allow null Master in MastershipTerm

Change-Id: I840354eb6d0b5a1bac91887a41626c33c49d592c

@@ -55,13 +55,8 @@ public final class MastershipTerm {
         }
         if (other instanceof MastershipTerm) {
             MastershipTerm that = (MastershipTerm) other;
-            if (!this.master.equals(that.master)) {
-                return false;
-            }
-            if (this.termNumber != that.termNumber) {
-                return false;
-            }
-            return true;
+            return Objects.equals(this.master, that.master) &&
+                    Objects.equals(this.termNumber, that.termNumber);
         }
         return false;
     }

@@ -257,7 +257,8 @@ public class DeviceManager
             MastershipTerm term = mastershipService.requestTermService()
                     .getMastershipTerm(deviceId);
 
-            if (!term.master().equals(clusterService.getLocalNode().id())) {
+            final NodeId myNodeId = clusterService.getLocalNode().id();
+            if (!myNodeId.equals(term.master())) {
                 // lost mastership after requestRole told this instance was MASTER.
                 log.info("lost mastership before getting term info.");
                 return;

@@ -139,14 +139,14 @@ public class MastershipManagerTest {
     public void termService() {
         MastershipTermService ts = mgr.requestTermService();
 
-        //term = 0 for both
+        //term = 1 for both
         mgr.setRole(NID_LOCAL, DEV_MASTER, MASTER);
-        assertEquals("inconsistent term: ", 0, ts.getMastershipTerm(DEV_MASTER).termNumber());
+        assertEquals("inconsistent term: ", 1, ts.getMastershipTerm(DEV_MASTER).termNumber());
 
-        //hand devices to NID_LOCAL and back: term = 2
+        //hand devices to NID_LOCAL and back: term = 1 + 2
         mgr.setRole(NID_OTHER, DEV_MASTER, MASTER);
         mgr.setRole(NID_LOCAL, DEV_MASTER, MASTER);
-        assertEquals("inconsistent terms: ", 2, ts.getMastershipTerm(DEV_MASTER).termNumber());
+        assertEquals("inconsistent terms: ", 3, ts.getMastershipTerm(DEV_MASTER).termNumber());
     }
 
     private final class TestClusterService implements ClusterService {

@@ -60,8 +60,10 @@ public class DistributedMastershipStore
 extends AbstractHazelcastStore<MastershipEvent, MastershipStoreDelegate>
 implements MastershipStore {
 
+    //term number representing that master has never been chosen yet
+    private static final Integer NOTHING = 0;
     //initial term/TTL value
-    private static final Integer INIT = 0;
+    private static final Integer INIT = 1;
 
     //device to node roles
     protected SMap<DeviceId, RoleValue> roleMap;
@@ -256,8 +258,8 @@ implements MastershipStore {
             RoleValue rv = getRoleValue(deviceId);
             final Integer term = terms.get(deviceId);
             final NodeId master = rv.get(MASTER);
-            if ((master == null) || (term == null)) {
-                return null;
+            if (term == null) {
+                return MastershipTerm.of(null, NOTHING);
             }
             return MastershipTerm.of(master, term);
         } finally {

@@ -149,7 +149,7 @@ public class DistributedMastershipStoreTest {
         assertEquals("wrong role for NONE:", MASTER, dms.requestRole(DID1));
         assertTrue("wrong state for store:", !dms.terms.isEmpty());
         assertEquals("wrong term",
-                MastershipTerm.of(N1, 0), dms.getTermFor(DID1));
+                MastershipTerm.of(N1, 1), dms.getTermFor(DID1));
 
         //CN2 now local. DID2 has N1 as MASTER so N2 is STANDBY
         testStore.setCurrent(CN2);
@@ -172,15 +172,15 @@ public class DistributedMastershipStoreTest {
         //switch over to N2
         assertEquals("wrong event:", Type.MASTER_CHANGED, dms.setMaster(N2, DID1).type());
         System.out.println(dms.getTermFor(DID1).master() + ":" + dms.getTermFor(DID1).termNumber());
-        assertEquals("wrong term", MastershipTerm.of(N2, 1), dms.getTermFor(DID1));
+        assertEquals("wrong term", MastershipTerm.of(N2, 2), dms.getTermFor(DID1));
 
         //orphan switch - should be rare case
         assertEquals("wrong event:", Type.MASTER_CHANGED, dms.setMaster(N2, DID2).type());
-        assertEquals("wrong term", MastershipTerm.of(N2, 0), dms.getTermFor(DID2));
+        assertEquals("wrong term", MastershipTerm.of(N2, 1), dms.getTermFor(DID2));
         //disconnect and reconnect - sign of failing re-election or single-instance channel
         dms.roleMap.clear();
         dms.setMaster(N2, DID2);
-        assertEquals("wrong term", MastershipTerm.of(N2, 1), dms.getTermFor(DID2));
+        assertEquals("wrong term", MastershipTerm.of(N2, 2), dms.getTermFor(DID2));
     }
 
     @Test

@@ -38,15 +38,14 @@ public class MastershipTermSerializer extends Serializer<MastershipTerm> {
 
     @Override
     public MastershipTerm read(Kryo kryo, Input input, Class<MastershipTerm> type) {
-        final NodeId node = new NodeId(input.readString());
+        final NodeId node = (NodeId) kryo.readClassAndObject(input);
         final int term = input.readInt();
         return MastershipTerm.of(node, term);
     }
 
     @Override
     public void write(Kryo kryo, Output output, MastershipTerm object) {
-        output.writeString(object.master().toString());
+        kryo.writeClassAndObject(output, object.master());
         output.writeInt(object.termNumber());
     }
-
 }

@@ -201,6 +201,7 @@ public class KryoSerializerTest {
     @Test
     public void testMastershipTerm() {
         testSerialized(MastershipTerm.of(new NodeId("foo"), 2));
+        testSerialized(MastershipTerm.of(null, 0));
     }
 
     @Test

@@ -62,6 +62,9 @@ public class SimpleMastershipStore
 
     public static final IpAddress LOCALHOST = IpAddress.valueOf("127.0.0.1");
 
+    private static final int NOTHING = 0;
+    private static final int INIT = 1;
+
     private ControllerNode instance =
             new DefaultControllerNode(new NodeId("local"), LOCALHOST);
 
@@ -97,7 +100,7 @@ public class SimpleMastershipStore
                     break;
                 case NONE:
                     masterMap.put(deviceId, nodeId);
-                    termMap.put(deviceId, new AtomicInteger());
+                    termMap.put(deviceId, new AtomicInteger(INIT));
                     backups.add(nodeId);
                     break;
                 default:
@@ -149,7 +152,7 @@ public class SimpleMastershipStore
                     NodeId rel = reelect(node);
                     if (rel == null) {
                         masterMap.put(deviceId, node);
-                        termMap.put(deviceId, new AtomicInteger());
+                        termMap.put(deviceId, new AtomicInteger(INIT));
                         role = MastershipRole.MASTER;
                     }
                     backups.add(node);
@@ -159,7 +162,7 @@ public class SimpleMastershipStore
                 //first to get to it, say we are master
                 synchronized (this) {
                     masterMap.put(deviceId, node);
-                    termMap.put(deviceId, new AtomicInteger());
+                    termMap.put(deviceId, new AtomicInteger(INIT));
                     backups.add(node);
                     role = MastershipRole.MASTER;
                 }
@@ -194,9 +197,8 @@ public class SimpleMastershipStore
 
     @Override
     public MastershipTerm getTermFor(DeviceId deviceId) {
-        if ((masterMap.get(deviceId) == null) ||
-                (termMap.get(deviceId) == null)) {
-            return null;
+        if ((termMap.get(deviceId) == null)) {
+            return MastershipTerm.of(masterMap.get(deviceId), NOTHING);
         }
         return MastershipTerm.of(
                 masterMap.get(deviceId), termMap.get(deviceId).get());
@@ -220,7 +222,7 @@ public class SimpleMastershipStore
                 case STANDBY:
                 case NONE:
                     if (!termMap.containsKey(deviceId)) {
-                        termMap.put(deviceId, new AtomicInteger());
+                        termMap.put(deviceId, new AtomicInteger(INIT));
                     }
                     backups.add(nodeId);
                     break;