[breaking] EventCoalescor is now abstract and generified

The default implementation, the old EventCoalescor, is implemented as
a private static inner class of the EventCoalescor, it's an implementation
called "generic". It might be built, using the factory method:
"EventCoalescor.generic"

So FileWatchEventCoalescor inherit from EventCoalescor for the type FileWatchEvent.

Author: a-peyrard

restx-barbarywatch/src/main/java/restx/common/watch/BarbaryWatchService.java

@@ -49,7 +49,7 @@ private static class WatchDir implements Closeable{
         private final WatchService watcher;
         private final Map<WatchKey, Path> keys;
         private final boolean recursive;
-        private final EventCoalescor coalescor;
+        private final EventCoalescor<Object> coalescor;
         private final Path root;
         private boolean trace = false;
 
@@ -98,7 +98,7 @@ public FileVisitResult preVisitDirectory(Path dir, BasicFileAttributes attrs)
             this.keys = new HashMap<>();
             this.recursive = settings.recurse();
             this.root = dir;
-            this.coalescor = new EventCoalescor(eventBus, settings.coalescePeriod());
+            this.coalescor = EventCoalescor.generic(eventBus, settings.coalescePeriod());
 
             if (recursive) {
                 registerAll(dir);

restx-common/src/main/java/restx/common/watch/EventCoalescor.java

@@ -22,39 +22,63 @@
  *     Other similar events occuring within the period are simply not discarded.
  * </p>
  */
-public class EventCoalescor implements Closeable {
-    private final ScheduledExecutorService executor = Executors.newSingleThreadScheduledExecutor();
-    private final EventBus eventBus;
-    private final long coalescePeriod;
+public abstract class EventCoalescor<T> implements Closeable {
 
-    private final Set<Object> queue = new LinkedHashSet<>();
+	/**
+	 * Create an instance of an {@link EventCoalescor} which accept all kind of events,
+	 * as it is untyped.
+	 *
+	 * @param eventBus the event bus where to post processed events
+	 * @param coalescePeriod the coalesce period
+	 * @return the generic event coalescor
+	 */
+	public static EventCoalescor<Object> generic(EventBus eventBus, long coalescePeriod) {
+		return new GenericEventCoalescor(eventBus, coalescePeriod);
+	}
 
-    public EventCoalescor(EventBus eventBus, long coalescePeriod) {
+    final ScheduledExecutorService executor = Executors.newSingleThreadScheduledExecutor();
+    final EventBus eventBus;
+    final long coalescePeriod;
+
+    EventCoalescor(EventBus eventBus, long coalescePeriod) {
         this.eventBus = eventBus;
         this.coalescePeriod = coalescePeriod;
     }
 
-    public void post(final Object event) {
-        synchronized (queue) {
-            if (queue.add(event)) {
-                executor.schedule(new Runnable() {
-                    @Override
-                    public void run() {
-                        try {
-                            eventBus.post(event);
-                        } finally {
-                            synchronized (queue) {
-                                queue.remove(event);
-                            }
-                        }
-                    }
-                }, coalescePeriod, TimeUnit.MILLISECONDS);
-            }
-        }
-    }
+	public abstract void post(final T event);
 
     @Override
     public void close() throws IOException {
         executor.shutdownNow();
     }
+
+	/**
+	 * generic coalescor, using untyped events
+	 */
+	private static class GenericEventCoalescor extends EventCoalescor<Object> {
+		private final Set<Object> queue = new LinkedHashSet<>();
+
+		private GenericEventCoalescor(EventBus eventBus, long coalescePeriod) {
+			super(eventBus, coalescePeriod);
+		}
+
+		public void post(final Object event) {
+			synchronized (queue) {
+				if (queue.add(event)) {
+					executor.schedule(new Runnable() {
+						@Override
+						public void run() {
+							try {
+								eventBus.post(event);
+							} finally {
+								synchronized (queue) {
+									queue.remove(event);
+								}
+							}
+						}
+					}, coalescePeriod, TimeUnit.MILLISECONDS);
+				}
+			}
+		}
+	}
 }

restx-common/src/main/java/restx/common/watch/FileWatchEventCoalescor.java

@@ -2,15 +2,11 @@
 
 import com.google.common.eventbus.EventBus;
 
-import java.io.Closeable;
-import java.io.IOException;
 import java.nio.file.Path;
 import java.nio.file.StandardWatchEventKinds;
 import java.util.ArrayDeque;
 import java.util.Deque;
 import java.util.HashMap;
-import java.util.concurrent.Executors;
-import java.util.concurrent.ScheduledExecutorService;
 import java.util.concurrent.TimeUnit;
 
 /**
@@ -25,17 +21,12 @@
  *
  * @author apeyrard
  */
-public class FileWatchEventCoalescor implements Closeable {
-
-	private final ScheduledExecutorService executor = Executors.newSingleThreadScheduledExecutor();
-	private final EventBus eventBus;
-	private final long coalescePeriod;
+public class FileWatchEventCoalescor extends EventCoalescor<FileWatchEvent> {
 
 	private final HashMap<FileWatchEventKey, Deque<EventReference>> queue = new HashMap<>();
 
 	public FileWatchEventCoalescor(EventBus eventBus, long coalescePeriod) {
-		this.eventBus = eventBus;
-		this.coalescePeriod = coalescePeriod;
+		super(eventBus, coalescePeriod);
 	}
 
 	/**
@@ -157,11 +148,6 @@ void clear() {
 		}
 	}
 
-	@Override
-	public void close() throws IOException {
-		executor.shutdownNow();
-	}
-
 	/**
 	 * key used for the storage of an event, composed by file paths, two event with same keys, are for the same physical file
 	 */

restx-common/src/main/java/restx/common/watch/StdWatcherService.java

@@ -44,7 +44,7 @@ private static class WatchDir implements Closeable {
         private final WatchService watcher;
         private final Map<WatchKey,Path> keys;
         private final boolean recursive;
-        private final EventCoalescor coalescor;
+        private final EventCoalescor<Object> coalescor;
         private final Path root;
         private boolean trace = false;
 
@@ -96,7 +96,7 @@ public FileVisitResult preVisitDirectory(Path dir, BasicFileAttributes attrs)
             this.keys = new HashMap<>();
             this.recursive = settings.recurse();
             this.root = dir;
-            this.coalescor = new EventCoalescor(eventBus, settings.coalescePeriod());
+            this.coalescor = EventCoalescor.generic(eventBus, settings.coalescePeriod());
 
             if (recursive) {
                 registerAll(dir);

restx-common/src/test/java/restx/common/watch/EventCoalescorTest.java

@@ -1,14 +1,15 @@
 package restx.common.watch;
 
+import static org.assertj.core.api.Assertions.assertThat;
+
+
 import com.google.common.eventbus.EventBus;
 import com.google.common.eventbus.Subscribe;
 import org.junit.Test;
 
 import java.util.ArrayList;
 import java.util.List;
 
-import static org.assertj.core.api.Assertions.assertThat;
-
 /**
  * User: xavierhanin
  * Date: 9/11/13
@@ -27,7 +28,7 @@ public void onMessage(String msg) {
             }
         });
 
-        EventCoalescor coalescor = new EventCoalescor(eventBus, 30);
+        EventCoalescor coalescor = EventCoalescor.generic(eventBus, 30);
 
         coalescor.post("test1");
         coalescor.post("test2");