BATCH-2052: StaxEventItemWriter should only force sync once per chunk

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

@@ -614,6 +614,7 @@ InitializingBean {
 					});
 
 					writer.setEncoding(encoding);
+					writer.setForceSync(forceSync);
 					return writer;
 				}
 				else {
@@ -627,7 +628,7 @@ InitializingBean {
 						}
 					};
 
-					return new BufferedWriter(writer);
+					return writer;
 				}
 			}
 			catch (UnsupportedCharsetException ucse) {

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

@@ -395,7 +395,6 @@ ResourceAwareItemWriterItemStream<T>, InitializingBean {
 	/**
 	 * Helper method for opening output source at given file position
 	 */
-	@SuppressWarnings("resource")
 	private void open(long position, boolean restarted) {
 
 		File file;
@@ -443,25 +442,20 @@ ResourceAwareItemWriterItemStream<T>, InitializingBean {
 				});
 
 				writer.setEncoding(encoding);
+				writer.setForceSync(forceSync);
 				bufferedWriter = writer;
 			}
 			else {
-				Writer writer = new BufferedWriter(new OutputStreamWriter(os, encoding)) {
-					@Override
-					public void flush() throws IOException {
-						super.flush();
-						if (forceSync) {
-							channel.force(false);
-						}
-					}
-				};
-				bufferedWriter = writer;
+				bufferedWriter =  new BufferedWriter(new OutputStreamWriter(os, encoding));
 			}
 			delegateEventWriter = createXmlEventWriter(outputFactory, bufferedWriter);
 			eventWriter = new NoStartEndDocumentStreamWriter(delegateEventWriter);
 			initNamespaceContext(delegateEventWriter);
 			if (!restarted) {
 				startDocument(delegateEventWriter);
+				if (forceSync) {
+					channel.force(false);
+				}
 			}
 		}
 		catch (XMLStreamException xse) {
@@ -470,8 +464,10 @@ ResourceAwareItemWriterItemStream<T>, InitializingBean {
 		catch (UnsupportedEncodingException e) {
 			throw new DataAccessResourceFailureException("Unable to write to file resource: [" + resource
 					+ "] with encoding=[" + encoding + "]", e);
+		} 
+		catch (IOException e) {
+			throw new DataAccessResourceFailureException("Unable to write to file resource: [" + resource + "]", e);
 		}
-
 	}
 
 	/**
@@ -716,9 +712,15 @@ ResourceAwareItemWriterItemStream<T>, InitializingBean {
 		}
 		try {
 			eventWriter.flush();
+			if (forceSync) {
+				channel.force(false);
+			}			
 		}
 		catch (XMLStreamException e) {
 			throw new WriteFailedException("Failed to flush the events", e);
+		} 
+		catch (IOException e) {
+			throw new WriteFailedException("Failed to flush the events", e);
 		}
 
 	}

spring-batch-infrastructure/src/main/java/org/springframework/batch/support/transaction/TransactionAwareBufferedWriter.java

@@ -48,12 +48,14 @@ public class TransactionAwareBufferedWriter extends Writer {
 	private FileChannel channel;
 
 	private final Runnable closeCallback;
-	
+
 	// default encoding for writing to output files - set to UTF-8.
 	private static final String DEFAULT_CHARSET = "UTF-8";
-	
+
 	private String encoding = DEFAULT_CHARSET;
-	
+
+	private boolean forceSync = false;
+
 	/**
 	 * Create a new instance with the underlying file channel provided, and a callback
 	 * to execute on close. The callback should clean up related resources like
@@ -74,6 +76,19 @@ public class TransactionAwareBufferedWriter extends Writer {
 		this.encoding = encoding;
 	}
 
+	/**
+	 * Flag to indicate that changes should be force-synced to disk on flush.
+	 * Defaults to false, which means that even with a local disk changes could
+	 * be lost if the OS crashes in between a write and a cache flush. Setting
+	 * to true may result in slower performance for usage patterns involving
+	 * many frequent writes.
+	 * 
+	 * @param forceSync the flag value to set
+	 */
+	public void setForceSync(boolean forceSync) {
+		this.forceSync = forceSync;
+	}
+
 	/**
 	 * @return
 	 */
@@ -88,7 +103,7 @@ public class TransactionAwareBufferedWriter extends Writer {
 				public void afterCompletion(int status) {
 					clear();
 				}
-				
+
 				@Override
 				public void beforeCommit(boolean readOnly) {
 					try {
@@ -112,6 +127,9 @@ public class TransactionAwareBufferedWriter extends Writer {
 						if(bytesWritten != bufferLength) {
 							throw new IOException("All bytes to be written were not successfully written");
 						}
+						if (forceSync) {
+							channel.force(false);
+						}
 						if (TransactionSynchronizationManager.hasResource(closeKey)) {
 							closeCallback.run();
 						}
@@ -145,7 +163,7 @@ public class TransactionAwareBufferedWriter extends Writer {
 		if (!transactionActive()) {
 			return 0L;
 		}
-		try {			
+		try {
 			return getCurrentBuffer().toString().getBytes(encoding).length;
 		} catch (UnsupportedEncodingException e) {
 			throw new WriteFailedException("Could not determine buffer size because of unsupported encoding: " + encoding, e);
@@ -182,7 +200,7 @@ public class TransactionAwareBufferedWriter extends Writer {
 	 */
 	@Override
 	public void flush() throws IOException {
-		if (!transactionActive()) {
+		if (!transactionActive() && forceSync) {
 			channel.force(false);
 		}
 	}