override
+		public E previous() {
+			return it.next();
+		}
+
+		@Override
+		public int nextIndex() {
+			return base.size() - it.nextIndex();
+		}
+
+		@Override
+		public int previousIndex() {
+			return nextIndex() - 1;
+		}
+
+		@Override
+		public void remove() {
+			it.remove();
+		}
+
+		@Override
+		public void set(E e) {
+			it.set(e);
+		}
+
+		@Override
+		public void add(E e) {
+			it.add(e);
+			it.previous();
+		}
+	}
+
+	/**
+	 * Reverses the elements of an array in-place.
+	 *
+	 * @param <T> the array component type
+	 * @param array the array to be reversed
+	 * @return the reversed array, always the same array as the argument
+	 */
+	static <T> T[] reverse(T[] array) {
+
+		int limit = array.length / 2;
+
+		for (int i = 0, j = array.length - 1; i < limit; i++, j--) {
+			swap(array, i, j);
+		}
+
+		return array;
+	}
+
+	private static <T> void swap(T[] array, int indexOne, int indexTwo) {
+		T element = array[indexOne];
+		array[indexOne] = array[indexTwo];
+		array[indexTwo] = element;
+	}
+
+	static <T> T[] toArrayReversed(Collection<?> collection, T[] array) {
+
+		T[] newArray = reverse(collection.toArray(Arrays.copyOfRange(array, 0, 0)));
+
+		if (newArray.length > array.length) {
+			return newArray;
+		} else {
+			System.arraycopy(newArray, 0, array, 0, newArray.length);
+			if (array.length > newArray.length) {
+				array[newArray.length] = null;
+			}
+			return array;
+		}
+	}
+
+	static void checkClosedRange(int index, int size) {
+		if (index < 0 || index > size) {
+			throw new IndexOutOfBoundsException("Index: " + index + ", Size: " + size);
+		}
+	}
+}