Move ChainableDataTreeListener to tools-api

Change-Id: I9401d9a623a0ac141d0f6d03bbf9ce2810da1462
Signed-off-by: David Suarez <david.suarez.fuentes@gmail.com>

diff --git a/api/src/main/java/org/opendaylight/genius/tools/mdsal/listener/ChainableDataTreeChangeListener.java b/api/src/main/java/org/opendaylight/genius/tools/mdsal/listener/ChainableDataTreeChangeListener.java
new file mode 100644 (file)
index 0000000..6d96303
--- /dev/null
+++ b/api/src/main/java/org/opendaylight/genius/tools/mdsal/listener/ChainableDataTreeChangeListener.java
@@ -0,0 +1,45 @@
+/*
+ * Copyright (c) 2016 Red Hat, Inc. and others. All rights reserved.
+ *
+ * This program and the accompanying materials are made available under the
+ * terms of the Eclipse Public License v1.0 which accompanies this distribution,
+ * and is available at http://www.eclipse.org/legal/epl-v10.html
+ */
+package org.opendaylight.genius.tools.mdsal.listener;
+
+import java.util.EventListener;
+import org.opendaylight.controller.md.sal.binding.api.DataTreeChangeListener;
+import org.opendaylight.yangtools.yang.binding.DataObject;
+
+/**
+ * {@link DataTreeChangeListener} which can notify another DataTreeChangeListener.
+ *
+ * @author Michael Vorburger, based on discussions with Stephen Kitt
+ */
+public interface ChainableDataTreeChangeListener<T extends DataObject> extends EventListener {
+
+    /**
+     * Adds a "chained" DataTreeChangeListener, to which
+     * {@link DataTreeChangeListener#onDataTreeChanged(java.util.Collection)}
+     * calls are forwarded BEFORE having been processed by this DataTreeChangeListener.
+     *
+     * <p>If an asychronous DataTreeChangeListener supports chaining, it must forward
+     * the onDataTreeChanged() call BEFORE event are submitted to its async executor for processing.
+     *
+     * @param listener the chained DataTreeChangeListener to invoke after this one
+     */
+    void addBeforeListener(DataTreeChangeListener<T> listener);
+
+    /**
+     * Adds a "chained" DataTreeChangeListener, to which
+     * {@link DataTreeChangeListener#onDataTreeChanged(java.util.Collection)}
+     * calls are forwarded AFTER having been processed by this DataTreeChangeListener.
+     *
+     * <p>If an asychronous DataTreeChangeListener supports chaining, it must forward
+     * the onDataTreeChanged() call ONLY AFTER its async executor processed the event.
+     *
+     * @param listener the chained DataTreeChangeListener to invoke after this one
+     */
+    void addAfterListener(DataTreeChangeListener<T> listener);
+
+}

diff --git a/api/src/main/java/org/opendaylight/genius/tools/mdsal/listener/ChainableDataTreeChangeListenerImpl.java b/api/src/main/java/org/opendaylight/genius/tools/mdsal/listener/ChainableDataTreeChangeListenerImpl.java
new file mode 100644 (file)
index 0000000..de8ca20
--- /dev/null
+++ b/api/src/main/java/org/opendaylight/genius/tools/mdsal/listener/ChainableDataTreeChangeListenerImpl.java
@@ -0,0 +1,68 @@
+/*
+ * Copyright (c) 2016 Red Hat, Inc. and others. All rights reserved.
+ *
+ * This program and the accompanying materials are made available under the
+ * terms of the Eclipse Public License v1.0 which accompanies this distribution,
+ * and is available at http://www.eclipse.org/legal/epl-v10.html
+ */
+package org.opendaylight.genius.tools.mdsal.listener;
+
+import java.util.Collection;
+import java.util.List;
+import java.util.concurrent.CopyOnWriteArrayList;
+import org.opendaylight.controller.md.sal.binding.api.DataTreeChangeListener;
+import org.opendaylight.controller.md.sal.binding.api.DataTreeModification;
+import org.opendaylight.yangtools.yang.binding.DataObject;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+/**
+ * Default implementation of ChainableDataTreeChangeListener.
+ *
+ * <p>Suitable as a delegate for listeners implementing ChainableDataTreeChangeListener.
+ *
+ * @author Michael Vorburger
+ */
+public final class ChainableDataTreeChangeListenerImpl<T extends DataObject>
+        implements ChainableDataTreeChangeListener<T> {
+
+    private static final Logger LOG = LoggerFactory.getLogger(ChainableDataTreeChangeListenerImpl.class);
+
+    private final List<DataTreeChangeListener<T>> beforeListeners = new CopyOnWriteArrayList<>();
+    private final List<DataTreeChangeListener<T>> afterListeners = new CopyOnWriteArrayList<>();
+
+    @Override
+    public void addBeforeListener(DataTreeChangeListener<T> listener) {
+        beforeListeners.add(listener);
+    }
+
+    @Override
+    public void addAfterListener(DataTreeChangeListener<T> listener) {
+        afterListeners.add(listener);
+    }
+
+    @SuppressWarnings("checkstyle:IllegalCatch")
+    public void notifyBeforeOnDataTreeChanged(Collection<DataTreeModification<T>> changes) {
+        for (DataTreeChangeListener<T> listener : beforeListeners) {
+            try {
+                listener.onDataTreeChanged(changes);
+            } catch (Exception e) {
+                LOG.error("Caught Exception from a before listener's onDataChanged(); "
+                        + "nevertheless proceeding with others, if any", e);
+            }
+        }
+    }
+
+    @SuppressWarnings("checkstyle:IllegalCatch")
+    public void notifyAfterOnDataTreeChanged(Collection<DataTreeModification<T>> changes) {
+        for (DataTreeChangeListener<T> listener : afterListeners) {
+            try {
+                listener.onDataTreeChanged(changes);
+            } catch (Exception e) {
+                LOG.error("Caught Exception from an after listener's onDataChanged(); "
+                        + "nevertheless proceeding with others, if any", e);
+            }
+        }
+    }
+
+}