opendaylight/md-sal/sal-distributed-datastore/src/test/java/org/opendaylight/controller/cluster/datastore/AbstractShardTest.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;
   9
  10 import static org.junit.Assert.assertEquals;
  11 import static org.junit.Assert.assertNotNull;
  12 import static org.junit.Assert.assertTrue;
  13 import static org.junit.Assert.fail;
  14 import static org.mockito.Matchers.any;
  15 import static org.mockito.Mockito.doAnswer;
  16 import static org.mockito.Mockito.doNothing;
  17 import static org.mockito.Mockito.doReturn;
  18 import static org.mockito.Mockito.mock;
  19 import static org.opendaylight.controller.cluster.datastore.DataStoreVersions.CURRENT_VERSION;
  20 import akka.actor.ActorRef;
  21 import akka.actor.PoisonPill;
  22 import akka.actor.Props;
  23 import akka.dispatch.Dispatchers;
  24 import akka.japi.Creator;
  25 import akka.pattern.Patterns;
  26 import akka.testkit.TestActorRef;
  27 import akka.util.Timeout;
  28 import com.google.common.base.Function;
  29 import com.google.common.base.Optional;
  30 import com.google.common.util.concurrent.Futures;
  31 import com.google.common.util.concurrent.ListenableFuture;
  32 import com.google.common.util.concurrent.Uninterruptibles;
  33 import java.util.Collections;
  34 import java.util.Set;
  35 import java.util.concurrent.CountDownLatch;
  36 import java.util.concurrent.ExecutionException;
  37 import java.util.concurrent.TimeUnit;
  38 import java.util.concurrent.TimeoutException;
  39 import java.util.concurrent.atomic.AtomicInteger;
  40 import org.junit.After;
  41 import org.junit.Assert;
  42 import org.junit.Before;
  43 import org.mockito.invocation.InvocationOnMock;
  44 import org.mockito.stubbing.Answer;
  45 import org.opendaylight.controller.cluster.access.concepts.MemberName;
  46 import org.opendaylight.controller.cluster.datastore.DatastoreContext.Builder;
  47 import org.opendaylight.controller.cluster.datastore.identifiers.ShardIdentifier;
  48 import org.opendaylight.controller.cluster.datastore.messages.BatchedModifications;
  49 import org.opendaylight.controller.cluster.datastore.messages.ForwardedReadyTransaction;
  50 import org.opendaylight.controller.cluster.datastore.modification.MutableCompositeModification;
  51 import org.opendaylight.controller.cluster.datastore.modification.WriteModification;
  52 import org.opendaylight.controller.cluster.datastore.utils.SerializationUtils;
  53 import org.opendaylight.controller.cluster.raft.ReplicatedLogEntry;
  54 import org.opendaylight.controller.cluster.raft.Snapshot;
  55 import org.opendaylight.controller.cluster.raft.TestActorFactory;
  56 import org.opendaylight.controller.cluster.raft.utils.InMemoryJournal;
  57 import org.opendaylight.controller.cluster.raft.utils.InMemorySnapshotStore;
  58 import org.opendaylight.controller.md.cluster.datastore.model.CarsModel;
  59 import org.opendaylight.controller.md.cluster.datastore.model.TestModel;
  60 import org.opendaylight.yangtools.concepts.Identifier;
  61 import org.opendaylight.yangtools.yang.data.api.YangInstanceIdentifier;
  62 import org.opendaylight.yangtools.yang.data.api.YangInstanceIdentifier.PathArgument;
  63 import org.opendaylight.yangtools.yang.data.api.schema.DataContainerChild;
  64 import org.opendaylight.yangtools.yang.data.api.schema.MapEntryNode;
  65 import org.opendaylight.yangtools.yang.data.api.schema.NormalizedNode;
  66 import org.opendaylight.yangtools.yang.data.api.schema.tree.DataTree;
  67 import org.opendaylight.yangtools.yang.data.api.schema.tree.DataTreeCandidate;
  68 import org.opendaylight.yangtools.yang.data.api.schema.tree.DataTreeCandidateNode;
  69 import org.opendaylight.yangtools.yang.data.api.schema.tree.DataTreeCandidateTip;
  70 import org.opendaylight.yangtools.yang.data.api.schema.tree.DataTreeModification;
  71 import org.opendaylight.yangtools.yang.data.api.schema.tree.DataValidationFailedException;
  72 import org.opendaylight.yangtools.yang.data.api.schema.tree.ModificationType;
  73 import org.opendaylight.yangtools.yang.data.api.schema.tree.TreeType;
  74 import org.opendaylight.yangtools.yang.data.impl.schema.ImmutableNodes;
  75 import org.opendaylight.yangtools.yang.data.impl.schema.tree.InMemoryDataTreeFactory;
  76 import org.opendaylight.yangtools.yang.model.api.SchemaContext;
  77 import scala.concurrent.Await;
  78 import scala.concurrent.Future;
  79 import scala.concurrent.duration.Duration;
  80
  81 /**
  82  * Abstract base for shard unit tests.
  83  *
  84  * @author Thomas Pantelis
  85  */
  86 public abstract class AbstractShardTest extends AbstractActorTest{
  87     protected static final SchemaContext SCHEMA_CONTEXT = TestModel.createTestContext();
  88
  89     private static final AtomicInteger NEXT_SHARD_NUM = new AtomicInteger();
  90
  91     protected final ShardIdentifier shardID = ShardIdentifier.create("inventory", MemberName.forName("member-1"),
  92         "config" + NEXT_SHARD_NUM.getAndIncrement());
  93
  94     protected final Builder dataStoreContextBuilder = DatastoreContext.newBuilder().
  95             shardJournalRecoveryLogBatchSize(3).shardSnapshotBatchCount(5000).
  96             shardHeartbeatIntervalInMillis(100);
  97
  98     protected final TestActorFactory actorFactory = new TestActorFactory(getSystem());
  99
 100     @Before
 101     public void setUp() {
 102         InMemorySnapshotStore.clear();
 103         InMemoryJournal.clear();
 104     }
 105
 106     @After
 107     public void tearDown() {
 108         InMemorySnapshotStore.clear();
 109         InMemoryJournal.clear();
 110         actorFactory.close();
 111     }
 112
 113     protected DatastoreContext newDatastoreContext() {
 114         return dataStoreContextBuilder.build();
 115     }
 116
 117     protected Props newShardProps() {
 118         return newShardBuilder().props();
 119     }
 120
 121     protected Shard.Builder newShardBuilder() {
 122         return Shard.builder().id(shardID).datastoreContext(newDatastoreContext()).schemaContext(SCHEMA_CONTEXT);
 123     }
 124
 125     protected void testRecovery(final Set<Integer> listEntryKeys) throws Exception {
 126         // Create the actor and wait for recovery complete.
 127
 128         final int nListEntries = listEntryKeys.size();
 129
 130         final CountDownLatch recoveryComplete = new CountDownLatch(1);
 131
 132         @SuppressWarnings("serial")
 133         final Creator<Shard> creator = new Creator<Shard>() {
 134             @Override
 135             public Shard create() throws Exception {
 136                 return new Shard(newShardBuilder()) {
 137                     @Override
 138                     protected void onRecoveryComplete() {
 139                         try {
 140                             super.onRecoveryComplete();
 141                         } finally {
 142                             recoveryComplete.countDown();
 143                         }
 144                     }
 145                 };
 146             }
 147         };
 148
 149         final TestActorRef<Shard> shard = TestActorRef.create(getSystem(),
 150                 Props.create(new DelegatingShardCreator(creator)).withDispatcher(Dispatchers.DefaultDispatcherId()), "testRecovery");
 151
 152         assertEquals("Recovery complete", true, recoveryComplete.await(5, TimeUnit.SECONDS));
 153
 154         // Verify data in the data store.
 155
 156         final NormalizedNode<?, ?> outerList = readStore(shard, TestModel.OUTER_LIST_PATH);
 157         assertNotNull(TestModel.OUTER_LIST_QNAME.getLocalName() + " not found", outerList);
 158         assertTrue(TestModel.OUTER_LIST_QNAME.getLocalName() + " value is not Iterable",
 159                 outerList.getValue() instanceof Iterable);
 160         for(final Object entry: (Iterable<?>) outerList.getValue()) {
 161             assertTrue(TestModel.OUTER_LIST_QNAME.getLocalName() + " entry is not MapEntryNode",
 162                     entry instanceof MapEntryNode);
 163             final MapEntryNode mapEntry = (MapEntryNode)entry;
 164             final Optional<DataContainerChild<? extends PathArgument, ?>> idLeaf =
 165                     mapEntry.getChild(new YangInstanceIdentifier.NodeIdentifier(TestModel.ID_QNAME));
 166             assertTrue("Missing leaf " + TestModel.ID_QNAME.getLocalName(), idLeaf.isPresent());
 167             final Object value = idLeaf.get().getValue();
 168             assertTrue("Unexpected value for leaf "+ TestModel.ID_QNAME.getLocalName() + ": " + value,
 169                     listEntryKeys.remove(value));
 170         }
 171
 172         if(!listEntryKeys.isEmpty()) {
 173             fail("Missing " + TestModel.OUTER_LIST_QNAME.getLocalName() + " entries with keys: " +
 174                     listEntryKeys);
 175         }
 176
 177         assertEquals("Last log index", nListEntries,
 178                 shard.underlyingActor().getShardMBean().getLastLogIndex());
 179         assertEquals("Commit index", nListEntries,
 180                 shard.underlyingActor().getShardMBean().getCommitIndex());
 181         assertEquals("Last applied", nListEntries,
 182                 shard.underlyingActor().getShardMBean().getLastApplied());
 183
 184         shard.tell(PoisonPill.getInstance(), ActorRef.noSender());
 185     }
 186
 187     protected void verifyLastApplied(final TestActorRef<Shard> shard, final long expectedValue) {
 188         long lastApplied = -1;
 189         for(int i = 0; i < 20 * 5; i++) {
 190             lastApplied = shard.underlyingActor().getShardMBean().getLastApplied();
 191             if(lastApplied == expectedValue) {
 192                 return;
 193             }
 194             Uninterruptibles.sleepUninterruptibly(50, TimeUnit.MILLISECONDS);
 195         }
 196
 197         Assert.fail(String.format("Expected last applied: %d, Actual: %d", expectedValue, lastApplied));
 198     }
 199
 200     protected ShardDataTreeCohort setupMockWriteTransaction(final String cohortName,
 201             final ShardDataTree dataStore, final YangInstanceIdentifier path, final NormalizedNode<?, ?> data,
 202             final MutableCompositeModification modification) {
 203         return setupMockWriteTransaction(cohortName, dataStore, path, data, modification, null);
 204     }
 205
 206     protected ShardDataTreeCohort setupMockWriteTransaction(final String cohortName,
 207             final ShardDataTree dataStore, final YangInstanceIdentifier path, final NormalizedNode<?, ?> data,
 208             final MutableCompositeModification modification,
 209             final Function<ShardDataTreeCohort, ListenableFuture<Void>> preCommit) {
 210
 211         final ReadWriteShardDataTreeTransaction tx = dataStore.newReadWriteTransaction("setup-mock-" + cohortName, null);
 212         tx.getSnapshot().write(path, data);
 213         final ShardDataTreeCohort cohort = createDelegatingMockCohort(cohortName, dataStore.finishTransaction(tx), preCommit);
 214
 215         modification.addModification(new WriteModification(path, data));
 216
 217         return cohort;
 218     }
 219
 220     protected ShardDataTreeCohort createDelegatingMockCohort(final String cohortName,
 221             final ShardDataTreeCohort actual) {
 222         return createDelegatingMockCohort(cohortName, actual, null);
 223     }
 224
 225     protected ShardDataTreeCohort createDelegatingMockCohort(final String cohortName,
 226             final ShardDataTreeCohort actual,
 227             final Function<ShardDataTreeCohort, ListenableFuture<Void>> preCommit) {
 228         final ShardDataTreeCohort cohort = mock(ShardDataTreeCohort.class, cohortName);
 229
 230         doAnswer(new Answer<ListenableFuture<Boolean>>() {
 231             @Override
 232             public ListenableFuture<Boolean> answer(final InvocationOnMock invocation) {
 233                 return actual.canCommit();
 234             }
 235         }).when(cohort).canCommit();
 236
 237         doAnswer(new Answer<ListenableFuture<Void>>() {
 238             @Override
 239             public ListenableFuture<Void> answer(final InvocationOnMock invocation) throws Throwable {
 240                 if(preCommit != null) {
 241                     return preCommit.apply(actual);
 242                 } else {
 243                     return actual.preCommit();
 244                 }
 245             }
 246         }).when(cohort).preCommit();
 247
 248         doAnswer(new Answer<ListenableFuture<Void>>() {
 249             @Override
 250             public ListenableFuture<Void> answer(final InvocationOnMock invocation) throws Throwable {
 251                 return actual.commit();
 252             }
 253         }).when(cohort).commit();
 254
 255         doAnswer(new Answer<ListenableFuture<Void>>() {
 256             @Override
 257             public ListenableFuture<Void> answer(final InvocationOnMock invocation) throws Throwable {
 258                 return actual.abort();
 259             }
 260         }).when(cohort).abort();
 261
 262         doAnswer(new Answer<DataTreeCandidateTip>() {
 263             @Override
 264             public DataTreeCandidateTip answer(final InvocationOnMock invocation) {
 265                 return actual.getCandidate();
 266             }
 267         }).when(cohort).getCandidate();
 268
 269         return cohort;
 270     }
 271
 272     protected Object prepareReadyTransactionMessage(boolean remoteReadWriteTransaction, Shard shard, ShardDataTreeCohort cohort,
 273                                                                   String transactionID,
 274                                                                   MutableCompositeModification modification,
 275                                                                   boolean doCommitOnReady) {
 276         if(remoteReadWriteTransaction){
 277             return prepareForwardedReadyTransaction(cohort, transactionID, CURRENT_VERSION,
 278                     doCommitOnReady);
 279         } else {
 280             setupCohortDecorator(shard, cohort);
 281             return prepareBatchedModifications(transactionID, modification, doCommitOnReady);
 282         }
 283     }
 284
 285     protected ShardDataTreeCohort mockShardDataTreeCohort() {
 286         ShardDataTreeCohort cohort = mock(ShardDataTreeCohort.class);
 287         doReturn(Futures.immediateFuture(Boolean.TRUE)).when(cohort).canCommit();
 288         doReturn(Futures.immediateFuture(null)).when(cohort).preCommit();
 289         doReturn(Futures.immediateFuture(null)).when(cohort).commit();
 290         doReturn(mockCandidate("candidate")).when(cohort).getCandidate();
 291         return cohort;
 292     }
 293
 294     static ShardDataTreeTransactionParent newShardDataTreeTransactionParent(ShardDataTreeCohort cohort) {
 295         ShardDataTreeTransactionParent mockParent = mock(ShardDataTreeTransactionParent.class);
 296         doReturn(cohort).when(mockParent).finishTransaction(any(ReadWriteShardDataTreeTransaction.class));
 297         doNothing().when(mockParent).abortTransaction(any(AbstractShardDataTreeTransaction.class));
 298         return mockParent;
 299     }
 300
 301     protected ForwardedReadyTransaction prepareForwardedReadyTransaction(ShardDataTreeCohort cohort,
 302             String transactionID, short version, boolean doCommitOnReady) {
 303         return new ForwardedReadyTransaction(transactionID, version,
 304                 new ReadWriteShardDataTreeTransaction(newShardDataTreeTransactionParent(cohort), transactionID,
 305                         mock(DataTreeModification.class)), doCommitOnReady);
 306     }
 307
 308     protected Object prepareReadyTransactionMessage(boolean remoteReadWriteTransaction, Shard shard, ShardDataTreeCohort cohort,
 309                                                                   String transactionID,
 310                                                                   MutableCompositeModification modification) {
 311         return prepareReadyTransactionMessage(remoteReadWriteTransaction, shard, cohort, transactionID, modification, false);
 312     }
 313
 314     protected void setupCohortDecorator(Shard shard, final ShardDataTreeCohort cohort) {
 315         shard.getCommitCoordinator().setCohortDecorator(new ShardCommitCoordinator.CohortDecorator() {
 316             @Override
 317             public ShardDataTreeCohort decorate(Identifier transactionID, ShardDataTreeCohort actual) {
 318                 return cohort;
 319             }
 320         });
 321     }
 322
 323     protected BatchedModifications prepareBatchedModifications(String transactionID,
 324                                                                MutableCompositeModification modification) {
 325         return prepareBatchedModifications(transactionID, modification, false);
 326     }
 327
 328     private static BatchedModifications prepareBatchedModifications(String transactionID,
 329                                                              MutableCompositeModification modification,
 330                                                              boolean doCommitOnReady) {
 331         final BatchedModifications batchedModifications = new BatchedModifications(transactionID, CURRENT_VERSION, null);
 332         batchedModifications.addModification(modification);
 333         batchedModifications.setReady(true);
 334         batchedModifications.setDoCommitOnReady(doCommitOnReady);
 335         batchedModifications.setTotalMessagesSent(1);
 336         return batchedModifications;
 337     }
 338
 339
 340     public static NormalizedNode<?,?> readStore(final TestActorRef<? extends Shard> shard, final YangInstanceIdentifier id)
 341             throws ExecutionException, InterruptedException {
 342         return shard.underlyingActor().getDataStore().readNode(id).orNull();
 343     }
 344
 345     public static NormalizedNode<?,?> readStore(final DataTree store, final YangInstanceIdentifier id) {
 346         return store.takeSnapshot().readNode(id).orNull();
 347     }
 348
 349     public static void writeToStore(final TestActorRef<Shard> shard, final YangInstanceIdentifier id,
 350             final NormalizedNode<?,?> node) throws InterruptedException, ExecutionException {
 351         Future<Object> future = Patterns.ask(shard, newBatchedModifications("tx", id, node, true, true, 1),
 352                 new Timeout(5, TimeUnit.SECONDS));
 353         try {
 354             Await.ready(future, Duration.create(5, TimeUnit.SECONDS));
 355         } catch(TimeoutException e) {
 356             throw new ExecutionException(e);
 357         }
 358     }
 359
 360     public static void writeToStore(final ShardDataTree store, final YangInstanceIdentifier id,
 361             final NormalizedNode<?,?> node) throws InterruptedException, ExecutionException {
 362         final ReadWriteShardDataTreeTransaction transaction = store.newReadWriteTransaction("writeToStore", null);
 363
 364         transaction.getSnapshot().write(id, node);
 365         final ShardDataTreeCohort cohort = transaction.ready();
 366         cohort.canCommit().get();
 367         cohort.preCommit().get();
 368         cohort.commit();
 369     }
 370
 371     public static void mergeToStore(final ShardDataTree store, final YangInstanceIdentifier id,
 372             final NormalizedNode<?,?> node) throws InterruptedException, ExecutionException {
 373         final ReadWriteShardDataTreeTransaction transaction = store.newReadWriteTransaction("writeToStore", null);
 374
 375         transaction.getSnapshot().merge(id, node);
 376         final ShardDataTreeCohort cohort = transaction.ready();
 377         cohort.canCommit().get();
 378         cohort.preCommit().get();
 379         cohort.commit();
 380     }
 381
 382     public static void writeToStore(final DataTree store, final YangInstanceIdentifier id,
 383             final NormalizedNode<?,?> node) throws DataValidationFailedException {
 384         final DataTreeModification transaction = store.takeSnapshot().newModification();
 385
 386         transaction.write(id, node);
 387         transaction.ready();
 388         store.validate(transaction);
 389         final DataTreeCandidate candidate = store.prepare(transaction);
 390         store.commit(candidate);
 391     }
 392
 393     DataTree setupInMemorySnapshotStore() throws DataValidationFailedException {
 394         final DataTree testStore = InMemoryDataTreeFactory.getInstance().create(TreeType.OPERATIONAL);
 395         testStore.setSchemaContext(SCHEMA_CONTEXT);
 396
 397         writeToStore(testStore, TestModel.TEST_PATH, ImmutableNodes.containerNode(TestModel.TEST_QNAME));
 398
 399         final NormalizedNode<?, ?> root = readStore(testStore, YangInstanceIdentifier.EMPTY);
 400
 401         InMemorySnapshotStore.addSnapshot(shardID.toString(), Snapshot.create(
 402                 SerializationUtils.serializeNormalizedNode(root),
 403                 Collections.<ReplicatedLogEntry>emptyList(), 0, 1, -1, -1));
 404         return testStore;
 405     }
 406
 407     static DataTreeCandidatePayload payloadForModification(final DataTree source, final DataTreeModification mod) throws DataValidationFailedException {
 408         source.validate(mod);
 409         final DataTreeCandidate candidate = source.prepare(mod);
 410         source.commit(candidate);
 411         return DataTreeCandidatePayload.create(candidate);
 412     }
 413
 414     static BatchedModifications newBatchedModifications(final String transactionID, final YangInstanceIdentifier path,
 415             final NormalizedNode<?, ?> data, final boolean ready, final boolean doCommitOnReady, final int messagesSent) {
 416         return newBatchedModifications(transactionID, null, path, data, ready, doCommitOnReady, messagesSent);
 417     }
 418
 419     static BatchedModifications newBatchedModifications(final String transactionID, final String transactionChainID,
 420             final YangInstanceIdentifier path, final NormalizedNode<?, ?> data, final boolean ready, final boolean doCommitOnReady,
 421             final int messagesSent) {
 422         final BatchedModifications batched = new BatchedModifications(transactionID, CURRENT_VERSION, transactionChainID);
 423         batched.addModification(new WriteModification(path, data));
 424         batched.setReady(ready);
 425         batched.setDoCommitOnReady(doCommitOnReady);
 426         batched.setTotalMessagesSent(messagesSent);
 427         return batched;
 428     }
 429
 430     @SuppressWarnings("unchecked")
 431     static void verifyOuterListEntry(final TestActorRef<Shard> shard, final Object expIDValue) throws Exception {
 432         final NormalizedNode<?, ?> outerList = readStore(shard, TestModel.OUTER_LIST_PATH);
 433         assertNotNull(TestModel.OUTER_LIST_QNAME.getLocalName() + " not found", outerList);
 434         assertTrue(TestModel.OUTER_LIST_QNAME.getLocalName() + " value is not Iterable",
 435                 outerList.getValue() instanceof Iterable);
 436         final Object entry = ((Iterable<Object>)outerList.getValue()).iterator().next();
 437         assertTrue(TestModel.OUTER_LIST_QNAME.getLocalName() + " entry is not MapEntryNode",
 438                 entry instanceof MapEntryNode);
 439         final MapEntryNode mapEntry = (MapEntryNode)entry;
 440         final Optional<DataContainerChild<? extends PathArgument, ?>> idLeaf =
 441                 mapEntry.getChild(new YangInstanceIdentifier.NodeIdentifier(TestModel.ID_QNAME));
 442         assertTrue("Missing leaf " + TestModel.ID_QNAME.getLocalName(), idLeaf.isPresent());
 443         assertEquals(TestModel.ID_QNAME.getLocalName() + " value", expIDValue, idLeaf.get().getValue());
 444     }
 445
 446     public static DataTreeCandidateTip mockCandidate(final String name) {
 447         final DataTreeCandidateTip mockCandidate = mock(DataTreeCandidateTip.class, name);
 448         final DataTreeCandidateNode mockCandidateNode = mock(DataTreeCandidateNode.class, name + "-node");
 449         doReturn(ModificationType.WRITE).when(mockCandidateNode).getModificationType();
 450         doReturn(Optional.of(ImmutableNodes.containerNode(CarsModel.CARS_QNAME))).when(mockCandidateNode).getDataAfter();
 451         doReturn(CarsModel.BASE_PATH).when(mockCandidate).getRootPath();
 452         doReturn(mockCandidateNode).when(mockCandidate).getRootNode();
 453         return mockCandidate;
 454     }
 455
 456     static DataTreeCandidateTip mockUnmodifiedCandidate(final String name) {
 457         final DataTreeCandidateTip mockCandidate = mock(DataTreeCandidateTip.class, name);
 458         final DataTreeCandidateNode mockCandidateNode = mock(DataTreeCandidateNode.class, name + "-node");
 459         doReturn(ModificationType.UNMODIFIED).when(mockCandidateNode).getModificationType();
 460         doReturn(YangInstanceIdentifier.EMPTY).when(mockCandidate).getRootPath();
 461         doReturn(mockCandidateNode).when(mockCandidate).getRootNode();
 462         return mockCandidate;
 463     }
 464
 465     static void commitTransaction(final DataTree store, final DataTreeModification modification) throws DataValidationFailedException {
 466         modification.ready();
 467         store.validate(modification);
 468         store.commit(store.prepare(modification));
 469     }
 470
 471     @SuppressWarnings("serial")
 472     public static final class DelegatingShardCreator implements Creator<Shard> {
 473         private final Creator<Shard> delegate;
 474
 475         DelegatingShardCreator(final Creator<Shard> delegate) {
 476             this.delegate = delegate;
 477         }
 478
 479         @Override
 480         public Shard create() throws Exception {
 481             return delegate.create();
 482         }
 483     }
 484 }