opendaylight/md-sal/sal-distributed-datastore/src/test/java/org/opendaylight/controller/cluster/datastore/entityownership/DistributedEntityOwnershipIntegrationTest.java

   1 /*
   2  * Copyright (c) 2015 Brocade Communications Systems, Inc. and others.  All rights reserved.
   3  *
   4  * This program and the accompanying materials are made available under the
   5  * terms of the Eclipse Public License v1.0 which accompanies this distribution,
   6  * and is available at http://www.eclipse.org/legal/epl-v10.html
   7  */
   8 package org.opendaylight.controller.cluster.datastore.entityownership;
   9
  10 import static org.junit.Assert.assertEquals;
  11 import static org.junit.Assert.assertFalse;
  12 import static org.junit.Assert.assertTrue;
  13 import static org.mockito.AdditionalMatchers.or;
  14 import static org.mockito.Mockito.atMost;
  15 import static org.mockito.Mockito.doNothing;
  16 import static org.mockito.Mockito.reset;
  17 import static org.mockito.Mockito.timeout;
  18 import static org.mockito.Mockito.verify;
  19 import static org.opendaylight.controller.cluster.datastore.entityownership.AbstractEntityOwnershipTest.ownershipChange;
  20 import static org.opendaylight.controller.cluster.datastore.entityownership.DistributedEntityOwnershipService.ENTITY_OWNERSHIP_SHARD_NAME;
  21 import static org.opendaylight.controller.cluster.datastore.entityownership.EntityOwnersModel.CANDIDATE_NAME_NODE_ID;
  22 import static org.opendaylight.controller.cluster.datastore.entityownership.EntityOwnersModel.entityPath;
  23 import akka.actor.ActorSystem;
  24 import akka.actor.Address;
  25 import akka.actor.AddressFromURIString;
  26 import akka.actor.Status.Failure;
  27 import akka.actor.Status.Success;
  28 import akka.cluster.Cluster;
  29 import akka.testkit.JavaTestKit;
  30 import com.google.common.base.Function;
  31 import com.google.common.base.Optional;
  32 import com.google.common.base.Stopwatch;
  33 import com.google.common.util.concurrent.Uninterruptibles;
  34 import com.typesafe.config.ConfigFactory;
  35 import java.util.ArrayList;
  36 import java.util.Arrays;
  37 import java.util.Collection;
  38 import java.util.concurrent.TimeUnit;
  39 import org.junit.After;
  40 import org.junit.Before;
  41 import org.junit.Test;
  42 import org.mockito.ArgumentCaptor;
  43 import org.mockito.Mock;
  44 import org.mockito.Mockito;
  45 import org.mockito.MockitoAnnotations;
  46 import org.opendaylight.controller.cluster.datastore.DatastoreContext;
  47 import org.opendaylight.controller.cluster.datastore.DistributedDataStore;
  48 import org.opendaylight.controller.cluster.datastore.IntegrationTestKit;
  49 import org.opendaylight.controller.cluster.datastore.entityownership.selectionstrategy.EntityOwnerSelectionStrategyConfig;
  50 import org.opendaylight.controller.cluster.datastore.messages.AddShardReplica;
  51 import org.opendaylight.controller.md.cluster.datastore.model.SchemaContextHelper;
  52 import org.opendaylight.controller.md.sal.common.api.clustering.CandidateAlreadyRegisteredException;
  53 import org.opendaylight.controller.md.sal.common.api.clustering.Entity;
  54 import org.opendaylight.controller.md.sal.common.api.clustering.EntityOwnershipCandidateRegistration;
  55 import org.opendaylight.controller.md.sal.common.api.clustering.EntityOwnershipChange;
  56 import org.opendaylight.controller.md.sal.common.api.clustering.EntityOwnershipListener;
  57 import org.opendaylight.controller.md.sal.common.api.clustering.EntityOwnershipState;
  58 import org.opendaylight.yang.gen.v1.urn.opendaylight.params.xml.ns.yang.controller.md.sal.clustering.entity.owners.rev150804.entity.owners.entity.type.entity.Candidate;
  59 import org.opendaylight.yangtools.yang.data.api.YangInstanceIdentifier;
  60 import org.opendaylight.yangtools.yang.data.api.schema.MapEntryNode;
  61 import org.opendaylight.yangtools.yang.data.api.schema.MapNode;
  62 import org.opendaylight.yangtools.yang.data.api.schema.NormalizedNode;
  63 import org.opendaylight.yangtools.yang.model.api.SchemaContext;
  64
  65 /**
  66  * End-to-end integration tests for the entity ownership functionality.
  67  *
  68  * @author Thomas Pantelis
  69  */
  70 public class DistributedEntityOwnershipIntegrationTest {
  71     private static final Address MEMBER_1_ADDRESS = AddressFromURIString.parse("akka.tcp://cluster-test@127.0.0.1:2558");
  72     private static final String MODULE_SHARDS_CONFIG = "module-shards-default.conf";
  73     private static final String MODULE_SHARDS_MEMBER_1_CONFIG = "module-shards-default-member-1.conf";
  74     private static final String ENTITY_TYPE1 = "entityType1";
  75     private static final String ENTITY_TYPE2 = "entityType2";
  76     private static final Entity ENTITY1 = new Entity(ENTITY_TYPE1, "entity1");
  77     private static final Entity ENTITY1_2 = new Entity(ENTITY_TYPE2, "entity1");
  78     private static final Entity ENTITY2 = new Entity(ENTITY_TYPE1, "entity2");
  79     private static final Entity ENTITY3 = new Entity(ENTITY_TYPE1, "entity3");
  80     private static final Entity ENTITY4 = new Entity(ENTITY_TYPE1, "entity4");
  81     private static final SchemaContext SCHEMA_CONTEXT = SchemaContextHelper.entityOwners();
  82
  83     private ActorSystem leaderSystem;
  84     private ActorSystem follower1System;
  85     private ActorSystem follower2System;
  86
  87     private final DatastoreContext.Builder leaderDatastoreContextBuilder =
  88             DatastoreContext.newBuilder().shardHeartbeatIntervalInMillis(100).shardElectionTimeoutFactor(5);
  89
  90     private final DatastoreContext.Builder followerDatastoreContextBuilder =
  91             DatastoreContext.newBuilder().shardHeartbeatIntervalInMillis(100).shardElectionTimeoutFactor(10000);
  92
  93     private DistributedDataStore leaderDistributedDataStore;
  94     private DistributedDataStore follower1DistributedDataStore;
  95     private DistributedDataStore follower2DistributedDataStore;
  96     private DistributedEntityOwnershipService leaderEntityOwnershipService;
  97     private DistributedEntityOwnershipService follower1EntityOwnershipService;
  98     private DistributedEntityOwnershipService follower2EntityOwnershipService;
  99     private IntegrationTestKit leaderTestKit;
 100     private IntegrationTestKit follower1TestKit;
 101     private IntegrationTestKit follower2TestKit;
 102
 103     @Mock
 104     private EntityOwnershipListener leaderMockListener;
 105
 106     @Mock
 107     private EntityOwnershipListener leaderMockListener2;
 108
 109     @Mock
 110     private EntityOwnershipListener follower1MockListener;
 111
 112     @Mock
 113     private EntityOwnershipListener follower2MockListener;
 114
 115     @Before
 116     public void setUp() {
 117         MockitoAnnotations.initMocks(this);
 118     }
 119
 120     @After
 121     public void tearDown() {
 122         if(leaderSystem != null) {
 123             JavaTestKit.shutdownActorSystem(leaderSystem);
 124         }
 125
 126         if(follower1System != null) {
 127             JavaTestKit.shutdownActorSystem(follower1System);
 128         }
 129
 130         if(follower2System != null) {
 131             JavaTestKit.shutdownActorSystem(follower2System);
 132         }
 133     }
 134
 135     private void startAllSystems() {
 136         startLeaderSystem();
 137         startFollower1System();
 138         startFollower2System();
 139     }
 140
 141     private void startFollower2System() {
 142         follower2System = ActorSystem.create("cluster-test", ConfigFactory.load().getConfig("Member3"));
 143         Cluster.get(follower2System).join(MEMBER_1_ADDRESS);
 144     }
 145
 146     private void startFollower1System() {
 147         follower1System = ActorSystem.create("cluster-test", ConfigFactory.load().getConfig("Member2"));
 148         Cluster.get(follower1System).join(MEMBER_1_ADDRESS);
 149     }
 150
 151     private void startLeaderSystem() {
 152         leaderSystem = ActorSystem.create("cluster-test", ConfigFactory.load().getConfig("Member1"));
 153         Cluster.get(leaderSystem).join(MEMBER_1_ADDRESS);
 154     }
 155
 156     private void initDatastores(String type) {
 157         initLeaderDatastore(type, MODULE_SHARDS_CONFIG);
 158
 159         initFollower1Datastore(type, MODULE_SHARDS_CONFIG);
 160
 161         follower2TestKit = new IntegrationTestKit(follower2System, followerDatastoreContextBuilder);
 162         follower2DistributedDataStore = follower2TestKit.setupDistributedDataStore(
 163                 type, MODULE_SHARDS_CONFIG, false, SCHEMA_CONTEXT);
 164
 165         leaderDistributedDataStore.waitTillReady();
 166         follower1DistributedDataStore.waitTillReady();
 167         follower2DistributedDataStore.waitTillReady();
 168
 169         startLeaderService();
 170
 171         startFollower1Service();
 172
 173         follower2EntityOwnershipService = new DistributedEntityOwnershipService(follower2DistributedDataStore,
 174                 EntityOwnerSelectionStrategyConfig.newBuilder().build());
 175         follower2EntityOwnershipService.start();
 176
 177         leaderTestKit.waitUntilLeader(leaderDistributedDataStore.getActorContext(), ENTITY_OWNERSHIP_SHARD_NAME);
 178     }
 179
 180     private void startFollower1Service() {
 181         follower1EntityOwnershipService = new DistributedEntityOwnershipService(follower1DistributedDataStore,
 182                 EntityOwnerSelectionStrategyConfig.newBuilder().build());
 183         follower1EntityOwnershipService.start();
 184     }
 185
 186     private void startLeaderService() {
 187         leaderEntityOwnershipService = new DistributedEntityOwnershipService(leaderDistributedDataStore,
 188                 EntityOwnerSelectionStrategyConfig.newBuilder().build());
 189         leaderEntityOwnershipService.start();
 190     }
 191
 192     private void initFollower1Datastore(String type, String moduleConfig) {
 193         follower1TestKit = new IntegrationTestKit(follower1System, followerDatastoreContextBuilder);
 194         follower1DistributedDataStore = follower1TestKit.setupDistributedDataStore(
 195                 type, moduleConfig, false, SCHEMA_CONTEXT);
 196     }
 197
 198     private void initLeaderDatastore(String type, String moduleConfig) {
 199         leaderTestKit = new IntegrationTestKit(leaderSystem, leaderDatastoreContextBuilder);
 200         leaderDistributedDataStore = leaderTestKit.setupDistributedDataStore(
 201                 type, moduleConfig, false, SCHEMA_CONTEXT);
 202     }
 203
 204     @Test
 205     public void test() throws Exception {
 206         startAllSystems();
 207         initDatastores("test");
 208
 209         leaderEntityOwnershipService.registerListener(ENTITY_TYPE1, leaderMockListener);
 210         leaderEntityOwnershipService.registerListener(ENTITY_TYPE2, leaderMockListener2);
 211         follower1EntityOwnershipService.registerListener(ENTITY_TYPE1, follower1MockListener);
 212
 213         // Register leader candidate for entity1 and verify it becomes owner
 214
 215         leaderEntityOwnershipService.registerCandidate(ENTITY1);
 216         verify(leaderMockListener, timeout(5000)).ownershipChanged(ownershipChange(ENTITY1, false, true, true));
 217         verify(follower1MockListener, timeout(5000)).ownershipChanged(ownershipChange(ENTITY1, false, false, true));
 218         reset(leaderMockListener, follower1MockListener);
 219
 220         verifyGetOwnershipState(leaderEntityOwnershipService, ENTITY1, true, true);
 221         verifyGetOwnershipState(follower1EntityOwnershipService, ENTITY1, false, true);
 222
 223         // Register leader candidate for entity1_2 (same id, different type) and verify it becomes owner
 224
 225         leaderEntityOwnershipService.registerCandidate(ENTITY1_2);
 226         verify(leaderMockListener2, timeout(5000)).ownershipChanged(ownershipChange(ENTITY1_2, false, true, true));
 227         verify(leaderMockListener, timeout(300).never()).ownershipChanged(ownershipChange(ENTITY1_2));
 228         reset(leaderMockListener2);
 229
 230         // Register follower1 candidate for entity1 and verify it gets added but doesn't become owner
 231
 232         follower1EntityOwnershipService.registerCandidate(ENTITY1);
 233         verifyCandidates(leaderDistributedDataStore, ENTITY1, "member-1", "member-2");
 234         verifyOwner(leaderDistributedDataStore, ENTITY1, "member-1");
 235         verify(leaderMockListener, timeout(300).never()).ownershipChanged(ownershipChange(ENTITY1));
 236         verify(follower1MockListener, timeout(300).never()).ownershipChanged(ownershipChange(ENTITY1));
 237
 238         // Register follower1 candidate for entity2 and verify it becomes owner
 239
 240         follower1EntityOwnershipService.registerCandidate(ENTITY2);
 241         verify(follower1MockListener, timeout(5000)).ownershipChanged(ownershipChange(ENTITY2, false, true, true));
 242         verify(leaderMockListener, timeout(5000)).ownershipChanged(ownershipChange(ENTITY2, false, false, true));
 243         reset(leaderMockListener, follower1MockListener);
 244
 245         // Register follower2 candidate for entity2 and verify it gets added but doesn't become owner
 246
 247         follower2EntityOwnershipService.registerListener(ENTITY_TYPE1, follower2MockListener);
 248         follower2EntityOwnershipService.registerCandidate(ENTITY2);
 249         verifyCandidates(leaderDistributedDataStore, ENTITY2, "member-2", "member-3");
 250         verifyOwner(leaderDistributedDataStore, ENTITY2, "member-2");
 251
 252         // Unregister follower1 candidate for entity2 and verify follower2 becomes owner
 253
 254         follower1EntityOwnershipService.unregisterCandidate(ENTITY2);
 255         verifyCandidates(leaderDistributedDataStore, ENTITY2, "member-3");
 256         verifyOwner(leaderDistributedDataStore, ENTITY2, "member-3");
 257         verify(follower1MockListener, timeout(5000)).ownershipChanged(ownershipChange(ENTITY2, true, false, true));
 258         verify(leaderMockListener, timeout(5000)).ownershipChanged(ownershipChange(ENTITY2, false, false, true));
 259
 260         // Depending on timing, follower2MockListener could get ownershipChanged with "false, false, true" if
 261         // if the original ownership change with "member-2 is replicated to follower2 after the listener is
 262         // registered.
 263         Uninterruptibles.sleepUninterruptibly(500, TimeUnit.MILLISECONDS);
 264         verify(follower2MockListener, atMost(1)).ownershipChanged(ownershipChange(ENTITY2, false, false, true));
 265         verify(follower2MockListener, timeout(5000)).ownershipChanged(ownershipChange(ENTITY2, false, true, true));
 266
 267         // Register follower1 candidate for entity3 and verify it becomes owner
 268
 269         follower1EntityOwnershipService.registerCandidate(ENTITY3);
 270         verifyOwner(leaderDistributedDataStore, ENTITY3, "member-2");
 271         verify(follower1MockListener, timeout(5000)).ownershipChanged(ownershipChange(ENTITY3, false, true, true));
 272         verify(follower2MockListener, timeout(5000)).ownershipChanged(ownershipChange(ENTITY3, false, false, true));
 273         verify(leaderMockListener, timeout(5000)).ownershipChanged(ownershipChange(ENTITY3, false, false, true));
 274
 275         // Register follower2 candidate for entity4 and verify it becomes owner
 276
 277         follower2EntityOwnershipService.registerCandidate(ENTITY4);
 278         verifyOwner(leaderDistributedDataStore, ENTITY4, "member-3");
 279         verify(follower2MockListener, timeout(5000)).ownershipChanged(ownershipChange(ENTITY4, false, true, true));
 280         verify(follower1MockListener, timeout(5000)).ownershipChanged(ownershipChange(ENTITY4, false, false, true));
 281         verify(leaderMockListener, timeout(5000)).ownershipChanged(ownershipChange(ENTITY4, false, false, true));
 282         reset(follower1MockListener, follower2MockListener);
 283
 284         // Register follower1 candidate for entity4 and verify it gets added but doesn't become owner
 285
 286         follower1EntityOwnershipService.registerCandidate(ENTITY4);
 287         verifyCandidates(leaderDistributedDataStore, ENTITY4, "member-3", "member-2");
 288         verifyOwner(leaderDistributedDataStore, ENTITY4, "member-3");
 289
 290         // Shutdown follower2 and verify it's owned entities (entity 2 & 4) get re-assigned
 291
 292         reset(leaderMockListener, follower1MockListener);
 293         JavaTestKit.shutdownActorSystem(follower2System);
 294
 295         verify(follower1MockListener, timeout(15000).times(2)).ownershipChanged(or(ownershipChange(ENTITY4, false, true, true),
 296                 ownershipChange(ENTITY2, false, false, false)));
 297         verify(leaderMockListener, timeout(15000).times(2)).ownershipChanged(or(ownershipChange(ENTITY4, false, false, true),
 298                 ownershipChange(ENTITY2, false, false, false)));
 299         verifyOwner(leaderDistributedDataStore, ENTITY2, ""); // no other candidate
 300
 301         // Register leader candidate for entity2 and verify it becomes owner
 302
 303         leaderEntityOwnershipService.registerCandidate(ENTITY2);
 304         verify(leaderMockListener, timeout(5000)).ownershipChanged(ownershipChange(ENTITY2, false, true, true));
 305         verifyOwner(leaderDistributedDataStore, ENTITY2, "member-1");
 306
 307         // Unregister leader candidate for entity2 and verify the owner is cleared
 308
 309         leaderEntityOwnershipService.unregisterCandidate(ENTITY2);
 310         verifyOwner(leaderDistributedDataStore, ENTITY2, "");
 311         verify(leaderMockListener, timeout(5000)).ownershipChanged(ownershipChange(ENTITY2, true, false, false));
 312         verify(follower1MockListener, timeout(5000)).ownershipChanged(ownershipChange(ENTITY2, false, false, false));
 313     }
 314
 315     /**
 316      * Reproduces bug <a href="https://bugs.opendaylight.org/show_bug.cgi?id=4554">4554</a>
 317      *
 318      * @throws CandidateAlreadyRegisteredException
 319      */
 320     @Test
 321     public void testCloseCandidateRegistrationInQuickSuccession() throws CandidateAlreadyRegisteredException {
 322         startAllSystems();
 323         initDatastores("testCloseCandidateRegistrationInQuickSuccession");
 324
 325         leaderEntityOwnershipService.registerListener(ENTITY_TYPE1, leaderMockListener);
 326         follower1EntityOwnershipService.registerListener(ENTITY_TYPE1, follower1MockListener);
 327         follower2EntityOwnershipService.registerListener(ENTITY_TYPE1, follower2MockListener);
 328
 329         final EntityOwnershipCandidateRegistration candidate1 = leaderEntityOwnershipService.registerCandidate(ENTITY1);
 330         final EntityOwnershipCandidateRegistration candidate2 = follower1EntityOwnershipService.registerCandidate(ENTITY1);
 331         final EntityOwnershipCandidateRegistration candidate3 = follower2EntityOwnershipService.registerCandidate(ENTITY1);
 332
 333         verify(leaderMockListener, timeout(5000)).ownershipChanged(ownershipChange(ENTITY1, false, true, true));
 334
 335         Mockito.reset(leaderMockListener);
 336
 337         candidate1.close();
 338         candidate2.close();
 339         candidate3.close();
 340
 341         ArgumentCaptor<EntityOwnershipChange> leaderChangeCaptor = ArgumentCaptor.forClass(EntityOwnershipChange.class);
 342         ArgumentCaptor<EntityOwnershipChange> follower1ChangeCaptor = ArgumentCaptor.forClass(EntityOwnershipChange.class);
 343         ArgumentCaptor<EntityOwnershipChange> follower2ChangeCaptor = ArgumentCaptor.forClass(EntityOwnershipChange.class);
 344         doNothing().when(leaderMockListener).ownershipChanged(leaderChangeCaptor.capture());
 345         doNothing().when(follower1MockListener).ownershipChanged(follower1ChangeCaptor.capture());
 346         doNothing().when(follower2MockListener).ownershipChanged(follower2ChangeCaptor.capture());
 347
 348         boolean passed = false;
 349         for(int i=0;i<100;i++) {
 350             Uninterruptibles.sleepUninterruptibly(50, TimeUnit.MILLISECONDS);
 351             if(!leaderEntityOwnershipService.getOwnershipState(ENTITY1).get().hasOwner() &&
 352                     !follower1EntityOwnershipService.getOwnershipState(ENTITY1).get().hasOwner() &&
 353                     !follower2EntityOwnershipService.getOwnershipState(ENTITY1).get().hasOwner()) {
 354                 passed = true;
 355                 break;
 356             }
 357         }
 358
 359         assertTrue("No ownership change message was sent with hasOwner=false", passed);
 360
 361         assertFalse(leaderChangeCaptor.getAllValues().get(leaderChangeCaptor.getAllValues().size()-1).hasOwner());
 362         assertFalse(follower1ChangeCaptor.getAllValues().get(follower1ChangeCaptor.getAllValues().size()-1).hasOwner());
 363         assertFalse(follower2ChangeCaptor.getAllValues().get(follower2ChangeCaptor.getAllValues().size()-1).hasOwner());
 364     }
 365
 366     /**
 367      * Tests bootstrapping the entity-ownership shard when there's no shards initially configured for local
 368      * member. The entity-ownership shard is initially created as inactive (ie remains a follower), requiring
 369      * an AddShardReplica request to join it to an existing leader.
 370      */
 371     @Test
 372     public void testEntityOwnershipShardBootstrapping() throws Throwable {
 373         startLeaderSystem();
 374         startFollower1System();
 375         String type = "testEntityOwnershipShardBootstrapping";
 376         initLeaderDatastore(type, MODULE_SHARDS_MEMBER_1_CONFIG);
 377         initFollower1Datastore(type, MODULE_SHARDS_MEMBER_1_CONFIG);
 378
 379         leaderDistributedDataStore.waitTillReady();
 380         follower1DistributedDataStore.waitTillReady();
 381
 382         startLeaderService();
 383         startFollower1Service();
 384
 385         leaderTestKit.waitUntilLeader(leaderDistributedDataStore.getActorContext(), ENTITY_OWNERSHIP_SHARD_NAME);
 386
 387         leaderEntityOwnershipService.registerListener(ENTITY_TYPE1, leaderMockListener);
 388
 389         // Register a candidate for follower1 - should get queued since follower1 has no leader
 390         follower1EntityOwnershipService.registerCandidate(ENTITY1);
 391         verify(leaderMockListener, timeout(300).never()).ownershipChanged(ownershipChange(ENTITY1));
 392
 393         // Add replica in follower1
 394         AddShardReplica addReplica = new AddShardReplica(ENTITY_OWNERSHIP_SHARD_NAME);
 395         follower1DistributedDataStore.getActorContext().getShardManager().tell(addReplica , follower1TestKit.getRef());
 396         Object reply = follower1TestKit.expectMsgAnyClassOf(JavaTestKit.duration("5 sec"), Success.class, Failure.class);
 397         if(reply instanceof Failure) {
 398             throw ((Failure)reply).cause();
 399         }
 400
 401         // The queued candidate registration should proceed
 402         verify(leaderMockListener, timeout(5000)).ownershipChanged(ownershipChange(ENTITY1));
 403
 404     }
 405
 406     private static void verifyGetOwnershipState(DistributedEntityOwnershipService service, Entity entity,
 407             boolean isOwner, boolean hasOwner) {
 408         Optional<EntityOwnershipState> state = service.getOwnershipState(entity);
 409         assertEquals("getOwnershipState present", true, state.isPresent());
 410         assertEquals("isOwner", isOwner, state.get().isOwner());
 411         assertEquals("hasOwner", hasOwner, state.get().hasOwner());
 412     }
 413
 414     private static void verifyCandidates(DistributedDataStore dataStore, Entity entity, String... expCandidates) throws Exception {
 415         AssertionError lastError = null;
 416         Stopwatch sw = Stopwatch.createStarted();
 417         while(sw.elapsed(TimeUnit.MILLISECONDS) <= 5000) {
 418             Optional<NormalizedNode<?, ?>> possible = dataStore.newReadOnlyTransaction().read(
 419                     entityPath(entity.getType(), entity.getId()).node(Candidate.QNAME)).get(5, TimeUnit.SECONDS);
 420             try {
 421                 assertEquals("Candidates not found for " + entity, true, possible.isPresent());
 422                 Collection<String> actual = new ArrayList<>();
 423                 for(MapEntryNode candidate: ((MapNode)possible.get()).getValue()) {
 424                     actual.add(candidate.getChild(CANDIDATE_NAME_NODE_ID).get().getValue().toString());
 425                 }
 426
 427                 assertEquals("Candidates for " + entity, Arrays.asList(expCandidates), actual);
 428                 return;
 429             } catch (AssertionError e) {
 430                 lastError = e;
 431                 Uninterruptibles.sleepUninterruptibly(300, TimeUnit.MILLISECONDS);
 432             }
 433         }
 434
 435         throw lastError;
 436     }
 437
 438     private static void verifyOwner(final DistributedDataStore dataStore, Entity entity, String expOwner) {
 439         AbstractEntityOwnershipTest.verifyOwner(expOwner, entity.getType(), entity.getId(),
 440                 new Function<YangInstanceIdentifier, NormalizedNode<?,?>>() {
 441                     @Override
 442                     public NormalizedNode<?, ?> apply(YangInstanceIdentifier path) {
 443                         try {
 444                             return dataStore.newReadOnlyTransaction().read(path).get(5, TimeUnit.SECONDS).get();
 445                         } catch (Exception e) {
 446                             return null;
 447                         }
 448                     }
 449                 });
 450     }
 451 }