add more javadoc and minor code cleanups

Author: zhongkechen

sdk/src/main/java/software/amazon/lambda/durable/BaseContext.java

@@ -26,8 +26,18 @@ protected BaseContext(
     }
 
     // =============== accessors ================
+    /**
+     * Gets a logger with additional information of the current execution context.
+     *
+     * @return a DurableLogger instance
+     */
     public abstract DurableLogger getLogger();
 
+    /**
+     * Returns the AWS Lambda runtime context.
+     *
+     * @return the Lambda context
+     */
     public Context getLambdaContext() {
         return lambdaContext;
     }

sdk/src/main/java/software/amazon/lambda/durable/DurableContext.java

@@ -23,14 +23,12 @@
 public class DurableContext extends BaseContext {
     private final AtomicInteger operationCounter;
     private final DurableLogger logger;
-    private final ExecutionContext executionContext;
 
     /** Shared initialization — sets all fields but performs no thread registration. */
     private DurableContext(
             ExecutionManager executionManager, DurableConfig durableConfig, Context lambdaContext, String contextId) {
         super(executionManager, durableConfig, lambdaContext, contextId);
         this.operationCounter = new AtomicInteger(0);
-        this.executionContext = new ExecutionContext(executionManager.getDurableExecutionArn());
 
         var requestId = lambdaContext != null ? lambdaContext.getAwsRequestId() : null;
         this.logger = new DurableLogger(
@@ -73,6 +71,7 @@ public DurableContext createChildContext(String childContextId) {
     /**
      * Creates a step context for executing step operations.
      *
+     * @param stepOperationId the ID of the step operation (used for thread registration)
      * @return a new StepContext instance
      */
     public StepContext createStepContext(String stepOperationId) {
@@ -307,21 +306,19 @@ public <T> DurableFuture<T> runInChildContextAsync(
     }
 
     // =============== accessors ================
-
     /**
-     * Gets a logger with additional information of the current execution context.
+     * Returns a logger with execution context information for replay-aware logging.
      *
-     * @return a DurableLogger instance
+     * @return the durable logger
      */
     public DurableLogger getLogger() {
         return logger;
     }
 
     /**
      * Get the next operationId. For root contexts, returns sequential IDs like "1", "2", "3". For child contexts,
-     * prefixes with the getContextId() to ensure global uniqueness, e.g. "1-1", "1-2" for operations inside child
-     * context "1". This matches the JavaScript SDK's stepPrefix convention and prevents ID collisions in checkpoint
-     * batches.
+     * prefixes with the contextId to ensure global uniqueness, e.g. "1-1", "1-2" for operations inside child context
+     * "1". This matches the JavaScript SDK's stepPrefix convention and prevents ID collisions in checkpoint batches.
      */
     private String nextOperationId() {
         var counter = String.valueOf(operationCounter.incrementAndGet());

sdk/src/main/java/software/amazon/lambda/durable/StepContext.java

@@ -16,11 +16,14 @@ public class StepContext extends BaseContext {
      * @param executionManager Manages durable execution state and operations
      * @param durableConfig Configuration for durable execution behavior
      * @param lambdaContext AWS Lambda runtime context
-     * @param contextId Unique identifier for this context instance
+     * @param stepOperationId Unique identifier for this context instance
      */
     protected StepContext(
-            ExecutionManager executionManager, DurableConfig durableConfig, Context lambdaContext, String contextId) {
-        super(executionManager, durableConfig, lambdaContext, contextId);
+            ExecutionManager executionManager,
+            DurableConfig durableConfig,
+            Context lambdaContext,
+            String stepOperationId) {
+        super(executionManager, durableConfig, lambdaContext, stepOperationId);
 
         var requestId = lambdaContext != null ? lambdaContext.getAwsRequestId() : null;
         this.logger = new DurableLogger(

sdk/src/main/java/software/amazon/lambda/durable/operation/CallbackOperation.java

@@ -2,8 +2,6 @@
 // SPDX-License-Identifier: Apache-2.0
 package software.amazon.lambda.durable.operation;
 
-import org.slf4j.Logger;
-import org.slf4j.LoggerFactory;
 import software.amazon.awssdk.services.lambda.model.CallbackOptions;
 import software.amazon.awssdk.services.lambda.model.OperationAction;
 import software.amazon.awssdk.services.lambda.model.OperationType;
@@ -18,8 +16,6 @@
 /** Durable operation for creating and waiting on external callbacks. */
 public class CallbackOperation<T> extends BaseDurableOperation<T> implements DurableCallbackFuture<T> {
 
-    private static final Logger logger = LoggerFactory.getLogger(CallbackOperation.class);
-
     private final CallbackConfig config;
 
     private String callbackId;

sdk/src/main/java/software/amazon/lambda/durable/operation/ChildContextOperation.java

@@ -5,6 +5,7 @@
 import static software.amazon.lambda.durable.model.OperationSubType.RUN_IN_CHILD_CONTEXT;
 
 import java.nio.charset.StandardCharsets;
+import java.util.concurrent.ExecutorService;
 import java.util.function.Function;
 import software.amazon.awssdk.services.lambda.model.ContextOptions;
 import software.amazon.awssdk.services.lambda.model.ErrorObject;
@@ -34,6 +35,7 @@ public class ChildContextOperation<T> extends BaseDurableOperation<T> {
     private static final int LARGE_RESULT_THRESHOLD = 256 * 1024;
 
     private final Function<DurableContext, T> function;
+    private final ExecutorService userExecutor;
     private boolean replayChildContext;
     private T reconstructedResult;
 
@@ -46,6 +48,7 @@ public ChildContextOperation(
             DurableContext durableContext) {
         super(operationId, name, OperationType.CONTEXT, resultTypeToken, resultSerDes, durableContext);
         this.function = function;
+        this.userExecutor = getContext().getDurableConfig().getExecutorService();
     }
 
     @Override
@@ -93,7 +96,7 @@ private void executeChildContext() {
         // registerActiveThread is idempotent (no-op if already registered).
         registerActiveThread(contextId);
 
-        getContext().getDurableConfig().getExecutorService().execute(() -> {
+        userExecutor.execute(() -> {
             setCurrentThreadContext(new ThreadContext(contextId, ThreadType.CONTEXT));
             try {
                 var childContext = getContext().createChildContext(contextId);