Serialization optimization for DDB enhanced Client

.changes/next-release/feature-AmazonDynamoDBEnhancedClient-798234c.json

@@ -0,0 +1,6 @@
+{
+    "type": "feature",
+    "category": "Amazon DynamoDB Enhanced Client",
+    "contributor": "",
+    "description": "Optimize implementation of the `EnhancedDocument#toJson()` and `EnhancedDocument#getJson()`."
+}

services-custom/dynamodb-enhanced/src/main/java/software/amazon/awssdk/enhanced/dynamodb/internal/document/DefaultEnhancedDocument.java

@@ -17,8 +17,6 @@
 
 import static java.util.Collections.unmodifiableList;
 import static java.util.Collections.unmodifiableMap;
-import static software.amazon.awssdk.enhanced.dynamodb.internal.document.JsonStringFormatHelper.addEscapeCharacters;
-import static software.amazon.awssdk.enhanced.dynamodb.internal.document.JsonStringFormatHelper.stringValue;
 
 import java.util.ArrayList;
 import java.util.Arrays;
@@ -193,7 +191,7 @@ public String getJson(String attributeName) {
         if (attributeValue == null) {
             return null;
         }
-        return stringValue(JSON_ATTRIBUTE_CONVERTER.transformTo(attributeValue));
+        return DocumentJsonSerializer.serializeSingleAttributeValue(attributeValue);
     }
 
     @Override
@@ -230,12 +228,7 @@ public String toJson() {
         if (nonAttributeValueMap.isEmpty()) {
             return "{}";
         }
-        return attributeValueMap.getValue().entrySet().stream()
-                                .map(entry -> "\""
-                                              + addEscapeCharacters(entry.getKey())
-                                              + "\":"
-                                              + stringValue(JSON_ATTRIBUTE_CONVERTER.transformTo(entry.getValue())))
-                                .collect(Collectors.joining(",", "{", "}"));
+        return DocumentJsonSerializer.serializeAttributeValueMap(attributeValueMap.getValue());
     }
 
     @Override

services-custom/dynamodb-enhanced/src/main/java/software/amazon/awssdk/enhanced/dynamodb/internal/document/DocumentJsonSerializer.java

@@ -0,0 +1,121 @@
+/*
+ * 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.internal.document;
+
+import java.io.IOException;
+import java.io.OutputStream;
+import java.nio.charset.StandardCharsets;
+import java.util.Map;
+import software.amazon.awssdk.annotations.SdkInternalApi;
+import software.amazon.awssdk.core.SdkBytes;
+import software.amazon.awssdk.protocols.json.SdkJsonGenerator;
+import software.amazon.awssdk.services.dynamodb.model.AttributeValue;
+import software.amazon.awssdk.thirdparty.jackson.core.JsonFactory;
+import software.amazon.awssdk.thirdparty.jackson.core.JsonGenerator;
+
+/**
+ * JSON serializer for DynamoDB Enhanced Client document operations.
+ */
+@SdkInternalApi
+final class DocumentJsonSerializer {
+    private static final JsonFactory JSON_FACTORY = new JsonFactory() {
+        @Override
+        public JsonGenerator createGenerator(OutputStream out) throws IOException {
+            return super.createGenerator(out).enable(JsonGenerator.Feature.COMBINE_UNICODE_SURROGATES_IN_UTF8);
+        }
+    };
+
+    private DocumentJsonSerializer() {
+    }
+
+    public static String serializeAttributeValueMap(Map<String, AttributeValue> map) {
+        SdkJsonGenerator jsonGen = new SdkJsonGenerator(JSON_FACTORY, "application/json");
+
+        jsonGen.writeStartObject();
+        map.forEach((key, value) -> {
+            jsonGen.writeFieldName(key);
+            serializeAttributeValue(jsonGen, value);
+        });
+        jsonGen.writeEndObject();
+
+        return new String(jsonGen.getBytes(), StandardCharsets.UTF_8);
+    }
+
+    public static String serializeSingleAttributeValue(AttributeValue av) {
+        SdkJsonGenerator jsonGen = new SdkJsonGenerator(JSON_FACTORY, "application/json");
+        serializeAttributeValue(jsonGen, av);
+        return new String(jsonGen.getBytes(), StandardCharsets.UTF_8);
+    }
+
+    public static void serializeAttributeValue(SdkJsonGenerator generator, AttributeValue av) {
+        switch (av.type()) {
+            case NUL:
+                generator.writeNull();
+                break;
+            case S:
+                generator.writeValue(av.s());
+                break;
+            case N:
+                generator.writeNumber(av.n());
+                break;
+            case BOOL:
+                generator.writeValue(av.bool());
+                break;
+            case B:
+                generator.writeValue(av.b().asByteBuffer());
+                break;
+            case L:
+                generator.writeStartArray();
+                for (AttributeValue item : av.l()) {
+                    serializeAttributeValue(generator, item);
+                }
+                generator.writeEndArray();
+                break;
+            case M:
+                generator.writeStartObject();
+                for (Map.Entry<String, AttributeValue> entry : av.m().entrySet()) {
+                    generator.writeFieldName(entry.getKey());
+                    serializeAttributeValue(generator, entry.getValue());
+                }
+                generator.writeEndObject();
+                break;
+            case SS:
+                generator.writeStartArray();
+                for (String s : av.ss()) {
+                    generator.writeValue(s);
+                }
+                generator.writeEndArray();
+                break;
+            case NS:
+                generator.writeStartArray();
+                for (String n : av.ns()) {
+                    generator.writeNumber(n);
+                }
+                generator.writeEndArray();
+                break;
+            case BS:
+                generator.writeStartArray();
+                for (SdkBytes b : av.bs()) {
+                    generator.writeValue(b.asByteBuffer());
+                }
+                generator.writeEndArray();
+                break;
+            default:
+                throw new IllegalArgumentException("Unsupported AttributeValue type: " + av.type());
+        }
+    }
+
+}

services-custom/dynamodb-enhanced/src/test/java/software/amazon/awssdk/enhanced/dynamodb/document/DocumentTableSchemaTest.java

@@ -31,6 +31,7 @@
 import org.junit.jupiter.params.ParameterizedTest;
 import org.junit.jupiter.params.provider.ArgumentsSource;
 import software.amazon.awssdk.enhanced.dynamodb.AttributeValueType;
+import software.amazon.awssdk.enhanced.dynamodb.DefaultAttributeConverterProvider;
 import software.amazon.awssdk.enhanced.dynamodb.EnhancedType;
 import software.amazon.awssdk.enhanced.dynamodb.TableMetadata;
 import software.amazon.awssdk.enhanced.dynamodb.converters.document.CustomAttributeForDocumentConverterProvider;