Add classesloaded.txt with a list of all loaded Java classes.

Author: David-DAM

powertools-batch/pom.xml

@@ -60,6 +60,10 @@
             <artifactId>sdk-core</artifactId>
             <scope>provided</scope>
         </dependency>
+        <dependency>
+            <groupId>org.crac</groupId>
+            <artifactId>crac</artifactId>
+        </dependency>
 
         <!-- Test dependencies -->
         <dependency>
@@ -94,4 +98,25 @@
         </dependency>
     </dependencies>
 
+    <profiles>
+        <profile>
+            <id>generate-classesloaded-file</id>
+            <build>
+                <plugins>
+                    <plugin>
+                        <groupId>org.apache.maven.plugins</groupId>
+                        <artifactId>maven-surefire-plugin</artifactId>
+                        <configuration>
+                            <argLine>
+                                -Xlog:class+load=info:classesloaded.txt
+                                --add-opens java.base/java.util=ALL-UNNAMED
+                                --add-opens java.base/java.lang=ALL-UNNAMED
+                            </argLine>
+                        </configuration>
+                    </plugin>
+                </plugins>
+            </build>
+        </profile>
+    </profiles>
+
 </project>

powertools-batch/src/main/java/software/amazon/lambda/powertools/batch/BatchMessageHandlerBuilder.java

@@ -14,9 +14,13 @@
 
 package software.amazon.lambda.powertools.batch;
 
+import org.crac.Context;
+import org.crac.Core;
+import org.crac.Resource;
 import software.amazon.lambda.powertools.batch.builder.DynamoDbBatchMessageHandlerBuilder;
 import software.amazon.lambda.powertools.batch.builder.KinesisBatchMessageHandlerBuilder;
 import software.amazon.lambda.powertools.batch.builder.SqsBatchMessageHandlerBuilder;
+import software.amazon.lambda.powertools.common.internal.ClassPreLoader;
 
 /**
  * A builder-style interface we can use to build batch processing handlers for SQS, Kinesis Streams,
@@ -27,7 +31,15 @@
  *
  * @see <a href="https://docs.powertools.aws.dev/lambda/java/utilities/batch/">Powertools for AWS Lambda (Java) Batch Documentation</a>
  **/
-public class BatchMessageHandlerBuilder {
+public class BatchMessageHandlerBuilder implements Resource {
+
+    // Dummy instance to register BatchMessageHandlerBuilder with CRaC
+    private static final BatchMessageHandlerBuilder INSTANCE = new BatchMessageHandlerBuilder();
+
+    // Static block to ensure CRaC registration happens at class loading time
+    static {
+        Core.getGlobalContext().register(INSTANCE);
+    }
 
     /**
      * Build an SQS-batch message handler.
@@ -55,4 +67,14 @@ public DynamoDbBatchMessageHandlerBuilder withDynamoDbBatchHandler() {
     public KinesisBatchMessageHandlerBuilder withKinesisBatchHandler() {
         return new KinesisBatchMessageHandlerBuilder();
     }
+
+    @Override
+    public void beforeCheckpoint(Context<? extends Resource> context) throws Exception {
+        ClassPreLoader.preloadClasses();
+    }
+
+    @Override
+    public void afterRestore(Context<? extends Resource> context) throws Exception {
+        // No action needed after restore
+    }
 }