[POC] Optimistic Locking for Delete Operations

services-custom/dynamodb-enhanced/src/main/java/software/amazon/awssdk/enhanced/dynamodb/DynamoDbAsyncTable.java

@@ -247,6 +247,10 @@ default CompletableFuture<T> deleteItem(T keyItem) {
         throw new UnsupportedOperationException();
     }
 
+    default CompletableFuture<T> deleteItem(T keyItem, boolean useOptimisticLocking) {
+        throw new UnsupportedOperationException();
+    }
+
     /**
      * Deletes a single item from the mapped table using a supplied primary {@link Key}.
      * <p>

services-custom/dynamodb-enhanced/src/main/java/software/amazon/awssdk/enhanced/dynamodb/DynamoDbTable.java

@@ -245,6 +245,10 @@ default T deleteItem(T keyItem) {
         throw new UnsupportedOperationException();
     }
 
+    default T deleteItem(T keyItem, boolean useOptimisticLocking) {
+        throw new UnsupportedOperationException();
+    }
+
     /**
      * Deletes a single item from the mapped table using a supplied primary {@link Key}.
      * <p>

services-custom/dynamodb-enhanced/src/main/java/software/amazon/awssdk/enhanced/dynamodb/internal/client/DefaultDynamoDbAsyncTable.java

@@ -16,6 +16,7 @@
 package software.amazon.awssdk.enhanced.dynamodb.internal.client;
 
 import static software.amazon.awssdk.enhanced.dynamodb.internal.EnhancedClientUtils.createKeyFromItem;
+import static software.amazon.awssdk.enhanced.dynamodb.model.OptimisticLockingHelper.conditionallyApplyOptimisticLocking;
 
 import java.util.ArrayList;
 import java.util.concurrent.CompletableFuture;
@@ -124,28 +125,55 @@ public CompletableFuture<Void> createTable() {
                                                      .build());
     }
 
+    /**
+     * Supports optimistic locking via {@link software.amazon.awssdk.enhanced.dynamodb.model.OptimisticLockingHelper}.
+     */
     @Override
     public CompletableFuture<T> deleteItem(DeleteItemEnhancedRequest request) {
         TableOperation<T, ?, ?, DeleteItemEnhancedResponse<T>> operation = DeleteItemOperation.create(request);
         return operation.executeOnPrimaryIndexAsync(tableSchema, tableName, extension, dynamoDbClient)
                         .thenApply(DeleteItemEnhancedResponse::attributes);
     }
 
+    /**
+     * Supports optimistic locking via {@link software.amazon.awssdk.enhanced.dynamodb.model.OptimisticLockingHelper}.
+     */
     @Override
     public CompletableFuture<T> deleteItem(Consumer<DeleteItemEnhancedRequest.Builder> requestConsumer) {
         DeleteItemEnhancedRequest.Builder builder = DeleteItemEnhancedRequest.builder();
         requestConsumer.accept(builder);
         return deleteItem(builder.build());
     }
 
+    /**
+     * Does not support optimistic locking. Use {@link #deleteItem(Object, boolean)} for optimistic locking support.
+     */
     @Override
     public CompletableFuture<T> deleteItem(Key key) {
         return deleteItem(r -> r.key(key));
     }
 
+    /**
+     * @deprecated Use {@link #deleteItem(Object, boolean)} instead to explicitly control optimistic locking behavior.
+     */
     @Override
+    @Deprecated
     public CompletableFuture<T> deleteItem(T keyItem) {
-        return deleteItem(keyFrom(keyItem));
+        return deleteItem(keyItem, false);
+    }
+
+    /**
+     * Deletes an item from the table with optional optimistic locking.
+     *
+     * @param keyItem the item containing the key to delete
+     * @param useOptimisticLocking if true, applies optimistic locking if the item has version information
+     * @return a CompletableFuture containing the deleted item, or null if the item was not found
+     */
+    @Override
+    public CompletableFuture<T> deleteItem(T keyItem, boolean useOptimisticLocking) {
+        DeleteItemEnhancedRequest request = DeleteItemEnhancedRequest.builder().key(keyFrom(keyItem)).build();
+        request = conditionallyApplyOptimisticLocking(request, keyItem, tableSchema, useOptimisticLocking);
+        return deleteItem(request);
     }
 
     @Override
@@ -311,7 +339,7 @@ public CompletableFuture<T> updateItem(T item) {
     public Key keyFrom(T item) {
         return createKeyFromItem(item, tableSchema, TableMetadata.primaryIndexName());
     }
-
+    
 
     @Override
     public CompletableFuture<Void> deleteTable() {

services-custom/dynamodb-enhanced/src/main/java/software/amazon/awssdk/enhanced/dynamodb/internal/client/DefaultDynamoDbTable.java

@@ -16,6 +16,7 @@
 package software.amazon.awssdk.enhanced.dynamodb.internal.client;
 
 import static software.amazon.awssdk.enhanced.dynamodb.internal.EnhancedClientUtils.createKeyFromItem;
+import static software.amazon.awssdk.enhanced.dynamodb.model.OptimisticLockingHelper.conditionallyApplyOptimisticLocking;
 
 import java.util.ArrayList;
 import java.util.function.Consumer;
@@ -126,27 +127,54 @@ public void createTable() {
                                               .build());
     }
 
+    /**
+     * Supports optimistic locking via {@link software.amazon.awssdk.enhanced.dynamodb.model.OptimisticLockingHelper}.
+     */
     @Override
     public T deleteItem(DeleteItemEnhancedRequest request) {
         TableOperation<T, ?, ?, DeleteItemEnhancedResponse<T>> operation = DeleteItemOperation.create(request);
         return operation.executeOnPrimaryIndex(tableSchema, tableName, extension, dynamoDbClient).attributes();
     }
 
+    /**
+     * Supports optimistic locking via {@link software.amazon.awssdk.enhanced.dynamodb.model.OptimisticLockingHelper}.
+     */
     @Override
     public T deleteItem(Consumer<DeleteItemEnhancedRequest.Builder> requestConsumer) {
         DeleteItemEnhancedRequest.Builder builder = DeleteItemEnhancedRequest.builder();
         requestConsumer.accept(builder);
         return deleteItem(builder.build());
     }
 
+    /**
+     * Does not support optimistic locking. Use {@link #deleteItem(Object, boolean)} for optimistic locking support.
+     */
     @Override
     public T deleteItem(Key key) {
         return deleteItem(r -> r.key(key));
     }
 
+    /**
+     * @deprecated Use {@link #deleteItem(Object, boolean)} instead to explicitly control optimistic locking behavior.
+     */
     @Override
+    @Deprecated
     public T deleteItem(T keyItem) {
-        return deleteItem(keyFrom(keyItem));
+        return deleteItem(keyItem, false);
+    }
+
+    /**
+     * Deletes an item from the table with optional optimistic locking.
+     *
+     * @param keyItem the item containing the key to delete
+     * @param useOptimisticLocking if true, applies optimistic locking if the item has version information
+     * @return the deleted item, or null if the item was not found
+     */
+    @Override
+    public T deleteItem(T keyItem, boolean useOptimisticLocking) {
+        DeleteItemEnhancedRequest request = DeleteItemEnhancedRequest.builder().key(keyFrom(keyItem)).build();
+        request = conditionallyApplyOptimisticLocking(request, keyItem, tableSchema, useOptimisticLocking);
+        return deleteItem(request);
     }
 
     @Override

services-custom/dynamodb-enhanced/src/main/java/software/amazon/awssdk/enhanced/dynamodb/model/DeleteItemEnhancedRequest.java

@@ -15,6 +15,8 @@
 
 package software.amazon.awssdk.enhanced.dynamodb.model;
 
+import static software.amazon.awssdk.enhanced.dynamodb.model.OptimisticLockingHelper.createVersionCondition;
+
 import java.util.Objects;
 import java.util.function.Consumer;
 import software.amazon.awssdk.annotations.NotThreadSafe;
@@ -24,6 +26,7 @@
 import software.amazon.awssdk.enhanced.dynamodb.DynamoDbTable;
 import software.amazon.awssdk.enhanced.dynamodb.Expression;
 import software.amazon.awssdk.enhanced.dynamodb.Key;
+import software.amazon.awssdk.services.dynamodb.model.AttributeValue;
 import software.amazon.awssdk.services.dynamodb.model.DeleteItemRequest;
 import software.amazon.awssdk.services.dynamodb.model.PutItemRequest;
 import software.amazon.awssdk.services.dynamodb.model.ReturnConsumedCapacity;
@@ -289,6 +292,22 @@ public Builder returnValuesOnConditionCheckFailure(String returnValuesOnConditio
             return this;
         }
 
+        /**
+         * Adds optimistic locking to this delete request.
+         * <p>
+         * This method applies a condition expression that ensures the delete operation only succeeds
+         * if the version attribute of the item matches the provided expected value.
+         *
+         * @param versionValue the expected version value that must match for the deletion to succeed
+         * @param versionAttributeName the name of the version attribute in the DynamoDB table
+         * @return a builder of this type with optimistic locking condition applied
+         * @throws IllegalArgumentException if any parameter is null
+         */
+        public Builder withOptimisticLocking(AttributeValue versionValue, String versionAttributeName) {
+            Expression optimisticLockingCondition = createVersionCondition(versionValue, versionAttributeName);
+            return conditionExpression(optimisticLockingCondition);
+        }
+
         public DeleteItemEnhancedRequest build() {
             return new DeleteItemEnhancedRequest(this);
         }

services-custom/dynamodb-enhanced/src/main/java/software/amazon/awssdk/enhanced/dynamodb/model/OptimisticLockingHelper.java

@@ -0,0 +1,145 @@
+/*
+ * Copyright Amazon.com, Inc. or its affiliates. All Rights Reserved.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License").
+ * You may not use this file except in compliance with the License.
+ * A copy of the License is located at
+ *
+ *  http://aws.amazon.com/apache2.0
+ *
+ * or in the "license" file accompanying this file. This file 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 software.amazon.awssdk.enhanced.dynamodb.model;
+
+import java.util.Optional;
+import software.amazon.awssdk.annotations.SdkPublicApi;
+import software.amazon.awssdk.enhanced.dynamodb.Expression;
+import software.amazon.awssdk.enhanced.dynamodb.TableSchema;
+import software.amazon.awssdk.services.dynamodb.model.AttributeValue;
+
+/**
+ * Utility class for adding optimistic locking to DynamoDB delete operations.
+ * <p>
+ * Optimistic locking prevents concurrent modifications by checking that an item's version hasn't changed since it was last read.
+ * If the version has changed, the delete operation fails with a {@code ConditionalCheckFailedException}.
+ */
+@SdkPublicApi
+public final class OptimisticLockingHelper {
+
+    private OptimisticLockingHelper() {
+    }
+
+    /**
+     * Adds optimistic locking to a delete request.
+     *
+     * @param request              the original delete request
+     * @param versionValue         the expected version value
+     * @param versionAttributeName the version attribute name
+     * @return delete request with optimistic locking condition
+     */
+    public static DeleteItemEnhancedRequest withOptimisticLocking(
+        DeleteItemEnhancedRequest request, AttributeValue versionValue, String versionAttributeName) {
+
+        Expression conditionExpression = createVersionCondition(versionValue, versionAttributeName);
+        return request.toBuilder()
+                      .conditionExpression(conditionExpression)
+                      .build();
+    }
+
+    /**
+     * Adds optimistic locking to a transactional delete request.
+     *
+     * @param request              the original transactional delete request
+     * @param versionValue         the expected version value
+     * @param versionAttributeName the version attribute name
+     * @return transactional delete request with optimistic locking condition
+     */
+    public static TransactDeleteItemEnhancedRequest withOptimisticLocking(
+        TransactDeleteItemEnhancedRequest request, AttributeValue versionValue, String versionAttributeName) {
+
+        Expression conditionExpression = createVersionCondition(versionValue, versionAttributeName);
+        return request.toBuilder()
+                      .conditionExpression(conditionExpression)
+                      .build();
+    }
+
+    /**
+     * Conditionally applies optimistic locking if enabled and version information exists.
+     *
+     * @param <T>                  the type of the item
+     * @param request              the original delete request
+     * @param keyItem              the item containing version information
+     * @param tableSchema          the table schema
+     * @param useOptimisticLocking if true, applies optimistic locking
+     * @return delete request with optimistic locking if enabled and version exists, otherwise original request
+     */
+    public static <T> DeleteItemEnhancedRequest conditionallyApplyOptimisticLocking(
+        DeleteItemEnhancedRequest request, T keyItem, TableSchema<T> tableSchema, boolean useOptimisticLocking) {
+
+        if (!useOptimisticLocking) {
+            return request;
+        }
+
+        return getVersionAttributeName(tableSchema)
+            .map(versionAttributeName -> {
+                AttributeValue version = tableSchema.attributeValue(keyItem, versionAttributeName);
+                return version != null ? withOptimisticLocking(request, version, versionAttributeName) : request;
+            })
+            .orElse(request);
+    }
+
+    /**
+     * Conditionally applies optimistic locking if enabled and version information exists.
+     *
+     * @param <T>                  the type of the item
+     * @param request              the original transactional delete request
+     * @param keyItem              the item containing version information
+     * @param tableSchema          the table schema
+     * @param useOptimisticLocking if true, applies optimistic locking
+     * @return delete request with optimistic locking if enabled and version exists, otherwise original request
+     */
+    public static <T> TransactDeleteItemEnhancedRequest conditionallyApplyOptimisticLocking(
+        TransactDeleteItemEnhancedRequest request, T keyItem, TableSchema<T> tableSchema, boolean useOptimisticLocking) {
+
+        if (!useOptimisticLocking) {
+            return request;
+        }
+
+        return getVersionAttributeName(tableSchema)
+            .map(versionAttributeName -> {
+                AttributeValue version = tableSchema.attributeValue(keyItem, versionAttributeName);
+                return version != null ? withOptimisticLocking(request, version, versionAttributeName) : request;
+            })
+            .orElse(request);
+    }
+
+
+    /**
+     * Creates a version condition expression.
+     *
+     * @param versionValue         the expected version value
+     * @param versionAttributeName the version attribute name
+     * @return version check condition expression
+     */
+    public static Expression createVersionCondition(AttributeValue versionValue, String versionAttributeName) {
+        return Expression.builder()
+                         .expression(versionAttributeName + " = :version_value")
+                         .putExpressionValue(":version_value", versionValue)
+                         .build();
+    }
+
+    /**
+     * Gets the version attribute name from table schema.
+     *
+     * @param <T>         the type of the item
+     * @param tableSchema the table schema
+     * @return version attribute name if present, empty otherwise
+     */
+    public static <T> Optional<String> getVersionAttributeName(TableSchema<T> tableSchema) {
+        return tableSchema.tableMetadata().customMetadataObject("VersionedRecordExtension:VersionAttribute", String.class);
+    }
+}

services-custom/dynamodb-enhanced/src/main/java/software/amazon/awssdk/enhanced/dynamodb/model/TransactDeleteItemEnhancedRequest.java

@@ -15,6 +15,8 @@
 
 package software.amazon.awssdk.enhanced.dynamodb.model;
 
+import static software.amazon.awssdk.enhanced.dynamodb.model.OptimisticLockingHelper.createVersionCondition;
+
 import java.util.Objects;
 import java.util.function.Consumer;
 import software.amazon.awssdk.annotations.NotThreadSafe;
@@ -24,6 +26,7 @@
 import software.amazon.awssdk.enhanced.dynamodb.DynamoDbEnhancedClient;
 import software.amazon.awssdk.enhanced.dynamodb.Expression;
 import software.amazon.awssdk.enhanced.dynamodb.Key;
+import software.amazon.awssdk.services.dynamodb.model.AttributeValue;
 import software.amazon.awssdk.services.dynamodb.model.ReturnValuesOnConditionCheckFailure;
 
 /**
@@ -215,6 +218,21 @@ public Builder returnValuesOnConditionCheckFailure(String returnValuesOnConditio
             return this;
         }
 
+        /**
+         * Adds optimistic locking to this transactional delete request.
+         * <p>
+         * This method applies a condition expression that ensures the delete operation only succeeds if the version attribute of
+         * the item matches the provided expected value. If the condition fails, the entire transaction will be cancelled.
+         *
+         * @param versionValue the expected version value that must match for the deletion to succeed
+         * @param versionAttributeName the name of the version attribute in the DynamoDB table
+         * @return a builder of this type with optimistic locking condition applied
+         * @throws IllegalArgumentException if any parameter is null
+         */
+        public Builder withOptimisticLocking(AttributeValue versionValue, String versionAttributeName) {
+            Expression optimisticLockingCondition = createVersionCondition(versionValue, versionAttributeName);
+            return conditionExpression(optimisticLockingCondition);
+        }
 
         public TransactDeleteItemEnhancedRequest build() {
             return new TransactDeleteItemEnhancedRequest(this);