Use the Chunk API consistently

This commit replaces the usage of List with Chunk
where appropriate. Summary of changes:

- The Chunk class was moved from the `org.springframework.batch.core.step.item` package to the `org.springframework.batch.item` package
- The signature of the method `ItemWriter#write(List)` was changed to `ItemWriter#write(Chunk)`
- All implementations of `ItemWriter` were updated to use the Chunk API instead of List
- All methods in the `ItemWriteListener` interface were updated to use the Chunk API instead of List
- All implementations of `ItemWriteListener` were updated to use the Chunk API instead of List
- The constructor of `ChunkRequest` was changed to accept a Chunk instead of a Collection of items
- The return type of `ChunkRequest#getItems()` was changed from List to Chunk

Resolves #3954

Author: fmbenhassine

spring-batch-core/src/main/java/org/springframework/batch/core/ItemWriteListener.java

@@ -18,12 +18,13 @@
 import java.util.List;
 
 import org.springframework.batch.core.scope.context.ChunkContext;
+import org.springframework.batch.item.Chunk;
 import org.springframework.batch.item.ItemWriter;
 
 /**
  * <p>
  * Listener interface for the writing of items. Implementations of this interface are
- * notified before, after, and in case of any exception thrown while writing a list of
+ * notified before, after, and in case of any exception thrown while writing a chunk of
  * items.
  * </p>
  *
@@ -42,19 +43,18 @@
 public interface ItemWriteListener<S> extends StepListener {
 
 	/**
-	 * Called before {@link ItemWriter#write(java.util.List)}
+	 * Called before {@link ItemWriter#write(Chunk)}
 	 * @param items to be written
 	 */
-	default void beforeWrite(List<? extends S> items) {
+	default void beforeWrite(Chunk<? extends S> items) {
 	}
 
 	/**
-	 * Called after {@link ItemWriter#write(java.util.List)}. This is called before any
-	 * transaction is committed, and before
-	 * {@link ChunkListener#afterChunk(ChunkContext)}.
+	 * Called after {@link ItemWriter#write(Chunk)}. This is called before any transaction
+	 * is committed, and before {@link ChunkListener#afterChunk(ChunkContext)}.
 	 * @param items written items
 	 */
-	default void afterWrite(List<? extends S> items) {
+	default void afterWrite(Chunk<? extends S> items) {
 	}
 
 	/**
@@ -64,7 +64,7 @@ default void afterWrite(List<? extends S> items) {
 	 * @param exception thrown from {@link ItemWriter}
 	 * @param items attempted to be written.
 	 */
-	default void onWriteError(Exception exception, List<? extends S> items) {
+	default void onWriteError(Exception exception, Chunk<? extends S> items) {
 	}
 
 }

spring-batch-core/src/main/java/org/springframework/batch/core/annotation/AfterWrite.java

@@ -27,12 +27,14 @@
 
 /**
  * Marks a method to be called after an item is passed to an {@link ItemWriter}. Note that
- * this annotation takes a {@link List} because Spring Batch generally processes a group
- * of items (for the sake of efficiency).<br>
+ * this annotation takes a {@link org.springframework.batch.item.Chunk} because Spring
+ * Batch generally processes a group of items (for the sake of efficiency).<br>
  * <br>
- * Expected signature: void afterWrite({@link List}&lt;? extends S&gt; items)
+ * Expected signature: void afterWrite({@link org.springframework.batch.item.Chunk}&lt;?
+ * extends S&gt; items)
  *
  * @author Lucas Ward
+ * @author Mahmoud Ben Hassine
  * @since 2.0
  * @see ItemWriteListener
  */

spring-batch-core/src/main/java/org/springframework/batch/core/annotation/BeforeWrite.java

@@ -26,11 +26,13 @@
 import org.springframework.batch.item.ItemWriter;
 
 /**
- * Marks a method to be called before an item is passed to an {@link ItemWriter}. <br>
+ * Marks a method to be called before a chunk is passed to an {@link ItemWriter}. <br>
  * <br>
- * Expected signature: void beforeWrite({@link List}&lt;? extends S&gt; items)
+ * Expected signature: void beforeWrite({@link org.springframework.batch.item.Chunk}&lt;?
+ * extends S&gt; items)
  *
  * @author Lucas Ward
+ * @author Mahmoud Ben Hassine
  * @since 2.0
  * @see ItemWriteListener
  */

spring-batch-core/src/main/java/org/springframework/batch/core/annotation/OnWriteError.java

@@ -27,13 +27,14 @@
 
 /**
  * Marks a method to be called if an exception is thrown by an {@link ItemWriter}. Note
- * that this annotation takes a {@link List} because Spring Batch generally processes a
- * group of items (for the sake of efficiency).<br>
+ * that this annotation takes a {@link org.springframework.batch.item.Chunk} because
+ * Spring Batch generally processes a group of items (for the sake of efficiency).<br>
  * <br>
- * Expected signature: void onWriteError({@link Exception} exception, {@link List}&lt;?
- * extends S&gt; items)
+ * Expected signature: void onWriteError({@link Exception} exception,
+ * {@link org.springframework.batch.item.Chunk}&lt;? extends S&gt; items)
  *
  * @author Lucas Ward
+ * @author Mahmoud Ben Hassine
  * @since 2.0
  * @see ItemWriteListener
  */

spring-batch-core/src/main/java/org/springframework/batch/core/listener/CompositeItemWriteListener.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2006-2013 the original author or authors.
+ * Copyright 2006-2022 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -19,11 +19,13 @@
 import java.util.List;
 
 import org.springframework.batch.core.ItemWriteListener;
+import org.springframework.batch.item.Chunk;
 import org.springframework.core.Ordered;
 
 /**
  * @author Lucas Ward
  * @author Dave Syer
+ * @author Mahmoud Ben Hassine
  *
  */
 public class CompositeItemWriteListener<S> implements ItemWriteListener<S> {
@@ -50,10 +52,10 @@ public void register(ItemWriteListener<? super S> itemWriteListener) {
 	/**
 	 * Call the registered listeners in reverse order, respecting and prioritising those
 	 * that implement {@link Ordered}.
-	 * @see ItemWriteListener#afterWrite(java.util.List)
+	 * @see ItemWriteListener#afterWrite(Chunk)
 	 */
 	@Override
-	public void afterWrite(List<? extends S> items) {
+	public void afterWrite(Chunk<? extends S> items) {
 		for (Iterator<ItemWriteListener<? super S>> iterator = listeners.reverse(); iterator.hasNext();) {
 			ItemWriteListener<? super S> listener = iterator.next();
 			listener.afterWrite(items);
@@ -63,10 +65,10 @@ public void afterWrite(List<? extends S> items) {
 	/**
 	 * Call the registered listeners in order, respecting and prioritising those that
 	 * implement {@link Ordered}.
-	 * @see ItemWriteListener#beforeWrite(List)
+	 * @see ItemWriteListener#beforeWrite(Chunk)
 	 */
 	@Override
-	public void beforeWrite(List<? extends S> items) {
+	public void beforeWrite(Chunk<? extends S> items) {
 		for (Iterator<ItemWriteListener<? super S>> iterator = listeners.iterator(); iterator.hasNext();) {
 			ItemWriteListener<? super S> listener = iterator.next();
 			listener.beforeWrite(items);
@@ -76,10 +78,10 @@ public void beforeWrite(List<? extends S> items) {
 	/**
 	 * Call the registered listeners in reverse order, respecting and prioritising those
 	 * that implement {@link Ordered}.
-	 * @see ItemWriteListener#onWriteError(Exception, List)
+	 * @see ItemWriteListener#onWriteError(Exception, Chunk)
 	 */
 	@Override
-	public void onWriteError(Exception ex, List<? extends S> items) {
+	public void onWriteError(Exception ex, Chunk<? extends S> items) {
 		for (Iterator<ItemWriteListener<? super S>> iterator = listeners.reverse(); iterator.hasNext();) {
 			ItemWriteListener<? super S> listener = iterator.next();
 			listener.onWriteError(ex, items);

spring-batch-core/src/main/java/org/springframework/batch/core/listener/MulticasterBatchListener.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2006-2021 the original author or authors.
+ * Copyright 2006-2022 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -28,6 +28,7 @@
 import org.springframework.batch.core.StepExecutionListener;
 import org.springframework.batch.core.StepListener;
 import org.springframework.batch.core.scope.context.ChunkContext;
+import org.springframework.batch.item.Chunk;
 import org.springframework.batch.item.ItemStream;
 import org.springframework.lang.Nullable;
 
@@ -241,10 +242,10 @@ public void onReadError(Exception ex) {
 	}
 
 	/**
-	 * @see ItemWriteListener#afterWrite(List)
+	 * @see ItemWriteListener#afterWrite(Chunk)
 	 */
 	@Override
-	public void afterWrite(List<? extends S> items) {
+	public void afterWrite(Chunk<? extends S> items) {
 		try {
 			itemWriteListener.afterWrite(items);
 		}
@@ -254,10 +255,10 @@ public void afterWrite(List<? extends S> items) {
 	}
 
 	/**
-	 * @see ItemWriteListener#beforeWrite(List)
+	 * @see ItemWriteListener#beforeWrite(Chunk)
 	 */
 	@Override
-	public void beforeWrite(List<? extends S> items) {
+	public void beforeWrite(Chunk<? extends S> items) {
 		try {
 			itemWriteListener.beforeWrite(items);
 		}
@@ -267,10 +268,10 @@ public void beforeWrite(List<? extends S> items) {
 	}
 
 	/**
-	 * @see ItemWriteListener#onWriteError(Exception, List)
+	 * @see ItemWriteListener#onWriteError(Exception, Chunk)
 	 */
 	@Override
-	public void onWriteError(Exception ex, List<? extends S> items) {
+	public void onWriteError(Exception ex, Chunk<? extends S> items) {
 		try {
 			itemWriteListener.onWriteError(ex, items);
 		}

spring-batch-core/src/main/java/org/springframework/batch/core/listener/StepListenerMetaData.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2013 the original author or authors.
+ * Copyright 2002-2022 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -46,6 +46,7 @@
 import org.springframework.batch.core.annotation.OnSkipInWrite;
 import org.springframework.batch.core.annotation.OnWriteError;
 import org.springframework.batch.core.scope.context.ChunkContext;
+import org.springframework.batch.item.Chunk;
 
 /**
  * Enumeration for {@link StepListener} meta data, which ties together the names of
@@ -72,10 +73,10 @@ public enum StepListenerMetaData implements ListenerMetaData {
 			Object.class),
 	ON_PROCESS_ERROR("onProcessError", "on-process-error-method", OnProcessError.class, ItemProcessListener.class,
 			Object.class, Exception.class),
-	BEFORE_WRITE("beforeWrite", "before-write-method", BeforeWrite.class, ItemWriteListener.class, List.class),
-	AFTER_WRITE("afterWrite", "after-write-method", AfterWrite.class, ItemWriteListener.class, List.class),
+	BEFORE_WRITE("beforeWrite", "before-write-method", BeforeWrite.class, ItemWriteListener.class, Chunk.class),
+	AFTER_WRITE("afterWrite", "after-write-method", AfterWrite.class, ItemWriteListener.class, Chunk.class),
 	ON_WRITE_ERROR("onWriteError", "on-write-error-method", OnWriteError.class, ItemWriteListener.class,
-			Exception.class, List.class),
+			Exception.class, Chunk.class),
 	ON_SKIP_IN_READ("onSkipInRead", "on-skip-in-read-method", OnSkipInRead.class, SkipListener.class, Throwable.class),
 	ON_SKIP_IN_PROCESS("onSkipInProcess", "on-skip-in-process-method", OnSkipInProcess.class, SkipListener.class,
 			Object.class, Throwable.class),

spring-batch-core/src/main/java/org/springframework/batch/core/step/item/ChunkOrientedTasklet.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2006-2019 the original author or authors.
+ * Copyright 2006-2022 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -21,13 +21,15 @@
 import org.springframework.batch.core.StepContribution;
 import org.springframework.batch.core.scope.context.ChunkContext;
 import org.springframework.batch.core.step.tasklet.Tasklet;
+import org.springframework.batch.item.Chunk;
 import org.springframework.batch.repeat.RepeatStatus;
 import org.springframework.lang.Nullable;
 
 /**
  * A {@link Tasklet} implementing variations on read-process-write item handling.
  *
  * @author Dave Syer
+ * @author Mahmoud Ben Hassine
  * @param <I> input item type
  */
 public class ChunkOrientedTasklet<I> implements Tasklet {

spring-batch-core/src/main/java/org/springframework/batch/core/step/item/ChunkProcessor.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2006-2007 the original author or authors.
+ * Copyright 2006-2022 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -17,9 +17,10 @@
 package org.springframework.batch.core.step.item;
 
 import org.springframework.batch.core.StepContribution;
+import org.springframework.batch.item.Chunk;
 
 /**
- * Interface defined for processing {@link Chunk}s.
+ * Interface defined for processing {@link org.springframework.batch.item.Chunk}s.
  *
  * @since 2.0
  */

spring-batch-core/src/main/java/org/springframework/batch/core/step/item/ChunkProvider.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2006-2007 the original author or authors.
+ * Copyright 2006-2022 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -17,10 +17,11 @@
 package org.springframework.batch.core.step.item;
 
 import org.springframework.batch.core.StepContribution;
+import org.springframework.batch.item.Chunk;
 
 /**
- * Interface for providing {@link Chunk}s to be processed, used by the
- * {@link ChunkOrientedTasklet}
+ * Interface for providing {@link org.springframework.batch.item.Chunk}s to be processed,
+ * used by the {@link ChunkOrientedTasklet}
  *
  * @since 2.0
  * @see ChunkOrientedTasklet

spring-batch-core/src/main/java/org/springframework/batch/core/step/item/DefaultItemFailureHandler.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2006-2008 the original author or authors.
+ * Copyright 2006-2022 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -20,6 +20,7 @@
 import org.apache.commons.logging.Log;
 import org.apache.commons.logging.LogFactory;
 import org.springframework.batch.core.listener.ItemListenerSupport;
+import org.springframework.batch.item.Chunk;
 
 /**
  * Default implementation of the {@link ItemListenerSupport} class that writes all
@@ -28,6 +29,7 @@
  * object.
  *
  * @author Lucas Ward
+ * @author Mahmoud Ben Hassine
  *
  */
 public class DefaultItemFailureHandler extends ItemListenerSupport<Object, Object> {
@@ -45,7 +47,7 @@ public void onReadError(Exception ex) {
 	}
 
 	@Override
-	public void onWriteError(Exception ex, List<? extends Object> item) {
+	public void onWriteError(Exception ex, Chunk<? extends Object> item) {
 		try {
 			logger.error("Error encountered while writing item: [ " + item + "]", ex);
 		}

spring-batch-core/src/main/java/org/springframework/batch/core/step/item/FaultTolerantChunkProcessor.java

@@ -34,8 +34,10 @@
 import org.springframework.batch.core.step.skip.SkipLimitExceededException;
 import org.springframework.batch.core.step.skip.SkipListenerFailedException;
 import org.springframework.batch.core.step.skip.SkipPolicy;
+import org.springframework.batch.item.Chunk;
 import org.springframework.batch.item.ItemProcessor;
 import org.springframework.batch.item.ItemWriter;
+import org.springframework.batch.item.SkipWrapper;
 import org.springframework.classify.BinaryExceptionClassifier;
 import org.springframework.classify.Classifier;
 import org.springframework.retry.ExhaustedRetryException;
@@ -337,7 +339,7 @@ public Object doWithRetry(RetryContext context) throws Exception {
 					Timer.Sample sample = BatchMetrics.createTimerSample();
 					String status = BatchMetrics.STATUS_SUCCESS;
 					try {
-						doWrite(outputs.getItems());
+						doWrite(outputs);
 					}
 					catch (Exception e) {
 						status = BatchMetrics.STATUS_FAILURE;
@@ -590,7 +592,7 @@ private void scan(final StepContribution contribution, final Chunk<I> inputs, fi
 			}
 		}
 
-		List<O> items = Collections.singletonList(outputIterator.next());
+		Chunk<O> items = Chunk.of(outputIterator.next());
 		inputIterator.next();
 		try {
 			writeItems(items);

spring-batch-core/src/main/java/org/springframework/batch/core/step/item/FaultTolerantChunkProvider.java

@@ -23,6 +23,7 @@
 import org.springframework.batch.core.step.skip.SkipListenerFailedException;
 import org.springframework.batch.core.step.skip.SkipPolicy;
 import org.springframework.batch.core.step.skip.SkipPolicyFailedException;
+import org.springframework.batch.item.Chunk;
 import org.springframework.batch.item.ItemReader;
 import org.springframework.batch.repeat.RepeatOperations;
 import org.springframework.classify.BinaryExceptionClassifier;