[ONOS-2607] BGP LS topology provider interface and listen on Node and Link chang…

…es of BGP Controller.

Change-Id: Iccd4af75e25c3d4da703bd8e34afb19aabf096a4

@@ -17,13 +17,14 @@
 package org.onosproject.bgp.controller;
 
 import java.util.Map;
+import java.util.Set;
 
 import org.onosproject.bgpio.exceptions.BGPParseException;
 import org.onosproject.bgpio.protocol.BGPMessage;
 
 /**
- * Abstraction of an BGP controller. Serves as a one stop shop for obtaining BGP devices and (un)register listeners
- * on bgp events
+ * Abstraction of an BGP controller. Serves as a one stop shop for obtaining BGP devices and (un)register listeners on
+ * bgp events
  */
 public interface BGPController {
 
@@ -43,6 +44,34 @@ public interface BGPController {
     BGPPeer getPeer(BGPId bgpId);
 
     /**
+     * Register a listener for BGP message events.
+     *
+     * @param listener the listener to notify
+     */
+    void addListener(BgpNodeListener listener);
+
+    /**
+     * Unregister a listener.
+     *
+     * @param listener the listener to unregister
+     */
+    void removeListener(BgpNodeListener listener);
+
+    /**
+     * Register a listener for BGP message events.
+     *
+     * @param listener the listener to notify
+     */
+    void addLinkListener(BgpLinkListener listener);
+
+    /**
+     * Unregister a listener.
+     *
+     * @param listener the listener to unregister
+     */
+    void removeLinkListener(BgpLinkListener listener);
+
+    /**
      * Send a message to a particular bgp peer.
      *
      * @param bgpId the id of the peer to send message.
@@ -92,4 +121,18 @@ public interface BGPController {
      * @return connectedPeers connected peers
      */
     Map<BGPId, BGPPeer> connectedPeers();
-}
\ No newline at end of file
+
+    /**
+     * Return BGP node listener.
+     *
+     * @return node listener
+     */
+    Set<BgpNodeListener> listener();
+
+    /**
+     * Return BGP link listener.
+     *
+     * @return link listener
+     */
+    Set<BgpLinkListener> linkListener();
+}

@@ -16,7 +16,9 @@
 
 package org.onosproject.bgp.controller.impl;
 
+import java.util.Set;
 import java.util.concurrent.ConcurrentHashMap;
+import java.util.concurrent.CopyOnWriteArraySet;
 import java.util.concurrent.locks.Lock;
 import java.util.concurrent.locks.ReentrantLock;
 
@@ -28,6 +30,8 @@ import org.onosproject.bgp.controller.BGPCfg;
 import org.onosproject.bgp.controller.BGPController;
 import org.onosproject.bgp.controller.BGPId;
 import org.onosproject.bgp.controller.BGPPeer;
+import org.onosproject.bgp.controller.BgpLinkListener;
+import org.onosproject.bgp.controller.BgpNodeListener;
 import org.onosproject.bgp.controller.BgpPeerManager;
 import org.onosproject.bgpio.exceptions.BGPParseException;
 import org.onosproject.bgpio.protocol.BGPMessage;
@@ -43,6 +47,10 @@ public class BGPControllerImpl implements BGPController {
     protected ConcurrentHashMap<BGPId, BGPPeer> connectedPeers = new ConcurrentHashMap<BGPId, BGPPeer>();
 
     protected BGPPeerManagerImpl peerManager = new BGPPeerManagerImpl();
+
+    protected Set<BgpNodeListener> bgpNodeListener = new CopyOnWriteArraySet<>();
+    protected Set<BgpLinkListener> bgpLinkListener = new CopyOnWriteArraySet<>();
+
     final Controller ctrl = new Controller(this);
 
     private BGPConfig bgpconfig = new BGPConfig();
@@ -72,6 +80,36 @@ public class BGPControllerImpl implements BGPController {
     }
 
     @Override
+    public void addListener(BgpNodeListener listener) {
+        this.bgpNodeListener.add(listener);
+    }
+
+    @Override
+    public void removeListener(BgpNodeListener listener) {
+        this.bgpNodeListener.remove(listener);
+    }
+
+    @Override
+    public Set<BgpNodeListener> listener() {
+        return bgpNodeListener;
+    }
+
+    @Override
+    public void addLinkListener(BgpLinkListener listener) {
+        this.bgpLinkListener.add(listener);
+    }
+
+    @Override
+    public void removeLinkListener(BgpLinkListener listener) {
+        this.bgpLinkListener.remove(listener);
+    }
+
+    @Override
+    public Set<BgpLinkListener> linkListener() {
+        return bgpLinkListener;
+    }
+
+    @Override
     public void writeMsg(BGPId bgpId, BGPMessage msg) {
         this.getPeer(bgpId).sendMessage(msg);
     }