Add a set of synchronous version of methods for MastershipService

Change-Id: I61da650eb545c14b5fa824ac92d1ebe62126dec3
diff --git a/core/api/src/main/java/org/onosproject/mastership/MastershipAdminService.java b/core/api/src/main/java/org/onosproject/mastership/MastershipAdminService.java
index 4d21233..091cf8e 100644
--- a/core/api/src/main/java/org/onosproject/mastership/MastershipAdminService.java
+++ b/core/api/src/main/java/org/onosproject/mastership/MastershipAdminService.java
@@ -16,7 +16,9 @@
 package org.onosproject.mastership;
 
 import java.util.concurrent.CompletableFuture;
+import java.util.concurrent.TimeUnit;
 
+import org.onlab.util.Tools;
 import org.onosproject.cluster.NodeId;
 import org.onosproject.net.DeviceId;
 import org.onosproject.net.MastershipRole;
@@ -26,6 +28,8 @@
  */
 public interface MastershipAdminService {
 
+    long TIMEOUT_MILLIS = 3000;
+
     /**
      * Applies the current mastership role for the specified device.
      *
@@ -37,6 +41,18 @@
     CompletableFuture<Void> setRole(NodeId instance, DeviceId deviceId, MastershipRole role);
 
     /**
+     * Synchronous version of setRole.
+     * Applies the current mastership role for the specified device.
+     *
+     * @param instance controller instance identifier
+     * @param deviceId device identifier
+     * @param role     requested role
+     */
+    default void setRoleSync(NodeId instance, DeviceId deviceId, MastershipRole role) {
+        Tools.futureGetOrElse(setRole(instance, deviceId, role), TIMEOUT_MILLIS, TimeUnit.MILLISECONDS, null);
+    }
+
+    /**
      * Balances the mastership to be shared as evenly as possibly by all
      * online instances.
      */