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