OPEN - issue BATCH-209: standard session option for HibernateCursorInputSource

http://opensource.atlassian.com/projects/spring/browse/BATCH-209

Applied patch from Robert.

infrastructure/src/main/java/org/springframework/batch/io/cursor/HibernateCursorInputSource.java

@@ -18,6 +18,7 @@ package org.springframework.batch.io.cursor;
 import java.util.Properties;
 
 import org.hibernate.ScrollableResults;
+import org.hibernate.Session;
 import org.hibernate.SessionFactory;
 import org.hibernate.StatelessSession;
 import org.springframework.batch.io.InputSource;
@@ -36,6 +37,17 @@ import org.springframework.util.ClassUtils;
 /**
  * {@link InputSource} for reading database records built on top of Hibernate.
  * 
+ * It executes the HQL {@link #queryString} when initialized and iterates over
+ * the result set as {@link #read()} method is called, returning an object corresponding
+ * to current row.
+ * 
+ * Input source can be configured to use either {@link StatelessSession} sufficient
+ * for simple mappings without the need to cascade to associated objects or standard hibernate
+ * {@link Session} for more advanced mappings or when caching is desired.
+ * 
+ * When stateful session is used it will be cleared after successful commit *without* being flushed
+ * (no inserts or updates are expected).
+ * 
  * @author Robert Kasanicky
  */
 public class HibernateCursorInputSource implements InputSource, Restartable, InitializingBean, DisposableBean,
@@ -44,13 +56,21 @@ public class HibernateCursorInputSource implements InputSource, Restartable, Ini
 	private static final String RESTART_DATA_ROW_NUMBER_KEY = ClassUtils.getShortName(HibernateCursorInputSource.class)+".rowNumber";
 
 	private SessionFactory sessionFactory;
-	private StatelessSession session;
+	
+	private StatelessSession statelessSession;
+	
+	private Session statefulSession;
+	
 	private ScrollableResults cursor;
+	
 	private String queryString;
 	
+	private boolean useStatelessSession = true;
+	
 	private int lastCommitRowNumber = 0;
 	
 	private boolean initialized = false;
+	
 	private TransactionSynchronization synchronization = new HibernateInputSourceTransactionSynchronization();
 	
 	
@@ -66,25 +86,37 @@ public class HibernateCursorInputSource implements InputSource, Restartable, Ini
 	}
 
 	/**
-	 * Close the resultset cursor and hibernate session.
+	 * Closes the result set cursor and hibernate session.
 	 */
 	public void close() {
 		initialized = false;
 		cursor.close();
-		session.close();
+		if (useStatelessSession) {
+			statelessSession.close();
+		} else {
+			statefulSession.close();
+		}
 	}
 
 	/**
-	 * Create cursor for the query
+	 * Creates cursor for the query.
 	 */
 	public void open() {
-		session = sessionFactory.openStatelessSession();
-		cursor = session.createQuery(queryString).scroll();
+		if (useStatelessSession) {
+			statelessSession = sessionFactory.openStatelessSession();
+			cursor = statelessSession.createQuery(queryString).scroll();
+		} else {
+			statefulSession = sessionFactory.openSession();
+			cursor = statefulSession.createQuery(queryString).scroll();
+		}
 		
 		BatchTransactionSynchronizationManager.registerSynchronization(synchronization );
 		initialized = true;
 	}
 
+	/**
+	 * @param sessionFactory hibernate session factory
+	 */
 	public void setSessionFactory(SessionFactory sessionFactory) {
 		this.sessionFactory = sessionFactory;
 	}
@@ -98,10 +130,24 @@ public class HibernateCursorInputSource implements InputSource, Restartable, Ini
 		close();
 	}
 
+	/**
+	 * @param queryString HQL query string
+	 */
 	public void setQueryString(String queryString) {
 		this.queryString = queryString;
 	}
 
+	/**
+	 * Can be set only in uninitialized state.
+	 * @param useStatelessSession 	
+	 * <code>true</code> to use {@link StatelessSession} 
+	 * <code>false</code> to use standard hibernate {@link Session}
+	 */
+	public void setUseStatelessSession(boolean useStatelessSession) {
+		Assert.state(!initialized);
+		this.useStatelessSession = useStatelessSession;
+	}
+
 	/**
 	 * @return the current row number wrapped as <code>RestartData</code>
 	 */
@@ -113,7 +159,7 @@ public class HibernateCursorInputSource implements InputSource, Restartable, Ini
 	}
 
 	/**
-	 * Set the cursor to the received row number.
+	 * Sets the cursor to the received row number.
 	 */
 	public void restoreFrom(RestartData data) {
 		Assert.state(!initialized,
@@ -138,6 +184,9 @@ public class HibernateCursorInputSource implements InputSource, Restartable, Ini
 				cursor.setRowNumber(lastCommitRowNumber);
 			} else if (status == TransactionSynchronization.STATUS_COMMITTED) {
 				lastCommitRowNumber = cursor.getRowNumber();
+				if (!useStatelessSession) {
+					statefulSession.clear();
+				}
 			}
 		}
 	}

infrastructure/src/test/java/org/springframework/batch/io/cursor/HibernateCursorInputSourceIntegrationTests.java

@@ -1,36 +1,61 @@
 package org.springframework.batch.io.cursor;
 
 import org.hibernate.SessionFactory;
+import org.hibernate.StatelessSession;
 import org.springframework.batch.io.InputSource;
-import org.springframework.batch.io.cursor.HibernateCursorInputSource;
 import org.springframework.batch.io.support.AbstractDataSourceInputSourceIntegrationTests;
 import org.springframework.core.io.ClassPathResource;
 import org.springframework.core.io.Resource;
 import org.springframework.orm.hibernate3.LocalSessionFactoryBean;
 
 /**
- * Tests for {@link HibernateCursorInputSource}
+ * Tests for {@link HibernateCursorInputSource} using {@link StatelessSession}.
  * 
  * @author Robert Kasanicky
  */
-public class HibernateInputSourceIntegrationTests extends AbstractDataSourceInputSourceIntegrationTests {
+public class HibernateCursorInputSourceIntegrationTests extends AbstractDataSourceInputSourceIntegrationTests {
 
 	protected InputSource createInputSource() throws Exception {
 		LocalSessionFactoryBean factoryBean = new LocalSessionFactoryBean();
 		factoryBean.setDataSource(super.getJdbcTemplate().getDataSource());
-		factoryBean.setMappingLocations(new Resource[]{new ClassPathResource("Foo.hbm.xml", getClass())});
+		factoryBean.setMappingLocations(new Resource[] { new ClassPathResource("Foo.hbm.xml", getClass()) });
 		factoryBean.afterPropertiesSet();
-		
+
 		SessionFactory sessionFactory = (SessionFactory) factoryBean.getObject();
-		
+
 		String hsqlQuery = "from Foo";
-		
+
 		HibernateCursorInputSource inputSource = new HibernateCursorInputSource();
 		inputSource.setQueryString(hsqlQuery);
 		inputSource.setSessionFactory(sessionFactory);
+		inputSource.setUseStatelessSession(isUseStatelessSession());
 		inputSource.afterPropertiesSet();
-		
+
 		return inputSource;
 	}
 
+	protected boolean isUseStatelessSession() {
+		return true;
+	}
+
+	/**
+	 * Exception scenario.
+	 * 
+	 * {@link HibernateCursorInputSource#setUseStatelessSession(boolean)} can be
+	 * called only in uninitialized state.
+	 */
+	public void testSetUseStatelessSession() {
+		HibernateCursorInputSource inputSource = ((HibernateCursorInputSource) source);
+
+		// initialize and call setter => error
+		inputSource.open();
+		try {
+			inputSource.setUseStatelessSession(false);
+			fail();
+		}
+		catch (IllegalStateException e) {
+			// expected
+		}
+	}
+
 }

infrastructure/src/test/java/org/springframework/batch/io/cursor/HibernateCursorInputSourceStatefulIntegrationTests.java

@@ -0,0 +1,16 @@
+package org.springframework.batch.io.cursor;
+
+import org.hibernate.Session;
+
+/**
+ * Tests for {@link HibernateCursorInputSource} using standard hibernate {@link Session}.
+ * 
+ * @author Robert Kasanicky
+ */
+public class HibernateCursorInputSourceStatefulIntegrationTests extends HibernateCursorInputSourceIntegrationTests{
+
+	protected boolean isUseStatelessSession() {
+		return false;
+	}
+	
+}