Make sure we purge transaction on abort
[controller.git] / opendaylight / md-sal / sal-distributed-datastore / src / main / java / org / opendaylight / controller / cluster / datastore / Shard.java
1 /*
2  * Copyright (c) 2014 Cisco 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 akka.actor.ActorRef;
11 import akka.actor.ActorSelection;
12 import akka.actor.Cancellable;
13 import akka.actor.ExtendedActorSystem;
14 import akka.actor.Props;
15 import akka.actor.Status;
16 import akka.actor.Status.Failure;
17 import akka.serialization.JavaSerializer;
18 import akka.serialization.Serialization;
19 import com.google.common.annotations.VisibleForTesting;
20 import com.google.common.base.Optional;
21 import com.google.common.base.Preconditions;
22 import com.google.common.base.Ticker;
23 import com.google.common.base.Verify;
24 import com.google.common.collect.ImmutableList;
25 import com.google.common.collect.ImmutableMap;
26 import com.google.common.collect.Range;
27 import java.io.IOException;
28 import java.util.Arrays;
29 import java.util.Collection;
30 import java.util.Collections;
31 import java.util.Map;
32 import java.util.concurrent.TimeUnit;
33 import org.eclipse.jdt.annotation.NonNull;
34 import org.eclipse.jdt.annotation.Nullable;
35 import org.opendaylight.controller.cluster.access.ABIVersion;
36 import org.opendaylight.controller.cluster.access.commands.ConnectClientRequest;
37 import org.opendaylight.controller.cluster.access.commands.ConnectClientSuccess;
38 import org.opendaylight.controller.cluster.access.commands.LocalHistoryRequest;
39 import org.opendaylight.controller.cluster.access.commands.NotLeaderException;
40 import org.opendaylight.controller.cluster.access.commands.OutOfSequenceEnvelopeException;
41 import org.opendaylight.controller.cluster.access.commands.TransactionRequest;
42 import org.opendaylight.controller.cluster.access.concepts.ClientIdentifier;
43 import org.opendaylight.controller.cluster.access.concepts.FrontendIdentifier;
44 import org.opendaylight.controller.cluster.access.concepts.LocalHistoryIdentifier;
45 import org.opendaylight.controller.cluster.access.concepts.Request;
46 import org.opendaylight.controller.cluster.access.concepts.RequestEnvelope;
47 import org.opendaylight.controller.cluster.access.concepts.RequestException;
48 import org.opendaylight.controller.cluster.access.concepts.RequestSuccess;
49 import org.opendaylight.controller.cluster.access.concepts.RetiredGenerationException;
50 import org.opendaylight.controller.cluster.access.concepts.RuntimeRequestException;
51 import org.opendaylight.controller.cluster.access.concepts.SliceableMessage;
52 import org.opendaylight.controller.cluster.access.concepts.TransactionIdentifier;
53 import org.opendaylight.controller.cluster.access.concepts.UnsupportedRequestException;
54 import org.opendaylight.controller.cluster.common.actor.CommonConfig;
55 import org.opendaylight.controller.cluster.common.actor.Dispatchers;
56 import org.opendaylight.controller.cluster.common.actor.Dispatchers.DispatcherType;
57 import org.opendaylight.controller.cluster.common.actor.MessageTracker;
58 import org.opendaylight.controller.cluster.common.actor.MessageTracker.Error;
59 import org.opendaylight.controller.cluster.common.actor.MeteringBehavior;
60 import org.opendaylight.controller.cluster.datastore.exceptions.NoShardLeaderException;
61 import org.opendaylight.controller.cluster.datastore.identifiers.ShardIdentifier;
62 import org.opendaylight.controller.cluster.datastore.jmx.mbeans.shard.ShardDataTreeListenerInfoMXBeanImpl;
63 import org.opendaylight.controller.cluster.datastore.jmx.mbeans.shard.ShardMBeanFactory;
64 import org.opendaylight.controller.cluster.datastore.jmx.mbeans.shard.ShardStats;
65 import org.opendaylight.controller.cluster.datastore.messages.AbortTransaction;
66 import org.opendaylight.controller.cluster.datastore.messages.ActorInitialized;
67 import org.opendaylight.controller.cluster.datastore.messages.BatchedModifications;
68 import org.opendaylight.controller.cluster.datastore.messages.CanCommitTransaction;
69 import org.opendaylight.controller.cluster.datastore.messages.CloseTransactionChain;
70 import org.opendaylight.controller.cluster.datastore.messages.CommitTransaction;
71 import org.opendaylight.controller.cluster.datastore.messages.CreateTransaction;
72 import org.opendaylight.controller.cluster.datastore.messages.CreateTransactionReply;
73 import org.opendaylight.controller.cluster.datastore.messages.ForwardedReadyTransaction;
74 import org.opendaylight.controller.cluster.datastore.messages.GetShardDataTree;
75 import org.opendaylight.controller.cluster.datastore.messages.MakeLeaderLocal;
76 import org.opendaylight.controller.cluster.datastore.messages.OnDemandShardState;
77 import org.opendaylight.controller.cluster.datastore.messages.PeerAddressResolved;
78 import org.opendaylight.controller.cluster.datastore.messages.PersistAbortTransactionPayload;
79 import org.opendaylight.controller.cluster.datastore.messages.ReadyLocalTransaction;
80 import org.opendaylight.controller.cluster.datastore.messages.RegisterDataTreeChangeListener;
81 import org.opendaylight.controller.cluster.datastore.messages.ShardLeaderStateChanged;
82 import org.opendaylight.controller.cluster.datastore.messages.UpdateSchemaContext;
83 import org.opendaylight.controller.cluster.datastore.persisted.AbortTransactionPayload;
84 import org.opendaylight.controller.cluster.datastore.persisted.DatastoreSnapshot;
85 import org.opendaylight.controller.cluster.datastore.persisted.DatastoreSnapshot.ShardSnapshot;
86 import org.opendaylight.controller.cluster.messaging.MessageAssembler;
87 import org.opendaylight.controller.cluster.messaging.MessageSlicer;
88 import org.opendaylight.controller.cluster.messaging.SliceOptions;
89 import org.opendaylight.controller.cluster.notifications.LeaderStateChanged;
90 import org.opendaylight.controller.cluster.notifications.RegisterRoleChangeListener;
91 import org.opendaylight.controller.cluster.notifications.RoleChangeNotifier;
92 import org.opendaylight.controller.cluster.raft.LeadershipTransferFailedException;
93 import org.opendaylight.controller.cluster.raft.RaftActor;
94 import org.opendaylight.controller.cluster.raft.RaftActorRecoveryCohort;
95 import org.opendaylight.controller.cluster.raft.RaftActorSnapshotCohort;
96 import org.opendaylight.controller.cluster.raft.RaftState;
97 import org.opendaylight.controller.cluster.raft.base.messages.FollowerInitialSyncUpStatus;
98 import org.opendaylight.controller.cluster.raft.client.messages.OnDemandRaftState;
99 import org.opendaylight.controller.cluster.raft.messages.AppendEntriesReply;
100 import org.opendaylight.controller.cluster.raft.messages.RequestLeadership;
101 import org.opendaylight.controller.cluster.raft.messages.ServerRemoved;
102 import org.opendaylight.controller.cluster.raft.protobuff.client.messages.Payload;
103 import org.opendaylight.yangtools.concepts.Identifier;
104 import org.opendaylight.yangtools.yang.data.api.schema.tree.DataTree;
105 import org.opendaylight.yangtools.yang.data.api.schema.tree.DataValidationFailedException;
106 import org.opendaylight.yangtools.yang.data.api.schema.tree.TreeType;
107 import org.opendaylight.yangtools.yang.model.api.SchemaContext;
108 import org.opendaylight.yangtools.yang.model.api.SchemaContextProvider;
109 import scala.concurrent.duration.FiniteDuration;
110
111 /**
112  * A Shard represents a portion of the logical data tree.
113  *
114  * <p>
115  * Our Shard uses InMemoryDataTree as it's internal representation and delegates all requests it
116  */
117 public class Shard extends RaftActor {
118
119     @VisibleForTesting
120     static final Object TX_COMMIT_TIMEOUT_CHECK_MESSAGE = new Object() {
121         @Override
122         public String toString() {
123             return "txCommitTimeoutCheck";
124         }
125     };
126
127     @VisibleForTesting
128     static final Object GET_SHARD_MBEAN_MESSAGE = new Object() {
129         @Override
130         public String toString() {
131             return "getShardMBeanMessage";
132         }
133     };
134
135     static final Object RESUME_NEXT_PENDING_TRANSACTION = new Object() {
136         @Override
137         public String toString() {
138             return "resumeNextPendingTransaction";
139         }
140     };
141
142     // FIXME: shard names should be encapsulated in their own class and this should be exposed as a constant.
143     public static final String DEFAULT_NAME = "default";
144
145     private static final Collection<ABIVersion> SUPPORTED_ABIVERSIONS;
146
147     static {
148         final ABIVersion[] values = ABIVersion.values();
149         final ABIVersion[] real = Arrays.copyOfRange(values, 1, values.length - 1);
150         SUPPORTED_ABIVERSIONS = ImmutableList.copyOf(real).reverse();
151     }
152
153     // FIXME: make this a dynamic property based on mailbox size and maximum number of clients
154     private static final int CLIENT_MAX_MESSAGES = 1000;
155
156     // The state of this Shard
157     private final ShardDataTree store;
158
159     /// The name of this shard
160     private final String name;
161
162     private final String shardName;
163
164     private final ShardStats shardMBean;
165
166     private final ShardDataTreeListenerInfoMXBeanImpl listenerInfoMXBean;
167
168     private DatastoreContext datastoreContext;
169
170     private final ShardCommitCoordinator commitCoordinator;
171
172     private long transactionCommitTimeout;
173
174     private Cancellable txCommitTimeoutCheckSchedule;
175
176     private final Optional<ActorRef> roleChangeNotifier;
177
178     private final MessageTracker appendEntriesReplyTracker;
179
180     private final ShardTransactionActorFactory transactionActorFactory;
181
182     private final ShardSnapshotCohort snapshotCohort;
183
184     private final DataTreeChangeListenerSupport treeChangeSupport = new DataTreeChangeListenerSupport(this);
185
186     private ShardSnapshot restoreFromSnapshot;
187
188     private final ShardTransactionMessageRetrySupport messageRetrySupport;
189
190     private final FrontendMetadata frontendMetadata;
191     private Map<FrontendIdentifier, LeaderFrontendState> knownFrontends = ImmutableMap.of();
192     private boolean paused;
193
194     private final MessageSlicer responseMessageSlicer;
195     private final Dispatchers dispatchers;
196
197     private final MessageAssembler requestMessageAssembler;
198
199     protected Shard(final AbstractBuilder<?, ?> builder) {
200         super(builder.getId().toString(), builder.getPeerAddresses(),
201                 Optional.of(builder.getDatastoreContext().getShardRaftConfig()), DataStoreVersions.CURRENT_VERSION);
202
203         this.name = builder.getId().toString();
204         this.shardName = builder.getId().getShardName();
205         this.datastoreContext = builder.getDatastoreContext();
206         this.restoreFromSnapshot = builder.getRestoreFromSnapshot();
207         this.frontendMetadata = new FrontendMetadata(name);
208
209         setPersistence(datastoreContext.isPersistent());
210
211         LOG.info("Shard created : {}, persistent : {}", name, datastoreContext.isPersistent());
212
213         ShardDataTreeChangeListenerPublisherActorProxy treeChangeListenerPublisher =
214                 new ShardDataTreeChangeListenerPublisherActorProxy(getContext(), name + "-DTCL-publisher", name);
215         if (builder.getDataTree() != null) {
216             store = new ShardDataTree(this, builder.getSchemaContext(), builder.getDataTree(),
217                     treeChangeListenerPublisher, name, frontendMetadata);
218         } else {
219             store = new ShardDataTree(this, builder.getSchemaContext(), builder.getTreeType(),
220                     builder.getDatastoreContext().getStoreRoot(), treeChangeListenerPublisher, name, frontendMetadata);
221         }
222
223         shardMBean = ShardMBeanFactory.getShardStatsMBean(name, datastoreContext.getDataStoreMXBeanType(), this);
224
225         if (isMetricsCaptureEnabled()) {
226             getContext().become(new MeteringBehavior(this));
227         }
228
229         commitCoordinator = new ShardCommitCoordinator(store, LOG, this.name);
230
231         setTransactionCommitTimeout();
232
233         // create a notifier actor for each cluster member
234         roleChangeNotifier = createRoleChangeNotifier(name);
235
236         appendEntriesReplyTracker = new MessageTracker(AppendEntriesReply.class,
237                 getRaftActorContext().getConfigParams().getIsolatedCheckIntervalInMillis());
238
239         dispatchers = new Dispatchers(context().system().dispatchers());
240         transactionActorFactory = new ShardTransactionActorFactory(store, datastoreContext,
241             dispatchers.getDispatcherPath(Dispatchers.DispatcherType.Transaction),
242                 self(), getContext(), shardMBean, builder.getId().getShardName());
243
244         snapshotCohort = ShardSnapshotCohort.create(getContext(), builder.getId().getMemberName(), store, LOG,
245             this.name);
246
247         messageRetrySupport = new ShardTransactionMessageRetrySupport(this);
248
249         responseMessageSlicer = MessageSlicer.builder().logContext(this.name)
250                 .messageSliceSize(datastoreContext.getMaximumMessageSliceSize())
251                 .fileBackedStreamFactory(getRaftActorContext().getFileBackedOutputStreamFactory())
252                 .expireStateAfterInactivity(2, TimeUnit.MINUTES).build();
253
254         requestMessageAssembler = MessageAssembler.builder().logContext(this.name)
255                 .fileBackedStreamFactory(getRaftActorContext().getFileBackedOutputStreamFactory())
256                 .assembledMessageCallback((message, sender) -> self().tell(message, sender))
257                 .expireStateAfterInactivity(datastoreContext.getRequestTimeout(), TimeUnit.NANOSECONDS).build();
258
259         listenerInfoMXBean = new ShardDataTreeListenerInfoMXBeanImpl(name, datastoreContext.getDataStoreMXBeanType(),
260                 self());
261         listenerInfoMXBean.register();
262     }
263
264     private void setTransactionCommitTimeout() {
265         transactionCommitTimeout = TimeUnit.MILLISECONDS.convert(
266                 datastoreContext.getShardTransactionCommitTimeoutInSeconds(), TimeUnit.SECONDS) / 2;
267     }
268
269     private Optional<ActorRef> createRoleChangeNotifier(final String shardId) {
270         ActorRef shardRoleChangeNotifier = this.getContext().actorOf(
271             RoleChangeNotifier.getProps(shardId), shardId + "-notifier");
272         return Optional.of(shardRoleChangeNotifier);
273     }
274
275     @Override
276     public void postStop() {
277         LOG.info("Stopping Shard {}", persistenceId());
278
279         super.postStop();
280
281         messageRetrySupport.close();
282
283         if (txCommitTimeoutCheckSchedule != null) {
284             txCommitTimeoutCheckSchedule.cancel();
285         }
286
287         commitCoordinator.abortPendingTransactions("Transaction aborted due to shutdown.", this);
288
289         shardMBean.unregisterMBean();
290         listenerInfoMXBean.unregister();
291     }
292
293     @Override
294     protected void handleRecover(final Object message) {
295         LOG.debug("{}: onReceiveRecover: Received message {} from {}", persistenceId(), message.getClass(),
296             getSender());
297
298         super.handleRecover(message);
299         if (LOG.isTraceEnabled()) {
300             appendEntriesReplyTracker.begin();
301         }
302     }
303
304     @Override
305     protected void handleNonRaftCommand(final Object message) {
306         try (MessageTracker.Context context = appendEntriesReplyTracker.received(message)) {
307             final Optional<Error> maybeError = context.error();
308             if (maybeError.isPresent()) {
309                 LOG.trace("{} : AppendEntriesReply failed to arrive at the expected interval {}", persistenceId(),
310                     maybeError.get());
311             }
312
313             store.resetTransactionBatch();
314
315             if (message instanceof RequestEnvelope) {
316                 handleRequestEnvelope((RequestEnvelope)message);
317             } else if (MessageAssembler.isHandledMessage(message)) {
318                 handleRequestAssemblerMessage(message);
319             } else if (message instanceof ConnectClientRequest) {
320                 handleConnectClient((ConnectClientRequest)message);
321             } else if (CreateTransaction.isSerializedType(message)) {
322                 handleCreateTransaction(message);
323             } else if (message instanceof BatchedModifications) {
324                 handleBatchedModifications((BatchedModifications)message);
325             } else if (message instanceof ForwardedReadyTransaction) {
326                 handleForwardedReadyTransaction((ForwardedReadyTransaction) message);
327             } else if (message instanceof ReadyLocalTransaction) {
328                 handleReadyLocalTransaction((ReadyLocalTransaction)message);
329             } else if (CanCommitTransaction.isSerializedType(message)) {
330                 handleCanCommitTransaction(CanCommitTransaction.fromSerializable(message));
331             } else if (CommitTransaction.isSerializedType(message)) {
332                 handleCommitTransaction(CommitTransaction.fromSerializable(message));
333             } else if (AbortTransaction.isSerializedType(message)) {
334                 handleAbortTransaction(AbortTransaction.fromSerializable(message));
335             } else if (CloseTransactionChain.isSerializedType(message)) {
336                 closeTransactionChain(CloseTransactionChain.fromSerializable(message));
337             } else if (message instanceof RegisterDataTreeChangeListener) {
338                 treeChangeSupport.onMessage((RegisterDataTreeChangeListener) message, isLeader(), hasLeader());
339             } else if (message instanceof UpdateSchemaContext) {
340                 updateSchemaContext((UpdateSchemaContext) message);
341             } else if (message instanceof PeerAddressResolved) {
342                 PeerAddressResolved resolved = (PeerAddressResolved) message;
343                 setPeerAddress(resolved.getPeerId(), resolved.getPeerAddress());
344             } else if (TX_COMMIT_TIMEOUT_CHECK_MESSAGE.equals(message)) {
345                 commitTimeoutCheck();
346             } else if (message instanceof DatastoreContext) {
347                 onDatastoreContext((DatastoreContext)message);
348             } else if (message instanceof RegisterRoleChangeListener) {
349                 roleChangeNotifier.get().forward(message, context());
350             } else if (message instanceof FollowerInitialSyncUpStatus) {
351                 shardMBean.setFollowerInitialSyncStatus(((FollowerInitialSyncUpStatus) message).isInitialSyncDone());
352                 context().parent().tell(message, self());
353             } else if (GET_SHARD_MBEAN_MESSAGE.equals(message)) {
354                 sender().tell(getShardMBean(), self());
355             } else if (message instanceof GetShardDataTree) {
356                 sender().tell(store.getDataTree(), self());
357             } else if (message instanceof ServerRemoved) {
358                 context().parent().forward(message, context());
359             } else if (ShardTransactionMessageRetrySupport.TIMER_MESSAGE_CLASS.isInstance(message)) {
360                 messageRetrySupport.onTimerMessage(message);
361             } else if (message instanceof DataTreeCohortActorRegistry.CohortRegistryCommand) {
362                 store.processCohortRegistryCommand(getSender(),
363                         (DataTreeCohortActorRegistry.CohortRegistryCommand) message);
364             } else if (message instanceof PersistAbortTransactionPayload) {
365                 final TransactionIdentifier txId = ((PersistAbortTransactionPayload) message).getTransactionId();
366                 persistPayload(txId, AbortTransactionPayload.create(
367                         txId, datastoreContext.getInitialPayloadSerializedBufferCapacity()), true);
368                 store.purgeTransaction(txId, null);
369             } else if (message instanceof MakeLeaderLocal) {
370                 onMakeLeaderLocal();
371             } else if (RESUME_NEXT_PENDING_TRANSACTION.equals(message)) {
372                 store.resumeNextPendingTransaction();
373             } else if (!responseMessageSlicer.handleMessage(message)) {
374                 super.handleNonRaftCommand(message);
375             }
376         }
377     }
378
379     private void handleRequestAssemblerMessage(final Object message) {
380         dispatchers.getDispatcher(DispatcherType.Serialization).execute(() -> {
381             JavaSerializer.currentSystem().value_$eq((ExtendedActorSystem) context().system());
382             requestMessageAssembler.handleMessage(message, self());
383         });
384     }
385
386     @SuppressWarnings("checkstyle:IllegalCatch")
387     private void handleRequestEnvelope(final RequestEnvelope envelope) {
388         final long now = ticker().read();
389         try {
390             final RequestSuccess<?, ?> success = handleRequest(envelope, now);
391             if (success != null) {
392                 final long executionTimeNanos = ticker().read() - now;
393                 if (success instanceof SliceableMessage) {
394                     dispatchers.getDispatcher(DispatcherType.Serialization).execute(() ->
395                         responseMessageSlicer.slice(SliceOptions.builder().identifier(success.getTarget())
396                             .message(envelope.newSuccessEnvelope(success, executionTimeNanos))
397                             .sendTo(envelope.getMessage().getReplyTo()).replyTo(self())
398                             .onFailureCallback(t -> LOG.warn("Error slicing response {}", success, t)).build()));
399                 } else {
400                     envelope.sendSuccess(success, executionTimeNanos);
401                 }
402             }
403         } catch (RequestException e) {
404             LOG.debug("{}: request {} failed", persistenceId(), envelope, e);
405             envelope.sendFailure(e, ticker().read() - now);
406         } catch (Exception e) {
407             LOG.debug("{}: request {} caused failure", persistenceId(), envelope, e);
408             envelope.sendFailure(new RuntimeRequestException("Request failed to process", e),
409                 ticker().read() - now);
410         }
411     }
412
413     private void commitTimeoutCheck() {
414         store.checkForExpiredTransactions(transactionCommitTimeout, this::updateAccess);
415         commitCoordinator.checkForExpiredTransactions(transactionCommitTimeout, this);
416         requestMessageAssembler.checkExpiredAssembledMessageState();
417     }
418
419     private Optional<Long> updateAccess(final SimpleShardDataTreeCohort cohort) {
420         final FrontendIdentifier frontend = cohort.getIdentifier().getHistoryId().getClientId().getFrontendId();
421         final LeaderFrontendState state = knownFrontends.get(frontend);
422         if (state == null) {
423             // Not tell-based protocol, do nothing
424             return Optional.absent();
425         }
426
427         if (isIsolatedLeader()) {
428             // We are isolated and no new request can come through until we emerge from it. We are still updating
429             // liveness of frontend when we see it attempting to communicate. Use the last access timer.
430             return Optional.of(state.getLastSeenTicks());
431         }
432
433         // If this frontend has freshly connected, give it some time to catch up before killing its transactions.
434         return Optional.of(state.getLastConnectTicks());
435     }
436
437     private void onMakeLeaderLocal() {
438         LOG.debug("{}: onMakeLeaderLocal received", persistenceId());
439         if (isLeader()) {
440             getSender().tell(new Status.Success(null), getSelf());
441             return;
442         }
443
444         final ActorSelection leader = getLeader();
445
446         if (leader == null) {
447             // Leader is not present. The cluster is most likely trying to
448             // elect a leader and we should let that run its normal course
449
450             // TODO we can wait for the election to complete and retry the
451             // request. We can also let the caller retry by sending a flag
452             // in the response indicating the request is "reTryable".
453             getSender().tell(new Failure(
454                     new LeadershipTransferFailedException("We cannot initiate leadership transfer to local node. "
455                             + "Currently there is no leader for " + persistenceId())),
456                     getSelf());
457             return;
458         }
459
460         leader.tell(new RequestLeadership(getId(), getSender()), getSelf());
461     }
462
463     // Acquire our frontend tracking handle and verify generation matches
464     private @Nullable LeaderFrontendState findFrontend(final ClientIdentifier clientId) throws RequestException {
465         final LeaderFrontendState existing = knownFrontends.get(clientId.getFrontendId());
466         if (existing != null) {
467             final int cmp = Long.compareUnsigned(existing.getIdentifier().getGeneration(), clientId.getGeneration());
468             if (cmp == 0) {
469                 existing.touch();
470                 return existing;
471             }
472             if (cmp > 0) {
473                 LOG.debug("{}: rejecting request from outdated client {}", persistenceId(), clientId);
474                 throw new RetiredGenerationException(clientId.getGeneration(),
475                     existing.getIdentifier().getGeneration());
476             }
477
478             LOG.info("{}: retiring state {}, outdated by request from client {}", persistenceId(), existing, clientId);
479             existing.retire();
480             knownFrontends.remove(clientId.getFrontendId());
481         } else {
482             LOG.debug("{}: client {} is not yet known", persistenceId(), clientId);
483         }
484
485         return null;
486     }
487
488     private LeaderFrontendState getFrontend(final ClientIdentifier clientId) throws RequestException {
489         final LeaderFrontendState ret = findFrontend(clientId);
490         if (ret != null) {
491             return ret;
492         }
493
494         // TODO: a dedicated exception would be better, but this is technically true, too
495         throw new OutOfSequenceEnvelopeException(0);
496     }
497
498     private static @NonNull ABIVersion selectVersion(final ConnectClientRequest message) {
499         final Range<ABIVersion> clientRange = Range.closed(message.getMinVersion(), message.getMaxVersion());
500         for (ABIVersion v : SUPPORTED_ABIVERSIONS) {
501             if (clientRange.contains(v)) {
502                 return v;
503             }
504         }
505
506         throw new IllegalArgumentException(String.format(
507             "No common version between backend versions %s and client versions %s", SUPPORTED_ABIVERSIONS,
508             clientRange));
509     }
510
511     @SuppressWarnings("checkstyle:IllegalCatch")
512     private void handleConnectClient(final ConnectClientRequest message) {
513         try {
514             final ClientIdentifier clientId = message.getTarget();
515             final LeaderFrontendState existing = findFrontend(clientId);
516             if (existing != null) {
517                 existing.touch();
518             }
519
520             if (!isLeader() || !isLeaderActive()) {
521                 LOG.info("{}: not currently leader, rejecting request {}. isLeader: {}, isLeaderActive: {},"
522                                 + "isLeadershipTransferInProgress: {}.",
523                         persistenceId(), message, isLeader(), isLeaderActive(), isLeadershipTransferInProgress());
524                 throw new NotLeaderException(getSelf());
525             }
526
527             final ABIVersion selectedVersion = selectVersion(message);
528             final LeaderFrontendState frontend;
529             if (existing == null) {
530                 frontend = new LeaderFrontendState(persistenceId(), clientId, store);
531                 knownFrontends.put(clientId.getFrontendId(), frontend);
532                 LOG.debug("{}: created state {} for client {}", persistenceId(), frontend, clientId);
533             } else {
534                 frontend = existing;
535             }
536
537             frontend.reconnect();
538             message.getReplyTo().tell(new ConnectClientSuccess(message.getTarget(), message.getSequence(), getSelf(),
539                 ImmutableList.of(), store.getDataTree(), CLIENT_MAX_MESSAGES).toVersion(selectedVersion),
540                 ActorRef.noSender());
541         } catch (RequestException | RuntimeException e) {
542             message.getReplyTo().tell(new Failure(e), ActorRef.noSender());
543         }
544     }
545
546     private @Nullable RequestSuccess<?, ?> handleRequest(final RequestEnvelope envelope, final long now)
547             throws RequestException {
548         // We are not the leader, hence we want to fail-fast.
549         if (!isLeader() || paused || !isLeaderActive()) {
550             LOG.debug("{}: not currently active leader, rejecting request {}. isLeader: {}, isLeaderActive: {},"
551                             + "isLeadershipTransferInProgress: {}, paused: {}",
552                     persistenceId(), envelope, isLeader(), isLeaderActive(), isLeadershipTransferInProgress(), paused);
553             throw new NotLeaderException(getSelf());
554         }
555
556         final Request<?, ?> request = envelope.getMessage();
557         if (request instanceof TransactionRequest) {
558             final TransactionRequest<?> txReq = (TransactionRequest<?>)request;
559             final ClientIdentifier clientId = txReq.getTarget().getHistoryId().getClientId();
560             return getFrontend(clientId).handleTransactionRequest(txReq, envelope, now);
561         } else if (request instanceof LocalHistoryRequest) {
562             final LocalHistoryRequest<?> lhReq = (LocalHistoryRequest<?>)request;
563             final ClientIdentifier clientId = lhReq.getTarget().getClientId();
564             return getFrontend(clientId).handleLocalHistoryRequest(lhReq, envelope, now);
565         } else {
566             LOG.warn("{}: rejecting unsupported request {}", persistenceId(), request);
567             throw new UnsupportedRequestException(request);
568         }
569     }
570
571     private boolean hasLeader() {
572         return getLeaderId() != null;
573     }
574
575     public int getPendingTxCommitQueueSize() {
576         return store.getQueueSize();
577     }
578
579     public int getCohortCacheSize() {
580         return commitCoordinator.getCohortCacheSize();
581     }
582
583     @Override
584     protected Optional<ActorRef> getRoleChangeNotifier() {
585         return roleChangeNotifier;
586     }
587
588     String getShardName() {
589         return shardName;
590     }
591
592     @Override
593     protected LeaderStateChanged newLeaderStateChanged(final String memberId, final String leaderId,
594             final short leaderPayloadVersion) {
595         return isLeader() ? new ShardLeaderStateChanged(memberId, leaderId, store.getDataTree(), leaderPayloadVersion)
596                 : new ShardLeaderStateChanged(memberId, leaderId, leaderPayloadVersion);
597     }
598
599     protected void onDatastoreContext(final DatastoreContext context) {
600         datastoreContext = context;
601
602         setTransactionCommitTimeout();
603
604         setPersistence(datastoreContext.isPersistent());
605
606         updateConfigParams(datastoreContext.getShardRaftConfig());
607     }
608
609     // applyState() will be invoked once consensus is reached on the payload
610     void persistPayload(final Identifier id, final Payload payload, final boolean batchHint) {
611         boolean canSkipPayload = !hasFollowers() && !persistence().isRecoveryApplicable();
612         if (canSkipPayload) {
613             applyState(self(), id, payload);
614         } else {
615             // We are faking the sender
616             persistData(self(), id, payload, batchHint);
617         }
618     }
619
620     private void handleCommitTransaction(final CommitTransaction commit) {
621         if (isLeader()) {
622             commitCoordinator.handleCommit(commit.getTransactionId(), getSender(), this);
623         } else {
624             ActorSelection leader = getLeader();
625             if (leader == null) {
626                 messageRetrySupport.addMessageToRetry(commit, getSender(),
627                         "Could not commit transaction " + commit.getTransactionId());
628             } else {
629                 LOG.debug("{}: Forwarding CommitTransaction to leader {}", persistenceId(), leader);
630                 leader.forward(commit, getContext());
631             }
632         }
633     }
634
635     private void handleCanCommitTransaction(final CanCommitTransaction canCommit) {
636         LOG.debug("{}: Can committing transaction {}", persistenceId(), canCommit.getTransactionId());
637
638         if (isLeader()) {
639             commitCoordinator.handleCanCommit(canCommit.getTransactionId(), getSender(), this);
640         } else {
641             ActorSelection leader = getLeader();
642             if (leader == null) {
643                 messageRetrySupport.addMessageToRetry(canCommit, getSender(),
644                         "Could not canCommit transaction " + canCommit.getTransactionId());
645             } else {
646                 LOG.debug("{}: Forwarding CanCommitTransaction to leader {}", persistenceId(), leader);
647                 leader.forward(canCommit, getContext());
648             }
649         }
650     }
651
652     @SuppressWarnings("checkstyle:IllegalCatch")
653     protected void handleBatchedModificationsLocal(final BatchedModifications batched, final ActorRef sender) {
654         try {
655             commitCoordinator.handleBatchedModifications(batched, sender, this);
656         } catch (Exception e) {
657             LOG.error("{}: Error handling BatchedModifications for Tx {}", persistenceId(),
658                     batched.getTransactionId(), e);
659             sender.tell(new Failure(e), getSelf());
660         }
661     }
662
663     private void handleBatchedModifications(final BatchedModifications batched) {
664         // This message is sent to prepare the modifications transaction directly on the Shard as an
665         // optimization to avoid the extra overhead of a separate ShardTransaction actor. On the last
666         // BatchedModifications message, the caller sets the ready flag in the message indicating
667         // modifications are complete. The reply contains the cohort actor path (this actor) for the caller
668         // to initiate the 3-phase commit. This also avoids the overhead of sending an additional
669         // ReadyTransaction message.
670
671         // If we're not the leader then forward to the leader. This is a safety measure - we shouldn't
672         // normally get here if we're not the leader as the front-end (TransactionProxy) should determine
673         // the primary/leader shard. However with timing and caching on the front-end, there's a small
674         // window where it could have a stale leader during leadership transitions.
675         //
676         boolean isLeaderActive = isLeaderActive();
677         if (isLeader() && isLeaderActive) {
678             handleBatchedModificationsLocal(batched, getSender());
679         } else {
680             ActorSelection leader = getLeader();
681             if (!isLeaderActive || leader == null) {
682                 messageRetrySupport.addMessageToRetry(batched, getSender(),
683                         "Could not process BatchedModifications " + batched.getTransactionId());
684             } else {
685                 // If this is not the first batch and leadership changed in between batched messages,
686                 // we need to reconstruct previous BatchedModifications from the transaction
687                 // DataTreeModification, honoring the max batched modification count, and forward all the
688                 // previous BatchedModifications to the new leader.
689                 Collection<BatchedModifications> newModifications = commitCoordinator
690                         .createForwardedBatchedModifications(batched,
691                                 datastoreContext.getShardBatchedModificationCount());
692
693                 LOG.debug("{}: Forwarding {} BatchedModifications to leader {}", persistenceId(),
694                         newModifications.size(), leader);
695
696                 for (BatchedModifications bm : newModifications) {
697                     leader.forward(bm, getContext());
698                 }
699             }
700         }
701     }
702
703     private boolean failIfIsolatedLeader(final ActorRef sender) {
704         if (isIsolatedLeader()) {
705             sender.tell(new Failure(new NoShardLeaderException(String.format(
706                     "Shard %s was the leader but has lost contact with all of its followers. Either all"
707                     + " other follower nodes are down or this node is isolated by a network partition.",
708                     persistenceId()))), getSelf());
709             return true;
710         }
711
712         return false;
713     }
714
715     protected boolean isIsolatedLeader() {
716         return getRaftState() == RaftState.IsolatedLeader;
717     }
718
719     @SuppressWarnings("checkstyle:IllegalCatch")
720     private void handleReadyLocalTransaction(final ReadyLocalTransaction message) {
721         LOG.debug("{}: handleReadyLocalTransaction for {}", persistenceId(), message.getTransactionId());
722
723         boolean isLeaderActive = isLeaderActive();
724         if (isLeader() && isLeaderActive) {
725             try {
726                 commitCoordinator.handleReadyLocalTransaction(message, getSender(), this);
727             } catch (Exception e) {
728                 LOG.error("{}: Error handling ReadyLocalTransaction for Tx {}", persistenceId(),
729                         message.getTransactionId(), e);
730                 getSender().tell(new Failure(e), getSelf());
731             }
732         } else {
733             ActorSelection leader = getLeader();
734             if (!isLeaderActive || leader == null) {
735                 messageRetrySupport.addMessageToRetry(message, getSender(),
736                         "Could not process ready local transaction " + message.getTransactionId());
737             } else {
738                 LOG.debug("{}: Forwarding ReadyLocalTransaction to leader {}", persistenceId(), leader);
739                 message.setRemoteVersion(getCurrentBehavior().getLeaderPayloadVersion());
740                 leader.forward(message, getContext());
741             }
742         }
743     }
744
745     private void handleForwardedReadyTransaction(final ForwardedReadyTransaction forwardedReady) {
746         LOG.debug("{}: handleForwardedReadyTransaction for {}", persistenceId(), forwardedReady.getTransactionId());
747
748         boolean isLeaderActive = isLeaderActive();
749         if (isLeader() && isLeaderActive) {
750             commitCoordinator.handleForwardedReadyTransaction(forwardedReady, getSender(), this);
751         } else {
752             ActorSelection leader = getLeader();
753             if (!isLeaderActive || leader == null) {
754                 messageRetrySupport.addMessageToRetry(forwardedReady, getSender(),
755                         "Could not process forwarded ready transaction " + forwardedReady.getTransactionId());
756             } else {
757                 LOG.debug("{}: Forwarding ForwardedReadyTransaction to leader {}", persistenceId(), leader);
758
759                 ReadyLocalTransaction readyLocal = new ReadyLocalTransaction(forwardedReady.getTransactionId(),
760                         forwardedReady.getTransaction().getSnapshot(), forwardedReady.isDoImmediateCommit(),
761                         forwardedReady.getParticipatingShardNames());
762                 readyLocal.setRemoteVersion(getCurrentBehavior().getLeaderPayloadVersion());
763                 leader.forward(readyLocal, getContext());
764             }
765         }
766     }
767
768     private void handleAbortTransaction(final AbortTransaction abort) {
769         doAbortTransaction(abort.getTransactionId(), getSender());
770     }
771
772     void doAbortTransaction(final Identifier transactionID, final ActorRef sender) {
773         commitCoordinator.handleAbort(transactionID, sender, this);
774     }
775
776     private void handleCreateTransaction(final Object message) {
777         if (isLeader()) {
778             createTransaction(CreateTransaction.fromSerializable(message));
779         } else if (getLeader() != null) {
780             getLeader().forward(message, getContext());
781         } else {
782             getSender().tell(new Failure(new NoShardLeaderException(
783                     "Could not create a shard transaction", persistenceId())), getSelf());
784         }
785     }
786
787     private void closeTransactionChain(final CloseTransactionChain closeTransactionChain) {
788         if (isLeader()) {
789             final LocalHistoryIdentifier id = closeTransactionChain.getIdentifier();
790             // FIXME: CONTROLLER-1628: stage purge once no transactions are present
791             store.closeTransactionChain(id, null);
792             store.purgeTransactionChain(id, null);
793         } else if (getLeader() != null) {
794             getLeader().forward(closeTransactionChain, getContext());
795         } else {
796             LOG.warn("{}: Could not close transaction {}", persistenceId(), closeTransactionChain.getIdentifier());
797         }
798     }
799
800     @SuppressWarnings("checkstyle:IllegalCatch")
801     private void createTransaction(final CreateTransaction createTransaction) {
802         try {
803             if (TransactionType.fromInt(createTransaction.getTransactionType()) != TransactionType.READ_ONLY
804                     && failIfIsolatedLeader(getSender())) {
805                 return;
806             }
807
808             ActorRef transactionActor = createTransaction(createTransaction.getTransactionType(),
809                 createTransaction.getTransactionId());
810
811             getSender().tell(new CreateTransactionReply(Serialization.serializedActorPath(transactionActor),
812                     createTransaction.getTransactionId(), createTransaction.getVersion()).toSerializable(), getSelf());
813         } catch (Exception e) {
814             getSender().tell(new Failure(e), getSelf());
815         }
816     }
817
818     private ActorRef createTransaction(final int transactionType, final TransactionIdentifier transactionId) {
819         LOG.debug("{}: Creating transaction : {} ", persistenceId(), transactionId);
820         return transactionActorFactory.newShardTransaction(TransactionType.fromInt(transactionType),
821             transactionId);
822     }
823
824     private void updateSchemaContext(final UpdateSchemaContext message) {
825         updateSchemaContext(message.getSchemaContext());
826     }
827
828     @VisibleForTesting
829     void updateSchemaContext(final SchemaContext schemaContext) {
830         store.updateSchemaContext(schemaContext);
831     }
832
833     private boolean isMetricsCaptureEnabled() {
834         CommonConfig config = new CommonConfig(getContext().system().settings().config());
835         return config.isMetricCaptureEnabled();
836     }
837
838     @Override
839     @VisibleForTesting
840     public RaftActorSnapshotCohort getRaftActorSnapshotCohort() {
841         return snapshotCohort;
842     }
843
844     @Override
845     protected RaftActorRecoveryCohort getRaftActorRecoveryCohort() {
846         if (restoreFromSnapshot == null) {
847             return ShardRecoveryCoordinator.create(store, persistenceId(), LOG);
848         }
849
850         return ShardRecoveryCoordinator.forSnapshot(store, persistenceId(), LOG, restoreFromSnapshot.getSnapshot());
851     }
852
853     @Override
854     protected void onRecoveryComplete() {
855         restoreFromSnapshot = null;
856
857         //notify shard manager
858         getContext().parent().tell(new ActorInitialized(), getSelf());
859
860         // Being paranoid here - this method should only be called once but just in case...
861         if (txCommitTimeoutCheckSchedule == null) {
862             // Schedule a message to be periodically sent to check if the current in-progress
863             // transaction should be expired and aborted.
864             FiniteDuration period = FiniteDuration.create(transactionCommitTimeout / 3, TimeUnit.MILLISECONDS);
865             txCommitTimeoutCheckSchedule = getContext().system().scheduler().schedule(
866                     period, period, getSelf(),
867                     TX_COMMIT_TIMEOUT_CHECK_MESSAGE, getContext().dispatcher(), ActorRef.noSender());
868         }
869     }
870
871     @Override
872     protected void applyState(final ActorRef clientActor, final Identifier identifier, final Object data) {
873         if (data instanceof Payload) {
874             try {
875                 store.applyReplicatedPayload(identifier, (Payload)data);
876             } catch (DataValidationFailedException | IOException e) {
877                 LOG.error("{}: Error applying replica {}", persistenceId(), identifier, e);
878             }
879         } else {
880             LOG.error("{}: Unknown state for {} received {}", persistenceId(), identifier, data);
881         }
882     }
883
884     @Override
885     protected void onStateChanged() {
886         boolean isLeader = isLeader();
887         boolean hasLeader = hasLeader();
888         treeChangeSupport.onLeadershipChange(isLeader, hasLeader);
889
890         // If this actor is no longer the leader close all the transaction chains
891         if (!isLeader) {
892             if (LOG.isDebugEnabled()) {
893                 LOG.debug(
894                     "{}: onStateChanged: Closing all transaction chains because shard {} is no longer the leader",
895                     persistenceId(), getId());
896             }
897
898             paused = false;
899             store.purgeLeaderState();
900         }
901
902         if (hasLeader && !isIsolatedLeader()) {
903             messageRetrySupport.retryMessages();
904         }
905     }
906
907     @Override
908     protected void onLeaderChanged(final String oldLeader, final String newLeader) {
909         shardMBean.incrementLeadershipChangeCount();
910         paused = false;
911
912         if (!isLeader()) {
913             if (!knownFrontends.isEmpty()) {
914                 LOG.debug("{}: removing frontend state for {}", persistenceId(), knownFrontends.keySet());
915                 knownFrontends = ImmutableMap.of();
916             }
917
918             requestMessageAssembler.close();
919
920             if (!hasLeader()) {
921                 // No leader anywhere, nothing else to do
922                 return;
923             }
924
925             // Another leader was elected. If we were the previous leader and had pending transactions, convert
926             // them to transaction messages and send to the new leader.
927             ActorSelection leader = getLeader();
928             if (leader != null) {
929                 Collection<?> messagesToForward = convertPendingTransactionsToMessages();
930
931                 if (!messagesToForward.isEmpty()) {
932                     LOG.debug("{}: Forwarding {} pending transaction messages to leader {}", persistenceId(),
933                             messagesToForward.size(), leader);
934
935                     for (Object message : messagesToForward) {
936                         LOG.debug("{}: Forwarding pending transaction message {}", persistenceId(), message);
937
938                         leader.tell(message, self());
939                     }
940                 }
941             } else {
942                 commitCoordinator.abortPendingTransactions("The transacton was aborted due to inflight leadership "
943                         + "change and the leader address isn't available.", this);
944             }
945         } else {
946             // We have become the leader, we need to reconstruct frontend state
947             knownFrontends = Verify.verifyNotNull(frontendMetadata.toLeaderState(this));
948             LOG.debug("{}: became leader with frontend state for {}", persistenceId(), knownFrontends.keySet());
949         }
950
951         if (!isIsolatedLeader()) {
952             messageRetrySupport.retryMessages();
953         }
954     }
955
956     /**
957      * Clears all pending transactions and converts them to messages to be forwarded to a new leader.
958      *
959      * @return the converted messages
960      */
961     public Collection<?> convertPendingTransactionsToMessages() {
962         return commitCoordinator.convertPendingTransactionsToMessages(
963                 datastoreContext.getShardBatchedModificationCount());
964     }
965
966     @Override
967     protected void pauseLeader(final Runnable operation) {
968         LOG.debug("{}: In pauseLeader, operation: {}", persistenceId(), operation);
969         paused = true;
970
971         // Tell-based protocol can replay transaction state, so it is safe to blow it up when we are paused.
972         knownFrontends.values().forEach(LeaderFrontendState::retire);
973         knownFrontends = ImmutableMap.of();
974
975         store.setRunOnPendingTransactionsComplete(operation);
976     }
977
978     @Override
979     protected void unpauseLeader() {
980         LOG.debug("{}: In unpauseLeader", persistenceId());
981         paused = false;
982
983         store.setRunOnPendingTransactionsComplete(null);
984
985         // Restore tell-based protocol state as if we were becoming the leader
986         knownFrontends = Verify.verifyNotNull(frontendMetadata.toLeaderState(this));
987     }
988
989     @Override
990     protected OnDemandRaftState.AbstractBuilder<?, ?> newOnDemandRaftStateBuilder() {
991         return OnDemandShardState.newBuilder().treeChangeListenerActors(treeChangeSupport.getListenerActors())
992                 .commitCohortActors(store.getCohortActors());
993     }
994
995     @Override
996     public String persistenceId() {
997         return this.name;
998     }
999
1000     @VisibleForTesting
1001     ShardCommitCoordinator getCommitCoordinator() {
1002         return commitCoordinator;
1003     }
1004
1005     public DatastoreContext getDatastoreContext() {
1006         return datastoreContext;
1007     }
1008
1009     @VisibleForTesting
1010     public ShardDataTree getDataStore() {
1011         return store;
1012     }
1013
1014     @VisibleForTesting
1015     ShardStats getShardMBean() {
1016         return shardMBean;
1017     }
1018
1019     public static Builder builder() {
1020         return new Builder();
1021     }
1022
1023     public abstract static class AbstractBuilder<T extends AbstractBuilder<T, S>, S extends Shard> {
1024         private final Class<S> shardClass;
1025         private ShardIdentifier id;
1026         private Map<String, String> peerAddresses = Collections.emptyMap();
1027         private DatastoreContext datastoreContext;
1028         private SchemaContextProvider schemaContextProvider;
1029         private DatastoreSnapshot.ShardSnapshot restoreFromSnapshot;
1030         private DataTree dataTree;
1031         private volatile boolean sealed;
1032
1033         protected AbstractBuilder(final Class<S> shardClass) {
1034             this.shardClass = shardClass;
1035         }
1036
1037         protected void checkSealed() {
1038             Preconditions.checkState(!sealed, "Builder isalready sealed - further modifications are not allowed");
1039         }
1040
1041         @SuppressWarnings("unchecked")
1042         private T self() {
1043             return (T) this;
1044         }
1045
1046         public T id(final ShardIdentifier newId) {
1047             checkSealed();
1048             this.id = newId;
1049             return self();
1050         }
1051
1052         public T peerAddresses(final Map<String, String> newPeerAddresses) {
1053             checkSealed();
1054             this.peerAddresses = newPeerAddresses;
1055             return self();
1056         }
1057
1058         public T datastoreContext(final DatastoreContext newDatastoreContext) {
1059             checkSealed();
1060             this.datastoreContext = newDatastoreContext;
1061             return self();
1062         }
1063
1064         public T schemaContextProvider(final SchemaContextProvider newSchemaContextProvider) {
1065             checkSealed();
1066             this.schemaContextProvider = Preconditions.checkNotNull(newSchemaContextProvider);
1067             return self();
1068         }
1069
1070         public T restoreFromSnapshot(final DatastoreSnapshot.ShardSnapshot newRestoreFromSnapshot) {
1071             checkSealed();
1072             this.restoreFromSnapshot = newRestoreFromSnapshot;
1073             return self();
1074         }
1075
1076         public T dataTree(final DataTree newDataTree) {
1077             checkSealed();
1078             this.dataTree = newDataTree;
1079             return self();
1080         }
1081
1082         public ShardIdentifier getId() {
1083             return id;
1084         }
1085
1086         public Map<String, String> getPeerAddresses() {
1087             return peerAddresses;
1088         }
1089
1090         public DatastoreContext getDatastoreContext() {
1091             return datastoreContext;
1092         }
1093
1094         public SchemaContext getSchemaContext() {
1095             return Verify.verifyNotNull(schemaContextProvider.getSchemaContext());
1096         }
1097
1098         public DatastoreSnapshot.ShardSnapshot getRestoreFromSnapshot() {
1099             return restoreFromSnapshot;
1100         }
1101
1102         public DataTree getDataTree() {
1103             return dataTree;
1104         }
1105
1106         public TreeType getTreeType() {
1107             switch (datastoreContext.getLogicalStoreType()) {
1108                 case CONFIGURATION:
1109                     return TreeType.CONFIGURATION;
1110                 case OPERATIONAL:
1111                     return TreeType.OPERATIONAL;
1112                 default:
1113                     throw new IllegalStateException("Unhandled logical store type "
1114                             + datastoreContext.getLogicalStoreType());
1115             }
1116         }
1117
1118         protected void verify() {
1119             Preconditions.checkNotNull(id, "id should not be null");
1120             Preconditions.checkNotNull(peerAddresses, "peerAddresses should not be null");
1121             Preconditions.checkNotNull(datastoreContext, "dataStoreContext should not be null");
1122             Preconditions.checkNotNull(schemaContextProvider, "schemaContextProvider should not be null");
1123         }
1124
1125         public Props props() {
1126             sealed = true;
1127             verify();
1128             return Props.create(shardClass, this);
1129         }
1130     }
1131
1132     public static class Builder extends AbstractBuilder<Builder, Shard> {
1133         Builder() {
1134             super(Shard.class);
1135         }
1136     }
1137
1138     Ticker ticker() {
1139         return Ticker.systemTicker();
1140     }
1141
1142     void scheduleNextPendingTransaction() {
1143         self().tell(RESUME_NEXT_PENDING_TRANSACTION, ActorRef.noSender());
1144     }
1145 }

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