Rechedule discovery task only if role is MASTER. Also, start the scheduling...

Rechedule discovery task only if role is MASTER.  Also, start the scheduling when role is changed to master.

src/main/java/net/floodlightcontroller/linkdiscovery/internal/LinkDiscoveryManager.java

@@ -1585,7 +1585,8 @@ IFloodlightModule, IInfoProvider, IHAListener {
                 } catch (Exception e) {
                     log.error("Exception in LLDP send timer.", e);
                 } finally {
-                    if (!shuttingDown) {
+                    if (!shuttingDown &&
+                            floodlightProvider.getRole() == Role.MASTER) {
                         discoveryTask.reschedule(DISCOVERY_TASK_INTERVAL,
                                                 TimeUnit.SECONDS);
                     }
@@ -1606,7 +1607,8 @@ IFloodlightModule, IInfoProvider, IHAListener {
             }}, "Topology Updates");
         updatesThread.start();
 
-        discoveryTask.reschedule(DISCOVERY_TASK_INTERVAL, TimeUnit.SECONDS);
+        if (floodlightProvider.getRole() == Role.MASTER)
+            discoveryTask.reschedule(1, TimeUnit.MICROSECONDS);
         // Register for the OpenFlow messages we want to receive
         floodlightProvider.addOFMessageListener(OFType.PACKET_IN, this);
         floodlightProvider.addOFMessageListener(OFType.PORT_STATUS, this);
@@ -1712,19 +1714,17 @@ IFloodlightModule, IInfoProvider, IHAListener {
     }
 
     // IHARoleListener
-
     @Override
     public void roleChanged(Role oldRole, Role newRole) {
         switch(newRole) {
             case MASTER:
                 if (oldRole == Role.SLAVE) {
-                    clearAllLinks();
                     if (log.isTraceEnabled()) {
                         log.trace("Sending LLDPs " +
                                 "to HA change from SLAVE->MASTER");
                     }
                     clearAllLinks();
-                    discoverLinks();
+                    discoveryTask.reschedule(1, TimeUnit.MICROSECONDS);
                 }
                 break;
             case SLAVE: