Bump versions to 4.0.2-SNAPSHOT
[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 static com.google.common.base.Preconditions.checkState;
11 import static com.google.common.base.Verify.verify;
12 import static com.google.common.base.Verify.verifyNotNull;
13 import static java.util.Objects.requireNonNull;
14
15 import akka.actor.ActorRef;
16 import akka.actor.ActorSelection;
17 import akka.actor.Cancellable;
18 import akka.actor.ExtendedActorSystem;
19 import akka.actor.PoisonPill;
20 import akka.actor.Props;
21 import akka.actor.Status;
22 import akka.actor.Status.Failure;
23 import akka.persistence.RecoveryCompleted;
24 import akka.persistence.SnapshotOffer;
25 import akka.serialization.JavaSerializer;
26 import akka.serialization.Serialization;
27 import com.google.common.annotations.VisibleForTesting;
28 import com.google.common.base.Ticker;
29 import com.google.common.collect.ImmutableList;
30 import com.google.common.collect.ImmutableMap;
31 import com.google.common.collect.ImmutableSet;
32 import com.google.common.collect.Range;
33 import java.io.IOException;
34 import java.util.Arrays;
35 import java.util.Collection;
36 import java.util.Collections;
37 import java.util.HashMap;
38 import java.util.Map;
39 import java.util.Optional;
40 import java.util.OptionalLong;
41 import java.util.concurrent.TimeUnit;
42 import org.eclipse.jdt.annotation.NonNull;
43 import org.eclipse.jdt.annotation.Nullable;
44 import org.opendaylight.controller.cluster.access.ABIVersion;
45 import org.opendaylight.controller.cluster.access.commands.ConnectClientRequest;
46 import org.opendaylight.controller.cluster.access.commands.ConnectClientSuccess;
47 import org.opendaylight.controller.cluster.access.commands.LocalHistoryRequest;
48 import org.opendaylight.controller.cluster.access.commands.NotLeaderException;
49 import org.opendaylight.controller.cluster.access.commands.OutOfSequenceEnvelopeException;
50 import org.opendaylight.controller.cluster.access.commands.TransactionRequest;
51 import org.opendaylight.controller.cluster.access.concepts.ClientIdentifier;
52 import org.opendaylight.controller.cluster.access.concepts.FrontendIdentifier;
53 import org.opendaylight.controller.cluster.access.concepts.LocalHistoryIdentifier;
54 import org.opendaylight.controller.cluster.access.concepts.Request;
55 import org.opendaylight.controller.cluster.access.concepts.RequestEnvelope;
56 import org.opendaylight.controller.cluster.access.concepts.RequestException;
57 import org.opendaylight.controller.cluster.access.concepts.RequestSuccess;
58 import org.opendaylight.controller.cluster.access.concepts.RetiredGenerationException;
59 import org.opendaylight.controller.cluster.access.concepts.RuntimeRequestException;
60 import org.opendaylight.controller.cluster.access.concepts.SliceableMessage;
61 import org.opendaylight.controller.cluster.access.concepts.TransactionIdentifier;
62 import org.opendaylight.controller.cluster.access.concepts.UnsupportedRequestException;
63 import org.opendaylight.controller.cluster.common.actor.CommonConfig;
64 import org.opendaylight.controller.cluster.common.actor.Dispatchers;
65 import org.opendaylight.controller.cluster.common.actor.Dispatchers.DispatcherType;
66 import org.opendaylight.controller.cluster.common.actor.MessageTracker;
67 import org.opendaylight.controller.cluster.common.actor.MessageTracker.Error;
68 import org.opendaylight.controller.cluster.common.actor.MeteringBehavior;
69 import org.opendaylight.controller.cluster.datastore.actors.JsonExportActor;
70 import org.opendaylight.controller.cluster.datastore.exceptions.NoShardLeaderException;
71 import org.opendaylight.controller.cluster.datastore.identifiers.ShardIdentifier;
72 import org.opendaylight.controller.cluster.datastore.messages.AbortTransaction;
73 import org.opendaylight.controller.cluster.datastore.messages.ActorInitialized;
74 import org.opendaylight.controller.cluster.datastore.messages.BatchedModifications;
75 import org.opendaylight.controller.cluster.datastore.messages.CanCommitTransaction;
76 import org.opendaylight.controller.cluster.datastore.messages.CloseTransactionChain;
77 import org.opendaylight.controller.cluster.datastore.messages.CommitTransaction;
78 import org.opendaylight.controller.cluster.datastore.messages.CreateTransaction;
79 import org.opendaylight.controller.cluster.datastore.messages.CreateTransactionReply;
80 import org.opendaylight.controller.cluster.datastore.messages.DataTreeChangedReply;
81 import org.opendaylight.controller.cluster.datastore.messages.ForwardedReadyTransaction;
82 import org.opendaylight.controller.cluster.datastore.messages.GetKnownClients;
83 import org.opendaylight.controller.cluster.datastore.messages.GetKnownClientsReply;
84 import org.opendaylight.controller.cluster.datastore.messages.GetShardDataTree;
85 import org.opendaylight.controller.cluster.datastore.messages.MakeLeaderLocal;
86 import org.opendaylight.controller.cluster.datastore.messages.OnDemandShardState;
87 import org.opendaylight.controller.cluster.datastore.messages.PeerAddressResolved;
88 import org.opendaylight.controller.cluster.datastore.messages.ReadyLocalTransaction;
89 import org.opendaylight.controller.cluster.datastore.messages.RegisterDataTreeChangeListener;
90 import org.opendaylight.controller.cluster.datastore.messages.ShardLeaderStateChanged;
91 import org.opendaylight.controller.cluster.datastore.messages.UpdateSchemaContext;
92 import org.opendaylight.controller.cluster.datastore.persisted.DatastoreSnapshot;
93 import org.opendaylight.controller.cluster.datastore.persisted.DatastoreSnapshot.ShardSnapshot;
94 import org.opendaylight.controller.cluster.datastore.persisted.DisableTrackingPayload;
95 import org.opendaylight.controller.cluster.messaging.MessageAssembler;
96 import org.opendaylight.controller.cluster.messaging.MessageSlicer;
97 import org.opendaylight.controller.cluster.messaging.SliceOptions;
98 import org.opendaylight.controller.cluster.notifications.LeaderStateChanged;
99 import org.opendaylight.controller.cluster.notifications.RegisterRoleChangeListener;
100 import org.opendaylight.controller.cluster.notifications.RoleChangeNotifier;
101 import org.opendaylight.controller.cluster.raft.LeadershipTransferFailedException;
102 import org.opendaylight.controller.cluster.raft.RaftActor;
103 import org.opendaylight.controller.cluster.raft.RaftActorRecoveryCohort;
104 import org.opendaylight.controller.cluster.raft.RaftActorSnapshotCohort;
105 import org.opendaylight.controller.cluster.raft.RaftState;
106 import org.opendaylight.controller.cluster.raft.ReplicatedLogEntry;
107 import org.opendaylight.controller.cluster.raft.base.messages.FollowerInitialSyncUpStatus;
108 import org.opendaylight.controller.cluster.raft.client.messages.OnDemandRaftState;
109 import org.opendaylight.controller.cluster.raft.messages.AppendEntriesReply;
110 import org.opendaylight.controller.cluster.raft.messages.RequestLeadership;
111 import org.opendaylight.controller.cluster.raft.messages.ServerRemoved;
112 import org.opendaylight.controller.cluster.raft.protobuff.client.messages.Payload;
113 import org.opendaylight.yang.gen.v1.urn.opendaylight.params.xml.ns.yang.controller.config.distributed.datastore.provider.rev140612.DataStoreProperties.ExportOnRecovery;
114 import org.opendaylight.yangtools.concepts.Identifier;
115 import org.opendaylight.yangtools.yang.data.api.schema.tree.DataTree;
116 import org.opendaylight.yangtools.yang.data.api.schema.tree.DataValidationFailedException;
117 import org.opendaylight.yangtools.yang.data.api.schema.tree.TreeType;
118 import org.opendaylight.yangtools.yang.model.api.EffectiveModelContext;
119 import org.opendaylight.yangtools.yang.model.api.EffectiveModelContextProvider;
120 import scala.concurrent.duration.FiniteDuration;
121
122 /**
123  * A Shard represents a portion of the logical data tree.
124  *
125  * <p>
126  * Our Shard uses InMemoryDataTree as it's internal representation and delegates all requests it
127  */
128 // FIXME: non-final for testing?
129 public class Shard extends RaftActor {
130
131     @VisibleForTesting
132     static final Object TX_COMMIT_TIMEOUT_CHECK_MESSAGE = new Object() {
133         @Override
134         public String toString() {
135             return "txCommitTimeoutCheck";
136         }
137     };
138
139     @VisibleForTesting
140     static final Object GET_SHARD_MBEAN_MESSAGE = new Object() {
141         @Override
142         public String toString() {
143             return "getShardMBeanMessage";
144         }
145     };
146
147     static final Object RESUME_NEXT_PENDING_TRANSACTION = new Object() {
148         @Override
149         public String toString() {
150             return "resumeNextPendingTransaction";
151         }
152     };
153
154     // FIXME: shard names should be encapsulated in their own class and this should be exposed as a constant.
155     public static final String DEFAULT_NAME = "default";
156
157     private static final Collection<ABIVersion> SUPPORTED_ABIVERSIONS;
158
159     // Make sure to keep this in sync with the journal configuration in factory-akka.conf
160     public static final String NON_PERSISTENT_JOURNAL_ID = "akka.persistence.non-persistent.journal";
161
162     static {
163         final ABIVersion[] values = ABIVersion.values();
164         final ABIVersion[] real = Arrays.copyOfRange(values, 1, values.length - 1);
165         SUPPORTED_ABIVERSIONS = ImmutableList.copyOf(real).reverse();
166     }
167
168     // FIXME: make this a dynamic property based on mailbox size and maximum number of clients
169     private static final int CLIENT_MAX_MESSAGES = 1000;
170
171     // The state of this Shard
172     private final ShardDataTree store;
173
174     /// The name of this shard
175     private final String name;
176
177     private final String shardName;
178
179     private final ShardStats shardMBean;
180
181     private final ShardDataTreeListenerInfoMXBeanImpl listenerInfoMXBean;
182
183     private DatastoreContext datastoreContext;
184
185     private final ShardCommitCoordinator commitCoordinator;
186
187     private long transactionCommitTimeout;
188
189     private Cancellable txCommitTimeoutCheckSchedule;
190
191     private final Optional<ActorRef> roleChangeNotifier;
192
193     private final MessageTracker appendEntriesReplyTracker;
194
195     private final ShardTransactionActorFactory transactionActorFactory;
196
197     private final ShardSnapshotCohort snapshotCohort;
198
199     private final DataTreeChangeListenerSupport treeChangeSupport = new DataTreeChangeListenerSupport(this);
200
201     private ShardSnapshot restoreFromSnapshot;
202
203     private final ShardTransactionMessageRetrySupport messageRetrySupport;
204
205     @VisibleForTesting
206     final FrontendMetadata frontendMetadata;
207
208     private Map<FrontendIdentifier, LeaderFrontendState> knownFrontends = ImmutableMap.of();
209     private boolean paused;
210
211     private final MessageSlicer responseMessageSlicer;
212     private final Dispatchers dispatchers;
213
214     private final MessageAssembler requestMessageAssembler;
215
216     private final ExportOnRecovery exportOnRecovery;
217
218     private final ActorRef exportActor;
219
220     Shard(final AbstractBuilder<?, ?> builder) {
221         super(builder.getId().toString(), builder.getPeerAddresses(),
222                 Optional.of(builder.getDatastoreContext().getShardRaftConfig()), DataStoreVersions.CURRENT_VERSION);
223
224         this.name = builder.getId().toString();
225         this.shardName = builder.getId().getShardName();
226         this.datastoreContext = builder.getDatastoreContext();
227         this.restoreFromSnapshot = builder.getRestoreFromSnapshot();
228         this.frontendMetadata = new FrontendMetadata(name);
229         this.exportOnRecovery = datastoreContext.getExportOnRecovery();
230
231         switch (exportOnRecovery) {
232             case Json:
233                 exportActor = getContext().actorOf(JsonExportActor.props(builder.getSchemaContext(),
234                         datastoreContext.getRecoveryExportBaseDir()));
235                 break;
236             case Off:
237             default:
238                 exportActor = null;
239                 break;
240         }
241
242         setPersistence(datastoreContext.isPersistent());
243
244         LOG.info("Shard created : {}, persistent : {}", name, datastoreContext.isPersistent());
245
246         ShardDataTreeChangeListenerPublisherActorProxy treeChangeListenerPublisher =
247                 new ShardDataTreeChangeListenerPublisherActorProxy(getContext(), name + "-DTCL-publisher", name);
248         if (builder.getDataTree() != null) {
249             store = new ShardDataTree(this, builder.getSchemaContext(), builder.getDataTree(),
250                     treeChangeListenerPublisher, name,
251                     frontendMetadata);
252         } else {
253             store = new ShardDataTree(this, builder.getSchemaContext(), builder.getTreeType(),
254                     builder.getDatastoreContext().getStoreRoot(), treeChangeListenerPublisher, name,
255                     frontendMetadata);
256         }
257
258         shardMBean = ShardStats.create(name, datastoreContext.getDataStoreMXBeanType(), this);
259
260         if (isMetricsCaptureEnabled()) {
261             getContext().become(new MeteringBehavior(this));
262         }
263
264         commitCoordinator = new ShardCommitCoordinator(store, LOG, this.name);
265
266         setTransactionCommitTimeout();
267
268         // create a notifier actor for each cluster member
269         roleChangeNotifier = createRoleChangeNotifier(name);
270
271         appendEntriesReplyTracker = new MessageTracker(AppendEntriesReply.class,
272                 getRaftActorContext().getConfigParams().getIsolatedCheckIntervalInMillis());
273
274         dispatchers = new Dispatchers(context().system().dispatchers());
275         transactionActorFactory = new ShardTransactionActorFactory(store, datastoreContext,
276             dispatchers.getDispatcherPath(Dispatchers.DispatcherType.Transaction),
277                 self(), getContext(), shardMBean, builder.getId().getShardName());
278
279         snapshotCohort = ShardSnapshotCohort.create(getContext(), builder.getId().getMemberName(), store, LOG,
280             this.name, datastoreContext);
281
282         messageRetrySupport = new ShardTransactionMessageRetrySupport(this);
283
284         responseMessageSlicer = MessageSlicer.builder().logContext(this.name)
285                 .messageSliceSize(datastoreContext.getMaximumMessageSliceSize())
286                 .fileBackedStreamFactory(getRaftActorContext().getFileBackedOutputStreamFactory())
287                 .expireStateAfterInactivity(2, TimeUnit.MINUTES).build();
288
289         requestMessageAssembler = MessageAssembler.builder().logContext(this.name)
290                 .fileBackedStreamFactory(getRaftActorContext().getFileBackedOutputStreamFactory())
291                 .assembledMessageCallback((message, sender) -> self().tell(message, sender))
292                 .expireStateAfterInactivity(datastoreContext.getRequestTimeout(), TimeUnit.NANOSECONDS).build();
293
294         listenerInfoMXBean = new ShardDataTreeListenerInfoMXBeanImpl(name, datastoreContext.getDataStoreMXBeanType(),
295                 self());
296         listenerInfoMXBean.register();
297     }
298
299     private void setTransactionCommitTimeout() {
300         transactionCommitTimeout = TimeUnit.MILLISECONDS.convert(
301                 datastoreContext.getShardTransactionCommitTimeoutInSeconds(), TimeUnit.SECONDS) / 2;
302     }
303
304     private Optional<ActorRef> createRoleChangeNotifier(final String shardId) {
305         ActorRef shardRoleChangeNotifier = this.getContext().actorOf(
306             RoleChangeNotifier.getProps(shardId), shardId + "-notifier");
307         return Optional.of(shardRoleChangeNotifier);
308     }
309
310     @Override
311     public final void postStop() throws Exception {
312         LOG.info("Stopping Shard {}", persistenceId());
313
314         super.postStop();
315
316         messageRetrySupport.close();
317
318         if (txCommitTimeoutCheckSchedule != null) {
319             txCommitTimeoutCheckSchedule.cancel();
320         }
321
322         commitCoordinator.abortPendingTransactions("Transaction aborted due to shutdown.", this);
323
324         shardMBean.unregisterMBean();
325         listenerInfoMXBean.unregister();
326     }
327
328     @Override
329     protected final void handleRecover(final Object message) {
330         LOG.debug("{}: onReceiveRecover: Received message {} from {}", persistenceId(), message.getClass(),
331             getSender());
332
333         super.handleRecover(message);
334
335         switch (exportOnRecovery) {
336             case Json:
337                 if (message instanceof SnapshotOffer) {
338                     exportActor.tell(new JsonExportActor.ExportSnapshot(store.readCurrentData().get(), name),
339                             ActorRef.noSender());
340                 } else if (message instanceof ReplicatedLogEntry) {
341                     exportActor.tell(new JsonExportActor.ExportJournal((ReplicatedLogEntry) message),
342                             ActorRef.noSender());
343                 } else if (message instanceof RecoveryCompleted) {
344                     exportActor.tell(new JsonExportActor.FinishExport(name), ActorRef.noSender());
345                     exportActor.tell(PoisonPill.getInstance(), ActorRef.noSender());
346                 }
347                 break;
348             case Off:
349             default:
350                 break;
351         }
352
353         if (LOG.isTraceEnabled()) {
354             appendEntriesReplyTracker.begin();
355         }
356     }
357
358     @Override
359     // non-final for TestShard
360     protected void handleNonRaftCommand(final Object message) {
361         try (MessageTracker.Context context = appendEntriesReplyTracker.received(message)) {
362             final Optional<Error> maybeError = context.error();
363             if (maybeError.isPresent()) {
364                 LOG.trace("{} : AppendEntriesReply failed to arrive at the expected interval {}", persistenceId(),
365                     maybeError.get());
366             }
367
368             store.resetTransactionBatch();
369
370             if (message instanceof RequestEnvelope) {
371                 handleRequestEnvelope((RequestEnvelope)message);
372             } else if (MessageAssembler.isHandledMessage(message)) {
373                 handleRequestAssemblerMessage(message);
374             } else if (message instanceof ConnectClientRequest) {
375                 handleConnectClient((ConnectClientRequest)message);
376             } else if (CreateTransaction.isSerializedType(message)) {
377                 handleCreateTransaction(message);
378             } else if (message instanceof BatchedModifications) {
379                 handleBatchedModifications((BatchedModifications)message);
380             } else if (message instanceof ForwardedReadyTransaction) {
381                 handleForwardedReadyTransaction((ForwardedReadyTransaction) message);
382             } else if (message instanceof ReadyLocalTransaction) {
383                 handleReadyLocalTransaction((ReadyLocalTransaction)message);
384             } else if (CanCommitTransaction.isSerializedType(message)) {
385                 handleCanCommitTransaction(CanCommitTransaction.fromSerializable(message));
386             } else if (CommitTransaction.isSerializedType(message)) {
387                 handleCommitTransaction(CommitTransaction.fromSerializable(message));
388             } else if (AbortTransaction.isSerializedType(message)) {
389                 handleAbortTransaction(AbortTransaction.fromSerializable(message));
390             } else if (CloseTransactionChain.isSerializedType(message)) {
391                 closeTransactionChain(CloseTransactionChain.fromSerializable(message));
392             } else if (message instanceof DataTreeChangedReply) {
393                 // Ignore reply
394             } else if (message instanceof RegisterDataTreeChangeListener) {
395                 treeChangeSupport.onMessage((RegisterDataTreeChangeListener) message, isLeader(), hasLeader());
396             } else if (message instanceof UpdateSchemaContext) {
397                 updateSchemaContext((UpdateSchemaContext) message);
398             } else if (message instanceof PeerAddressResolved) {
399                 PeerAddressResolved resolved = (PeerAddressResolved) message;
400                 setPeerAddress(resolved.getPeerId(), resolved.getPeerAddress());
401             } else if (TX_COMMIT_TIMEOUT_CHECK_MESSAGE.equals(message)) {
402                 commitTimeoutCheck();
403             } else if (message instanceof DatastoreContext) {
404                 onDatastoreContext((DatastoreContext)message);
405             } else if (message instanceof RegisterRoleChangeListener) {
406                 roleChangeNotifier.get().forward(message, context());
407             } else if (message instanceof FollowerInitialSyncUpStatus) {
408                 shardMBean.setFollowerInitialSyncStatus(((FollowerInitialSyncUpStatus) message).isInitialSyncDone());
409                 context().parent().tell(message, self());
410             } else if (GET_SHARD_MBEAN_MESSAGE.equals(message)) {
411                 sender().tell(getShardMBean(), self());
412             } else if (message instanceof GetShardDataTree) {
413                 sender().tell(store.getDataTree(), self());
414             } else if (message instanceof ServerRemoved) {
415                 context().parent().forward(message, context());
416             } else if (ShardTransactionMessageRetrySupport.TIMER_MESSAGE_CLASS.isInstance(message)) {
417                 messageRetrySupport.onTimerMessage(message);
418             } else if (message instanceof DataTreeCohortActorRegistry.CohortRegistryCommand) {
419                 store.processCohortRegistryCommand(getSender(),
420                         (DataTreeCohortActorRegistry.CohortRegistryCommand) message);
421             } else if (message instanceof MakeLeaderLocal) {
422                 onMakeLeaderLocal();
423             } else if (RESUME_NEXT_PENDING_TRANSACTION.equals(message)) {
424                 store.resumeNextPendingTransaction();
425             } else if (GetKnownClients.INSTANCE.equals(message)) {
426                 handleGetKnownClients();
427             } else if (!responseMessageSlicer.handleMessage(message)) {
428                 super.handleNonRaftCommand(message);
429             }
430         }
431     }
432
433     private void handleRequestAssemblerMessage(final Object message) {
434         dispatchers.getDispatcher(DispatcherType.Serialization).execute(() -> {
435             JavaSerializer.currentSystem().value_$eq((ExtendedActorSystem) context().system());
436             requestMessageAssembler.handleMessage(message, self());
437         });
438     }
439
440     @SuppressWarnings("checkstyle:IllegalCatch")
441     private void handleRequestEnvelope(final RequestEnvelope envelope) {
442         final long now = ticker().read();
443         try {
444             final RequestSuccess<?, ?> success = handleRequest(envelope, now);
445             if (success != null) {
446                 final long executionTimeNanos = ticker().read() - now;
447                 if (success instanceof SliceableMessage) {
448                     dispatchers.getDispatcher(DispatcherType.Serialization).execute(() ->
449                         responseMessageSlicer.slice(SliceOptions.builder().identifier(success.getTarget())
450                             .message(envelope.newSuccessEnvelope(success, executionTimeNanos))
451                             .sendTo(envelope.getMessage().getReplyTo()).replyTo(self())
452                             .onFailureCallback(t -> LOG.warn("Error slicing response {}", success, t)).build()));
453                 } else {
454                     envelope.sendSuccess(success, executionTimeNanos);
455                 }
456             }
457         } catch (RequestException e) {
458             LOG.debug("{}: request {} failed", persistenceId(), envelope, e);
459             envelope.sendFailure(e, ticker().read() - now);
460         } catch (Exception e) {
461             LOG.debug("{}: request {} caused failure", persistenceId(), envelope, e);
462             envelope.sendFailure(new RuntimeRequestException("Request failed to process", e),
463                 ticker().read() - now);
464         }
465     }
466
467     private void commitTimeoutCheck() {
468         store.checkForExpiredTransactions(transactionCommitTimeout, this::updateAccess);
469         commitCoordinator.checkForExpiredTransactions(transactionCommitTimeout, this);
470         requestMessageAssembler.checkExpiredAssembledMessageState();
471     }
472
473     private OptionalLong updateAccess(final SimpleShardDataTreeCohort cohort) {
474         final FrontendIdentifier frontend = cohort.getIdentifier().getHistoryId().getClientId().getFrontendId();
475         final LeaderFrontendState state = knownFrontends.get(frontend);
476         if (state == null) {
477             // Not tell-based protocol, do nothing
478             return OptionalLong.empty();
479         }
480
481         if (isIsolatedLeader()) {
482             // We are isolated and no new request can come through until we emerge from it. We are still updating
483             // liveness of frontend when we see it attempting to communicate. Use the last access timer.
484             return OptionalLong.of(state.getLastSeenTicks());
485         }
486
487         // If this frontend has freshly connected, give it some time to catch up before killing its transactions.
488         return OptionalLong.of(state.getLastConnectTicks());
489     }
490
491     private void disableTracking(final DisableTrackingPayload payload) {
492         final ClientIdentifier clientId = payload.getIdentifier();
493         LOG.debug("{}: disabling tracking of {}", persistenceId(), clientId);
494         frontendMetadata.disableTracking(clientId);
495
496         if (isLeader()) {
497             final FrontendIdentifier frontendId = clientId.getFrontendId();
498             final LeaderFrontendState frontend = knownFrontends.get(frontendId);
499             if (frontend != null) {
500                 if (clientId.equals(frontend.getIdentifier())) {
501                     if (!(frontend instanceof LeaderFrontendState.Disabled)) {
502                         verify(knownFrontends.replace(frontendId, frontend,
503                             new LeaderFrontendState.Disabled(persistenceId(), clientId, store)));
504                         LOG.debug("{}: leader state for {} disabled", persistenceId(), clientId);
505                     } else {
506                         LOG.debug("{}: leader state {} is already disabled", persistenceId(), frontend);
507                     }
508                 } else {
509                     LOG.debug("{}: leader state {} does not match {}", persistenceId(), frontend, clientId);
510                 }
511             } else {
512                 LOG.debug("{}: leader state for {} not found", persistenceId(), clientId);
513                 knownFrontends.put(frontendId, new LeaderFrontendState.Disabled(persistenceId(), clientId,
514                     getDataStore()));
515             }
516         }
517     }
518
519     private void onMakeLeaderLocal() {
520         LOG.debug("{}: onMakeLeaderLocal received", persistenceId());
521         if (isLeader()) {
522             getSender().tell(new Status.Success(null), getSelf());
523             return;
524         }
525
526         final ActorSelection leader = getLeader();
527
528         if (leader == null) {
529             // Leader is not present. The cluster is most likely trying to
530             // elect a leader and we should let that run its normal course
531
532             // TODO we can wait for the election to complete and retry the
533             // request. We can also let the caller retry by sending a flag
534             // in the response indicating the request is "reTryable".
535             getSender().tell(new Failure(
536                     new LeadershipTransferFailedException("We cannot initiate leadership transfer to local node. "
537                             + "Currently there is no leader for " + persistenceId())),
538                     getSelf());
539             return;
540         }
541
542         leader.tell(new RequestLeadership(getId(), getSender()), getSelf());
543     }
544
545     // Acquire our frontend tracking handle and verify generation matches
546     private @Nullable LeaderFrontendState findFrontend(final ClientIdentifier clientId) throws RequestException {
547         final LeaderFrontendState existing = knownFrontends.get(clientId.getFrontendId());
548         if (existing != null) {
549             final int cmp = Long.compareUnsigned(existing.getIdentifier().getGeneration(), clientId.getGeneration());
550             if (cmp == 0) {
551                 existing.touch();
552                 return existing;
553             }
554             if (cmp > 0) {
555                 LOG.debug("{}: rejecting request from outdated client {}", persistenceId(), clientId);
556                 throw new RetiredGenerationException(clientId.getGeneration(),
557                     existing.getIdentifier().getGeneration());
558             }
559
560             LOG.info("{}: retiring state {}, outdated by request from client {}", persistenceId(), existing, clientId);
561             existing.retire();
562             knownFrontends.remove(clientId.getFrontendId());
563         } else {
564             LOG.debug("{}: client {} is not yet known", persistenceId(), clientId);
565         }
566
567         return null;
568     }
569
570     private LeaderFrontendState getFrontend(final ClientIdentifier clientId) throws RequestException {
571         final LeaderFrontendState ret = findFrontend(clientId);
572         if (ret != null) {
573             return ret;
574         }
575
576         // TODO: a dedicated exception would be better, but this is technically true, too
577         throw new OutOfSequenceEnvelopeException(0);
578     }
579
580     private static @NonNull ABIVersion selectVersion(final ConnectClientRequest message) {
581         final Range<ABIVersion> clientRange = Range.closed(message.getMinVersion(), message.getMaxVersion());
582         for (ABIVersion v : SUPPORTED_ABIVERSIONS) {
583             if (clientRange.contains(v)) {
584                 return v;
585             }
586         }
587
588         throw new IllegalArgumentException(String.format(
589             "No common version between backend versions %s and client versions %s", SUPPORTED_ABIVERSIONS,
590             clientRange));
591     }
592
593     @SuppressWarnings("checkstyle:IllegalCatch")
594     private void handleConnectClient(final ConnectClientRequest message) {
595         try {
596             final ClientIdentifier clientId = message.getTarget();
597             final LeaderFrontendState existing = findFrontend(clientId);
598             if (existing != null) {
599                 existing.touch();
600             }
601
602             if (!isLeader() || !isLeaderActive()) {
603                 LOG.info("{}: not currently leader, rejecting request {}. isLeader: {}, isLeaderActive: {},"
604                                 + "isLeadershipTransferInProgress: {}.",
605                         persistenceId(), message, isLeader(), isLeaderActive(), isLeadershipTransferInProgress());
606                 throw new NotLeaderException(getSelf());
607             }
608
609             final ABIVersion selectedVersion = selectVersion(message);
610             final LeaderFrontendState frontend;
611             if (existing == null) {
612                 frontend = new LeaderFrontendState.Enabled(persistenceId(), clientId, store);
613                 knownFrontends.put(clientId.getFrontendId(), frontend);
614                 LOG.debug("{}: created state {} for client {}", persistenceId(), frontend, clientId);
615             } else {
616                 frontend = existing;
617             }
618
619             frontend.reconnect();
620             message.getReplyTo().tell(new ConnectClientSuccess(message.getTarget(), message.getSequence(), getSelf(),
621                 ImmutableList.of(), store.getDataTree(), CLIENT_MAX_MESSAGES).toVersion(selectedVersion),
622                 ActorRef.noSender());
623         } catch (RequestException | RuntimeException e) {
624             message.getReplyTo().tell(new Failure(e), ActorRef.noSender());
625         }
626     }
627
628     private @Nullable RequestSuccess<?, ?> handleRequest(final RequestEnvelope envelope, final long now)
629             throws RequestException {
630         // We are not the leader, hence we want to fail-fast.
631         if (!isLeader() || paused || !isLeaderActive()) {
632             LOG.debug("{}: not currently active leader, rejecting request {}. isLeader: {}, isLeaderActive: {},"
633                             + "isLeadershipTransferInProgress: {}, paused: {}",
634                     persistenceId(), envelope, isLeader(), isLeaderActive(), isLeadershipTransferInProgress(), paused);
635             throw new NotLeaderException(getSelf());
636         }
637
638         final Request<?, ?> request = envelope.getMessage();
639         if (request instanceof TransactionRequest) {
640             final TransactionRequest<?> txReq = (TransactionRequest<?>)request;
641             final ClientIdentifier clientId = txReq.getTarget().getHistoryId().getClientId();
642             return getFrontend(clientId).handleTransactionRequest(txReq, envelope, now);
643         } else if (request instanceof LocalHistoryRequest) {
644             final LocalHistoryRequest<?> lhReq = (LocalHistoryRequest<?>)request;
645             final ClientIdentifier clientId = lhReq.getTarget().getClientId();
646             return getFrontend(clientId).handleLocalHistoryRequest(lhReq, envelope, now);
647         } else {
648             LOG.warn("{}: rejecting unsupported request {}", persistenceId(), request);
649             throw new UnsupportedRequestException(request);
650         }
651     }
652
653     private void handleGetKnownClients() {
654         final ImmutableSet<ClientIdentifier> clients;
655         if (isLeader()) {
656             clients = knownFrontends.values().stream()
657                     .map(LeaderFrontendState::getIdentifier)
658                     .collect(ImmutableSet.toImmutableSet());
659         } else {
660             clients = frontendMetadata.getClients();
661         }
662         sender().tell(new GetKnownClientsReply(clients), self());
663     }
664
665     private boolean hasLeader() {
666         return getLeaderId() != null;
667     }
668
669     final int getPendingTxCommitQueueSize() {
670         return store.getQueueSize();
671     }
672
673     final int getCohortCacheSize() {
674         return commitCoordinator.getCohortCacheSize();
675     }
676
677     @Override
678     protected final Optional<ActorRef> getRoleChangeNotifier() {
679         return roleChangeNotifier;
680     }
681
682     final String getShardName() {
683         return shardName;
684     }
685
686     @Override
687     protected final LeaderStateChanged newLeaderStateChanged(final String memberId, final String leaderId,
688             final short leaderPayloadVersion) {
689         return isLeader() ? new ShardLeaderStateChanged(memberId, leaderId, store.getDataTree(), leaderPayloadVersion)
690                 : new ShardLeaderStateChanged(memberId, leaderId, leaderPayloadVersion);
691     }
692
693     private void onDatastoreContext(final DatastoreContext context) {
694         datastoreContext = verifyNotNull(context);
695
696         setTransactionCommitTimeout();
697
698         setPersistence(datastoreContext.isPersistent());
699
700         updateConfigParams(datastoreContext.getShardRaftConfig());
701     }
702
703     // applyState() will be invoked once consensus is reached on the payload
704     // non-final for mocking
705     void persistPayload(final Identifier id, final Payload payload, final boolean batchHint) {
706         final boolean canSkipPayload = !hasFollowers() && !persistence().isRecoveryApplicable();
707         if (canSkipPayload) {
708             applyState(self(), id, payload);
709         } else {
710             // We are faking the sender
711             persistData(self(), id, payload, batchHint);
712         }
713     }
714
715     private void handleCommitTransaction(final CommitTransaction commit) {
716         final TransactionIdentifier txId = commit.getTransactionId();
717         if (isLeader()) {
718             askProtocolEncountered(txId);
719             commitCoordinator.handleCommit(txId, getSender(), this);
720         } else {
721             ActorSelection leader = getLeader();
722             if (leader == null) {
723                 messageRetrySupport.addMessageToRetry(commit, getSender(), "Could not commit transaction " + txId);
724             } else {
725                 LOG.debug("{}: Forwarding CommitTransaction to leader {}", persistenceId(), leader);
726                 leader.forward(commit, getContext());
727             }
728         }
729     }
730
731     private void handleCanCommitTransaction(final CanCommitTransaction canCommit) {
732         final TransactionIdentifier txId = canCommit.getTransactionId();
733         LOG.debug("{}: Can committing transaction {}", persistenceId(), txId);
734
735         if (isLeader()) {
736             askProtocolEncountered(txId);
737             commitCoordinator.handleCanCommit(txId, getSender(), this);
738         } else {
739             ActorSelection leader = getLeader();
740             if (leader == null) {
741                 messageRetrySupport.addMessageToRetry(canCommit, getSender(),
742                         "Could not canCommit transaction " + txId);
743             } else {
744                 LOG.debug("{}: Forwarding CanCommitTransaction to leader {}", persistenceId(), leader);
745                 leader.forward(canCommit, getContext());
746             }
747         }
748     }
749
750     @SuppressWarnings("checkstyle:IllegalCatch")
751     private void handleBatchedModificationsLocal(final BatchedModifications batched, final ActorRef sender) {
752         askProtocolEncountered(batched.getTransactionId());
753
754         try {
755             commitCoordinator.handleBatchedModifications(batched, sender, this);
756         } catch (Exception e) {
757             LOG.error("{}: Error handling BatchedModifications for Tx {}", persistenceId(),
758                     batched.getTransactionId(), e);
759             sender.tell(new Failure(e), getSelf());
760         }
761     }
762
763     private void handleBatchedModifications(final BatchedModifications batched) {
764         // This message is sent to prepare the modifications transaction directly on the Shard as an
765         // optimization to avoid the extra overhead of a separate ShardTransaction actor. On the last
766         // BatchedModifications message, the caller sets the ready flag in the message indicating
767         // modifications are complete. The reply contains the cohort actor path (this actor) for the caller
768         // to initiate the 3-phase commit. This also avoids the overhead of sending an additional
769         // ReadyTransaction message.
770
771         // If we're not the leader then forward to the leader. This is a safety measure - we shouldn't
772         // normally get here if we're not the leader as the front-end (TransactionProxy) should determine
773         // the primary/leader shard. However with timing and caching on the front-end, there's a small
774         // window where it could have a stale leader during leadership transitions.
775         //
776         boolean isLeaderActive = isLeaderActive();
777         if (isLeader() && isLeaderActive) {
778             handleBatchedModificationsLocal(batched, getSender());
779         } else {
780             ActorSelection leader = getLeader();
781             if (!isLeaderActive || leader == null) {
782                 messageRetrySupport.addMessageToRetry(batched, getSender(),
783                         "Could not process BatchedModifications " + batched.getTransactionId());
784             } else {
785                 // If this is not the first batch and leadership changed in between batched messages,
786                 // we need to reconstruct previous BatchedModifications from the transaction
787                 // DataTreeModification, honoring the max batched modification count, and forward all the
788                 // previous BatchedModifications to the new leader.
789                 Collection<BatchedModifications> newModifications = commitCoordinator
790                         .createForwardedBatchedModifications(batched,
791                                 datastoreContext.getShardBatchedModificationCount());
792
793                 LOG.debug("{}: Forwarding {} BatchedModifications to leader {}", persistenceId(),
794                         newModifications.size(), leader);
795
796                 for (BatchedModifications bm : newModifications) {
797                     leader.forward(bm, getContext());
798                 }
799             }
800         }
801     }
802
803     private boolean failIfIsolatedLeader(final ActorRef sender) {
804         if (isIsolatedLeader()) {
805             sender.tell(new Failure(new NoShardLeaderException(String.format(
806                     "Shard %s was the leader but has lost contact with all of its followers. Either all"
807                     + " other follower nodes are down or this node is isolated by a network partition.",
808                     persistenceId()))), getSelf());
809             return true;
810         }
811
812         return false;
813     }
814
815     protected boolean isIsolatedLeader() {
816         return getRaftState() == RaftState.IsolatedLeader;
817     }
818
819     @SuppressWarnings("checkstyle:IllegalCatch")
820     private void handleReadyLocalTransaction(final ReadyLocalTransaction message) {
821         LOG.debug("{}: handleReadyLocalTransaction for {}", persistenceId(), message.getTransactionId());
822
823         boolean isLeaderActive = isLeaderActive();
824         if (isLeader() && isLeaderActive) {
825             try {
826                 commitCoordinator.handleReadyLocalTransaction(message, getSender(), this);
827             } catch (Exception e) {
828                 LOG.error("{}: Error handling ReadyLocalTransaction for Tx {}", persistenceId(),
829                         message.getTransactionId(), e);
830                 getSender().tell(new Failure(e), getSelf());
831             }
832         } else {
833             ActorSelection leader = getLeader();
834             if (!isLeaderActive || leader == null) {
835                 messageRetrySupport.addMessageToRetry(message, getSender(),
836                         "Could not process ready local transaction " + message.getTransactionId());
837             } else {
838                 LOG.debug("{}: Forwarding ReadyLocalTransaction to leader {}", persistenceId(), leader);
839                 message.setRemoteVersion(getCurrentBehavior().getLeaderPayloadVersion());
840                 leader.forward(message, getContext());
841             }
842         }
843     }
844
845     private void handleForwardedReadyTransaction(final ForwardedReadyTransaction forwardedReady) {
846         LOG.debug("{}: handleForwardedReadyTransaction for {}", persistenceId(), forwardedReady.getTransactionId());
847
848         boolean isLeaderActive = isLeaderActive();
849         if (isLeader() && isLeaderActive) {
850             askProtocolEncountered(forwardedReady.getTransactionId());
851             commitCoordinator.handleForwardedReadyTransaction(forwardedReady, getSender(), this);
852         } else {
853             ActorSelection leader = getLeader();
854             if (!isLeaderActive || leader == null) {
855                 messageRetrySupport.addMessageToRetry(forwardedReady, getSender(),
856                         "Could not process forwarded ready transaction " + forwardedReady.getTransactionId());
857             } else {
858                 LOG.debug("{}: Forwarding ForwardedReadyTransaction to leader {}", persistenceId(), leader);
859
860                 ReadyLocalTransaction readyLocal = new ReadyLocalTransaction(forwardedReady.getTransactionId(),
861                         forwardedReady.getTransaction().getSnapshot(), forwardedReady.isDoImmediateCommit(),
862                         forwardedReady.getParticipatingShardNames());
863                 readyLocal.setRemoteVersion(getCurrentBehavior().getLeaderPayloadVersion());
864                 leader.forward(readyLocal, getContext());
865             }
866         }
867     }
868
869     private void handleAbortTransaction(final AbortTransaction abort) {
870         final TransactionIdentifier transactionId = abort.getTransactionId();
871         askProtocolEncountered(transactionId);
872         doAbortTransaction(transactionId, getSender());
873     }
874
875     final void doAbortTransaction(final Identifier transactionID, final ActorRef sender) {
876         commitCoordinator.handleAbort(transactionID, sender, this);
877     }
878
879     private void handleCreateTransaction(final Object message) {
880         if (isLeader()) {
881             createTransaction(CreateTransaction.fromSerializable(message));
882         } else if (getLeader() != null) {
883             getLeader().forward(message, getContext());
884         } else {
885             getSender().tell(new Failure(new NoShardLeaderException(
886                     "Could not create a shard transaction", persistenceId())), getSelf());
887         }
888     }
889
890     private void closeTransactionChain(final CloseTransactionChain closeTransactionChain) {
891         if (isLeader()) {
892             final LocalHistoryIdentifier id = closeTransactionChain.getIdentifier();
893             askProtocolEncountered(id.getClientId());
894             store.closeTransactionChain(id);
895         } else if (getLeader() != null) {
896             getLeader().forward(closeTransactionChain, getContext());
897         } else {
898             LOG.warn("{}: Could not close transaction {}", persistenceId(), closeTransactionChain.getIdentifier());
899         }
900     }
901
902     @SuppressWarnings("checkstyle:IllegalCatch")
903     private void createTransaction(final CreateTransaction createTransaction) {
904         askProtocolEncountered(createTransaction.getTransactionId());
905
906         try {
907             if (TransactionType.fromInt(createTransaction.getTransactionType()) != TransactionType.READ_ONLY
908                     && failIfIsolatedLeader(getSender())) {
909                 return;
910             }
911
912             ActorRef transactionActor = createTransaction(createTransaction.getTransactionType(),
913                 createTransaction.getTransactionId());
914
915             getSender().tell(new CreateTransactionReply(Serialization.serializedActorPath(transactionActor),
916                     createTransaction.getTransactionId(), createTransaction.getVersion()).toSerializable(), getSelf());
917         } catch (Exception e) {
918             getSender().tell(new Failure(e), getSelf());
919         }
920     }
921
922     private ActorRef createTransaction(final int transactionType, final TransactionIdentifier transactionId) {
923         LOG.debug("{}: Creating transaction : {} ", persistenceId(), transactionId);
924         return transactionActorFactory.newShardTransaction(TransactionType.fromInt(transactionType),
925             transactionId);
926     }
927
928     // Called on leader only
929     private void askProtocolEncountered(final TransactionIdentifier transactionId) {
930         askProtocolEncountered(transactionId.getHistoryId().getClientId());
931     }
932
933     // Called on leader only
934     private void askProtocolEncountered(final ClientIdentifier clientId) {
935         final FrontendIdentifier frontend = clientId.getFrontendId();
936         final LeaderFrontendState state = knownFrontends.get(frontend);
937         if (!(state instanceof LeaderFrontendState.Disabled)) {
938             LOG.debug("{}: encountered ask-based client {}, disabling transaction tracking", persistenceId(), clientId);
939             if (knownFrontends.isEmpty()) {
940                 knownFrontends = new HashMap<>();
941             }
942             knownFrontends.put(frontend, new LeaderFrontendState.Disabled(persistenceId(), clientId, getDataStore()));
943
944             persistPayload(clientId, DisableTrackingPayload.create(clientId,
945                 datastoreContext.getInitialPayloadSerializedBufferCapacity()), false);
946         }
947     }
948
949     private void updateSchemaContext(final UpdateSchemaContext message) {
950         updateSchemaContext(message.getEffectiveModelContext());
951     }
952
953     @VisibleForTesting
954     void updateSchemaContext(final @NonNull EffectiveModelContext schemaContext) {
955         store.updateSchemaContext(schemaContext);
956     }
957
958     private boolean isMetricsCaptureEnabled() {
959         CommonConfig config = new CommonConfig(getContext().system().settings().config());
960         return config.isMetricCaptureEnabled();
961     }
962
963     @Override
964     protected final RaftActorSnapshotCohort getRaftActorSnapshotCohort() {
965         return snapshotCohort;
966     }
967
968     @Override
969     protected final RaftActorRecoveryCohort getRaftActorRecoveryCohort() {
970         if (restoreFromSnapshot == null) {
971             return ShardRecoveryCoordinator.create(store, persistenceId(), LOG);
972         }
973
974         return ShardRecoveryCoordinator.forSnapshot(store, persistenceId(), LOG, restoreFromSnapshot.getSnapshot());
975     }
976
977     @Override
978     // non-final for testing
979     protected void onRecoveryComplete() {
980         restoreFromSnapshot = null;
981
982         //notify shard manager
983         getContext().parent().tell(new ActorInitialized(), getSelf());
984
985         // Being paranoid here - this method should only be called once but just in case...
986         if (txCommitTimeoutCheckSchedule == null) {
987             // Schedule a message to be periodically sent to check if the current in-progress
988             // transaction should be expired and aborted.
989             FiniteDuration period = FiniteDuration.create(transactionCommitTimeout / 3, TimeUnit.MILLISECONDS);
990             txCommitTimeoutCheckSchedule = getContext().system().scheduler().schedule(
991                     period, period, getSelf(),
992                     TX_COMMIT_TIMEOUT_CHECK_MESSAGE, getContext().dispatcher(), ActorRef.noSender());
993         }
994     }
995
996     @Override
997     protected final void applyState(final ActorRef clientActor, final Identifier identifier, final Object data) {
998         if (data instanceof Payload) {
999             if (data instanceof DisableTrackingPayload) {
1000                 disableTracking((DisableTrackingPayload) data);
1001                 return;
1002             }
1003
1004             try {
1005                 store.applyReplicatedPayload(identifier, (Payload)data);
1006             } catch (DataValidationFailedException | IOException e) {
1007                 LOG.error("{}: Error applying replica {}", persistenceId(), identifier, e);
1008             }
1009         } else {
1010             LOG.error("{}: Unknown state for {} received {}", persistenceId(), identifier, data);
1011         }
1012     }
1013
1014     @Override
1015     protected final void onStateChanged() {
1016         boolean isLeader = isLeader();
1017         boolean hasLeader = hasLeader();
1018         treeChangeSupport.onLeadershipChange(isLeader, hasLeader);
1019
1020         // If this actor is no longer the leader close all the transaction chains
1021         if (!isLeader) {
1022             if (LOG.isDebugEnabled()) {
1023                 LOG.debug(
1024                     "{}: onStateChanged: Closing all transaction chains because shard {} is no longer the leader",
1025                     persistenceId(), getId());
1026             }
1027
1028             paused = false;
1029             store.purgeLeaderState();
1030         }
1031
1032         if (hasLeader && !isIsolatedLeader()) {
1033             messageRetrySupport.retryMessages();
1034         }
1035     }
1036
1037     @Override
1038     protected final void onLeaderChanged(final String oldLeader, final String newLeader) {
1039         shardMBean.incrementLeadershipChangeCount();
1040         paused = false;
1041
1042         if (!isLeader()) {
1043             if (!knownFrontends.isEmpty()) {
1044                 LOG.debug("{}: removing frontend state for {}", persistenceId(), knownFrontends.keySet());
1045                 knownFrontends = ImmutableMap.of();
1046             }
1047
1048             requestMessageAssembler.close();
1049
1050             if (!hasLeader()) {
1051                 // No leader anywhere, nothing else to do
1052                 return;
1053             }
1054
1055             // Another leader was elected. If we were the previous leader and had pending transactions, convert
1056             // them to transaction messages and send to the new leader.
1057             ActorSelection leader = getLeader();
1058             if (leader != null) {
1059                 // Clears all pending transactions and converts them to messages to be forwarded to a new leader.
1060                 Collection<?> messagesToForward = commitCoordinator.convertPendingTransactionsToMessages(
1061                     datastoreContext.getShardBatchedModificationCount());
1062
1063                 if (!messagesToForward.isEmpty()) {
1064                     LOG.debug("{}: Forwarding {} pending transaction messages to leader {}", persistenceId(),
1065                             messagesToForward.size(), leader);
1066
1067                     for (Object message : messagesToForward) {
1068                         LOG.debug("{}: Forwarding pending transaction message {}", persistenceId(), message);
1069
1070                         leader.tell(message, self());
1071                     }
1072                 }
1073             } else {
1074                 commitCoordinator.abortPendingTransactions("The transacton was aborted due to inflight leadership "
1075                         + "change and the leader address isn't available.", this);
1076             }
1077         } else {
1078             // We have become the leader, we need to reconstruct frontend state
1079             knownFrontends = verifyNotNull(frontendMetadata.toLeaderState(this));
1080             LOG.debug("{}: became leader with frontend state for {}", persistenceId(), knownFrontends.keySet());
1081         }
1082
1083         if (!isIsolatedLeader()) {
1084             messageRetrySupport.retryMessages();
1085         }
1086     }
1087
1088     @Override
1089     protected final void pauseLeader(final Runnable operation) {
1090         LOG.debug("{}: In pauseLeader, operation: {}", persistenceId(), operation);
1091         paused = true;
1092
1093         // Tell-based protocol can replay transaction state, so it is safe to blow it up when we are paused.
1094         if (datastoreContext.isUseTellBasedProtocol()) {
1095             knownFrontends.values().forEach(LeaderFrontendState::retire);
1096             knownFrontends = ImmutableMap.of();
1097         }
1098
1099         store.setRunOnPendingTransactionsComplete(operation);
1100     }
1101
1102     @Override
1103     protected final void unpauseLeader() {
1104         LOG.debug("{}: In unpauseLeader", persistenceId());
1105         paused = false;
1106
1107         store.setRunOnPendingTransactionsComplete(null);
1108
1109         // Restore tell-based protocol state as if we were becoming the leader
1110         knownFrontends = verifyNotNull(frontendMetadata.toLeaderState(this));
1111     }
1112
1113     @Override
1114     protected final OnDemandRaftState.AbstractBuilder<?, ?> newOnDemandRaftStateBuilder() {
1115         return OnDemandShardState.newBuilder()
1116             .treeChangeListenerActors(treeChangeSupport.getListenerActors())
1117             .commitCohortActors(store.getCohortActors());
1118     }
1119
1120     @Override
1121     public final String persistenceId() {
1122         return this.name;
1123     }
1124
1125     @Override
1126     public final String journalPluginId() {
1127         // This method may be invoked from super constructor (wonderful), hence we also need to handle the case of
1128         // the field being uninitialized because our constructor is not finished.
1129         if (datastoreContext != null && !datastoreContext.isPersistent()) {
1130             return NON_PERSISTENT_JOURNAL_ID;
1131         }
1132         return super.journalPluginId();
1133     }
1134
1135     @VisibleForTesting
1136     final ShardCommitCoordinator getCommitCoordinator() {
1137         return commitCoordinator;
1138     }
1139
1140     // non-final for mocking
1141     DatastoreContext getDatastoreContext() {
1142         return datastoreContext;
1143     }
1144
1145     @VisibleForTesting
1146     final ShardDataTree getDataStore() {
1147         return store;
1148     }
1149
1150     @VisibleForTesting
1151     // non-final for mocking
1152     ShardStats getShardMBean() {
1153         return shardMBean;
1154     }
1155
1156     public static Builder builder() {
1157         return new Builder();
1158     }
1159
1160     public abstract static class AbstractBuilder<T extends AbstractBuilder<T, S>, S extends Shard> {
1161         private final Class<? extends S> shardClass;
1162         private ShardIdentifier id;
1163         private Map<String, String> peerAddresses = Collections.emptyMap();
1164         private DatastoreContext datastoreContext;
1165         private EffectiveModelContextProvider schemaContextProvider;
1166         private DatastoreSnapshot.ShardSnapshot restoreFromSnapshot;
1167         private DataTree dataTree;
1168
1169         private volatile boolean sealed;
1170
1171         AbstractBuilder(final Class<? extends S> shardClass) {
1172             this.shardClass = shardClass;
1173         }
1174
1175         final void checkSealed() {
1176             checkState(!sealed, "Builder is already sealed - further modifications are not allowed");
1177         }
1178
1179         @SuppressWarnings("unchecked")
1180         private T self() {
1181             return (T) this;
1182         }
1183
1184         public T id(final ShardIdentifier newId) {
1185             checkSealed();
1186             this.id = newId;
1187             return self();
1188         }
1189
1190         public T peerAddresses(final Map<String, String> newPeerAddresses) {
1191             checkSealed();
1192             this.peerAddresses = newPeerAddresses;
1193             return self();
1194         }
1195
1196         public T datastoreContext(final DatastoreContext newDatastoreContext) {
1197             checkSealed();
1198             this.datastoreContext = newDatastoreContext;
1199             return self();
1200         }
1201
1202         public T schemaContextProvider(final EffectiveModelContextProvider newSchemaContextProvider) {
1203             checkSealed();
1204             this.schemaContextProvider = requireNonNull(newSchemaContextProvider);
1205             return self();
1206         }
1207
1208         public T restoreFromSnapshot(final DatastoreSnapshot.ShardSnapshot newRestoreFromSnapshot) {
1209             checkSealed();
1210             this.restoreFromSnapshot = newRestoreFromSnapshot;
1211             return self();
1212         }
1213
1214         public T dataTree(final DataTree newDataTree) {
1215             checkSealed();
1216             this.dataTree = newDataTree;
1217             return self();
1218         }
1219
1220         public ShardIdentifier getId() {
1221             return id;
1222         }
1223
1224         public Map<String, String> getPeerAddresses() {
1225             return peerAddresses;
1226         }
1227
1228         public DatastoreContext getDatastoreContext() {
1229             return datastoreContext;
1230         }
1231
1232         public EffectiveModelContext getSchemaContext() {
1233             return verifyNotNull(schemaContextProvider.getEffectiveModelContext());
1234         }
1235
1236         public DatastoreSnapshot.ShardSnapshot getRestoreFromSnapshot() {
1237             return restoreFromSnapshot;
1238         }
1239
1240         public DataTree getDataTree() {
1241             return dataTree;
1242         }
1243
1244         public TreeType getTreeType() {
1245             switch (datastoreContext.getLogicalStoreType()) {
1246                 case CONFIGURATION:
1247                     return TreeType.CONFIGURATION;
1248                 case OPERATIONAL:
1249                     return TreeType.OPERATIONAL;
1250                 default:
1251                     throw new IllegalStateException("Unhandled logical store type "
1252                             + datastoreContext.getLogicalStoreType());
1253             }
1254         }
1255
1256         protected void verify() {
1257             requireNonNull(id, "id should not be null");
1258             requireNonNull(peerAddresses, "peerAddresses should not be null");
1259             requireNonNull(datastoreContext, "dataStoreContext should not be null");
1260             requireNonNull(schemaContextProvider, "schemaContextProvider should not be null");
1261         }
1262
1263         public Props props() {
1264             sealed = true;
1265             verify();
1266             return Props.create(shardClass, this);
1267         }
1268     }
1269
1270     public static class Builder extends AbstractBuilder<Builder, Shard> {
1271         Builder() {
1272             this(Shard.class);
1273         }
1274
1275         Builder(final Class<? extends Shard> shardClass) {
1276             super(shardClass);
1277         }
1278     }
1279
1280     Ticker ticker() {
1281         return Ticker.systemTicker();
1282     }
1283
1284     void scheduleNextPendingTransaction() {
1285         self().tell(RESUME_NEXT_PENDING_TRANSACTION, ActorRef.noSender());
1286     }
1287 }