OPEN - issue BATCH-788: Remove flush/clear from ItemWriter

Infrastructure and core working with no calls to flush (I think)

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

@@ -16,7 +16,8 @@
 package org.springframework.batch.item;
 
 /**
- * Unchecked exception indicating that an error has occurred while trying to call {@link ItemWriter#clear()}
+ * Unchecked exception indicating that an error has occurred while trying to
+ * clear a buffer on a rollback.
  * 
  * @author Lucas Ward
  * @author Ben Hale
@@ -24,7 +25,8 @@ package org.springframework.batch.item;
 public class ClearFailedException extends ItemWriterException {
 
 	/**
-	 * Create a new {@link ClearFailedException} based on a message and another exception.
+	 * Create a new {@link ClearFailedException} based on a message and another
+	 * exception.
 	 * 
 	 * @param message the message for this exception
 	 * @param cause the other exception

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

@@ -16,7 +16,7 @@
 package org.springframework.batch.item;
 
 /**
- * Unchecked exception indicating that an error has occurred while trying to call {@link ItemWriter#flush()}
+ * Unchecked exception indicating that an error has occurred while trying to flush a buffer.
  * 
  * @author Lucas Ward
  * @author Ben Hale

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

@@ -56,6 +56,7 @@ public interface ItemWriter<T> {
 	 * @throws FlushFailedException in case of an error.  If this exception is
 	 * thrown the writer may be in an inconsistent state and manual intervention
 	 * might be required to reconcile the data with persistent output.
+	 * @deprecated
 	 */
 	void flush() throws FlushFailedException;
 
@@ -65,6 +66,7 @@ public interface ItemWriter<T> {
 	 * @throws ClearFailedException in case of an error. If this exception is
 	 * thrown the writer may be in an inconsistent state and manual intervention
 	 * might be required to reconcile the data with persistent output.
+	 * @deprecated
 	 */
 	void clear() throws ClearFailedException;
 }

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

@@ -86,8 +86,6 @@ public class FlatFileItemWriter<T> extends ExecutionContextUserSupport implement
 
 	private String encoding = OutputState.DEFAULT_CHARSET;
 
-	private List<String> lineBuffer = new ArrayList<String>();
-
 	private List<String> headerLines = new ArrayList<String>();
 
 	private String lineSeparator = DEFAULT_LINE_SEPARATOR;
@@ -185,16 +183,24 @@ public class FlatFileItemWriter<T> extends ExecutionContextUserSupport implement
 	 */
 	public void write(List<? extends T> items) throws Exception {
 
-		for (T item : items) {
-
-			if (getOutputState().isInitialized()) {
-				lineBuffer.add(lineAggregator.aggregate(item) + lineSeparator);
-			}
-			else {
-				throw new WriterNotOpenException("Writer must be open before it can be written to");
-			}
-
+		if (!getOutputState().isInitialized()) {
+			throw new WriterNotOpenException("Writer must be open before it can be written to");
 		}
+
+		OutputState state = getOutputState();
+
+		for (T item : items) {
+			String line = lineAggregator.aggregate(item) + lineSeparator;
+			try {
+				state.write(line);
+			} catch (IOException e) {
+				throw new FlushFailedException(
+						"Could not write data.  The file may be corrupt.", e);
+			}
+		}
+
+		state.mark();
+
 	}
 
 	/**
@@ -222,7 +228,7 @@ public class FlatFileItemWriter<T> extends ExecutionContextUserSupport implement
 		}
 	}
 
-	private void doOpen(ExecutionContext executionContext) {
+	private void doOpen(ExecutionContext executionContext) throws ItemStreamException {
 		OutputState outputState = getOutputState();
 		if (executionContext.containsKey(getKey(RESTART_DATA_NAME))) {
 			outputState.restoreFrom(executionContext);
@@ -234,8 +240,14 @@ public class FlatFileItemWriter<T> extends ExecutionContextUserSupport implement
 			throw new ItemStreamException("Failed to initialize writer", ioe);
 		}
 		if (outputState.lastMarkedByteOffsetPosition == 0) {
-			for (String line : headerLines) {
-				lineBuffer.add(line + lineSeparator);
+			try {
+				for (String line : headerLines) {
+					outputState.write(line + lineSeparator);
+				}
+			}
+			catch (IOException e) {
+				throw new FlushFailedException(
+						"Could not write headers.  The file may be corrupt.", e);
 			}
 		}
 	}
@@ -264,17 +276,6 @@ public class FlatFileItemWriter<T> extends ExecutionContextUserSupport implement
 	}
 
 	public void flush() throws FlushFailedException {
-		OutputState state = getOutputState();
-		for (String line : lineBuffer) {
-			try {
-				state.write(line);
-			}
-			catch (IOException e) {
-				throw new FlushFailedException("Failed to write line to output file: " + line, e);
-			}
-		}
-		lineBuffer.clear();
-		state.mark();
 	}
 
 	// Returns object representing state.
@@ -501,7 +502,6 @@ public class FlatFileItemWriter<T> extends ExecutionContextUserSupport implement
 	}
 
 	public void clear() throws ClearFailedException {
-		lineBuffer.clear();
 	}
 
 }

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

@@ -20,8 +20,7 @@ import org.springframework.batch.item.FlushFailedException;
 import org.springframework.batch.item.ItemWriter;
 
 /**
- * Abstract {@link ItemWriter} that allows for base classes to only implement
- * the {@link #flush()} and {@link #clear()} methods if they need it.
+ * Abstract {@link ItemWriter}.
  * 
  * @author Lucas Ward
  */

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

@@ -3,8 +3,6 @@ package org.springframework.batch.item.support;
 import java.util.Arrays;
 import java.util.List;
 
-import org.springframework.batch.item.ClearFailedException;
-import org.springframework.batch.item.FlushFailedException;
 import org.springframework.batch.item.ItemWriter;
 
 /**
@@ -15,7 +13,7 @@ import org.springframework.batch.item.ItemWriter;
  * @author Robert Kasanicky
  * @author Dave Syer
  */
-public class CompositeItemWriter<T> implements ItemWriter<T> {
+public class CompositeItemWriter<T> extends AbstractItemWriter<T> {
 
 	private List<ItemWriter<? super T>> delegates;
 
@@ -32,16 +30,4 @@ public class CompositeItemWriter<T> implements ItemWriter<T> {
 		}
 	}
 
-	public void clear() throws ClearFailedException {
-		for (ItemWriter<? super T> writer : delegates) {
-			writer.clear();
-		}
-	}
-
-	public void flush() throws FlushFailedException {
-		for (ItemWriter<? super  T> writer : delegates) {
-			writer.flush();
-		}
-	}
-
 }

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

@@ -109,18 +109,11 @@ public class StaxEventItemWriter<T> extends ExecutionContextUserSupport implemen
 	// byte offset in file channel at last commit point
 	private long lastCommitPointPosition = 0;
 
-	// processed record count at last commit point
-	private long lastCommitPointRecordCount = 0;
-
 	// current count of processed records
 	private long currentRecordCount = 0;
 
 	private boolean saveState = true;
 
-	// holds the list of items for writing before they are actually written on
-	// #flush()
-	private List<T> buffer = new ArrayList<T>();
-
 	private List<? extends T> headers = new ArrayList<T>();
 
 	public StaxEventItemWriter() {
@@ -345,6 +338,8 @@ public class StaxEventItemWriter<T> extends ExecutionContextUserSupport implemen
 			}
 
 		}
+		
+		writer.flush();
 
 	}
 
@@ -384,8 +379,8 @@ public class StaxEventItemWriter<T> extends ExecutionContextUserSupport implemen
 			log.error(e);
 		}
 
-		flush();
 		try {
+			delegateEventWriter.flush();
 			endDocument(delegateEventWriter);
 			eventWriter.close();
 			channel.close();
@@ -399,15 +394,25 @@ public class StaxEventItemWriter<T> extends ExecutionContextUserSupport implemen
 	}
 
 	/**
-	 * Write the value object to internal buffer.
+	 * Write the value objects and flush them to the file.
 	 * 
-	 * @param item the value object
-	 * @see #flush()
+	 * @param items the value object
 	 */
-	public void write(List<? extends T> item) {
+	public void write(List<? extends T> items) {
 
-		currentRecordCount+=item.size();
-		buffer.addAll(item);
+		currentRecordCount+=items.size();
+
+		for (T item : items) {
+			serializer.serializeObject(eventWriter, item);
+		}
+		try {
+			eventWriter.flush();
+		}
+		catch (XMLStreamException e) {
+			throw new FlushFailedException("Failed to flush the events", e);
+		}
+
+		lastCommitPointPosition = getPosition();
 	}
 
 	/**
@@ -468,28 +473,12 @@ public class StaxEventItemWriter<T> extends ExecutionContextUserSupport implemen
 	 * Writes buffered items to XML stream and marks restore point.
 	 */
 	public void flush() throws FlushFailedException {
-
-		for (T item : buffer) {
-			serializer.serializeObject(eventWriter, item);
-		}
-		try {
-			eventWriter.flush();
-		}
-		catch (XMLStreamException e) {
-			throw new FlushFailedException("Failed to flush the events", e);
-		}
-		buffer.clear();
-
-		lastCommitPointPosition = getPosition();
-		lastCommitPointRecordCount = currentRecordCount;
 	}
 
 	/**
 	 * Clear the output buffer
 	 */
 	public void clear() throws ClearFailedException {
-		currentRecordCount = lastCommitPointRecordCount;
-		buffer.clear();
 	}
 
 }