IN PROGRESS - issue BATCH-7: Remove transaction synchronization and state management from input/output sources (formerly buffering)

http://jira.springframework.org/browse/BATCH-7

Added ItemStream as base interface for ItemReader/Writer.

spring-batch-infrastructure/src/main/java/org/springframework/batch/io/cursor/HibernateCursorItemReader.java

@@ -26,7 +26,6 @@ import org.hibernate.StatelessSession;
 import org.springframework.batch.io.Skippable;
 import org.springframework.batch.item.ItemReader;
 import org.springframework.batch.item.ItemStream;
-import org.springframework.batch.item.ResourceLifecycle;
 import org.springframework.batch.item.StreamContext;
 import org.springframework.batch.item.reader.AbstractItemReader;
 import org.springframework.batch.item.stream.GenericStreamContext;
@@ -58,7 +57,7 @@ import org.springframework.util.StringUtils;
  * @author Dave Syer
  */
 public class HibernateCursorItemReader extends AbstractItemReader implements ItemReader, ItemStream,
-		Skippable, InitializingBean, DisposableBean, ResourceLifecycle {
+		Skippable, InitializingBean, DisposableBean {
 
 	private static final String RESTART_DATA_ROW_NUMBER_KEY = ClassUtils
 			.getShortName(HibernateCursorItemReader.class)

spring-batch-infrastructure/src/main/java/org/springframework/batch/io/cursor/JdbcCursorItemReader.java

@@ -33,7 +33,6 @@ import org.springframework.batch.io.Skippable;
 import org.springframework.batch.io.support.AbstractTransactionalIoSource;
 import org.springframework.batch.item.ItemStream;
 import org.springframework.batch.item.KeyedItemReader;
-import org.springframework.batch.item.ResourceLifecycle;
 import org.springframework.batch.item.StreamContext;
 import org.springframework.batch.item.stream.GenericStreamContext;
 import org.springframework.batch.statistics.StatisticsProvider;
@@ -117,7 +116,7 @@ import org.springframework.util.StringUtils;
  * @author Peter Zozom
  */
 public class JdbcCursorItemReader extends AbstractTransactionalIoSource
-		implements KeyedItemReader, ResourceLifecycle, DisposableBean,
+		implements KeyedItemReader, DisposableBean,
 		InitializingBean, ItemStream, StatisticsProvider, Skippable {
 
 	private static Log log = LogFactory.getLog(JdbcCursorItemReader.class);

spring-batch-infrastructure/src/main/java/org/springframework/batch/io/driving/DrivingQueryItemReader.java

@@ -21,7 +21,6 @@ import java.util.List;
 import org.springframework.batch.io.support.AbstractTransactionalIoSource;
 import org.springframework.batch.item.ItemStream;
 import org.springframework.batch.item.KeyedItemReader;
-import org.springframework.batch.item.ResourceLifecycle;
 import org.springframework.batch.item.StreamContext;
 import org.springframework.batch.repeat.synch.BatchTransactionSynchronizationManager;
 import org.springframework.beans.factory.DisposableBean;
@@ -51,7 +50,7 @@ import org.springframework.util.Assert;
  * @since 1.0
  */
 public class DrivingQueryItemReader extends AbstractTransactionalIoSource
-		implements KeyedItemReader, ResourceLifecycle, InitializingBean,
+		implements KeyedItemReader, InitializingBean,
 		DisposableBean, ItemStream {
 
 	private boolean initialized = false;

spring-batch-infrastructure/src/main/java/org/springframework/batch/io/file/FlatFileItemWriter.java

@@ -33,7 +33,6 @@ import org.springframework.batch.io.exception.BatchEnvironmentException;
 import org.springframework.batch.io.support.AbstractTransactionalIoSource;
 import org.springframework.batch.item.ItemStream;
 import org.springframework.batch.item.ItemWriter;
-import org.springframework.batch.item.ResourceLifecycle;
 import org.springframework.batch.item.StreamContext;
 import org.springframework.batch.item.stream.GenericStreamContext;
 import org.springframework.batch.item.writer.ItemTransformer;
@@ -61,7 +60,7 @@ import org.springframework.util.Assert;
  * @author Dave Syer
  */
 public class FlatFileItemWriter extends AbstractTransactionalIoSource implements 
-	ItemWriter, ResourceLifecycle, ItemStream, StatisticsProvider, InitializingBean,
+	ItemWriter, ItemStream, StatisticsProvider, InitializingBean,
 	DisposableBean {
 
 	private static final String LINE_SEPARATOR = System.getProperty("line.separator");

spring-batch-infrastructure/src/main/java/org/springframework/batch/io/file/SimpleFlatFileItemReader.java

@@ -31,7 +31,6 @@ import org.springframework.batch.io.file.transform.AbstractLineTokenizer;
 import org.springframework.batch.io.file.transform.DelimitedLineTokenizer;
 import org.springframework.batch.io.file.transform.LineTokenizer;
 import org.springframework.batch.item.ItemReader;
-import org.springframework.batch.item.ResourceLifecycle;
 import org.springframework.batch.item.reader.AbstractItemReader;
 import org.springframework.beans.factory.DisposableBean;
 import org.springframework.beans.factory.InitializingBean;
@@ -171,11 +170,10 @@ public class SimpleFlatFileItemReader extends AbstractItemReader implements Item
 	}
 
 	/**
-	 * Close and null out the reader.
-	 * 
-	 * @see ResourceLifecycle
+	 * Close and null out the delegate line reader.
+	 * @throws Exception 
 	 */
-	public void close() {
+	public void close() throws Exception {
 		try {
 			if (reader != null) {
 				log.debug("Closing flat file for reading: "+resource);

spring-batch-infrastructure/src/main/java/org/springframework/batch/io/file/separator/LineReader.java

@@ -16,13 +16,12 @@
 package org.springframework.batch.io.file.separator;
 
 import org.springframework.batch.item.ItemReader;
-import org.springframework.batch.item.ResourceLifecycle;
 
 /**
  * @author Dave Syer
  *
  */
-public interface LineReader extends ResourceLifecycle, ItemReader {
+public interface LineReader extends ItemReader {
 
 	/**
 	 * @return

spring-batch-infrastructure/src/main/java/org/springframework/batch/io/file/separator/ResourceLineReader.java

@@ -27,7 +27,6 @@ import java.util.Iterator;
 
 import org.springframework.batch.io.exception.BatchEnvironmentException;
 import org.springframework.batch.item.ItemReader;
-import org.springframework.batch.item.ResourceLifecycle;
 import org.springframework.batch.item.reader.AbstractItemReader;
 import org.springframework.beans.factory.DisposableBean;
 import org.springframework.core.io.Resource;
@@ -56,7 +55,7 @@ import org.springframework.util.Assert;
  * @author Dave Syer
  * @author Rob Harrop
  */
-public class ResourceLineReader extends AbstractItemReader implements LineReader, ResourceLifecycle, ItemReader,
+public class ResourceLineReader extends AbstractItemReader implements LineReader, ItemReader,
 		DisposableBean {
 
 	private static final Collection DEFAULT_COMMENTS = Collections.singleton("#");

spring-batch-infrastructure/src/main/java/org/springframework/batch/io/support/HibernateAwareItemWriter.java

@@ -20,6 +20,7 @@ import java.util.Set;
 
 import org.hibernate.SessionFactory;
 import org.springframework.batch.item.ItemWriter;
+import org.springframework.batch.item.stream.ItemStreamAdapter;
 import org.springframework.batch.repeat.ExitStatus;
 import org.springframework.batch.repeat.RepeatContext;
 import org.springframework.batch.repeat.RepeatInterceptor;
@@ -44,7 +45,7 @@ import org.springframework.util.Assert;
  * @author Dave Syer
  * 
  */
-public class HibernateAwareItemWriter implements ItemWriter, RepeatInterceptor,
+public class HibernateAwareItemWriter extends ItemStreamAdapter implements ItemWriter, RepeatInterceptor,
 		InitializingBean {
 
 	/**

spring-batch-infrastructure/src/main/java/org/springframework/batch/io/xml/StaxEventItemReader.java

@@ -19,7 +19,6 @@ import org.springframework.batch.io.xml.stax.FragmentEventReader;
 import org.springframework.batch.io.xml.stax.TransactionalEventReader;
 import org.springframework.batch.item.ItemReader;
 import org.springframework.batch.item.ItemStream;
-import org.springframework.batch.item.ResourceLifecycle;
 import org.springframework.batch.item.StreamContext;
 import org.springframework.batch.item.reader.AbstractItemReader;
 import org.springframework.batch.item.stream.GenericStreamContext;
@@ -43,7 +42,7 @@ import org.springframework.util.Assert;
  * 
  * @author Robert Kasanicky
  */
-public class StaxEventItemReader extends AbstractItemReader implements ItemReader, ResourceLifecycle,
+public class StaxEventItemReader extends AbstractItemReader implements ItemReader,
 		Skippable, ItemStream, StatisticsProvider, InitializingBean, DisposableBean {
 
 	public static final String READ_COUNT_STATISTICS_NAME = "StaxEventReaderItemReader.readCount";

spring-batch-infrastructure/src/main/java/org/springframework/batch/io/xml/StaxEventItemWriter.java

@@ -18,7 +18,6 @@ import org.springframework.batch.io.support.FileUtils;
 import org.springframework.batch.io.xml.stax.NoStartEndDocumentStreamWriter;
 import org.springframework.batch.item.ItemStream;
 import org.springframework.batch.item.ItemWriter;
-import org.springframework.batch.item.ResourceLifecycle;
 import org.springframework.batch.item.StreamContext;
 import org.springframework.batch.item.stream.GenericStreamContext;
 import org.springframework.batch.repeat.synch.BatchTransactionSynchronizationManager;
@@ -42,7 +41,7 @@ import org.springframework.util.CollectionUtils;
  * @author Peter Zozom
  *
  */
-public class StaxEventItemWriter implements ItemWriter, ResourceLifecycle, ItemStream,
+public class StaxEventItemWriter implements ItemWriter, ItemStream,
 		StatisticsProvider, InitializingBean, DisposableBean {
 
 	// default encoding

spring-batch-infrastructure/src/main/java/org/springframework/batch/item/ItemReader.java

@@ -38,7 +38,7 @@ import org.springframework.batch.item.reader.AbstractItemReader;
  * @author Lucas Ward
  * @since 1.0
  */
-public interface ItemReader {
+public interface ItemReader extends ItemStream {
 
 	/**
 	 * Reads a piece of input data and advance to the next one. Implementations
@@ -51,9 +51,4 @@ public interface ItemReader {
 	 */
 	Object read() throws Exception;
 
-	/**
-	 * Close the reader, freeing any resources that may have been allocated
-	 * since the first call to read().
-	 */
-	void close() throws Exception;
 }

spring-batch-infrastructure/src/main/java/org/springframework/batch/item/ItemStream.java

@@ -35,6 +35,16 @@ package org.springframework.batch.item;
  * 
  */
 public interface ItemStream {
+	
+	void open() throws Exception;
+	
+	/**
+	 * Close the reader, freeing any resources that may have been allocated
+	 * since the first call to read().
+	 * 
+	 * @throws Exception if an underlying resource is unavailable
+	 */
+	void close() throws Exception;
 
 	/**
 	 * Get {@link StreamContext} representing this object's current state.

spring-batch-infrastructure/src/main/java/org/springframework/batch/item/ItemWriter.java

@@ -25,7 +25,7 @@ package org.springframework.batch.item;
  * @author Dave Syer
  * @author Lucas Ward
  */
-public interface ItemWriter {
+public interface ItemWriter extends ItemStream {
 
 	/**
 	 * Process the supplied data element. Will be called multiple times during a
@@ -38,10 +38,4 @@ public interface ItemWriter {
 	 */
 	public void write(Object item) throws Exception;
 	
-	/**
-	 * Close the writer, allowing all allocated resources to be cleaned up.
-	 * 
-	 * @throws Exception
-	 */
-	void close() throws Exception;
 }

spring-batch-infrastructure/src/main/java/org/springframework/batch/item/ResourceLifecycle.java

@@ -1,37 +0,0 @@
-/*
- * Copyright 2006-2007 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.
- * You may obtain a copy of the License at
- *
- *      http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License 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 org.springframework.batch.item;
-
-/**
- * Common interface for classes that require initialisation before they can be
- * used and need to free resources after they are no longer used.
- */
-public interface ResourceLifecycle {
-	/**
-	 * This method should be invoked by clients at the start of processing to
-	 * allow initialisation of resources.
-	 * 
-	 */
-	public void open();
-
-	/**
-	 * This method should be invoked by clients after the completion of each
-	 * step and the implementing class should close all managed resources.
-	 * 
-	 */
-	public void close();
-}

spring-batch-infrastructure/src/main/java/org/springframework/batch/item/reader/AbstractItemReader.java

@@ -17,19 +17,13 @@
 package org.springframework.batch.item.reader;
 
 import org.springframework.batch.item.ItemReader;
+import org.springframework.batch.item.stream.ItemStreamAdapter;
 
 /**
  * Base class for {@link ItemReader} implementations.
  * @author Dave Syer
  *
  */
-public abstract class AbstractItemReader implements ItemReader {
-	
-	/**
-	 * Do nothing.
-	 * @see org.springframework.batch.item.ItemReader#close()
-	 */
-	public void close() throws Exception {		
-	}
+public abstract class AbstractItemReader extends ItemStreamAdapter implements ItemReader {
 
 }

spring-batch-infrastructure/src/main/java/org/springframework/batch/item/reader/ItemReaderAdapter.java

@@ -16,7 +16,11 @@
 
 package org.springframework.batch.item.reader;
 
+import java.util.Properties;
+
 import org.springframework.batch.item.ItemReader;
+import org.springframework.batch.item.StreamContext;
+import org.springframework.batch.item.stream.GenericStreamContext;
 import org.springframework.batch.support.AbstractMethodInvokingDelegator;
 
 /**
@@ -35,10 +39,33 @@ public class ItemReaderAdapter extends AbstractMethodInvokingDelegator implement
 
 	/**
 	 * Do nothing.
-	 * 
-	 * @see org.springframework.batch.item.ItemReader#close()
+	 * @see org.springframework.batch.item.ItemStream#open()
+	 */
+	public void open() throws Exception {
+		// no-op
+	}
+	
+	/**
+	 * Do nothing.
+	 * @see org.springframework.batch.item.ItemStream#close()
 	 */
 	public void close() throws Exception {
+		// no-op
+	}
+
+	/**
+	 * Return empty {@link StreamContext}.
+	 * @see org.springframework.batch.item.ItemStream#getRestartData()
+	 */
+	public StreamContext getRestartData() {
+		return new GenericStreamContext(new Properties());
+	}
+	
+	/**
+	 * Do nothing.
+	 * @see org.springframework.batch.item.ItemStream#restoreFrom(org.springframework.batch.item.StreamContext)
+	 */
+	public void restoreFrom(StreamContext data) {
 		
 	}
 

spring-batch-infrastructure/src/main/java/org/springframework/batch/item/writer/AbstractItemWriter.java

@@ -1,31 +0,0 @@
-/*
- * Copyright 2006-2008 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.
- * You may obtain a copy of the License at
- *
- *      http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License 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 org.springframework.batch.item.writer;
-
-import org.springframework.batch.item.ItemWriter;
-
-/**
- * Abstract {@link ItemWriter} that allows for base classes to only
- * implement the close method if they need it.
- * 
- * @author Lucas Ward
- *
- */
-public abstract class AbstractItemWriter implements ItemWriter{
-
-	public void close() throws Exception {
-	}
-}

spring-batch-infrastructure/src/main/java/org/springframework/batch/item/writer/CompositeItemWriter.java

@@ -11,13 +11,14 @@ import org.springframework.batch.item.ItemStream;
 import org.springframework.batch.item.ItemWriter;
 import org.springframework.batch.item.StreamContext;
 import org.springframework.batch.item.stream.GenericStreamContext;
+import org.springframework.batch.item.stream.ItemStreamAdapter;
 
 /**
  * Runs a collection of ItemProcessors in fixed-order sequence.
  * 
  * @author Robert Kasanicky
  */
-public class CompositeItemWriter implements ItemWriter, ItemStream {
+public class CompositeItemWriter extends ItemStreamAdapter implements ItemWriter, ItemStream {
 
 	private static final String SEPARATOR = "#";
 
@@ -38,13 +39,8 @@ public class CompositeItemWriter implements ItemWriter, ItemStream {
 	 */
 	public StreamContext getRestartData() {
 		Properties props = createCompoundProperties(new PropertiesExtractor() {
-			public Properties extractProperties(Object o) {
-				if (o instanceof ItemStream) {
-					return ((ItemStream) o).getRestartData().getProperties();
-				}
-				else {
-					return null;
-				}
+			public Properties extractProperties(ItemStream o) {
+					return o.getRestartData().getProperties();
 			}
 		});
 		return new GenericStreamContext(props);
@@ -105,7 +101,7 @@ public class CompositeItemWriter implements ItemWriter, ItemStream {
 		Properties stats = new Properties();
 		int index = 0;
 		for (Iterator iterator = delegates.listIterator(); iterator.hasNext();) {
-			Properties writerStats = extractor.extractProperties(iterator.next());
+			Properties writerStats = extractor.extractProperties((ItemStream) iterator.next());
 			if (writerStats != null) {
 				for (Iterator iterator2 = writerStats.entrySet().iterator(); iterator2.hasNext();) {
 					Map.Entry entry = (Map.Entry) iterator2.next();
@@ -123,7 +119,7 @@ public class CompositeItemWriter implements ItemWriter, ItemStream {
 	 * null.
 	 */
 	private interface PropertiesExtractor {
-		Properties extractProperties(Object o);
+		Properties extractProperties(ItemStream o);
 	}
 	
 	public void close() throws Exception {

spring-batch-infrastructure/src/main/java/org/springframework/batch/item/writer/DelegatingItemWriter.java

@@ -7,6 +7,7 @@ import org.springframework.batch.item.ItemStream;
 import org.springframework.batch.item.ItemWriter;
 import org.springframework.batch.item.StreamContext;
 import org.springframework.batch.item.stream.GenericStreamContext;
+import org.springframework.batch.item.stream.ItemStreamAdapter;
 import org.springframework.beans.factory.InitializingBean;
 import org.springframework.util.Assert;
 
@@ -17,7 +18,7 @@ import org.springframework.util.Assert;
  * @author Dave Syer
  * @author Robert Kasanicky
  */
-public class DelegatingItemWriter implements ItemWriter, ItemStream, Skippable, InitializingBean {
+public class DelegatingItemWriter extends ItemStreamAdapter implements ItemWriter, Skippable, InitializingBean {
 
 	private ItemWriter writer;
 

spring-batch-infrastructure/src/main/java/org/springframework/batch/item/writer/ItemWriterAdapter.java

@@ -16,7 +16,11 @@
 
 package org.springframework.batch.item.writer;
 
+import java.util.Properties;
+
 import org.springframework.batch.item.ItemWriter;
+import org.springframework.batch.item.StreamContext;
+import org.springframework.batch.item.stream.GenericStreamContext;
 import org.springframework.batch.support.AbstractMethodInvokingDelegator;
 
 
@@ -34,13 +38,35 @@ public class ItemWriterAdapter extends AbstractMethodInvokingDelegator implement
     	invokeDelegateMethodWithArgument(item);
     }
 
-    /*
-     * No-op, can't call more than one method.
-     * 
-     * (non-Javadoc)
-     * @see org.springframework.batch.item.ItemWriter#close()
-     */
+	/**
+	 * Do nothing.
+	 * @see org.springframework.batch.item.ItemStream#open()
+	 */
+	public void open() throws Exception {
+		// no-op
+	}
+	
+	/**
+	 * Do nothing.
+	 * @see org.springframework.batch.item.ItemStream#close()
+	 */
 	public void close() throws Exception {
+		// no-op
+	}
+
+	/**
+	 * Return empty {@link StreamContext}.
+	 * @see org.springframework.batch.item.ItemStream#getRestartData()
+	 */
+	public StreamContext getRestartData() {
+		return new GenericStreamContext(new Properties());
+	}
+	
+	/**
+	 * Do nothing.
+	 * @see org.springframework.batch.item.ItemStream#restoreFrom(org.springframework.batch.item.StreamContext)
+	 */
+	public void restoreFrom(StreamContext data) {
 		
 	}
 	

spring-batch-infrastructure/src/main/java/org/springframework/batch/item/writer/PropertyExtractingDelegatingItemWriter.java

@@ -16,7 +16,11 @@
 
 package org.springframework.batch.item.writer;
 
+import java.util.Properties;
+
 import org.springframework.batch.item.ItemWriter;
+import org.springframework.batch.item.StreamContext;
+import org.springframework.batch.item.stream.GenericStreamContext;
 import org.springframework.batch.support.AbstractMethodInvokingDelegator;
 import org.springframework.beans.BeanWrapper;
 import org.springframework.beans.BeanWrapperImpl;
@@ -66,7 +70,35 @@ public class PropertyExtractingDelegatingItemWriter extends AbstractMethodInvoki
 		this.fieldsUsedAsTargetMethodArguments = fieldsUsedAsMethodArguments;
 	}
 
-
+	/**
+	 * Do nothing.
+	 * @see org.springframework.batch.item.ItemStream#open()
+	 */
+	public void open() throws Exception {
+		// no-op
+	}
+	
+	/**
+	 * Do nothing.
+	 * @see org.springframework.batch.item.ItemStream#close()
+	 */
 	public void close() throws Exception {
+		// no-op
+	}
+
+	/**
+	 * Return empty {@link StreamContext}.
+	 * @see org.springframework.batch.item.ItemStream#getRestartData()
+	 */
+	public StreamContext getRestartData() {
+		return new GenericStreamContext(new Properties());
+	}
+	
+	/**
+	 * Do nothing.
+	 * @see org.springframework.batch.item.ItemStream#restoreFrom(org.springframework.batch.item.StreamContext)
+	 */
+	public void restoreFrom(StreamContext data) {
+		
 	}
 }