openflow/j: Factor out Nicira Vendor Extensions initialization to util class

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

@@ -1767,21 +1767,9 @@ public class Controller implements IFloodlightProviderService,
     private void initVendorMessages() {
         // Configure openflowj to be able to parse the role request/reply
         // vendor messages.
-        OFBasicVendorId niciraVendorId = new OFBasicVendorId(
-                OFNiciraVendorData.NX_VENDOR_ID, 4);
-        OFVendorId.registerVendorId(niciraVendorId);
-        OFBasicVendorDataType roleRequestVendorData =
-                new OFBasicVendorDataType(
-                        OFRoleRequestVendorData.NXT_ROLE_REQUEST,
-                        OFRoleRequestVendorData.getInstantiable());
-        niciraVendorId.registerVendorDataType(roleRequestVendorData);
-        OFBasicVendorDataType roleReplyVendorData =
-                new OFBasicVendorDataType(
-                        OFRoleReplyVendorData.NXT_ROLE_REPLY,
-                        OFRoleReplyVendorData.getInstantiable());
-         niciraVendorId.registerVendorDataType(roleReplyVendorData);
+        OFNiciraVendorExtensions.initialize();
     }
-    
+
     /**
      * Initialize internal data structures
      */

src/main/java/org/openflow/vendor/nicira/OFNiciraVendorExtensions.java

+package org.openflow.vendor.nicira;
+
+import org.openflow.protocol.vendor.OFBasicVendorDataType;
+import org.openflow.protocol.vendor.OFBasicVendorId;
+import org.openflow.protocol.vendor.OFVendorId;
+
+public class OFNiciraVendorExtensions {
+    private static boolean initialized = false;
+
+    public static synchronized void initialize() {
+        if (initialized)
+            return;
+
+        // Configure openflowj to be able to parse the role request/reply
+        // vendor messages.
+        OFBasicVendorId niciraVendorId =
+                new OFBasicVendorId(OFNiciraVendorData.NX_VENDOR_ID, 4);
+        OFVendorId.registerVendorId(niciraVendorId);
+        OFBasicVendorDataType roleRequestVendorData =
+                new OFBasicVendorDataType(OFRoleRequestVendorData.NXT_ROLE_REQUEST,
+                        OFRoleRequestVendorData.getInstantiable());
+        niciraVendorId.registerVendorDataType(roleRequestVendorData);
+        OFBasicVendorDataType roleReplyVendorData =
+                new OFBasicVendorDataType(OFRoleReplyVendorData.NXT_ROLE_REPLY,
+                        OFRoleReplyVendorData.getInstantiable());
+        niciraVendorId.registerVendorDataType(roleReplyVendorData);
+
+        initialized = true;
+    }
+}