# HG changeset patch
# User Jaroslav Tulach <jtulach@netbeans.org>
# Date 1300643567 -3600
# Node ID 35da2d439e3d90c890384b0c0126281f97775f32
# Parent  c20d1d8ef2ca2ed2c5ca7c7f4308ee6238cb8d11
Calculator and various ways to deliver changes in its counter to listeners

diff -r c20d1d8ef2ca -r 35da2d439e3d samples/openfixed/nbproject/project.properties
--- a/samples/openfixed/nbproject/project.properties	Sun Mar 20 08:12:26 2011 +0100
+++ b/samples/openfixed/nbproject/project.properties	Sun Mar 20 18:52:47 2011 +0100
@@ -25,6 +25,7 @@
 dist.jar=${dist.dir}/openfixed.jar
 dist.javadoc.dir=${dist.dir}/javadoc
 excludes=
+file.reference.junit-4.4.jar=../libs/dist/junit-4.4.jar
 includes=**
 jar.compress=false
 javac.classpath=
@@ -37,7 +38,8 @@
 javac.target=1.6
 javac.test.classpath=\
     ${javac.classpath}:\
-    ${build.classes.dir}
+    ${build.classes.dir}:\
+    ${file.reference.junit-4.4.jar}
 javac.test.processorpath=\
     ${javac.test.classpath}
 javadoc.additionalparam=
diff -r c20d1d8ef2ca -r 35da2d439e3d samples/openfixed/src/org/apidesign/openfixed/AsyncEventSupport.java
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/samples/openfixed/src/org/apidesign/openfixed/AsyncEventSupport.java	Sun Mar 20 18:52:47 2011 +0100
@@ -0,0 +1,50 @@
+package org.apidesign.openfixed;
+
+import java.util.List;
+import java.util.concurrent.CopyOnWriteArrayList;
+import java.util.concurrent.Executor;
+import java.util.concurrent.Executors;
+
+/**
+ *
+ * @author Jaroslav Tulach <jtulach@netbeans.org>
+ */
+final class AsyncEventSupport implements EventSupport {
+    private final List<ModificationListener> listeners = new CopyOnWriteArrayList<ModificationListener>();
+    private static final Executor EXEC = Executors.newSingleThreadExecutor();
+    
+    AsyncEventSupport() {
+    }
+
+    @Override
+    public void fireModificationEvent(ModificationEvent ev) {
+        EXEC.execute(new Deliverable(ev, listeners.toArray(new ModificationListener[0])));
+    }
+
+    @Override
+    public void add(ModificationListener l) {
+        listeners.add(l);
+    }
+
+    @Override
+    public void remove(ModificationListener l) {
+        listeners.remove(l);
+    }
+    
+    private static class Deliverable implements Runnable {
+        final ModificationEvent ev;
+        final ModificationListener[] listeners;
+
+        public Deliverable(ModificationEvent ev, ModificationListener[] listeners) {
+            this.ev = ev;
+            this.listeners = listeners;
+        }
+
+        @Override
+        public void run() {
+            for (ModificationListener l : listeners) {
+                l.modification(ev);
+            }
+        }
+    }
+}
diff -r c20d1d8ef2ca -r 35da2d439e3d samples/openfixed/src/org/apidesign/openfixed/Calculator.java
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/samples/openfixed/src/org/apidesign/openfixed/Calculator.java	Sun Mar 20 18:52:47 2011 +0100
@@ -0,0 +1,49 @@
+package org.apidesign.openfixed;
+
+/** Sample bean using the {@link ModificationListener}
+ * to <b>add</b> numbers.
+ *
+ * @author Jaroslav Tulach <jtulach@netbeans.org>
+ */
+public final class Calculator {
+    private final EventSupport listeners;
+    private int sum;
+
+    private Calculator(EventSupport listeners) {
+        this.listeners = listeners;
+    }
+    
+    public static Calculator create() {
+        return new Calculator(new TrivialEventSupport());
+    }
+
+    public static Calculator createAsynch() {
+        return new Calculator(new AsyncEventSupport());
+    }
+
+    /** @since 2.0 */
+    public static Calculator createPending() {
+        return new Calculator(new PendingEventSupport());
+    }
+
+    /** @since 3.0 */
+    public static Calculator createBatch() {
+        return new Calculator(new PostEventSupport());
+    }
+
+    public synchronized void add(int add) {
+        sum += add;
+        listeners.fireModificationEvent(new ModificationEvent(this, add));
+    }
+    
+    public synchronized int getSum() {
+        return sum;
+    }
+    
+    public void addModificationListener(ModificationListener l) {
+        listeners.add(l);
+    }
+    public void removeModificationListener(ModificationListener l) {
+        listeners.remove(l);
+    }
+}
diff -r c20d1d8ef2ca -r 35da2d439e3d samples/openfixed/src/org/apidesign/openfixed/EventSupport.java
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/samples/openfixed/src/org/apidesign/openfixed/EventSupport.java	Sun Mar 20 18:52:47 2011 +0100
@@ -0,0 +1,19 @@
+/*
+ * To change this template, choose Tools | Templates
+ * and open the template in the editor.
+ */
+package org.apidesign.openfixed;
+
+/**
+ *
+ * @author Jaroslav Tulach <jtulach@netbeans.org>
+ */
+interface EventSupport {
+
+    public void fireModificationEvent(ModificationEvent ev);
+
+    public void add(ModificationListener l);
+
+    public void remove(ModificationListener l);
+    
+}
diff -r c20d1d8ef2ca -r 35da2d439e3d samples/openfixed/src/org/apidesign/openfixed/Growable.java
--- a/samples/openfixed/src/org/apidesign/openfixed/Growable.java	Sun Mar 20 08:12:26 2011 +0100
+++ /dev/null	Thu Jan 01 00:00:00 1970 +0000
@@ -1,19 +0,0 @@
-package org.apidesign.openfixed;
-
-import java.util.List;
-import java.util.concurrent.CopyOnWriteArrayList;
-
-/** Sample bean using the {@link GrowingListener}.
- *
- * @author Jaroslav Tulach <jtulach@netbeans.org>
- */
-public final class Growable {
-    private List<GrowingListener> listeners = new CopyOnWriteArrayList<GrowingListener>();
-    
-    public void addGrowingListener(GrowingListener l) {
-        listeners.add(l);
-    }
-    public void removeGrowingListener(GrowingListener l) {
-        listeners.remove(l);
-    }
-}
diff -r c20d1d8ef2ca -r 35da2d439e3d samples/openfixed/src/org/apidesign/openfixed/GrowingEvent.java
--- a/samples/openfixed/src/org/apidesign/openfixed/GrowingEvent.java	Sun Mar 20 08:12:26 2011 +0100
+++ /dev/null	Thu Jan 01 00:00:00 1970 +0000
@@ -1,25 +0,0 @@
-package org.apidesign.openfixed;
-
-import java.util.EventObject;
-
-// BEGIN: openfixed.event
-public final class GrowingEvent extends EventObject {
-    public GrowingEvent(Object source) {
-        super(source);
-    }
-// FINISH: openfixed.event
-    
-// BEGIN: openfixed.addgetter    
-    private int index;
-    /** @since 2.0 */
-    public GrowingEvent(Object source, int index) {
-        super(source);
-        this.index = index;
-    }
-
-    /** @since 2.0 */
-    public int getIndex() {
-        return index;
-    }
-// END: openfixed.addgetter    
-}
diff -r c20d1d8ef2ca -r 35da2d439e3d samples/openfixed/src/org/apidesign/openfixed/GrowingListener.java
--- a/samples/openfixed/src/org/apidesign/openfixed/GrowingListener.java	Sun Mar 20 08:12:26 2011 +0100
+++ /dev/null	Thu Jan 01 00:00:00 1970 +0000
@@ -1,9 +0,0 @@
-package org.apidesign.openfixed;
-
-import java.util.EventListener;
-
-// BEGIN: openfixed.listener
-public interface GrowingListener extends EventListener {
-    public void response(GrowingEvent ev);
-}
-// FINISH: openfixed.listener
diff -r c20d1d8ef2ca -r 35da2d439e3d samples/openfixed/src/org/apidesign/openfixed/ModificationEvent.java
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/samples/openfixed/src/org/apidesign/openfixed/ModificationEvent.java	Sun Mar 20 18:52:47 2011 +0100
@@ -0,0 +1,35 @@
+package org.apidesign.openfixed;
+
+import java.util.Collection;
+import java.util.EventObject;
+
+// BEGIN: openfixed.event
+public final class ModificationEvent extends EventObject {
+    private final int delta;
+    ModificationEvent(Object source, int delta) {
+        super(source);
+        this.delta = delta;
+    }
+    
+    public int getChange() {
+        return delta;
+    }
+    
+// FINISH: openfixed.event
+    
+// BEGIN: openfixed.addgetter    
+    int pending;
+    /** @since 2.0 */
+    public int getPending() {
+        return pending;
+    }
+// END: openfixed.addgetter    
+    
+// BEGIN: openfixed.mount
+    Collection<PostModificationListener> posts;
+    /** @since 3.0 */
+    public void postProcess(PostModificationListener p) {
+        posts.add(p);
+    }
+// END: openfixed.mount  
+}
diff -r c20d1d8ef2ca -r 35da2d439e3d samples/openfixed/src/org/apidesign/openfixed/ModificationListener.java
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/samples/openfixed/src/org/apidesign/openfixed/ModificationListener.java	Sun Mar 20 18:52:47 2011 +0100
@@ -0,0 +1,9 @@
+package org.apidesign.openfixed;
+
+import java.util.EventListener;
+
+// BEGIN: openfixed.listener
+public interface ModificationListener extends EventListener {
+    public void modification(ModificationEvent ev);
+}
+// FINISH: openfixed.listener
diff -r c20d1d8ef2ca -r 35da2d439e3d samples/openfixed/src/org/apidesign/openfixed/PendingEventSupport.java
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/samples/openfixed/src/org/apidesign/openfixed/PendingEventSupport.java	Sun Mar 20 18:52:47 2011 +0100
@@ -0,0 +1,67 @@
+package org.apidesign.openfixed;
+
+import java.util.List;
+import java.util.concurrent.CopyOnWriteArrayList;
+import java.util.concurrent.Executor;
+import java.util.concurrent.Executors;
+
+/**
+ *
+ * @author Jaroslav Tulach <jtulach@netbeans.org>
+ */
+final class PendingEventSupport implements EventSupport, Runnable {
+    private final List<ModificationListener> listeners = new CopyOnWriteArrayList<ModificationListener>();
+    private final List<Deliverable> deliverables = new CopyOnWriteArrayList<Deliverable>();
+    private static final Executor EXEC = Executors.newSingleThreadExecutor();
+    
+    PendingEventSupport() {
+    }
+
+    @Override
+    public void fireModificationEvent(ModificationEvent ev) {
+        synchronized (deliverables) {
+            final Deliverable d = new Deliverable(ev, listeners.toArray(new ModificationListener[0]));
+            deliverables.add(d);
+            EXEC.execute(this);
+        }
+    }
+
+    @Override
+    public void add(ModificationListener l) {
+        listeners.add(l);
+    }
+
+    @Override
+    public void remove(ModificationListener l) {
+        listeners.remove(l);
+    }
+
+    @Override
+    public void run() {
+        Deliverable[] pending;
+        synchronized (deliverables) {
+            if (deliverables.isEmpty()) {
+                return;
+            }
+            pending = deliverables.toArray(new Deliverable[0]);
+            deliverables.clear();
+        }
+        int pendingCount = pending.length;
+        for (Deliverable d : pending) {
+            d.ev.pending = --pendingCount;
+            for (ModificationListener l : d.listeners) {
+                l.modification(d.ev);
+            }
+        }
+    }
+    
+    private static class Deliverable {
+        final ModificationEvent ev;
+        final ModificationListener[] listeners;
+
+        public Deliverable(ModificationEvent ev, ModificationListener[] listeners) {
+            this.ev = ev;
+            this.listeners = listeners;
+        }
+    }
+}
diff -r c20d1d8ef2ca -r 35da2d439e3d samples/openfixed/src/org/apidesign/openfixed/PostEventSupport.java
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/samples/openfixed/src/org/apidesign/openfixed/PostEventSupport.java	Sun Mar 20 18:52:47 2011 +0100
@@ -0,0 +1,78 @@
+package org.apidesign.openfixed;
+
+import java.util.HashSet;
+import java.util.List;
+import java.util.Set;
+import java.util.concurrent.CopyOnWriteArrayList;
+import java.util.concurrent.Executor;
+import java.util.concurrent.Executors;
+
+/**
+ *
+ * @author Jaroslav Tulach <jtulach@netbeans.org>
+ */
+final class PostEventSupport implements EventSupport, Runnable {
+    private final List<ModificationListener> listeners = new CopyOnWriteArrayList<ModificationListener>();
+    private final List<Deliverable> deliverables = new CopyOnWriteArrayList<Deliverable>();
+    private static final Executor EXEC = Executors.newSingleThreadExecutor();
+    
+    PostEventSupport() {
+    }
+
+    @Override
+    public void fireModificationEvent(ModificationEvent ev) {
+        synchronized (deliverables) {
+            final Deliverable d = new Deliverable(ev, listeners.toArray(new ModificationListener[0]));
+            deliverables.add(d);
+            EXEC.execute(this);
+        }
+    }
+
+    @Override
+    public void add(ModificationListener l) {
+        listeners.add(l);
+    }
+
+    @Override
+    public void remove(ModificationListener l) {
+        listeners.remove(l);
+    }
+
+    @Override
+    public void run() {
+        Deliverable[] pending;
+        synchronized (deliverables) {
+            if (deliverables.isEmpty()) {
+                return;
+            }
+            pending = deliverables.toArray(new Deliverable[0]);
+            deliverables.clear();
+        }
+        Calculator calc = null;
+        Set<PostModificationListener> notify = new HashSet<PostModificationListener>();
+        int pendingCount = pending.length;
+        for (Deliverable d : pending) {
+            calc = (Calculator)d.ev.getSource();
+            d.ev.pending = --pendingCount;
+            d.ev.posts = notify;
+            for (ModificationListener l : d.listeners) {
+                l.modification(d.ev);
+            }
+            d.ev.posts = null;
+        }
+        
+        for (PostModificationListener pml : notify) {
+            pml.postProcess(new PostModificationEvent(calc));
+        }
+    }
+    
+    private static class Deliverable {
+        final ModificationEvent ev;
+        final ModificationListener[] listeners;
+
+        public Deliverable(ModificationEvent ev, ModificationListener[] listeners) {
+            this.ev = ev;
+            this.listeners = listeners;
+        }
+    }
+}
diff -r c20d1d8ef2ca -r 35da2d439e3d samples/openfixed/src/org/apidesign/openfixed/PostModificationEvent.java
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/samples/openfixed/src/org/apidesign/openfixed/PostModificationEvent.java	Sun Mar 20 18:52:47 2011 +0100
@@ -0,0 +1,14 @@
+/*
+ * To change this template, choose Tools | Templates
+ * and open the template in the editor.
+ */
+package org.apidesign.openfixed;
+
+import java.util.EventObject;
+// BEGIN: openfixed.postevent
+public final class PostModificationEvent extends EventObject {
+    PostModificationEvent(Calculator calc) {
+        super(calc);
+    }
+}
+// END: openfixed.postevent
diff -r c20d1d8ef2ca -r 35da2d439e3d samples/openfixed/src/org/apidesign/openfixed/PostModificationListener.java
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/samples/openfixed/src/org/apidesign/openfixed/PostModificationListener.java	Sun Mar 20 18:52:47 2011 +0100
@@ -0,0 +1,9 @@
+package org.apidesign.openfixed;
+
+import java.util.EventListener;
+
+// BEGIN: openfixed.postprocessor
+public interface PostModificationListener extends EventListener {
+    public void postProcess(PostModificationEvent ev);
+}
+// END: openfixed.postprocessor
diff -r c20d1d8ef2ca -r 35da2d439e3d samples/openfixed/src/org/apidesign/openfixed/TrivialEventSupport.java
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/samples/openfixed/src/org/apidesign/openfixed/TrivialEventSupport.java	Sun Mar 20 18:52:47 2011 +0100
@@ -0,0 +1,37 @@
+/*
+ * To change this template, choose Tools | Templates
+ * and open the template in the editor.
+ */
+package org.apidesign.openfixed;
+
+import java.util.List;
+import java.util.concurrent.CopyOnWriteArrayList;
+
+/**
+ *
+ * @author Jaroslav Tulach <jtulach@netbeans.org>
+ */
+final class TrivialEventSupport implements EventSupport {
+    List<ModificationListener> listener = new CopyOnWriteArrayList<ModificationListener>();
+    
+    TrivialEventSupport() {
+    }
+
+    @Override
+    public void fireModificationEvent(ModificationEvent ev) {
+        for (ModificationListener l : listener) {
+            l.modification(ev);
+        }
+    }
+
+    @Override
+    public void add(ModificationListener l) {
+        listener.add(l);
+    }
+
+    @Override
+    public void remove(ModificationListener l) {
+        listener.remove(l);
+    }
+    
+}
diff -r c20d1d8ef2ca -r 35da2d439e3d samples/openfixed/test/org/apidesign/openfixed/AsyncTest.java
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/samples/openfixed/test/org/apidesign/openfixed/AsyncTest.java	Sun Mar 20 18:52:47 2011 +0100
@@ -0,0 +1,18 @@
+package org.apidesign.openfixed;
+
+/** Test the Calculator.createAsynch() behavior.
+ *
+ * @author Jaroslav Tulach <jtulach@netbeans.org>
+ */
+public final class AsyncTest extends CalculatorBase {
+    
+    public AsyncTest(String testName) {
+        super(testName);
+    }
+
+    @Override
+    protected Calculator create() {
+        return Calculator.createAsynch();
+    }
+
+}
diff -r c20d1d8ef2ca -r 35da2d439e3d samples/openfixed/test/org/apidesign/openfixed/BasicTest.java
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/samples/openfixed/test/org/apidesign/openfixed/BasicTest.java	Sun Mar 20 18:52:47 2011 +0100
@@ -0,0 +1,16 @@
+package org.apidesign.openfixed;
+
+/** Test the Calculator.create() behavior.
+ *
+ * @author Jaroslav Tulach <jtulach@netbeans.org>
+ */
+public final class BasicTest extends CalculatorBase {
+    public BasicTest(String testName) {
+        super(testName);
+    }
+
+    @Override
+    protected Calculator create() {
+        return Calculator.create();
+    }
+}
diff -r c20d1d8ef2ca -r 35da2d439e3d samples/openfixed/test/org/apidesign/openfixed/CalculatorBase.java
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/samples/openfixed/test/org/apidesign/openfixed/CalculatorBase.java	Sun Mar 20 18:52:47 2011 +0100
@@ -0,0 +1,64 @@
+package org.apidesign.openfixed;
+
+import java.util.ArrayList;
+import java.util.List;
+import junit.framework.TestCase;
+
+public abstract class CalculatorBase extends TestCase {
+    
+    public CalculatorBase(String testName) {
+        super(testName);
+    }
+    
+    protected abstract Calculator create();
+
+    public void testSumAndListeners() throws Exception {
+        Calculator a = create();
+        MockListener l = new MockListener();
+        a.addModificationListener(l);
+        a.add(5);
+        a.add(10);
+        a.add(20);
+        int ch = allChanges(l.assertEvents("Three changes", 3));
+        assertEquals("35 was the change", 35, ch);
+        assertEquals("Current value", 35, a.getSum());
+        a.add(-5);
+        int ch2 = allChanges(l.assertEvents("One change", 1));
+        assertEquals("minus five was the change", -5, ch2);
+        assertEquals("Final value", 30, a.getSum());
+    }
+    
+    private static int allChanges(List<ModificationEvent> events) {
+        int changes = 0;
+        for (ModificationEvent me : events) {
+            changes += me.getChange();
+        }
+        return changes;
+    }
+    
+    public static class MockListener implements ModificationListener {
+        private List<ModificationEvent> events;
+        
+        @Override
+        public synchronized void modification(ModificationEvent ev) {
+            if (events == null) {
+                events = new ArrayList<ModificationEvent>();
+            }
+            events.add(ev);
+        }
+        
+        public synchronized List<ModificationEvent> assertEvents(String msg, int cnt) 
+        throws InterruptedException {
+            for (int i = 0; i < 10; i++) {
+                if (events != null && events.size() >= cnt) {
+                    break;
+                }
+                wait(1000);
+            }
+            assertEquals(msg + ":\n" + events, cnt, events.size());
+            List<ModificationEvent> res = events;
+            events = null;
+            return res;
+        }
+    } // end of ModificationListener
+}
diff -r c20d1d8ef2ca -r 35da2d439e3d samples/openfixed/test/org/apidesign/openfixed/PendingTest.java
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/samples/openfixed/test/org/apidesign/openfixed/PendingTest.java	Sun Mar 20 18:52:47 2011 +0100
@@ -0,0 +1,60 @@
+package org.apidesign.openfixed;
+
+import java.util.List;
+import java.util.concurrent.CountDownLatch;
+
+/** Test the Calculator.createPending() behavior.
+ *
+ * @author Jaroslav Tulach <jtulach@netbeans.org>
+ */
+public class PendingTest extends CalculatorBase {
+    
+    public PendingTest(String testName) {
+        super(testName);
+    }
+
+    @Override
+    protected Calculator create() {
+        return Calculator.createPending();
+    }
+
+    public void testPendingEvents() throws Exception {
+        BlockingListener bl = new BlockingListener();
+        
+        Calculator calc = create();
+        calc.addModificationListener(bl);
+        
+        calc.add(10);
+        bl.first.await();
+        
+        calc.add(1);
+        calc.add(2);
+        calc.add(3);
+        
+        bl.cdl.countDown();
+        
+        List<ModificationEvent> events = bl.assertEvents("Four changes together", 4);
+        
+        assertEquals("No pending events for first event", 0, events.get(0).getPending());
+        assertEquals("Group of three, two remaining", 2, events.get(1).getPending());
+        assertEquals("Group of three, one remaining", 1, events.get(2).getPending());
+        assertEquals("Group of three, last one", 0, events.get(3).getPending());
+    }
+    
+    static class BlockingListener extends MockListener {
+        CountDownLatch first = new CountDownLatch(1);
+        CountDownLatch cdl = new CountDownLatch(1);
+
+        @Override
+        public synchronized void modification(ModificationEvent ev) {
+            try {
+                first.countDown();
+                cdl.await();
+            } catch (InterruptedException ex) {
+                throw new IllegalStateException(ex);
+            }
+            super.modification(ev);
+        }
+    }
+    
+}
diff -r c20d1d8ef2ca -r 35da2d439e3d samples/openfixed/test/org/apidesign/openfixed/PostTest.java
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/samples/openfixed/test/org/apidesign/openfixed/PostTest.java	Sun Mar 20 18:52:47 2011 +0100
@@ -0,0 +1,62 @@
+package org.apidesign.openfixed;
+
+import java.util.concurrent.CountDownLatch;
+
+/** Test the Calculator.createPending() behavior.
+ *
+ * @author Jaroslav Tulach <jtulach@netbeans.org>
+ */
+public final class PostTest extends PendingTest {
+    
+    public PostTest(String testName) {
+        super(testName);
+    }
+
+    @Override
+    protected Calculator create() {
+        return Calculator.createBatch();
+    }
+
+    public void testPostModificationEvents() throws Exception {
+        class PostListener extends BlockingListener implements PostModificationListener {
+            int cnt;
+
+            @Override
+            public synchronized void modification(ModificationEvent ev) {
+                // registers for callback when batch processing is over:
+                ev.postProcess(this);
+                super.modification(ev);
+            }
+
+            @Override
+            public synchronized void postProcess(PostModificationEvent ev) {
+                cnt++;
+            }
+            
+            public synchronized void assertPostProcess(String msg, int expected) throws InterruptedException {
+                for (int i = 0; i < 10; i++) {
+                    if (cnt >= expected) {
+                        break;
+                    }
+                    wait(1000);
+                }
+                assertEquals(msg, expected, cnt);
+                cnt = 0;
+            }
+        }
+        PostListener bl = new PostListener();
+        
+        Calculator calc = create();
+        calc.addModificationListener(bl);
+        
+        calc.add(10);
+        bl.first.await();
+        
+        calc.add(1);
+        calc.add(2);
+        calc.add(3);
+        
+        bl.cdl.countDown();
+        bl.assertPostProcess("Two postprocessings (one for 10), then for the rest", 2);
+    }
+}