BATCH-365: Added flush() and clear() to ItemWriter interface. These should be removed from ItemStream after the same is done for the ItemReader interface.

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

@@ -52,6 +52,10 @@ import org.springframework.util.Assert;
  * 
  * Use {@link #write(String)} method to output a line to an item writer.
  * 
+ * <p>This class will be updated in the future to use a buffering approach
+ * to handling transactions, rather than outputting directly to the file and
+ * truncating on rollback</p>
+ * 
  * @author Waseem Malik
  * @author Tomas Slanina
  * @author Robert Kasanicky
@@ -465,23 +469,31 @@ public class FlatFileItemWriter extends AbstractTransactionalIoSource implements
 		return true;
 	}
 
-	/*
+	/* To be deleted once interface changes are complete
 	 * (non-Javadoc)
 	 * @see org.springframework.batch.io.support.AbstractTransactionalIoSource#mark(org.springframework.batch.item.ExecutionContext)
 	 */
 	public void mark() {
-		getOutputState().mark();
+		
 	}
 
-	/*
+	/* To be deleted once interface changes are complete
 	 * (non-Javadoc)
 	 * @see org.springframework.batch.io.support.AbstractTransactionalIoSource#reset(org.springframework.batch.item.ExecutionContext)
 	 */
 	public void reset() throws ResetFailedException {
+
+	}
+
+	public void clear() throws Exception {
 		try {
 			getOutputState().reset();
 		} catch (BatchCriticalException e) {
 			throw new ResetFailedException(e);
 		}
 	}
+
+	public void flush() throws Exception {
+		getOutputState().mark();
+	}
 }

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

@@ -146,32 +146,7 @@ public class HibernateAwareItemWriter implements ItemWriter, RepeatListener, Ini
 	 * @see org.springframework.batch.repeat.RepeatListener#close(org.springframework.batch.repeat.RepeatContext)
 	 */
 	public void close(RepeatContext context) {
-		try {
-			if (delegate instanceof RepeatListener) {
-				RepeatListener interceptor = (RepeatListener) delegate;
-				interceptor.close(context);
-			}
-			flush();
-		} catch (RuntimeException e) {
-			synchronized (failed) {
-				failed.addAll(getProcessed());
-			}
-			// onError will not be called after close() by the framework so we
-			// have to do it here.
-			onError(context, e);
-			throw e;
-		}
-		unsetContext();
-	}
 
-	/**
-	 * Wrapper for Hibernate flush.
-	 */
-	private void flush() {
-		hibernateTemplate.flush();
-		// This should happen when the transaction commits anyway, but to be
-		// sure...
-		hibernateTemplate.clear();
 	}
 
 	/**
@@ -246,7 +221,7 @@ public class HibernateAwareItemWriter implements ItemWriter, RepeatListener, Ini
 	 * 
 	 * @return the context
 	 */
-	private void flushIfNecessary(Object output) {
+	private void flushIfNecessary(Object output) throws Exception{
 		RepeatContext context = (RepeatContext) TransactionSynchronizationManager.getResource(WRITER_REPEAT_CONTEXT);
 		boolean flush;
 		synchronized (failed) {
@@ -264,4 +239,34 @@ public class HibernateAwareItemWriter implements ItemWriter, RepeatListener, Ini
 
 	}
 
+	public void clear() throws Exception {
+		if(delegate != null){
+			delegate.clear();
+		}
+		hibernateTemplate.clear();
+	}
+
+	/**
+	 * Flush the Hibernate session.  The delegate flush will also be called before finishing.
+	 */
+	public void flush() throws Exception {
+		try {
+			if (delegate != null) {
+				delegate.flush();
+			}
+			hibernateTemplate.flush();
+			// This should happen when the transaction commits anyway, but to be
+			// sure...
+			hibernateTemplate.clear();
+		} catch (RuntimeException e) {
+			synchronized (failed) {
+				failed.addAll(getProcessed());
+			}
+			// This used to contain a call to onError, however, I think this
+			// should be handled within the step.
+			throw e;
+		}
+		unsetContext();
+	}
+
 }

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

@@ -438,20 +438,27 @@ public class StaxEventItemWriter implements ItemWriter, ItemStream, Initializing
 		return true;
 	}
 
-	/*
+	/* TODO remove once ItemStream interface is modified.
 	 * (non-Javadoc)
 	 * @see org.springframework.batch.item.ItemStream#mark(org.springframework.batch.item.ExecutionContext)
 	 */
 	public void mark() {
+	}
+	
+	public void flush() throws Exception {
 		lastCommitPointPosition = getPosition();
 		lastCommitPointRecordCount = currentRecordCount;
 	}
 
-	/*
+	/* TODO remove once ItemStream interface is modified.
 	 * (non-Javadoc)
 	 * @see org.springframework.batch.item.ItemStream#reset(org.springframework.batch.item.ExecutionContext)
 	 */
 	public void reset() {
+
+	}
+	
+	public void clear() throws Exception {
 		currentRecordCount = lastCommitPointRecordCount;
 		// close output
 		close();

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

@@ -17,10 +17,18 @@
 package org.springframework.batch.item;
 
 /**
- * Basic interface for generic output operations. Class implementing this
+ * <p>Basic interface for generic output operations. Class implementing this
  * interface will be responsible for serializing objects as necessary.
  * Generally, it is responsibility of implementing class to decide which
- * technology to use for mapping and how it should be configured.
+ * technology to use for mapping and how it should be configured.</p>
+ * 
+ * <p>
+ * Due to the nature of batch processing, it is expected that most writers
+ * will buffer output.  A flush method is provided to the interface in order
+ * to ensure that any buffers can be flushed before a transaction is
+ * committed.  Along the same lines, if a transaction has been rolled back,
+ * then the contents of any buffers should be thrown away.
+ * </p>
  * 
  * @author Dave Syer
  * @author Lucas Ward
@@ -38,4 +46,19 @@ public interface ItemWriter {
 	 */
 	public void write(Object item) throws Exception;
 	
+	/**
+	 * Flush any buffers that are being held.  This will usually be performed
+	 * prior to committing any transactions.
+	 * 
+	 * @throws Exception
+	 */
+	public void flush() throws Exception;
+	
+	/**
+	 * Clear any buffers that are being held.  This will usually be performed
+	 * prior to rolling back any transactions.
+	 * 
+	 * @throws Exception
+	 */
+	public void clear() throws Exception;
 }

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

@@ -19,11 +19,17 @@ import org.springframework.batch.item.ItemWriter;
 
 /**
  * Abstract {@link ItemWriter} that allows for base classes to only
- * implement the close method if they need it.
+ * implement the close method if they need it.  Because it is likely
+ * that the flush and clear methods may not need to be implemented,
+ * they are provided in this class.
  * 
  * @author Lucas Ward
- *
  */
 public abstract class AbstractItemWriter implements ItemWriter{
-
+	
+	public void flush() throws Exception {
+	}
+	
+	public void clear() throws Exception {
+	}
 }

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

@@ -1,6 +1,5 @@
 package org.springframework.batch.item.writer;
 
-import org.springframework.batch.io.Skippable;
 import org.springframework.batch.item.ItemWriter;
 import org.springframework.beans.factory.InitializingBean;
 import org.springframework.util.Assert;
@@ -11,7 +10,7 @@ import org.springframework.util.Assert;
  * @author Dave Syer
  * @author Robert Kasanicky
  */
-public class DelegatingItemWriter implements ItemWriter, Skippable, InitializingBean {
+public class DelegatingItemWriter implements ItemWriter, InitializingBean {
 
 	private ItemWriter writer;
 
@@ -43,14 +42,22 @@ public class DelegatingItemWriter implements ItemWriter, Skippable, Initializing
 		this.writer = writer;
 	}
 
-	public void skip() {
-		if (writer instanceof Skippable) {
-			((Skippable) writer).skip();
-		}
-	}
-
 	public void afterPropertiesSet() throws Exception {
 		Assert.notNull(writer);
 	}
 
+	/**
+	 * Delegates to {@link ItemWriter#clear()}
+	 */
+	public void clear() throws Exception {
+		writer.clear();
+	}
+
+	/**
+	 * Delegates to {@link ItemWriter#flush()}
+	 */
+	public void flush() throws Exception {
+		writer.flush();
+	}
+
 }

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

@@ -37,11 +37,15 @@ public class ItemWriterAdapter extends AbstractMethodInvokingDelegator implement
     /*
      * No-op, can't call more than one method.
      * 
-     * (non-Javadoc)
-     * @see org.springframework.batch.item.ItemWriter#close()
      */
-	public void close() throws Exception {
-		
+	public void clear() throws Exception {
+	}
+
+    /*
+     * No-op, can't call more than one method.
+     * 
+     */
+	public void flush() throws Exception {
 	}
 	
 }

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

@@ -67,6 +67,10 @@ public class PropertyExtractingDelegatingItemWriter extends AbstractMethodInvoki
 	}
 
 
-	public void close() throws Exception {
+	public void clear() throws Exception {
+	}
+
+
+	public void flush() throws Exception {
 	}
 }