98b02432e516b045fbf957d1f6ec065ee1726ccb
[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             } else if (message instanceof MakeLeaderLocal) {
369                 onMakeLeaderLocal();
370             } else if (RESUME_NEXT_PENDING_TRANSACTION.equals(message)) {
371                 store.resumeNextPendingTransaction();
372             } else if (!responseMessageSlicer.handleMessage(message)) {
373                 super.handleNonRaftCommand(message);
374             }
375         }
376     }
377
378     private void handleRequestAssemblerMessage(final Object message) {
379         dispatchers.getDispatcher(DispatcherType.Serialization).execute(() -> {
380             JavaSerializer.currentSystem().value_$eq((ExtendedActorSystem) context().system());
381             requestMessageAssembler.handleMessage(message, self());
382         });
383     }
384
385     @SuppressWarnings("checkstyle:IllegalCatch")
386     private void handleRequestEnvelope(final RequestEnvelope envelope) {
387         final long now = ticker().read();
388         try {
389             final RequestSuccess<?, ?> success = handleRequest(envelope, now);
390             if (success != null) {
391                 final long executionTimeNanos = ticker().read() - now;
392                 if (success instanceof SliceableMessage) {
393                     dispatchers.getDispatcher(DispatcherType.Serialization).execute(() ->
394                         responseMessageSlicer.slice(SliceOptions.builder().identifier(success.getTarget())
395                             .message(envelope.newSuccessEnvelope(success, executionTimeNanos))
396                             .sendTo(envelope.getMessage().getReplyTo()).replyTo(self())
397                             .onFailureCallback(t -> LOG.warn("Error slicing response {}", success, t)).build()));
398                 } else {
399                     envelope.sendSuccess(success, executionTimeNanos);
400                 }
401             }
402         } catch (RequestException e) {
403             LOG.debug("{}: request {} failed", persistenceId(), envelope, e);
404             envelope.sendFailure(e, ticker().read() - now);
405         } catch (Exception e) {
406             LOG.debug("{}: request {} caused failure", persistenceId(), envelope, e);
407             envelope.sendFailure(new RuntimeRequestException("Request failed to process", e),
408                 ticker().read() - now);
409         }
410     }
411
412     private void commitTimeoutCheck() {
413         store.checkForExpiredTransactions(transactionCommitTimeout, this::updateAccess);
414         commitCoordinator.checkForExpiredTransactions(transactionCommitTimeout, this);
415         requestMessageAssembler.checkExpiredAssembledMessageState();
416     }
417
418     private Optional<Long> updateAccess(final SimpleShardDataTreeCohort cohort) {
419         final FrontendIdentifier frontend = cohort.getIdentifier().getHistoryId().getClientId().getFrontendId();
420         final LeaderFrontendState state = knownFrontends.get(frontend);
421         if (state == null) {
422             // Not tell-based protocol, do nothing
423             return Optional.absent();
424         }
425
426         if (isIsolatedLeader()) {
427             // We are isolated and no new request can come through until we emerge from it. We are still updating
428             // liveness of frontend when we see it attempting to communicate. Use the last access timer.
429             return Optional.of(state.getLastSeenTicks());
430         }
431
432         // If this frontend has freshly connected, give it some time to catch up before killing its transactions.
433         return Optional.of(state.getLastConnectTicks());
434     }
435
436     private void onMakeLeaderLocal() {
437         LOG.debug("{}: onMakeLeaderLocal received", persistenceId());
438         if (isLeader()) {
439             getSender().tell(new Status.Success(null), getSelf());
440             return;
441         }
442
443         final ActorSelection leader = getLeader();
444
445         if (leader == null) {
446             // Leader is not present. The cluster is most likely trying to
447             // elect a leader and we should let that run its normal course
448
449             // TODO we can wait for the election to complete and retry the
450             // request. We can also let the caller retry by sending a flag
451             // in the response indicating the request is "reTryable".
452             getSender().tell(new Failure(
453                     new LeadershipTransferFailedException("We cannot initiate leadership transfer to local node. "
454                             + "Currently there is no leader for " + persistenceId())),
455                     getSelf());
456             return;
457         }
458
459         leader.tell(new RequestLeadership(getId(), getSender()), getSelf());
460     }
461
462     // Acquire our frontend tracking handle and verify generation matches
463     private @Nullable LeaderFrontendState findFrontend(final ClientIdentifier clientId) throws RequestException {
464         final LeaderFrontendState existing = knownFrontends.get(clientId.getFrontendId());
465         if (existing != null) {
466             final int cmp = Long.compareUnsigned(existing.getIdentifier().getGeneration(), clientId.getGeneration());
467             if (cmp == 0) {
468                 existing.touch();
469                 return existing;
470             }
471             if (cmp > 0) {
472                 LOG.debug("{}: rejecting request from outdated client {}", persistenceId(), clientId);
473                 throw new RetiredGenerationException(clientId.getGeneration(),
474                     existing.getIdentifier().getGeneration());
475             }
476
477             LOG.info("{}: retiring state {}, outdated by request from client {}", persistenceId(), existing, clientId);
478             existing.retire();
479             knownFrontends.remove(clientId.getFrontendId());
480         } else {
481             LOG.debug("{}: client {} is not yet known", persistenceId(), clientId);
482         }
483
484         return null;
485     }
486
487     private LeaderFrontendState getFrontend(final ClientIdentifier clientId) throws RequestException {
488         final LeaderFrontendState ret = findFrontend(clientId);
489         if (ret != null) {
490             return ret;
491         }
492
493         // TODO: a dedicated exception would be better, but this is technically true, too
494         throw new OutOfSequenceEnvelopeException(0);
495     }
496
497     private static @NonNull ABIVersion selectVersion(final ConnectClientRequest message) {
498         final Range<ABIVersion> clientRange = Range.closed(message.getMinVersion(), message.getMaxVersion());
499         for (ABIVersion v : SUPPORTED_ABIVERSIONS) {
500             if (clientRange.contains(v)) {
501                 return v;
502             }
503         }
504
505         throw new IllegalArgumentException(String.format(
506             "No common version between backend versions %s and client versions %s", SUPPORTED_ABIVERSIONS,
507             clientRange));
508     }
509
510     @SuppressWarnings("checkstyle:IllegalCatch")
511     private void handleConnectClient(final ConnectClientRequest message) {
512         try {
513             final ClientIdentifier clientId = message.getTarget();
514             final LeaderFrontendState existing = findFrontend(clientId);
515             if (existing != null) {
516                 existing.touch();
517             }
518
519             if (!isLeader() || !isLeaderActive()) {
520                 LOG.info("{}: not currently leader, rejecting request {}. isLeader: {}, isLeaderActive: {},"
521                                 + "isLeadershipTransferInProgress: {}.",
522                         persistenceId(), message, isLeader(), isLeaderActive(), isLeadershipTransferInProgress());
523                 throw new NotLeaderException(getSelf());
524             }
525
526             final ABIVersion selectedVersion = selectVersion(message);
527             final LeaderFrontendState frontend;
528             if (existing == null) {
529                 frontend = new LeaderFrontendState(persistenceId(), clientId, store);
530                 knownFrontends.put(clientId.getFrontendId(), frontend);
531                 LOG.debug("{}: created state {} for client {}", persistenceId(), frontend, clientId);
532             } else {
533                 frontend = existing;
534             }
535
536             frontend.reconnect();
537             message.getReplyTo().tell(new ConnectClientSuccess(message.getTarget(), message.getSequence(), getSelf(),
538                 ImmutableList.of(), store.getDataTree(), CLIENT_MAX_MESSAGES).toVersion(selectedVersion),
539                 ActorRef.noSender());
540         } catch (RequestException | RuntimeException e) {
541             message.getReplyTo().tell(new Failure(e), ActorRef.noSender());
542         }
543     }
544
545     private @Nullable RequestSuccess<?, ?> handleRequest(final RequestEnvelope envelope, final long now)
546             throws RequestException {
547         // We are not the leader, hence we want to fail-fast.
548         if (!isLeader() || paused || !isLeaderActive()) {
549             LOG.debug("{}: not currently active leader, rejecting request {}. isLeader: {}, isLeaderActive: {},"
550                             + "isLeadershipTransferInProgress: {}, paused: {}",
551                     persistenceId(), envelope, isLeader(), isLeaderActive(), isLeadershipTransferInProgress(), paused);
552             throw new NotLeaderException(getSelf());
553         }
554
555         final Request<?, ?> request = envelope.getMessage();
556         if (request instanceof TransactionRequest) {
557             final TransactionRequest<?> txReq = (TransactionRequest<?>)request;
558             final ClientIdentifier clientId = txReq.getTarget().getHistoryId().getClientId();
559             return getFrontend(clientId).handleTransactionRequest(txReq, envelope, now);
560         } else if (request instanceof LocalHistoryRequest) {
561             final LocalHistoryRequest<?> lhReq = (LocalHistoryRequest<?>)request;
562             final ClientIdentifier clientId = lhReq.getTarget().getClientId();
563             return getFrontend(clientId).handleLocalHistoryRequest(lhReq, envelope, now);
564         } else {
565             LOG.warn("{}: rejecting unsupported request {}", persistenceId(), request);
566             throw new UnsupportedRequestException(request);
567         }
568     }
569
570     private boolean hasLeader() {
571         return getLeaderId() != null;
572     }
573
574     public int getPendingTxCommitQueueSize() {
575         return store.getQueueSize();
576     }
577
578     public int getCohortCacheSize() {
579         return commitCoordinator.getCohortCacheSize();
580     }
581
582     @Override
583     protected Optional<ActorRef> getRoleChangeNotifier() {
584         return roleChangeNotifier;
585     }
586
587     String getShardName() {
588         return shardName;
589     }
590
591     @Override
592     protected LeaderStateChanged newLeaderStateChanged(final String memberId, final String leaderId,
593             final short leaderPayloadVersion) {
594         return isLeader() ? new ShardLeaderStateChanged(memberId, leaderId, store.getDataTree(), leaderPayloadVersion)
595                 : new ShardLeaderStateChanged(memberId, leaderId, leaderPayloadVersion);
596     }
597
598     protected void onDatastoreContext(final DatastoreContext context) {
599         datastoreContext = context;
600
601         setTransactionCommitTimeout();
602
603         setPersistence(datastoreContext.isPersistent());
604
605         updateConfigParams(datastoreContext.getShardRaftConfig());
606     }
607
608     // applyState() will be invoked once consensus is reached on the payload
609     void persistPayload(final Identifier id, final Payload payload, final boolean batchHint) {
610         boolean canSkipPayload = !hasFollowers() && !persistence().isRecoveryApplicable();
611         if (canSkipPayload) {
612             applyState(self(), id, payload);
613         } else {
614             // We are faking the sender
615             persistData(self(), id, payload, batchHint);
616         }
617     }
618
619     private void handleCommitTransaction(final CommitTransaction commit) {
620         if (isLeader()) {
621             commitCoordinator.handleCommit(commit.getTransactionId(), getSender(), this);
622         } else {
623             ActorSelection leader = getLeader();
624             if (leader == null) {
625                 messageRetrySupport.addMessageToRetry(commit, getSender(),
626                         "Could not commit transaction " + commit.getTransactionId());
627             } else {
628                 LOG.debug("{}: Forwarding CommitTransaction to leader {}", persistenceId(), leader);
629                 leader.forward(commit, getContext());
630             }
631         }
632     }
633
634     private void handleCanCommitTransaction(final CanCommitTransaction canCommit) {
635         LOG.debug("{}: Can committing transaction {}", persistenceId(), canCommit.getTransactionId());
636
637         if (isLeader()) {
638             commitCoordinator.handleCanCommit(canCommit.getTransactionId(), getSender(), this);
639         } else {
640             ActorSelection leader = getLeader();
641             if (leader == null) {
642                 messageRetrySupport.addMessageToRetry(canCommit, getSender(),
643                         "Could not canCommit transaction " + canCommit.getTransactionId());
644             } else {
645                 LOG.debug("{}: Forwarding CanCommitTransaction to leader {}", persistenceId(), leader);
646                 leader.forward(canCommit, getContext());
647             }
648         }
649     }
650
651     @SuppressWarnings("checkstyle:IllegalCatch")
652     protected void handleBatchedModificationsLocal(final BatchedModifications batched, final ActorRef sender) {
653         try {
654             commitCoordinator.handleBatchedModifications(batched, sender, this);
655         } catch (Exception e) {
656             LOG.error("{}: Error handling BatchedModifications for Tx {}", persistenceId(),
657                     batched.getTransactionId(), e);
658             sender.tell(new Failure(e), getSelf());
659         }
660     }
661
662     private void handleBatchedModifications(final BatchedModifications batched) {
663         // This message is sent to prepare the modifications transaction directly on the Shard as an
664         // optimization to avoid the extra overhead of a separate ShardTransaction actor. On the last
665         // BatchedModifications message, the caller sets the ready flag in the message indicating
666         // modifications are complete. The reply contains the cohort actor path (this actor) for the caller
667         // to initiate the 3-phase commit. This also avoids the overhead of sending an additional
668         // ReadyTransaction message.
669
670         // If we're not the leader then forward to the leader. This is a safety measure - we shouldn't
671         // normally get here if we're not the leader as the front-end (TransactionProxy) should determine
672         // the primary/leader shard. However with timing and caching on the front-end, there's a small
673         // window where it could have a stale leader during leadership transitions.
674         //
675         boolean isLeaderActive = isLeaderActive();
676         if (isLeader() && isLeaderActive) {
677             handleBatchedModificationsLocal(batched, getSender());
678         } else {
679             ActorSelection leader = getLeader();
680             if (!isLeaderActive || leader == null) {
681                 messageRetrySupport.addMessageToRetry(batched, getSender(),
682                         "Could not process BatchedModifications " + batched.getTransactionId());
683             } else {
684                 // If this is not the first batch and leadership changed in between batched messages,
685                 // we need to reconstruct previous BatchedModifications from the transaction
686                 // DataTreeModification, honoring the max batched modification count, and forward all the
687                 // previous BatchedModifications to the new leader.
688                 Collection<BatchedModifications> newModifications = commitCoordinator
689                         .createForwardedBatchedModifications(batched,
690                                 datastoreContext.getShardBatchedModificationCount());
691
692                 LOG.debug("{}: Forwarding {} BatchedModifications to leader {}", persistenceId(),
693                         newModifications.size(), leader);
694
695                 for (BatchedModifications bm : newModifications) {
696                     leader.forward(bm, getContext());
697                 }
698             }
699         }
700     }
701
702     private boolean failIfIsolatedLeader(final ActorRef sender) {
703         if (isIsolatedLeader()) {
704             sender.tell(new Failure(new NoShardLeaderException(String.format(
705                     "Shard %s was the leader but has lost contact with all of its followers. Either all"
706                     + " other follower nodes are down or this node is isolated by a network partition.",
707                     persistenceId()))), getSelf());
708             return true;
709         }
710
711         return false;
712     }
713
714     protected boolean isIsolatedLeader() {
715         return getRaftState() == RaftState.IsolatedLeader;
716     }
717
718     @SuppressWarnings("checkstyle:IllegalCatch")
719     private void handleReadyLocalTransaction(final ReadyLocalTransaction message) {
720         LOG.debug("{}: handleReadyLocalTransaction for {}", persistenceId(), message.getTransactionId());
721
722         boolean isLeaderActive = isLeaderActive();
723         if (isLeader() && isLeaderActive) {
724             try {
725                 commitCoordinator.handleReadyLocalTransaction(message, getSender(), this);
726             } catch (Exception e) {
727                 LOG.error("{}: Error handling ReadyLocalTransaction for Tx {}", persistenceId(),
728                         message.getTransactionId(), e);
729                 getSender().tell(new Failure(e), getSelf());
730             }
731         } else {
732             ActorSelection leader = getLeader();
733             if (!isLeaderActive || leader == null) {
734                 messageRetrySupport.addMessageToRetry(message, getSender(),
735                         "Could not process ready local transaction " + message.getTransactionId());
736             } else {
737                 LOG.debug("{}: Forwarding ReadyLocalTransaction to leader {}", persistenceId(), leader);
738                 message.setRemoteVersion(getCurrentBehavior().getLeaderPayloadVersion());
739                 leader.forward(message, getContext());
740             }
741         }
742     }
743
744     private void handleForwardedReadyTransaction(final ForwardedReadyTransaction forwardedReady) {
745         LOG.debug("{}: handleForwardedReadyTransaction for {}", persistenceId(), forwardedReady.getTransactionId());
746
747         boolean isLeaderActive = isLeaderActive();
748         if (isLeader() && isLeaderActive) {
749             commitCoordinator.handleForwardedReadyTransaction(forwardedReady, getSender(), this);
750         } else {
751             ActorSelection leader = getLeader();
752             if (!isLeaderActive || leader == null) {
753                 messageRetrySupport.addMessageToRetry(forwardedReady, getSender(),
754                         "Could not process forwarded ready transaction " + forwardedReady.getTransactionId());
755             } else {
756                 LOG.debug("{}: Forwarding ForwardedReadyTransaction to leader {}", persistenceId(), leader);
757
758                 ReadyLocalTransaction readyLocal = new ReadyLocalTransaction(forwardedReady.getTransactionId(),
759                         forwardedReady.getTransaction().getSnapshot(), forwardedReady.isDoImmediateCommit(),
760                         forwardedReady.getParticipatingShardNames());
761                 readyLocal.setRemoteVersion(getCurrentBehavior().getLeaderPayloadVersion());
762                 leader.forward(readyLocal, getContext());
763             }
764         }
765     }
766
767     private void handleAbortTransaction(final AbortTransaction abort) {
768         doAbortTransaction(abort.getTransactionId(), getSender());
769     }
770
771     void doAbortTransaction(final Identifier transactionID, final ActorRef sender) {
772         commitCoordinator.handleAbort(transactionID, sender, this);
773     }
774
775     private void handleCreateTransaction(final Object message) {
776         if (isLeader()) {
777             createTransaction(CreateTransaction.fromSerializable(message));
778         } else if (getLeader() != null) {
779             getLeader().forward(message, getContext());
780         } else {
781             getSender().tell(new Failure(new NoShardLeaderException(
782                     "Could not create a shard transaction", persistenceId())), getSelf());
783         }
784     }
785
786     private void closeTransactionChain(final CloseTransactionChain closeTransactionChain) {
787         if (isLeader()) {
788             final LocalHistoryIdentifier id = closeTransactionChain.getIdentifier();
789             // FIXME: CONTROLLER-1628: stage purge once no transactions are present
790             store.closeTransactionChain(id, null);
791             store.purgeTransactionChain(id, null);
792         } else if (getLeader() != null) {
793             getLeader().forward(closeTransactionChain, getContext());
794         } else {
795             LOG.warn("{}: Could not close transaction {}", persistenceId(), closeTransactionChain.getIdentifier());
796         }
797     }
798
799     @SuppressWarnings("checkstyle:IllegalCatch")
800     private void createTransaction(final CreateTransaction createTransaction) {
801         try {
802             if (TransactionType.fromInt(createTransaction.getTransactionType()) != TransactionType.READ_ONLY
803                     && failIfIsolatedLeader(getSender())) {
804                 return;
805             }
806
807             ActorRef transactionActor = createTransaction(createTransaction.getTransactionType(),
808                 createTransaction.getTransactionId());
809
810             getSender().tell(new CreateTransactionReply(Serialization.serializedActorPath(transactionActor),
811                     createTransaction.getTransactionId(), createTransaction.getVersion()).toSerializable(), getSelf());
812         } catch (Exception e) {
813             getSender().tell(new Failure(e), getSelf());
814         }
815     }
816
817     private ActorRef createTransaction(final int transactionType, final TransactionIdentifier transactionId) {
818         LOG.debug("{}: Creating transaction : {} ", persistenceId(), transactionId);
819         return transactionActorFactory.newShardTransaction(TransactionType.fromInt(transactionType),
820             transactionId);
821     }
822
823     private void updateSchemaContext(final UpdateSchemaContext message) {
824         updateSchemaContext(message.getSchemaContext());
825     }
826
827     @VisibleForTesting
828     void updateSchemaContext(final SchemaContext schemaContext) {
829         store.updateSchemaContext(schemaContext);
830     }
831
832     private boolean isMetricsCaptureEnabled() {
833         CommonConfig config = new CommonConfig(getContext().system().settings().config());
834         return config.isMetricCaptureEnabled();
835     }
836
837     @Override
838     @VisibleForTesting
839     public RaftActorSnapshotCohort getRaftActorSnapshotCohort() {
840         return snapshotCohort;
841     }
842
843     @Override
844     protected RaftActorRecoveryCohort getRaftActorRecoveryCohort() {
845         if (restoreFromSnapshot == null) {
846             return ShardRecoveryCoordinator.create(store, persistenceId(), LOG);
847         }
848
849         return ShardRecoveryCoordinator.forSnapshot(store, persistenceId(), LOG, restoreFromSnapshot.getSnapshot());
850     }
851
852     @Override
853     protected void onRecoveryComplete() {
854         restoreFromSnapshot = null;
855
856         //notify shard manager
857         getContext().parent().tell(new ActorInitialized(), getSelf());
858
859         // Being paranoid here - this method should only be called once but just in case...
860         if (txCommitTimeoutCheckSchedule == null) {
861             // Schedule a message to be periodically sent to check if the current in-progress
862             // transaction should be expired and aborted.
863             FiniteDuration period = FiniteDuration.create(transactionCommitTimeout / 3, TimeUnit.MILLISECONDS);
864             txCommitTimeoutCheckSchedule = getContext().system().scheduler().schedule(
865                     period, period, getSelf(),
866                     TX_COMMIT_TIMEOUT_CHECK_MESSAGE, getContext().dispatcher(), ActorRef.noSender());
867         }
868     }
869
870     @Override
871     protected void applyState(final ActorRef clientActor, final Identifier identifier, final Object data) {
872         if (data instanceof Payload) {
873             try {
874                 store.applyReplicatedPayload(identifier, (Payload)data);
875             } catch (DataValidationFailedException | IOException e) {
876                 LOG.error("{}: Error applying replica {}", persistenceId(), identifier, e);
877             }
878         } else {
879             LOG.error("{}: Unknown state for {} received {}", persistenceId(), identifier, data);
880         }
881     }
882
883     @Override
884     protected void onStateChanged() {
885         boolean isLeader = isLeader();
886         boolean hasLeader = hasLeader();
887         treeChangeSupport.onLeadershipChange(isLeader, hasLeader);
888
889         // If this actor is no longer the leader close all the transaction chains
890         if (!isLeader) {
891             if (LOG.isDebugEnabled()) {
892                 LOG.debug(
893                     "{}: onStateChanged: Closing all transaction chains because shard {} is no longer the leader",
894                     persistenceId(), getId());
895             }
896
897             paused = false;
898             store.purgeLeaderState();
899         }
900
901         if (hasLeader && !isIsolatedLeader()) {
902             messageRetrySupport.retryMessages();
903         }
904     }
905
906     @Override
907     protected void onLeaderChanged(final String oldLeader, final String newLeader) {
908         shardMBean.incrementLeadershipChangeCount();
909         paused = false;
910
911         if (!isLeader()) {
912             if (!knownFrontends.isEmpty()) {
913                 LOG.debug("{}: removing frontend state for {}", persistenceId(), knownFrontends.keySet());
914                 knownFrontends = ImmutableMap.of();
915             }
916
917             requestMessageAssembler.close();
918
919             if (!hasLeader()) {
920                 // No leader anywhere, nothing else to do
921                 return;
922             }
923
924             // Another leader was elected. If we were the previous leader and had pending transactions, convert
925             // them to transaction messages and send to the new leader.
926             ActorSelection leader = getLeader();
927             if (leader != null) {
928                 Collection<?> messagesToForward = convertPendingTransactionsToMessages();
929
930                 if (!messagesToForward.isEmpty()) {
931                     LOG.debug("{}: Forwarding {} pending transaction messages to leader {}", persistenceId(),
932                             messagesToForward.size(), leader);
933
934                     for (Object message : messagesToForward) {
935                         LOG.debug("{}: Forwarding pending transaction message {}", persistenceId(), message);
936
937                         leader.tell(message, self());
938                     }
939                 }
940             } else {
941                 commitCoordinator.abortPendingTransactions("The transacton was aborted due to inflight leadership "
942                         + "change and the leader address isn't available.", this);
943             }
944         } else {
945             // We have become the leader, we need to reconstruct frontend state
946             knownFrontends = Verify.verifyNotNull(frontendMetadata.toLeaderState(this));
947             LOG.debug("{}: became leader with frontend state for {}", persistenceId(), knownFrontends.keySet());
948         }
949
950         if (!isIsolatedLeader()) {
951             messageRetrySupport.retryMessages();
952         }
953     }
954
955     /**
956      * Clears all pending transactions and converts them to messages to be forwarded to a new leader.
957      *
958      * @return the converted messages
959      */
960     public Collection<?> convertPendingTransactionsToMessages() {
961         return commitCoordinator.convertPendingTransactionsToMessages(
962                 datastoreContext.getShardBatchedModificationCount());
963     }
964
965     @Override
966     protected void pauseLeader(final Runnable operation) {
967         LOG.debug("{}: In pauseLeader, operation: {}", persistenceId(), operation);
968         paused = true;
969
970         // Tell-based protocol can replay transaction state, so it is safe to blow it up when we are paused.
971         knownFrontends.values().forEach(LeaderFrontendState::retire);
972         knownFrontends = ImmutableMap.of();
973
974         store.setRunOnPendingTransactionsComplete(operation);
975     }
976
977     @Override
978     protected void unpauseLeader() {
979         LOG.debug("{}: In unpauseLeader", persistenceId());
980         paused = false;
981
982         store.setRunOnPendingTransactionsComplete(null);
983
984         // Restore tell-based protocol state as if we were becoming the leader
985         knownFrontends = Verify.verifyNotNull(frontendMetadata.toLeaderState(this));
986     }
987
988     @Override
989     protected OnDemandRaftState.AbstractBuilder<?, ?> newOnDemandRaftStateBuilder() {
990         return OnDemandShardState.newBuilder().treeChangeListenerActors(treeChangeSupport.getListenerActors())
991                 .commitCohortActors(store.getCohortActors());
992     }
993
994     @Override
995     public String persistenceId() {
996         return this.name;
997     }
998
999     @VisibleForTesting
1000     ShardCommitCoordinator getCommitCoordinator() {
1001         return commitCoordinator;
1002     }
1003
1004     public DatastoreContext getDatastoreContext() {
1005         return datastoreContext;
1006     }
1007
1008     @VisibleForTesting
1009     public ShardDataTree getDataStore() {
1010         return store;
1011     }
1012
1013     @VisibleForTesting
1014     ShardStats getShardMBean() {
1015         return shardMBean;
1016     }
1017
1018     public static Builder builder() {
1019         return new Builder();
1020     }
1021
1022     public abstract static class AbstractBuilder<T extends AbstractBuilder<T, S>, S extends Shard> {
1023         private final Class<S> shardClass;
1024         private ShardIdentifier id;
1025         private Map<String, String> peerAddresses = Collections.emptyMap();
1026         private DatastoreContext datastoreContext;
1027         private SchemaContextProvider schemaContextProvider;
1028         private DatastoreSnapshot.ShardSnapshot restoreFromSnapshot;
1029         private DataTree dataTree;
1030         private volatile boolean sealed;
1031
1032         protected AbstractBuilder(final Class<S> shardClass) {
1033             this.shardClass = shardClass;
1034         }
1035
1036         protected void checkSealed() {
1037             Preconditions.checkState(!sealed, "Builder isalready sealed - further modifications are not allowed");
1038         }
1039
1040         @SuppressWarnings("unchecked")
1041         private T self() {
1042             return (T) this;
1043         }
1044
1045         public T id(final ShardIdentifier newId) {
1046             checkSealed();
1047             this.id = newId;
1048             return self();
1049         }
1050
1051         public T peerAddresses(final Map<String, String> newPeerAddresses) {
1052             checkSealed();
1053             this.peerAddresses = newPeerAddresses;
1054             return self();
1055         }
1056
1057         public T datastoreContext(final DatastoreContext newDatastoreContext) {
1058             checkSealed();
1059             this.datastoreContext = newDatastoreContext;
1060             return self();
1061         }
1062
1063         public T schemaContextProvider(final SchemaContextProvider newSchemaContextProvider) {
1064             checkSealed();
1065             this.schemaContextProvider = Preconditions.checkNotNull(newSchemaContextProvider);
1066             return self();
1067         }
1068
1069         public T restoreFromSnapshot(final DatastoreSnapshot.ShardSnapshot newRestoreFromSnapshot) {
1070             checkSealed();
1071             this.restoreFromSnapshot = newRestoreFromSnapshot;
1072             return self();
1073         }
1074
1075         public T dataTree(final DataTree newDataTree) {
1076             checkSealed();
1077             this.dataTree = newDataTree;
1078             return self();
1079         }
1080
1081         public ShardIdentifier getId() {
1082             return id;
1083         }
1084
1085         public Map<String, String> getPeerAddresses() {
1086             return peerAddresses;
1087         }
1088
1089         public DatastoreContext getDatastoreContext() {
1090             return datastoreContext;
1091         }
1092
1093         public SchemaContext getSchemaContext() {
1094             return Verify.verifyNotNull(schemaContextProvider.getSchemaContext());
1095         }
1096
1097         public DatastoreSnapshot.ShardSnapshot getRestoreFromSnapshot() {
1098             return restoreFromSnapshot;
1099         }
1100
1101         public DataTree getDataTree() {
1102             return dataTree;
1103         }
1104
1105         public TreeType getTreeType() {
1106             switch (datastoreContext.getLogicalStoreType()) {
1107                 case CONFIGURATION:
1108                     return TreeType.CONFIGURATION;
1109                 case OPERATIONAL:
1110                     return TreeType.OPERATIONAL;
1111                 default:
1112                     throw new IllegalStateException("Unhandled logical store type "
1113                             + datastoreContext.getLogicalStoreType());
1114             }
1115         }
1116
1117         protected void verify() {
1118             Preconditions.checkNotNull(id, "id should not be null");
1119             Preconditions.checkNotNull(peerAddresses, "peerAddresses should not be null");
1120             Preconditions.checkNotNull(datastoreContext, "dataStoreContext should not be null");
1121             Preconditions.checkNotNull(schemaContextProvider, "schemaContextProvider should not be null");
1122         }
1123
1124         public Props props() {
1125             sealed = true;
1126             verify();
1127             return Props.create(shardClass, this);
1128         }
1129     }
1130
1131     public static class Builder extends AbstractBuilder<Builder, Shard> {
1132         Builder() {
1133             super(Shard.class);
1134         }
1135     }
1136
1137     Ticker ticker() {
1138         return Ticker.systemTicker();
1139     }
1140
1141     void scheduleNextPendingTransaction() {
1142         self().tell(RESUME_NEXT_PENDING_TRANSACTION, ActorRef.noSender());
1143     }
1144 }

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