1 files changed, 58 insertions, 0 deletions
diff --git a/framework/src/onos/core/api/src/main/java/org/onosproject/event/AbstractListenerManager.java b/framework/src/onos/core/api/src/main/java/org/onosproject/event/AbstractListenerManager.java
new file mode 100644
index 00000000..cbe7421f
--- /dev/null
+++ b/framework/src/onos/core/api/src/main/java/org/onosproject/event/AbstractListenerManager.java
@@ -0,0 +1,58 @@
+/*
+ * Copyright 2015 Open Networking Laboratory
+ *
+ * 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.onosproject.event;
+
+import org.apache.felix.scr.annotations.Component;
+import org.apache.felix.scr.annotations.Reference;
+import org.apache.felix.scr.annotations.ReferenceCardinality;
+
+/**
+ * Basis for components which need to export listener mechanism.
+ */
+@Component(componentAbstract = true)
+public abstract class AbstractListenerManager<E extends Event, L extends EventListener<E>>
+    implements ListenerService<E, L> {
+
+    protected final ListenerRegistry<E, L> listenerRegistry = new ListenerRegistry<>();
+
+    @Reference(cardinality = ReferenceCardinality.MANDATORY_UNARY)
+    protected EventDeliveryService eventDispatcher;
+
+    @Override
+    public void addListener(L listener) {
+        listenerRegistry.addListener(listener);
+    }
+
+    @Override
+    public void removeListener(L listener) {
+        listenerRegistry.removeListener(listener);
+    }
+
+
+    /**
+     * Safely posts the specified event to the local event dispatcher.
+     * If there is no event dispatcher or if the event is null, this method
+     * is a noop.
+     *
+     * @param event event to be posted; may be null
+     */
+    protected void post(E event) {
+        if (event != null && eventDispatcher != null) {
+            eventDispatcher.post(event);
+        }
+    }
+
+}