Merge into master from pull request #190:

Don't set role again if it's the same. Partial fix for BSC-1835 (https://github.com/floodlight/floodlight/pull/190)

src/main/java/net/floodlightcontroller/core/internal/Controller.java

@@ -345,12 +345,14 @@ public class Controller implements IFloodlightProviderService,
     }
 
     @Override
-    public synchronized Role getRole() {
-        return role;
+    public Role getRole() {
+        synchronized(roleChanger) {
+            return role;
+        }
     }
     
     @Override
-    public synchronized void setRole(Role role) {
+    public void setRole(Role role) {
         if (role == null) throw new NullPointerException("Role can not be null.");
         
         // Need to synchronize to ensure a reliable ordering on role request
@@ -359,6 +361,11 @@ public class Controller implements IFloodlightProviderService,
         // timeout handling
         // @see RoleChanger
         synchronized(roleChanger) {
+            if (role.equals(this.role)) {
+                log.debug("Ignoring role change: role is already {}", role);
+                return;
+            }
+
             Role oldRole = this.role;
             this.role = role;