Call LineRecorder receiver's closeStream() (#433)

Under some circumstances (e.g. if the JVM is not stopped after processing)
the streams of receivers connected to LineRecorder are not closed, resulting
in empty or missing output data.

By switch from "implements ObjectPipe" to "extends DefaultObjectPipe" the "DefaultSender"
is used which implements the Sender interface. This ensures the proper closing of streams.

- complement test

metafacture-strings/src/main/java/org/metafacture/strings/LineRecorder.java

@@ -16,11 +16,11 @@
 package org.metafacture.strings;
 
 import org.metafacture.framework.FluxCommand;
-import org.metafacture.framework.ObjectPipe;
 import org.metafacture.framework.ObjectReceiver;
 import org.metafacture.framework.annotations.Description;
 import org.metafacture.framework.annotations.In;
 import org.metafacture.framework.annotations.Out;
+import org.metafacture.framework.helpers.DefaultObjectPipe;
 
 /**
  * Collects strings and emits them as records when a line matches the pattern.
@@ -34,7 +34,7 @@
 @In(String.class)
 @Out(String.class)
 @FluxCommand("lines-to-records")
-public final class LineRecorder implements ObjectPipe<String, ObjectReceiver<String>> {
+public final class LineRecorder extends DefaultObjectPipe<String, ObjectReceiver<String>> {
 
     private static final int SB_CAPACITY = 4096 * 7;
     // empty line is the default
@@ -70,34 +70,16 @@ record = new StringBuilder(SB_CAPACITY);
         }
     }
 
-    private boolean isClosed() {
-        return isClosed;
-    }
-
     @Override
-    public void resetStream() {
-        record = new StringBuilder(SB_CAPACITY);
-    }
-
-    @Override
-    public void closeStream() {
-        getReceiver().process(record.toString());
-        isClosed = true;
+    protected void onCloseStream() {
+        if (record.length() > 0) {
+            getReceiver().process(record.toString());
+        }
     }
 
     @Override
-    public <R extends ObjectReceiver<String>> R setReceiver(final R newReceiver) {
-        receiver = newReceiver;
-        return newReceiver;
-    }
-
-    /**
-     * Returns a reference to the downstream module.
-     *
-     * @return reference to the downstream module
-     */
-    protected ObjectReceiver<String> getReceiver() {
-        return receiver;
+    public void onResetStream() {
+        record = new StringBuilder(SB_CAPACITY);
     }
 
 }

metafacture-strings/src/test/java/org/metafacture/strings/LineRecorderTest.java

@@ -111,6 +111,7 @@ public void shouldEmitLastRecordWithoutRecordMarkerWhenClosingStream() {
                 LINE_SEPARATOR +
                 RECORD3_PART2 +
                 LINE_SEPARATOR);
+        ordered.verify(receiver).closeStream();
         ordered.verifyNoMoreInteractions();
     }