Skip EnhancedAttributeValue wrapping in converters transformTo when t…

services-custom/dynamodb-enhanced/src/main/java/software/amazon/awssdk/enhanced/dynamodb/internal/converter/attribute/ByteArrayAttributeConverter.java

@@ -69,7 +69,7 @@ public AttributeValue transformFrom(byte[] input) {
     @Override
     public byte[] transformTo(AttributeValue input) {
         if (input.b() != null) {
-            return EnhancedAttributeValue.fromBytes(input.b()).convert(VISITOR);
+            return input.b().asByteArray();
         }
 
         return EnhancedAttributeValue.fromAttributeValue(input).convert(VISITOR);

services-custom/dynamodb-enhanced/src/main/java/software/amazon/awssdk/enhanced/dynamodb/internal/converter/attribute/StringAttributeConverter.java

@@ -70,7 +70,10 @@ public AttributeValue transformFrom(String input) {
 
     @Override
     public String transformTo(AttributeValue input) {
-        return Visitor.toString(input);
+        if (input.s() != null) {
+            return input.s();
+        }
+        return EnhancedAttributeValue.fromAttributeValue(input).convert(Visitor.INSTANCE);
     }
 
     private static final class Visitor extends TypeConvertingVisitor<String> {

test/sdk-benchmarks/src/main/java/software/amazon/awssdk/benchmark/enhanced/dynamodb/ConverterBenchmark.java

@@ -0,0 +1,72 @@
+/*
+ * 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.benchmark.enhanced.dynamodb;
+
+import java.util.concurrent.TimeUnit;
+import org.openjdk.jmh.annotations.Benchmark;
+import org.openjdk.jmh.annotations.BenchmarkMode;
+import org.openjdk.jmh.annotations.Fork;
+import org.openjdk.jmh.annotations.Measurement;
+import org.openjdk.jmh.annotations.Mode;
+import org.openjdk.jmh.annotations.OutputTimeUnit;
+import org.openjdk.jmh.annotations.Scope;
+import org.openjdk.jmh.annotations.Setup;
+import org.openjdk.jmh.annotations.State;
+import org.openjdk.jmh.annotations.Warmup;
+import org.openjdk.jmh.infra.Blackhole;
+import software.amazon.awssdk.core.SdkBytes;
+import software.amazon.awssdk.enhanced.dynamodb.internal.converter.attribute.ByteArrayAttributeConverter;
+import software.amazon.awssdk.enhanced.dynamodb.internal.converter.attribute.StringAttributeConverter;
+import software.amazon.awssdk.services.dynamodb.model.AttributeValue;
+
+/**
+ * Micro-benchmark to isolate String and ByteArray converter optimization impact.
+ */
+@BenchmarkMode(Mode.SampleTime)
+@OutputTimeUnit(TimeUnit.NANOSECONDS)
+@Warmup(iterations = 5, time = 1)
+@Measurement(iterations = 10, time = 1)
+@Fork(2)
+@State(Scope.Benchmark)
+public class ConverterBenchmark {
+
+    private StringAttributeConverter stringConverter;
+    private ByteArrayAttributeConverter byteArrayConverter;
+
+    private AttributeValue stringAttributeValue;
+    private AttributeValue byteAttributeValue;
+
+    @Setup
+    public void setup() {
+        stringConverter = StringAttributeConverter.create();
+        byteArrayConverter = ByteArrayAttributeConverter.create();
+
+        stringAttributeValue = AttributeValue.builder().s("test-string-value").build();
+        byteAttributeValue = AttributeValue.builder().b(SdkBytes.fromUtf8String("test-bytes")).build();
+    }
+
+    @Benchmark
+    public void stringConverter(Blackhole blackhole) {
+        String result = stringConverter.transformTo(stringAttributeValue);
+        blackhole.consume(result);
+    }
+
+    @Benchmark
+    public void byteArrayConverter(Blackhole blackhole) {
+        byte[] result = byteArrayConverter.transformTo(byteAttributeValue);
+        blackhole.consume(result);
+    }
+}