Addressed #24

by letting DefaultSender ignore multiple invocations of closeStream().

Author: mgeipel

src/main/java/org/culturegraph/mf/framework/DefaultSender.java

@@ -13,96 +13,105 @@
  *  See the License for the specific language governing permissions and
  *  limitations under the License.
  */
-package org.culturegraph.mf.framework;
-
-/**
- * Default implementation for {@link Sender}s that simply 
- * stores a reference to the receiver and implements the
- * correct behaviour required by the LifeCycle interface.
- * 
- * @param <T> receiver base type of the downstream module
- * 
- * @see DefaultStreamPipe
- * @see DefaultObjectPipe
- * @see DefaultXmlPipe
- * 
- * @author Christoph Böhme
- * 
- */
-public class DefaultSender<T extends LifeCycle> implements Sender<T> {
-
+package org.culturegraph.mf.framework;
+
+/**
+ * Default implementation for {@link Sender}s that simply stores a reference to
+ * the receiver and implements the correct behaviour required by the LifeCycle
+ * interface.
+ * 
+ * @param <T>
+ *            receiver base type of the downstream module
+ * 
+ * @see DefaultStreamPipe
+ * @see DefaultObjectPipe
+ * @see DefaultXmlPipe
+ * 
+ * @author Christoph Böhme
+ * 
+ */
+public class DefaultSender<T extends LifeCycle> implements Sender<T> {
+
 	private T receiver;
-	
-	
-	@Override
-	public final <R extends T> R setReceiver(final R receiver) {
-		this.receiver = receiver;
-		onSetReceiver();
-		return receiver;
-	}
-
-	@Override
-	public final void resetStream() {
-		onResetStream();
-		if (receiver != null) {
-			receiver.resetStream();
-		}
-	}
-	
-	@Override
-	public final void closeStream() {
-		onCloseStream();
-		if (receiver != null) {
-			receiver.closeStream();
-		}
-	}
-
-	/**
-	 * Invoked when the sender is connected with a receiver.
-	 * This method is called after the receiver has been updated. Hence,
-	 * {@code getReceiver} will return a reference to the new receiver.
-	 */
-	protected void onSetReceiver() {
-		// Default implementation does nothing		
-	}
-
-	/**
-	 * Invoked when the {@code resetStream()} method is called.
-	 * Override this method to perform a reset of the module. 
-	 * 
-	 * Do not call the {@code resetStream()} method of the next module downstream. 
-	 * This is handled by the implementation of {@code resetStream()} in 
-	 * {@code DefaultSender}.
-	 * 
-	 * {@code onResetStream()} is called before {@code DefaultSender} calls the
-	 * {@code resetStream()} method of the downstream module.
-	 */
-	protected void onResetStream() {
-		// Default implementation does nothing		
-	}
-	
-	/**
-	 * Invoked when the {@code closeStream()} method is called. Override 
-	 * this method to close any resources used by the module. 
-	 * 
-	 * Do not call the {@code closeStream()} method of the next module 
-	 * downstream. This is handled by the implementation of 
-	 * {@code closeStream()} in {@code DefaultSender}.
-	 * 
-	 * {@code onCloseStream()} is called before {@code DefaultSender} calls 
-	 * the {@code closeStream()} method of the downstream module.
-	 */
-	protected void onCloseStream() {
-		// Default implementation does nothing		
-	}
-	
-	/**
-	 * Returns a reference to the downstream module.
-	 * 
-	 * @return reference to the downstream module
-	 */
-	protected final T getReceiver() {
-		return receiver;
-	}
-
-}
+	private boolean isClosed;
+
+	public boolean isClosed() {
+		return isClosed;
+	}
+		
+	@Override
+	public final <R extends T> R setReceiver(final R receiver) {
+		this.receiver = receiver;
+		onSetReceiver();
+		return receiver;
+	}
+
+	@Override
+	public final void resetStream() {
+		onResetStream();
+		if (receiver != null) {
+			receiver.resetStream();
+		}
+		isClosed = false;
+	}
+
+	@Override
+	public final void closeStream() {
+		if (!isClosed) {
+			onCloseStream();
+			if (receiver != null) {
+				receiver.closeStream();
+			}
+		}
+		isClosed = true;
+	}
+
+	/**
+	 * Invoked when the sender is connected with a receiver. This method is
+	 * called after the receiver has been updated. Hence, {@code getReceiver}
+	 * will return a reference to the new receiver.
+	 */
+	protected void onSetReceiver() {
+		// Default implementation does nothing
+	}
+
+	/**
+	 * Invoked when the {@code resetStream()} method is called. Override this
+	 * method to perform a reset of the module.
+	 * 
+	 * Do not call the {@code resetStream()} method of the next module
+	 * downstream. This is handled by the implementation of
+	 * {@code resetStream()} in {@code DefaultSender}.
+	 * 
+	 * {@code onResetStream()} is called before {@code DefaultSender} calls the
+	 * {@code resetStream()} method of the downstream module.
+	 */
+	protected void onResetStream() {
+		// Default implementation does nothing
+	}
+
+	/**
+	 * Invoked when the {@code closeStream()} method is called. Override this
+	 * method to close any resources used by the module.
+	 * 
+	 * Do not call the {@code closeStream()} method of the next module
+	 * downstream. This is handled by the implementation of
+	 * {@code closeStream()} in {@code DefaultSender}.
+	 * 
+	 * {@code onCloseStream()} is called before {@code DefaultSender} calls the
+	 * {@code closeStream()} method of the downstream module.
+	 */
+	protected void onCloseStream() {
+		// Default implementation does nothing
+	}
+
+	/**
+	 * Returns a reference to the downstream module.
+	 * 
+	 * @return reference to the downstream module
+	 */
+	protected final T getReceiver() {
+		return receiver;
+	}
+
+}

src/test/java/org/culturegraph/mf/framework/DefaultSenderTest.java

@@ -0,0 +1,71 @@
+/*
+ *  Copyright 2013 Deutsche Nationalbibliothek
+ *
+ *  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.culturegraph.mf.framework;
+
+
+
+import org.junit.Assert;
+import org.junit.Test;
+
+
+/**
+ * Tests Contract of {@link DefaultSender}.
+ * @author Markus M Geipel
+ *
+ */
+public final class DefaultSenderTest {
+
+	/**
+	 *  onCloseStream() must be called only once even if closeSteam is called several times
+	 */
+	@Test
+	public void testMultipleCloseStreamInvocations() {
+		final CloseCounter closeCounter = new CloseCounter();
+		
+		Assert.assertEquals(0, closeCounter.getCount());
+		Assert.assertFalse(closeCounter.isClosed());
+		
+		closeCounter.closeStream();
+		Assert.assertEquals(1, closeCounter.getCount());
+		Assert.assertTrue(closeCounter.isClosed());
+		
+		closeCounter.closeStream();
+		Assert.assertEquals(1, closeCounter.getCount());
+		Assert.assertTrue(closeCounter.isClosed());
+		
+		closeCounter.closeStream();
+		Assert.assertEquals(1, closeCounter.getCount());
+		Assert.assertTrue(closeCounter.isClosed());
+		
+	}
+	
+	/**
+	 *	counts invocation of onCloseStream()
+	 */
+	protected static final class CloseCounter extends DefaultSender<ObjectReceiver<Object>>{
+		private int count;
+		
+		@Override
+		protected void onCloseStream() {
+			++count;
+		}
+		
+		public int getCount() {
+			return count;
+		}
+	}
+
+}