opendaylight/md-sal/sal-distributed-datastore/src/main/java/org/opendaylight/controller/cluster/datastore/shardmanager/ShardManager.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
   9 package org.opendaylight.controller.cluster.datastore.shardmanager;
  10
  11 import static akka.pattern.Patterns.ask;
  12 import akka.actor.ActorRef;
  13 import akka.actor.Address;
  14 import akka.actor.Cancellable;
  15 import akka.actor.OneForOneStrategy;
  16 import akka.actor.PoisonPill;
  17 import akka.actor.Props;
  18 import akka.actor.Status;
  19 import akka.actor.SupervisorStrategy;
  20 import akka.cluster.ClusterEvent;
  21 import akka.dispatch.Futures;
  22 import akka.dispatch.OnComplete;
  23 import akka.japi.Function;
  24 import akka.pattern.Patterns;
  25 import akka.persistence.RecoveryCompleted;
  26 import akka.persistence.SaveSnapshotFailure;
  27 import akka.persistence.SaveSnapshotSuccess;
  28 import akka.persistence.SnapshotOffer;
  29 import akka.persistence.SnapshotSelectionCriteria;
  30 import akka.serialization.Serialization;
  31 import akka.util.Timeout;
  32 import com.google.common.annotations.VisibleForTesting;
  33 import com.google.common.base.Objects;
  34 import com.google.common.base.Optional;
  35 import com.google.common.base.Preconditions;
  36 import com.google.common.base.Strings;
  37 import com.google.common.base.Supplier;
  38 import com.google.common.collect.Sets;
  39 import java.io.ByteArrayInputStream;
  40 import java.io.ObjectInputStream;
  41 import java.util.ArrayList;
  42 import java.util.Collection;
  43 import java.util.Collections;
  44 import java.util.HashMap;
  45 import java.util.HashSet;
  46 import java.util.Iterator;
  47 import java.util.List;
  48 import java.util.Map;
  49 import java.util.Set;
  50 import java.util.concurrent.CountDownLatch;
  51 import java.util.concurrent.TimeUnit;
  52 import java.util.concurrent.TimeoutException;
  53 import javax.annotation.Nonnull;
  54 import javax.annotation.Nullable;
  55 import org.apache.commons.lang3.SerializationUtils;
  56 import org.opendaylight.controller.cluster.common.actor.AbstractUntypedPersistentActorWithMetering;
  57 import org.opendaylight.controller.cluster.datastore.ClusterWrapper;
  58 import org.opendaylight.controller.cluster.datastore.DatastoreContext;
  59 import org.opendaylight.controller.cluster.datastore.DatastoreContextFactory;
  60 import org.opendaylight.controller.cluster.datastore.Shard;
  61 import org.opendaylight.controller.cluster.datastore.config.Configuration;
  62 import org.opendaylight.controller.cluster.datastore.config.ModuleShardConfiguration;
  63 import org.opendaylight.controller.cluster.datastore.exceptions.AlreadyExistsException;
  64 import org.opendaylight.controller.cluster.datastore.exceptions.NoShardLeaderException;
  65 import org.opendaylight.controller.cluster.datastore.exceptions.NotInitializedException;
  66 import org.opendaylight.controller.cluster.datastore.exceptions.PrimaryNotFoundException;
  67 import org.opendaylight.controller.cluster.datastore.identifiers.ShardIdentifier;
  68 import org.opendaylight.controller.cluster.datastore.messages.ActorInitialized;
  69 import org.opendaylight.controller.cluster.datastore.messages.AddShardReplica;
  70 import org.opendaylight.controller.cluster.datastore.messages.CreateShard;
  71 import org.opendaylight.controller.cluster.datastore.messages.DatastoreSnapshot;
  72 import org.opendaylight.controller.cluster.datastore.messages.FindLocalShard;
  73 import org.opendaylight.controller.cluster.datastore.messages.FindPrimary;
  74 import org.opendaylight.controller.cluster.datastore.messages.LocalPrimaryShardFound;
  75 import org.opendaylight.controller.cluster.datastore.messages.LocalShardFound;
  76 import org.opendaylight.controller.cluster.datastore.messages.LocalShardNotFound;
  77 import org.opendaylight.controller.cluster.datastore.messages.PeerAddressResolved;
  78 import org.opendaylight.controller.cluster.datastore.messages.PeerDown;
  79 import org.opendaylight.controller.cluster.datastore.messages.PeerUp;
  80 import org.opendaylight.controller.cluster.datastore.messages.RemoteFindPrimary;
  81 import org.opendaylight.controller.cluster.datastore.messages.RemotePrimaryShardFound;
  82 import org.opendaylight.controller.cluster.datastore.messages.RemoveShardReplica;
  83 import org.opendaylight.controller.cluster.datastore.messages.ShardLeaderStateChanged;
  84 import org.opendaylight.controller.cluster.datastore.messages.UpdateSchemaContext;
  85 import org.opendaylight.controller.cluster.datastore.utils.Dispatchers;
  86 import org.opendaylight.controller.cluster.datastore.utils.PrimaryShardInfoFutureCache;
  87 import org.opendaylight.controller.cluster.notifications.RegisterRoleChangeListener;
  88 import org.opendaylight.controller.cluster.notifications.RoleChangeNotification;
  89 import org.opendaylight.controller.cluster.raft.RaftState;
  90 import org.opendaylight.controller.cluster.raft.base.messages.FollowerInitialSyncUpStatus;
  91 import org.opendaylight.controller.cluster.raft.base.messages.SwitchBehavior;
  92 import org.opendaylight.controller.cluster.raft.client.messages.GetSnapshot;
  93 import org.opendaylight.controller.cluster.raft.client.messages.Shutdown;
  94 import org.opendaylight.controller.cluster.raft.messages.AddServer;
  95 import org.opendaylight.controller.cluster.raft.messages.AddServerReply;
  96 import org.opendaylight.controller.cluster.raft.messages.RemoveServer;
  97 import org.opendaylight.controller.cluster.raft.messages.RemoveServerReply;
  98 import org.opendaylight.controller.cluster.raft.messages.ServerChangeStatus;
  99 import org.opendaylight.controller.cluster.raft.messages.ServerRemoved;
 100 import org.opendaylight.controller.cluster.raft.policy.DisableElectionsRaftPolicy;
 101 import org.opendaylight.yangtools.yang.data.api.schema.tree.DataTree;
 102 import org.opendaylight.yangtools.yang.model.api.SchemaContext;
 103 import org.slf4j.Logger;
 104 import org.slf4j.LoggerFactory;
 105 import scala.concurrent.ExecutionContext;
 106 import scala.concurrent.Future;
 107 import scala.concurrent.duration.Duration;
 108 import scala.concurrent.duration.FiniteDuration;
 109
 110 /**
 111  * The ShardManager has the following jobs,
 112  * <ul>
 113  * <li> Create all the local shard replicas that belong on this cluster member
 114  * <li> Find the address of the local shard
 115  * <li> Find the primary replica for any given shard
 116  * <li> Monitor the cluster members and store their addresses
 117  * <ul>
 118  */
 119 class ShardManager extends AbstractUntypedPersistentActorWithMetering {
 120
 121     private static final Logger LOG = LoggerFactory.getLogger(ShardManager.class);
 122
 123     // Stores a mapping between a shard name and it's corresponding information
 124     // Shard names look like inventory, topology etc and are as specified in
 125     // configuration
 126     private final Map<String, ShardInformation> localShards = new HashMap<>();
 127
 128     // The type of a ShardManager reflects the type of the datastore itself
 129     // A data store could be of type config/operational
 130     private final String type;
 131
 132     private final ClusterWrapper cluster;
 133
 134     private final Configuration configuration;
 135
 136     private final String shardDispatcherPath;
 137
 138     private final ShardManagerInfo mBean;
 139
 140     private DatastoreContextFactory datastoreContextFactory;
 141
 142     private final CountDownLatch waitTillReadyCountdownLatch;
 143
 144     private final PrimaryShardInfoFutureCache primaryShardInfoCache;
 145
 146     private final ShardPeerAddressResolver peerAddressResolver;
 147
 148     private SchemaContext schemaContext;
 149
 150     private DatastoreSnapshot restoreFromSnapshot;
 151
 152     private ShardManagerSnapshot currentSnapshot;
 153
 154     private final Set<String> shardReplicaOperationsInProgress = new HashSet<>();
 155
 156     private final String persistenceId;
 157
 158     ShardManager(AbstractShardManagerCreator<?> builder) {
 159         this.cluster = builder.getCluster();
 160         this.configuration = builder.getConfiguration();
 161         this.datastoreContextFactory = builder.getDdatastoreContextFactory();
 162         this.type = datastoreContextFactory.getBaseDatastoreContext().getDataStoreName();
 163         this.shardDispatcherPath =
 164                 new Dispatchers(context().system().dispatchers()).getDispatcherPath(Dispatchers.DispatcherType.Shard);
 165         this.waitTillReadyCountdownLatch = builder.getWaitTillReadyCountdownLatch();
 166         this.primaryShardInfoCache = builder.getPrimaryShardInfoCache();
 167         this.restoreFromSnapshot = builder.getRestoreFromSnapshot();
 168
 169         String possiblePersistenceId = datastoreContextFactory.getBaseDatastoreContext().getShardManagerPersistenceId();
 170         persistenceId = possiblePersistenceId != null ? possiblePersistenceId : "shard-manager-" + type;
 171
 172         peerAddressResolver = new ShardPeerAddressResolver(type, cluster.getCurrentMemberName());
 173
 174         // Subscribe this actor to cluster member events
 175         cluster.subscribeToMemberEvents(getSelf());
 176
 177         List<String> localShardActorNames = new ArrayList<>();
 178         mBean = ShardManagerInfo.createShardManagerMBean(cluster.getCurrentMemberName(),
 179                 "shard-manager-" + this.type,
 180                 datastoreContextFactory.getBaseDatastoreContext().getDataStoreMXBeanType(),
 181                 localShardActorNames);
 182         mBean.setShardManager(this);
 183     }
 184
 185     @Override
 186     public void postStop() {
 187         LOG.info("Stopping ShardManager {}", persistenceId());
 188
 189         mBean.unregisterMBean();
 190     }
 191
 192     @Override
 193     public void handleCommand(Object message) throws Exception {
 194         if (message  instanceof FindPrimary) {
 195             findPrimary((FindPrimary)message);
 196         } else if(message instanceof FindLocalShard){
 197             findLocalShard((FindLocalShard) message);
 198         } else if (message instanceof UpdateSchemaContext) {
 199             updateSchemaContext(message);
 200         } else if(message instanceof ActorInitialized) {
 201             onActorInitialized(message);
 202         } else if (message instanceof ClusterEvent.MemberUp){
 203             memberUp((ClusterEvent.MemberUp) message);
 204         } else if (message instanceof ClusterEvent.MemberExited){
 205             memberExited((ClusterEvent.MemberExited) message);
 206         } else if(message instanceof ClusterEvent.MemberRemoved) {
 207             memberRemoved((ClusterEvent.MemberRemoved) message);
 208         } else if(message instanceof ClusterEvent.UnreachableMember) {
 209             memberUnreachable((ClusterEvent.UnreachableMember)message);
 210         } else if(message instanceof ClusterEvent.ReachableMember) {
 211             memberReachable((ClusterEvent.ReachableMember) message);
 212         } else if(message instanceof DatastoreContextFactory) {
 213             onDatastoreContextFactory((DatastoreContextFactory)message);
 214         } else if(message instanceof RoleChangeNotification) {
 215             onRoleChangeNotification((RoleChangeNotification) message);
 216         } else if(message instanceof FollowerInitialSyncUpStatus){
 217             onFollowerInitialSyncStatus((FollowerInitialSyncUpStatus) message);
 218         } else if(message instanceof ShardNotInitializedTimeout) {
 219             onShardNotInitializedTimeout((ShardNotInitializedTimeout)message);
 220         } else if(message instanceof ShardLeaderStateChanged) {
 221             onLeaderStateChanged((ShardLeaderStateChanged) message);
 222         } else if(message instanceof SwitchShardBehavior){
 223             onSwitchShardBehavior((SwitchShardBehavior) message);
 224         } else if(message instanceof CreateShard) {
 225             onCreateShard((CreateShard)message);
 226         } else if(message instanceof AddShardReplica){
 227             onAddShardReplica((AddShardReplica)message);
 228         } else if(message instanceof ForwardedAddServerReply) {
 229             ForwardedAddServerReply msg = (ForwardedAddServerReply)message;
 230             onAddServerReply(msg.shardInfo, msg.addServerReply, getSender(), msg.leaderPath,
 231                     msg.removeShardOnFailure);
 232         } else if(message instanceof ForwardedAddServerFailure) {
 233             ForwardedAddServerFailure msg = (ForwardedAddServerFailure)message;
 234             onAddServerFailure(msg.shardName, msg.failureMessage, msg.failure, getSender(), msg.removeShardOnFailure);
 235         } else if(message instanceof PrimaryShardFoundForContext) {
 236             PrimaryShardFoundForContext primaryShardFoundContext = (PrimaryShardFoundForContext)message;
 237             onPrimaryShardFoundContext(primaryShardFoundContext);
 238         } else if(message instanceof RemoveShardReplica) {
 239             onRemoveShardReplica((RemoveShardReplica) message);
 240         } else if(message instanceof WrappedShardResponse){
 241             onWrappedShardResponse((WrappedShardResponse) message);
 242         } else if(message instanceof GetSnapshot) {
 243             onGetSnapshot();
 244         } else if(message instanceof ServerRemoved){
 245             onShardReplicaRemoved((ServerRemoved) message);
 246         } else if(message instanceof SaveSnapshotSuccess) {
 247             onSaveSnapshotSuccess((SaveSnapshotSuccess)message);
 248         } else if(message instanceof SaveSnapshotFailure) {
 249             LOG.error("{}: SaveSnapshotFailure received for saving snapshot of shards",
 250                     persistenceId(), ((SaveSnapshotFailure) message).cause());
 251         } else if(message instanceof Shutdown) {
 252             onShutDown();
 253         } else {
 254             unknownMessage(message);
 255         }
 256     }
 257
 258     private void onShutDown() {
 259         List<Future<Boolean>> stopFutures = new ArrayList<>(localShards.size());
 260         for (ShardInformation info : localShards.values()) {
 261             if (info.getActor() != null) {
 262                 LOG.debug("{}: Issuing gracefulStop to shard {}", persistenceId(), info.getShardId());
 263
 264                 FiniteDuration duration = info.getDatastoreContext().getShardRaftConfig().getElectionTimeOutInterval().$times(2);
 265                 stopFutures.add(Patterns.gracefulStop(info.getActor(), duration, Shutdown.INSTANCE));
 266             }
 267         }
 268
 269         LOG.info("Shutting down ShardManager {} - waiting on {} shards", persistenceId(), stopFutures.size());
 270
 271         ExecutionContext dispatcher = new Dispatchers(context().system().dispatchers()).getDispatcher(Dispatchers.DispatcherType.Client);
 272         Future<Iterable<Boolean>> combinedFutures = Futures.sequence(stopFutures, dispatcher);
 273
 274         combinedFutures.onComplete(new OnComplete<Iterable<Boolean>>() {
 275             @Override
 276             public void onComplete(Throwable failure, Iterable<Boolean> results) {
 277                 LOG.debug("{}: All shards shutdown - sending PoisonPill to self", persistenceId());
 278
 279                 self().tell(PoisonPill.getInstance(), self());
 280
 281                 if(failure != null) {
 282                     LOG.warn("{}: An error occurred attempting to shut down the shards", persistenceId(), failure);
 283                 } else {
 284                     int nfailed = 0;
 285                     for(Boolean r: results) {
 286                         if(!r) {
 287                             nfailed++;
 288                         }
 289                     }
 290
 291                     if(nfailed > 0) {
 292                         LOG.warn("{}: {} shards did not shut down gracefully", persistenceId(), nfailed);
 293                     }
 294                 }
 295             }
 296         }, dispatcher);
 297     }
 298
 299     private void onWrappedShardResponse(WrappedShardResponse message) {
 300         if (message.getResponse() instanceof RemoveServerReply) {
 301             onRemoveServerReply(getSender(), message.getShardId(), (RemoveServerReply) message.getResponse(),
 302                     message.getLeaderPath());
 303         }
 304     }
 305
 306     private void onRemoveServerReply(ActorRef originalSender, ShardIdentifier shardId, RemoveServerReply replyMsg,
 307             String leaderPath) {
 308         shardReplicaOperationsInProgress.remove(shardId);
 309
 310         LOG.debug ("{}: Received {} for shard {}", persistenceId(), replyMsg, shardId.getShardName());
 311
 312         if (replyMsg.getStatus() == ServerChangeStatus.OK) {
 313             LOG.debug ("{}: Leader shard successfully removed the replica shard {}", persistenceId(),
 314                     shardId.getShardName());
 315             originalSender.tell(new akka.actor.Status.Success(null), getSelf());
 316         } else {
 317             LOG.warn ("{}: Leader failed to remove shard replica {} with status {}",
 318                     persistenceId(), shardId, replyMsg.getStatus());
 319
 320             Exception failure = getServerChangeException(RemoveServer.class, replyMsg.getStatus(),
 321                     leaderPath, shardId);
 322             originalSender.tell(new akka.actor.Status.Failure(failure), getSelf());
 323         }
 324     }
 325
 326     private void onPrimaryShardFoundContext(PrimaryShardFoundForContext primaryShardFoundContext) {
 327         if(primaryShardFoundContext.getContextMessage() instanceof AddShardReplica) {
 328             addShard(primaryShardFoundContext.getShardName(), primaryShardFoundContext.getRemotePrimaryShardFound(),
 329                     getSender());
 330         } else if(primaryShardFoundContext.getContextMessage() instanceof RemoveShardReplica){
 331             removeShardReplica((RemoveShardReplica) primaryShardFoundContext.getContextMessage(),
 332                     primaryShardFoundContext.getShardName(), primaryShardFoundContext.getPrimaryPath(), getSender());
 333         }
 334     }
 335
 336     private void removeShardReplica(RemoveShardReplica contextMessage, final String shardName, final String primaryPath,
 337             final ActorRef sender) {
 338         if(isShardReplicaOperationInProgress(shardName, sender)) {
 339             return;
 340         }
 341
 342         shardReplicaOperationsInProgress.add(shardName);
 343
 344         final ShardIdentifier shardId = getShardIdentifier(contextMessage.getMemberName(), shardName);
 345
 346         final DatastoreContext datastoreContext = newShardDatastoreContextBuilder(shardName).build();
 347
 348         //inform ShardLeader to remove this shard as a replica by sending an RemoveServer message
 349         LOG.debug ("{}: Sending RemoveServer message to peer {} for shard {}", persistenceId(),
 350                 primaryPath, shardId);
 351
 352         Timeout removeServerTimeout = new Timeout(datastoreContext.getShardLeaderElectionTimeout().
 353                 duration());
 354         Future<Object> futureObj = ask(getContext().actorSelection(primaryPath),
 355                 new RemoveServer(shardId.toString()), removeServerTimeout);
 356
 357         futureObj.onComplete(new OnComplete<Object>() {
 358             @Override
 359             public void onComplete(Throwable failure, Object response) {
 360                 if (failure != null) {
 361                     String msg = String.format("RemoveServer request to leader %s for shard %s failed",
 362                             primaryPath, shardName);
 363
 364                     LOG.debug ("{}: {}", persistenceId(), msg, failure);
 365
 366                     // FAILURE
 367                     sender.tell(new Status.Failure(new RuntimeException(msg, failure)), self());
 368                 } else {
 369                     // SUCCESS
 370                     self().tell(new WrappedShardResponse(shardId, response, primaryPath), sender);
 371                 }
 372             }
 373         }, new Dispatchers(context().system().dispatchers()).getDispatcher(Dispatchers.DispatcherType.Client));
 374     }
 375
 376     private void onShardReplicaRemoved(ServerRemoved message) {
 377         final ShardIdentifier shardId = new ShardIdentifier.Builder().fromShardIdString(message.getServerId()).build();
 378         final ShardInformation shardInformation = localShards.remove(shardId.getShardName());
 379         if(shardInformation == null) {
 380             LOG.debug("{} : Shard replica {} is not present in list", persistenceId(), shardId.toString());
 381             return;
 382         } else if(shardInformation.getActor() != null) {
 383             LOG.debug("{} : Sending Shutdown to Shard actor {}", persistenceId(), shardInformation.getActor());
 384             shardInformation.getActor().tell(Shutdown.INSTANCE, self());
 385         }
 386         LOG.debug("{} : Local Shard replica for shard {} has been removed", persistenceId(), shardId.getShardName());
 387         persistShardList();
 388     }
 389
 390     private void onGetSnapshot() {
 391         LOG.debug("{}: onGetSnapshot", persistenceId());
 392
 393         List<String> notInitialized = null;
 394         for(ShardInformation shardInfo: localShards.values()) {
 395             if(!shardInfo.isShardInitialized()) {
 396                 if(notInitialized == null) {
 397                     notInitialized = new ArrayList<>();
 398                 }
 399
 400                 notInitialized.add(shardInfo.getShardName());
 401             }
 402         }
 403
 404         if(notInitialized != null) {
 405             getSender().tell(new akka.actor.Status.Failure(new IllegalStateException(String.format(
 406                     "%d shard(s) %s are not initialized", notInitialized.size(), notInitialized))), getSelf());
 407             return;
 408         }
 409
 410         byte[] shardManagerSnapshot = null;
 411         if(currentSnapshot != null) {
 412             shardManagerSnapshot = SerializationUtils.serialize(currentSnapshot);
 413         }
 414
 415         ActorRef replyActor = getContext().actorOf(ShardManagerGetSnapshotReplyActor.props(
 416                 new ArrayList<>(localShards.keySet()), type, shardManagerSnapshot , getSender(), persistenceId(),
 417                 datastoreContextFactory.getBaseDatastoreContext().getShardInitializationTimeout().duration()));
 418
 419         for(ShardInformation shardInfo: localShards.values()) {
 420             shardInfo.getActor().tell(GetSnapshot.INSTANCE, replyActor);
 421         }
 422     }
 423
 424     private void onCreateShard(CreateShard createShard) {
 425         LOG.debug("{}: onCreateShard: {}", persistenceId(), createShard);
 426
 427         Object reply;
 428         try {
 429             String shardName = createShard.getModuleShardConfig().getShardName();
 430             if(localShards.containsKey(shardName)) {
 431                 LOG.debug("{}: Shard {} already exists", persistenceId(), shardName);
 432                 reply = new akka.actor.Status.Success(String.format("Shard with name %s already exists", shardName));
 433             } else {
 434                 doCreateShard(createShard);
 435                 reply = new akka.actor.Status.Success(null);
 436             }
 437         } catch (Exception e) {
 438             LOG.error("{}: onCreateShard failed", persistenceId(), e);
 439             reply = new akka.actor.Status.Failure(e);
 440         }
 441
 442         if(getSender() != null && !getContext().system().deadLetters().equals(getSender())) {
 443             getSender().tell(reply, getSelf());
 444         }
 445     }
 446
 447     private void doCreateShard(CreateShard createShard) {
 448         ModuleShardConfiguration moduleShardConfig = createShard.getModuleShardConfig();
 449         String shardName = moduleShardConfig.getShardName();
 450
 451         configuration.addModuleShardConfiguration(moduleShardConfig);
 452
 453         DatastoreContext shardDatastoreContext = createShard.getDatastoreContext();
 454         if(shardDatastoreContext == null) {
 455             shardDatastoreContext = newShardDatastoreContext(shardName);
 456         } else {
 457             shardDatastoreContext = DatastoreContext.newBuilderFrom(shardDatastoreContext).shardPeerAddressResolver(
 458                     peerAddressResolver).build();
 459         }
 460
 461         ShardIdentifier shardId = getShardIdentifier(cluster.getCurrentMemberName(), shardName);
 462
 463         boolean shardWasInRecoveredSnapshot = currentSnapshot != null &&
 464                 currentSnapshot.getShardList().contains(shardName);
 465
 466         Map<String, String> peerAddresses;
 467         boolean isActiveMember;
 468         if(shardWasInRecoveredSnapshot || configuration.getMembersFromShardName(shardName).
 469                 contains(cluster.getCurrentMemberName())) {
 470             peerAddresses = getPeerAddresses(shardName);
 471             isActiveMember = true;
 472         } else {
 473             // The local member is not in the static shard member configuration and the shard did not
 474             // previously exist (ie !shardWasInRecoveredSnapshot). In this case we'll create
 475             // the shard with no peers and with elections disabled so it stays as follower. A
 476             // subsequent AddServer request will be needed to make it an active member.
 477             isActiveMember = false;
 478             peerAddresses = Collections.emptyMap();
 479             shardDatastoreContext = DatastoreContext.newBuilderFrom(shardDatastoreContext).
 480                     customRaftPolicyImplementation(DisableElectionsRaftPolicy.class.getName()).build();
 481         }
 482
 483         LOG.debug("{} doCreateShard: shardId: {}, memberNames: {}, peerAddresses: {}, isActiveMember: {}",
 484                 persistenceId(), shardId, moduleShardConfig.getShardMemberNames(), peerAddresses,
 485                 isActiveMember);
 486
 487         ShardInformation info = new ShardInformation(shardName, shardId, peerAddresses,
 488                 shardDatastoreContext, createShard.getShardBuilder(), peerAddressResolver);
 489         info.setActiveMember(isActiveMember);
 490         localShards.put(info.getShardName(), info);
 491
 492         mBean.addLocalShard(shardId.toString());
 493
 494         if(schemaContext != null) {
 495             info.setActor(newShardActor(schemaContext, info));
 496         }
 497     }
 498
 499     private DatastoreContext.Builder newShardDatastoreContextBuilder(String shardName) {
 500         return DatastoreContext.newBuilderFrom(datastoreContextFactory.getShardDatastoreContext(shardName)).
 501                 shardPeerAddressResolver(peerAddressResolver);
 502     }
 503
 504     private DatastoreContext newShardDatastoreContext(String shardName) {
 505         return newShardDatastoreContextBuilder(shardName).build();
 506     }
 507
 508     private void checkReady(){
 509         if (isReadyWithLeaderId()) {
 510             LOG.info("{}: All Shards are ready - data store {} is ready, available count is {}",
 511                     persistenceId(), type, waitTillReadyCountdownLatch.getCount());
 512
 513             waitTillReadyCountdownLatch.countDown();
 514         }
 515     }
 516
 517     private void onLeaderStateChanged(ShardLeaderStateChanged leaderStateChanged) {
 518         LOG.info("{}: Received LeaderStateChanged message: {}", persistenceId(), leaderStateChanged);
 519
 520         ShardInformation shardInformation = findShardInformation(leaderStateChanged.getMemberId());
 521         if(shardInformation != null) {
 522             shardInformation.setLocalDataTree(leaderStateChanged.getLocalShardDataTree());
 523             shardInformation.setLeaderVersion(leaderStateChanged.getLeaderPayloadVersion());
 524             if(shardInformation.setLeaderId(leaderStateChanged.getLeaderId())) {
 525                 primaryShardInfoCache.remove(shardInformation.getShardName());
 526             }
 527
 528             checkReady();
 529         } else {
 530             LOG.debug("No shard found with member Id {}", leaderStateChanged.getMemberId());
 531         }
 532     }
 533
 534     private void onShardNotInitializedTimeout(ShardNotInitializedTimeout message) {
 535         ShardInformation shardInfo = message.getShardInfo();
 536
 537         LOG.debug("{}: Received ShardNotInitializedTimeout message for shard {}", persistenceId(),
 538                 shardInfo.getShardName());
 539
 540         shardInfo.removeOnShardInitialized(message.getOnShardInitialized());
 541
 542         if(!shardInfo.isShardInitialized()) {
 543             LOG.debug("{}: Returning NotInitializedException for shard {}", persistenceId(), shardInfo.getShardName());
 544             message.getSender().tell(createNotInitializedException(shardInfo.shardId), getSelf());
 545         } else {
 546             LOG.debug("{}: Returning NoShardLeaderException for shard {}", persistenceId(), shardInfo.getShardName());
 547             message.getSender().tell(createNoShardLeaderException(shardInfo.shardId), getSelf());
 548         }
 549     }
 550
 551     private void onFollowerInitialSyncStatus(FollowerInitialSyncUpStatus status) {
 552         LOG.info("{} Received follower initial sync status for {} status sync done {}", persistenceId(),
 553                 status.getName(), status.isInitialSyncDone());
 554
 555         ShardInformation shardInformation = findShardInformation(status.getName());
 556
 557         if(shardInformation != null) {
 558             shardInformation.setFollowerSyncStatus(status.isInitialSyncDone());
 559
 560             mBean.setSyncStatus(isInSync());
 561         }
 562
 563     }
 564
 565     private void onRoleChangeNotification(RoleChangeNotification roleChanged) {
 566         LOG.info("{}: Received role changed for {} from {} to {}", persistenceId(), roleChanged.getMemberId(),
 567                 roleChanged.getOldRole(), roleChanged.getNewRole());
 568
 569         ShardInformation shardInformation = findShardInformation(roleChanged.getMemberId());
 570         if(shardInformation != null) {
 571             shardInformation.setRole(roleChanged.getNewRole());
 572             checkReady();
 573             mBean.setSyncStatus(isInSync());
 574         }
 575     }
 576
 577
 578     private ShardInformation findShardInformation(String memberId) {
 579         for(ShardInformation info : localShards.values()){
 580             if(info.getShardId().toString().equals(memberId)){
 581                 return info;
 582             }
 583         }
 584
 585         return null;
 586     }
 587
 588     private boolean isReadyWithLeaderId() {
 589         boolean isReady = true;
 590         for (ShardInformation info : localShards.values()) {
 591             if(!info.isShardReadyWithLeaderId()){
 592                 isReady = false;
 593                 break;
 594             }
 595         }
 596         return isReady;
 597     }
 598
 599     private boolean isInSync(){
 600         for (ShardInformation info : localShards.values()) {
 601             if(!info.isInSync()){
 602                 return false;
 603             }
 604         }
 605         return true;
 606     }
 607
 608     private void onActorInitialized(Object message) {
 609         final ActorRef sender = getSender();
 610
 611         if (sender == null) {
 612             return; //why is a non-actor sending this message? Just ignore.
 613         }
 614
 615         String actorName = sender.path().name();
 616         //find shard name from actor name; actor name is stringified shardId
 617         ShardIdentifier shardId = ShardIdentifier.builder().fromShardIdString(actorName).build();
 618
 619         if (shardId.getShardName() == null) {
 620             return;
 621         }
 622
 623         markShardAsInitialized(shardId.getShardName());
 624     }
 625
 626     private void markShardAsInitialized(String shardName) {
 627         LOG.debug("{}: Initializing shard [{}]", persistenceId(), shardName);
 628
 629         ShardInformation shardInformation = localShards.get(shardName);
 630         if (shardInformation != null) {
 631             shardInformation.setActorInitialized();
 632
 633             shardInformation.getActor().tell(new RegisterRoleChangeListener(), self());
 634         }
 635     }
 636
 637     @Override
 638     protected void handleRecover(Object message) throws Exception {
 639         if (message instanceof RecoveryCompleted) {
 640             onRecoveryCompleted();
 641         } else if (message instanceof SnapshotOffer) {
 642             applyShardManagerSnapshot((ShardManagerSnapshot)((SnapshotOffer) message).snapshot());
 643         }
 644     }
 645
 646     private void onRecoveryCompleted() {
 647         LOG.info("Recovery complete : {}", persistenceId());
 648
 649         // We no longer persist SchemaContext modules so delete all the prior messages from the akka
 650         // journal on upgrade from Helium.
 651         deleteMessages(lastSequenceNr());
 652
 653         if(currentSnapshot == null && restoreFromSnapshot != null &&
 654                 restoreFromSnapshot.getShardManagerSnapshot() != null) {
 655             try(ObjectInputStream ois = new ObjectInputStream(new ByteArrayInputStream(
 656                     restoreFromSnapshot.getShardManagerSnapshot()))) {
 657                 ShardManagerSnapshot snapshot = (ShardManagerSnapshot) ois.readObject();
 658
 659                 LOG.debug("{}: Deserialized restored ShardManagerSnapshot: {}", persistenceId(), snapshot);
 660
 661                 applyShardManagerSnapshot(snapshot);
 662             } catch(Exception e) {
 663                 LOG.error("{}: Error deserializing restored ShardManagerSnapshot", persistenceId(), e);
 664             }
 665         }
 666
 667         createLocalShards();
 668     }
 669
 670     private void findLocalShard(FindLocalShard message) {
 671         final ShardInformation shardInformation = localShards.get(message.getShardName());
 672
 673         if(shardInformation == null){
 674             getSender().tell(new LocalShardNotFound(message.getShardName()), getSelf());
 675             return;
 676         }
 677
 678         sendResponse(shardInformation, message.isWaitUntilInitialized(), false, new Supplier<Object>() {
 679             @Override
 680             public Object get() {
 681                 return new LocalShardFound(shardInformation.getActor());
 682             }
 683         });
 684     }
 685
 686     private void sendResponse(ShardInformation shardInformation, boolean doWait,
 687             boolean wantShardReady, final Supplier<Object> messageSupplier) {
 688         if (!shardInformation.isShardInitialized() || (wantShardReady && !shardInformation.isShardReadyWithLeaderId())) {
 689             if(doWait) {
 690                 final ActorRef sender = getSender();
 691                 final ActorRef self = self();
 692
 693                 Runnable replyRunnable = new Runnable() {
 694                     @Override
 695                     public void run() {
 696                         sender.tell(messageSupplier.get(), self);
 697                     }
 698                 };
 699
 700                 OnShardInitialized onShardInitialized = wantShardReady ? new OnShardReady(replyRunnable) :
 701                     new OnShardInitialized(replyRunnable);
 702
 703                 shardInformation.addOnShardInitialized(onShardInitialized);
 704
 705                 FiniteDuration timeout = shardInformation.getDatastoreContext().getShardInitializationTimeout().duration();
 706                 if(shardInformation.isShardInitialized()) {
 707                     // If the shard is already initialized then we'll wait enough time for the shard to
 708                     // elect a leader, ie 2 times the election timeout.
 709                     timeout = FiniteDuration.create(shardInformation.getDatastoreContext().getShardRaftConfig()
 710                             .getElectionTimeOutInterval().toMillis() * 2, TimeUnit.MILLISECONDS);
 711                 }
 712
 713                 LOG.debug("{}: Scheduling {} ms timer to wait for shard {}", persistenceId(), timeout.toMillis(),
 714                         shardInformation.getShardName());
 715
 716                 Cancellable timeoutSchedule = getContext().system().scheduler().scheduleOnce(
 717                         timeout, getSelf(),
 718                         new ShardNotInitializedTimeout(shardInformation, onShardInitialized, sender),
 719                         getContext().dispatcher(), getSelf());
 720
 721                 onShardInitialized.setTimeoutSchedule(timeoutSchedule);
 722
 723             } else if (!shardInformation.isShardInitialized()) {
 724                 LOG.debug("{}: Returning NotInitializedException for shard {}", persistenceId(),
 725                         shardInformation.getShardName());
 726                 getSender().tell(createNotInitializedException(shardInformation.shardId), getSelf());
 727             } else {
 728                 LOG.debug("{}: Returning NoShardLeaderException for shard {}", persistenceId(),
 729                         shardInformation.getShardName());
 730                 getSender().tell(createNoShardLeaderException(shardInformation.shardId), getSelf());
 731             }
 732
 733             return;
 734         }
 735
 736         getSender().tell(messageSupplier.get(), getSelf());
 737     }
 738
 739     private static NoShardLeaderException createNoShardLeaderException(ShardIdentifier shardId) {
 740         return new NoShardLeaderException(null, shardId.toString());
 741     }
 742
 743     private static NotInitializedException createNotInitializedException(ShardIdentifier shardId) {
 744         return new NotInitializedException(String.format(
 745                 "Found primary shard %s but it's not initialized yet. Please try again later", shardId));
 746     }
 747
 748     private void memberRemoved(ClusterEvent.MemberRemoved message) {
 749         String memberName = message.member().roles().iterator().next();
 750
 751         LOG.debug("{}: Received MemberRemoved: memberName: {}, address: {}", persistenceId(), memberName,
 752                 message.member().address());
 753
 754         peerAddressResolver.removePeerAddress(memberName);
 755
 756         for(ShardInformation info : localShards.values()){
 757             info.peerDown(memberName, getShardIdentifier(memberName, info.getShardName()).toString(), getSelf());
 758         }
 759     }
 760
 761     private void memberExited(ClusterEvent.MemberExited message) {
 762         String memberName = message.member().roles().iterator().next();
 763
 764         LOG.debug("{}: Received MemberExited: memberName: {}, address: {}", persistenceId(), memberName,
 765                 message.member().address());
 766
 767         peerAddressResolver.removePeerAddress(memberName);
 768
 769         for(ShardInformation info : localShards.values()){
 770             info.peerDown(memberName, getShardIdentifier(memberName, info.getShardName()).toString(), getSelf());
 771         }
 772     }
 773
 774     private void memberUp(ClusterEvent.MemberUp message) {
 775         String memberName = message.member().roles().iterator().next();
 776
 777         LOG.debug("{}: Received MemberUp: memberName: {}, address: {}", persistenceId(), memberName,
 778                 message.member().address());
 779
 780         addPeerAddress(memberName, message.member().address());
 781
 782         checkReady();
 783     }
 784
 785     private void addPeerAddress(String memberName, Address address) {
 786         peerAddressResolver.addPeerAddress(memberName, address);
 787
 788         for(ShardInformation info : localShards.values()){
 789             String shardName = info.getShardName();
 790             String peerId = getShardIdentifier(memberName, shardName).toString();
 791             info.updatePeerAddress(peerId, peerAddressResolver.getShardActorAddress(shardName, memberName), getSelf());
 792
 793             info.peerUp(memberName, peerId, getSelf());
 794         }
 795     }
 796
 797     private void memberReachable(ClusterEvent.ReachableMember message) {
 798         String memberName = message.member().roles().iterator().next();
 799         LOG.debug("Received ReachableMember: memberName {}, address: {}", memberName, message.member().address());
 800
 801         addPeerAddress(memberName, message.member().address());
 802
 803         markMemberAvailable(memberName);
 804     }
 805
 806     private void memberUnreachable(ClusterEvent.UnreachableMember message) {
 807         String memberName = message.member().roles().iterator().next();
 808         LOG.debug("Received UnreachableMember: memberName {}, address: {}", memberName, message.member().address());
 809
 810         markMemberUnavailable(memberName);
 811     }
 812
 813     private void markMemberUnavailable(final String memberName) {
 814         for(ShardInformation info : localShards.values()){
 815             String leaderId = info.getLeaderId();
 816             if(leaderId != null && leaderId.contains(memberName)) {
 817                 LOG.debug("Marking Leader {} as unavailable.", leaderId);
 818                 info.setLeaderAvailable(false);
 819
 820                 primaryShardInfoCache.remove(info.getShardName());
 821             }
 822
 823             info.peerDown(memberName, getShardIdentifier(memberName, info.getShardName()).toString(), getSelf());
 824         }
 825     }
 826
 827     private void markMemberAvailable(final String memberName) {
 828         for(ShardInformation info : localShards.values()){
 829             String leaderId = info.getLeaderId();
 830             if(leaderId != null && leaderId.contains(memberName)) {
 831                 LOG.debug("Marking Leader {} as available.", leaderId);
 832                 info.setLeaderAvailable(true);
 833             }
 834
 835             info.peerUp(memberName, getShardIdentifier(memberName, info.getShardName()).toString(), getSelf());
 836         }
 837     }
 838
 839     private void onDatastoreContextFactory(DatastoreContextFactory factory) {
 840         datastoreContextFactory = factory;
 841         for (ShardInformation info : localShards.values()) {
 842             info.setDatastoreContext(newShardDatastoreContext(info.getShardName()), getSelf());
 843         }
 844     }
 845
 846     private void onSwitchShardBehavior(SwitchShardBehavior message) {
 847         ShardIdentifier identifier = ShardIdentifier.builder().fromShardIdString(message.getShardName()).build();
 848
 849         ShardInformation shardInformation = localShards.get(identifier.getShardName());
 850
 851         if(shardInformation != null && shardInformation.getActor() != null) {
 852             shardInformation.getActor().tell(
 853                     new SwitchBehavior(message.getNewState(), message.getTerm()), getSelf());
 854         } else {
 855             LOG.warn("Could not switch the behavior of shard {} to {} - shard is not yet available",
 856                     message.getShardName(), message.getNewState());
 857         }
 858     }
 859
 860     /**
 861      * Notifies all the local shards of a change in the schema context
 862      *
 863      * @param message
 864      */
 865     private void updateSchemaContext(final Object message) {
 866         schemaContext = ((UpdateSchemaContext) message).getSchemaContext();
 867
 868         LOG.debug("Got updated SchemaContext: # of modules {}", schemaContext.getAllModuleIdentifiers().size());
 869
 870         for (ShardInformation info : localShards.values()) {
 871             if (info.getActor() == null) {
 872                 LOG.debug("Creating Shard {}", info.getShardId());
 873                 info.setActor(newShardActor(schemaContext, info));
 874             } else {
 875                 info.getActor().tell(message, getSelf());
 876             }
 877         }
 878     }
 879
 880     @VisibleForTesting
 881     protected ClusterWrapper getCluster() {
 882         return cluster;
 883     }
 884
 885     @VisibleForTesting
 886     protected ActorRef newShardActor(final SchemaContext schemaContext, ShardInformation info) {
 887         return getContext().actorOf(info.newProps(schemaContext)
 888                 .withDispatcher(shardDispatcherPath), info.getShardId().toString());
 889     }
 890
 891     private void findPrimary(FindPrimary message) {
 892         LOG.debug("{}: In findPrimary: {}", persistenceId(), message);
 893
 894         final String shardName = message.getShardName();
 895         final boolean canReturnLocalShardState = !(message instanceof RemoteFindPrimary);
 896
 897         // First see if the there is a local replica for the shard
 898         final ShardInformation info = localShards.get(shardName);
 899         if (info != null && info.isActiveMember()) {
 900             sendResponse(info, message.isWaitUntilReady(), true, new Supplier<Object>() {
 901                 @Override
 902                 public Object get() {
 903                     String primaryPath = info.getSerializedLeaderActor();
 904                     Object found = canReturnLocalShardState && info.isLeader() ?
 905                             new LocalPrimaryShardFound(primaryPath, info.getLocalShardDataTree().get()) :
 906                                 new RemotePrimaryShardFound(primaryPath, info.getLeaderVersion());
 907
 908                             if(LOG.isDebugEnabled()) {
 909                                 LOG.debug("{}: Found primary for {}: {}", persistenceId(), shardName, found);
 910                             }
 911
 912                             return found;
 913                 }
 914             });
 915
 916             return;
 917         }
 918
 919         final Collection<String> visitedAddresses;
 920         if(message instanceof RemoteFindPrimary) {
 921             visitedAddresses = ((RemoteFindPrimary)message).getVisitedAddresses();
 922         } else {
 923             visitedAddresses = new ArrayList<>(1);
 924         }
 925
 926         visitedAddresses.add(peerAddressResolver.getShardManagerActorPathBuilder(cluster.getSelfAddress()).toString());
 927
 928         for(String address: peerAddressResolver.getShardManagerPeerActorAddresses()) {
 929             if(visitedAddresses.contains(address)) {
 930                 continue;
 931             }
 932
 933             LOG.debug("{}: findPrimary for {} forwarding to remote ShardManager {}, visitedAddresses: {}",
 934                     persistenceId(), shardName, address, visitedAddresses);
 935
 936             getContext().actorSelection(address).forward(new RemoteFindPrimary(shardName,
 937                     message.isWaitUntilReady(), visitedAddresses), getContext());
 938             return;
 939         }
 940
 941         LOG.debug("{}: No shard found for {}", persistenceId(), shardName);
 942
 943         getSender().tell(new PrimaryNotFoundException(
 944                 String.format("No primary shard found for %s.", shardName)), getSelf());
 945     }
 946
 947     /**
 948      * Construct the name of the shard actor given the name of the member on
 949      * which the shard resides and the name of the shard
 950      *
 951      * @param memberName
 952      * @param shardName
 953      * @return
 954      */
 955     private ShardIdentifier getShardIdentifier(String memberName, String shardName){
 956         return peerAddressResolver.getShardIdentifier(memberName, shardName);
 957     }
 958
 959     /**
 960      * Create shards that are local to the member on which the ShardManager
 961      * runs
 962      *
 963      */
 964     private void createLocalShards() {
 965         String memberName = this.cluster.getCurrentMemberName();
 966         Collection<String> memberShardNames = this.configuration.getMemberShardNames(memberName);
 967
 968         Map<String, DatastoreSnapshot.ShardSnapshot> shardSnapshots = new HashMap<>();
 969         if(restoreFromSnapshot != null)
 970         {
 971             for(DatastoreSnapshot.ShardSnapshot snapshot: restoreFromSnapshot.getShardSnapshots()) {
 972                 shardSnapshots.put(snapshot.getName(), snapshot);
 973             }
 974         }
 975
 976         restoreFromSnapshot = null; // null out to GC
 977
 978         for(String shardName : memberShardNames){
 979             ShardIdentifier shardId = getShardIdentifier(memberName, shardName);
 980
 981             LOG.debug("{}: Creating local shard: {}", persistenceId(), shardId);
 982
 983             Map<String, String> peerAddresses = getPeerAddresses(shardName);
 984             localShards.put(shardName, new ShardInformation(shardName, shardId, peerAddresses,
 985                     newShardDatastoreContext(shardName), Shard.builder().restoreFromSnapshot(
 986                         shardSnapshots.get(shardName)), peerAddressResolver));
 987             mBean.addLocalShard(shardId.toString());
 988         }
 989     }
 990
 991     /**
 992      * Given the name of the shard find the addresses of all it's peers
 993      *
 994      * @param shardName
 995      */
 996     private Map<String, String> getPeerAddresses(String shardName) {
 997         Collection<String> members = configuration.getMembersFromShardName(shardName);
 998         Map<String, String> peerAddresses = new HashMap<>();
 999
1000         String currentMemberName = this.cluster.getCurrentMemberName();
1001
1002         for(String memberName : members) {
1003             if(!currentMemberName.equals(memberName)) {
1004                 ShardIdentifier shardId = getShardIdentifier(memberName, shardName);
1005                 String address = peerAddressResolver.getShardActorAddress(shardName, memberName);
1006                 peerAddresses.put(shardId.toString(), address);
1007             }
1008         }
1009         return peerAddresses;
1010     }
1011
1012     @Override
1013     public SupervisorStrategy supervisorStrategy() {
1014
1015         return new OneForOneStrategy(10, Duration.create("1 minute"),
1016                 new Function<Throwable, SupervisorStrategy.Directive>() {
1017             @Override
1018             public SupervisorStrategy.Directive apply(Throwable t) {
1019                 LOG.warn("Supervisor Strategy caught unexpected exception - resuming", t);
1020                 return SupervisorStrategy.resume();
1021             }
1022         }
1023                 );
1024
1025     }
1026
1027     @Override
1028     public String persistenceId() {
1029         return persistenceId;
1030     }
1031
1032     @VisibleForTesting
1033     ShardManagerInfoMBean getMBean(){
1034         return mBean;
1035     }
1036
1037     private boolean isShardReplicaOperationInProgress(final String shardName, final ActorRef sender) {
1038         if (shardReplicaOperationsInProgress.contains(shardName)) {
1039             String msg = String.format("A shard replica operation for %s is already in progress", shardName);
1040             LOG.debug ("{}: {}", persistenceId(), msg);
1041             sender.tell(new akka.actor.Status.Failure(new IllegalStateException(msg)), getSelf());
1042             return true;
1043         }
1044
1045         return false;
1046     }
1047
1048     private void onAddShardReplica (final AddShardReplica shardReplicaMsg) {
1049         final String shardName = shardReplicaMsg.getShardName();
1050
1051         LOG.debug("{}: onAddShardReplica: {}", persistenceId(), shardReplicaMsg);
1052
1053         // verify the shard with the specified name is present in the cluster configuration
1054         if (!(this.configuration.isShardConfigured(shardName))) {
1055             String msg = String.format("No module configuration exists for shard %s", shardName);
1056             LOG.debug ("{}: {}", persistenceId(), msg);
1057             getSender().tell(new akka.actor.Status.Failure(new IllegalArgumentException(msg)), getSelf());
1058             return;
1059         }
1060
1061         // Create the localShard
1062         if (schemaContext == null) {
1063             String msg = String.format(
1064                   "No SchemaContext is available in order to create a local shard instance for %s", shardName);
1065             LOG.debug ("{}: {}", persistenceId(), msg);
1066             getSender().tell(new akka.actor.Status.Failure(new IllegalStateException(msg)), getSelf());
1067             return;
1068         }
1069
1070         findPrimary(shardName, new AutoFindPrimaryFailureResponseHandler(getSender(), shardName, persistenceId(), getSelf()) {
1071             @Override
1072             public void onRemotePrimaryShardFound(RemotePrimaryShardFound response) {
1073                 getSelf().tell(new PrimaryShardFoundForContext(getShardName(), shardReplicaMsg, response), getTargetActor());
1074             }
1075
1076             @Override
1077             public void onLocalPrimaryFound(LocalPrimaryShardFound message) {
1078                 sendLocalReplicaAlreadyExistsReply(getShardName(), getTargetActor());
1079             }
1080
1081         });
1082     }
1083
1084     private void sendLocalReplicaAlreadyExistsReply(String shardName, ActorRef sender) {
1085         String msg = String.format("Local shard %s already exists", shardName);
1086         LOG.debug ("{}: {}", persistenceId(), msg);
1087         sender.tell(new akka.actor.Status.Failure(new AlreadyExistsException(msg)), getSelf());
1088     }
1089
1090     private void addShard(final String shardName, final RemotePrimaryShardFound response, final ActorRef sender) {
1091         if(isShardReplicaOperationInProgress(shardName, sender)) {
1092             return;
1093         }
1094
1095         shardReplicaOperationsInProgress.add(shardName);
1096
1097         final ShardInformation shardInfo;
1098         final boolean removeShardOnFailure;
1099         ShardInformation existingShardInfo = localShards.get(shardName);
1100         if(existingShardInfo == null) {
1101             removeShardOnFailure = true;
1102             ShardIdentifier shardId = getShardIdentifier(cluster.getCurrentMemberName(), shardName);
1103
1104             DatastoreContext datastoreContext = newShardDatastoreContextBuilder(shardName).customRaftPolicyImplementation(
1105                     DisableElectionsRaftPolicy.class.getName()).build();
1106
1107             shardInfo = new ShardInformation(shardName, shardId, getPeerAddresses(shardName), datastoreContext,
1108                     Shard.builder(), peerAddressResolver);
1109             shardInfo.setActiveMember(false);
1110             localShards.put(shardName, shardInfo);
1111             shardInfo.setActor(newShardActor(schemaContext, shardInfo));
1112         } else {
1113             removeShardOnFailure = false;
1114             shardInfo = existingShardInfo;
1115         }
1116
1117         String localShardAddress = peerAddressResolver.getShardActorAddress(shardName, cluster.getCurrentMemberName());
1118
1119         //inform ShardLeader to add this shard as a replica by sending an AddServer message
1120         LOG.debug ("{}: Sending AddServer message to peer {} for shard {}", persistenceId(),
1121                 response.getPrimaryPath(), shardInfo.getShardId());
1122
1123         Timeout addServerTimeout = new Timeout(shardInfo.getDatastoreContext().getShardLeaderElectionTimeout().
1124                 duration());
1125         Future<Object> futureObj = ask(getContext().actorSelection(response.getPrimaryPath()),
1126             new AddServer(shardInfo.getShardId().toString(), localShardAddress, true), addServerTimeout);
1127
1128         futureObj.onComplete(new OnComplete<Object>() {
1129             @Override
1130             public void onComplete(Throwable failure, Object addServerResponse) {
1131                 if (failure != null) {
1132                     LOG.debug ("{}: AddServer request to {} for {} failed", persistenceId(),
1133                             response.getPrimaryPath(), shardName, failure);
1134
1135                     String msg = String.format("AddServer request to leader %s for shard %s failed",
1136                             response.getPrimaryPath(), shardName);
1137                     self().tell(new ForwardedAddServerFailure(shardName, msg, failure, removeShardOnFailure), sender);
1138                 } else {
1139                     self().tell(new ForwardedAddServerReply(shardInfo, (AddServerReply)addServerResponse,
1140                             response.getPrimaryPath(), removeShardOnFailure), sender);
1141                 }
1142             }
1143         }, new Dispatchers(context().system().dispatchers()).getDispatcher(Dispatchers.DispatcherType.Client));
1144     }
1145
1146     private void onAddServerFailure(String shardName, String message, Throwable failure, ActorRef sender,
1147             boolean removeShardOnFailure) {
1148         shardReplicaOperationsInProgress.remove(shardName);
1149
1150         if(removeShardOnFailure) {
1151             ShardInformation shardInfo = localShards.remove(shardName);
1152             if (shardInfo.getActor() != null) {
1153                 shardInfo.getActor().tell(PoisonPill.getInstance(), getSelf());
1154             }
1155         }
1156
1157         sender.tell(new akka.actor.Status.Failure(message == null ? failure :
1158             new RuntimeException(message, failure)), getSelf());
1159     }
1160
1161     private void onAddServerReply(ShardInformation shardInfo, AddServerReply replyMsg, ActorRef sender,
1162             String leaderPath, boolean removeShardOnFailure) {
1163         String shardName = shardInfo.getShardName();
1164         shardReplicaOperationsInProgress.remove(shardName);
1165
1166         LOG.debug ("{}: Received {} for shard {} from leader {}", persistenceId(), replyMsg, shardName, leaderPath);
1167
1168         if (replyMsg.getStatus() == ServerChangeStatus.OK) {
1169             LOG.debug ("{}: Leader shard successfully added the replica shard {}", persistenceId(), shardName);
1170
1171             // Make the local shard voting capable
1172             shardInfo.setDatastoreContext(newShardDatastoreContext(shardName), getSelf());
1173             shardInfo.setActiveMember(true);
1174             persistShardList();
1175
1176             mBean.addLocalShard(shardInfo.getShardId().toString());
1177             sender.tell(new akka.actor.Status.Success(null), getSelf());
1178         } else if(replyMsg.getStatus() == ServerChangeStatus.ALREADY_EXISTS) {
1179             sendLocalReplicaAlreadyExistsReply(shardName, sender);
1180         } else {
1181             LOG.warn ("{}: Leader failed to add shard replica {} with status {}",
1182                     persistenceId(), shardName, replyMsg.getStatus());
1183
1184             Exception failure = getServerChangeException(AddServer.class, replyMsg.getStatus(), leaderPath, shardInfo.getShardId());
1185
1186             onAddServerFailure(shardName, null, failure, sender, removeShardOnFailure);
1187         }
1188     }
1189
1190     private static Exception getServerChangeException(Class<?> serverChange, ServerChangeStatus serverChangeStatus,
1191                                                String leaderPath, ShardIdentifier shardId) {
1192         Exception failure;
1193         switch (serverChangeStatus) {
1194             case TIMEOUT:
1195                 failure = new TimeoutException(String.format(
1196                         "The shard leader %s timed out trying to replicate the initial data to the new shard %s." +
1197                         "Possible causes - there was a problem replicating the data or shard leadership changed while replicating the shard data",
1198                         leaderPath, shardId.getShardName()));
1199                 break;
1200             case NO_LEADER:
1201                 failure = createNoShardLeaderException(shardId);
1202                 break;
1203             case NOT_SUPPORTED:
1204                 failure = new UnsupportedOperationException(String.format("%s request is not supported for shard %s",
1205                         serverChange.getSimpleName(), shardId.getShardName()));
1206                 break;
1207             default :
1208                 failure = new RuntimeException(String.format(
1209                         "%s request to leader %s for shard %s failed with status %s",
1210                         serverChange.getSimpleName(), leaderPath, shardId.getShardName(), serverChangeStatus));
1211         }
1212         return failure;
1213     }
1214
1215     private void onRemoveShardReplica (final RemoveShardReplica shardReplicaMsg) {
1216         LOG.debug("{}: onRemoveShardReplica: {}", persistenceId(), shardReplicaMsg);
1217
1218         findPrimary(shardReplicaMsg.getShardName(), new AutoFindPrimaryFailureResponseHandler(getSender(),
1219                 shardReplicaMsg.getShardName(), persistenceId(), getSelf()) {
1220             @Override
1221             public void onRemotePrimaryShardFound(RemotePrimaryShardFound response) {
1222                 getSelf().tell(new PrimaryShardFoundForContext(getShardName(), shardReplicaMsg, response), getTargetActor());
1223             }
1224
1225             @Override
1226             public void onLocalPrimaryFound(LocalPrimaryShardFound response) {
1227                 getSelf().tell(new PrimaryShardFoundForContext(getShardName(), shardReplicaMsg, response), getTargetActor());
1228             }
1229         });
1230     }
1231
1232     private void persistShardList() {
1233         List<String> shardList = new ArrayList<>(localShards.keySet());
1234         for (ShardInformation shardInfo : localShards.values()) {
1235             if (!shardInfo.isActiveMember()) {
1236                 shardList.remove(shardInfo.getShardName());
1237             }
1238         }
1239         LOG.debug ("{}: persisting the shard list {}", persistenceId(), shardList);
1240         saveSnapshot(updateShardManagerSnapshot(shardList));
1241     }
1242
1243     private ShardManagerSnapshot updateShardManagerSnapshot(List<String> shardList) {
1244         currentSnapshot = new ShardManagerSnapshot(shardList);
1245         return currentSnapshot;
1246     }
1247
1248     private void applyShardManagerSnapshot(ShardManagerSnapshot snapshot) {
1249         currentSnapshot = snapshot;
1250
1251         LOG.debug ("{}: onSnapshotOffer: {}", persistenceId(), currentSnapshot);
1252
1253         String currentMember = cluster.getCurrentMemberName();
1254         Set<String> configuredShardList =
1255             new HashSet<>(configuration.getMemberShardNames(currentMember));
1256         for (String shard : currentSnapshot.getShardList()) {
1257             if (!configuredShardList.contains(shard)) {
1258                 // add the current member as a replica for the shard
1259                 LOG.debug ("{}: adding shard {}", persistenceId(), shard);
1260                 configuration.addMemberReplicaForShard(shard, currentMember);
1261             } else {
1262                 configuredShardList.remove(shard);
1263             }
1264         }
1265         for (String shard : configuredShardList) {
1266             // remove the member as a replica for the shard
1267             LOG.debug ("{}: removing shard {}", persistenceId(), shard);
1268             configuration.removeMemberReplicaForShard(shard, currentMember);
1269         }
1270     }
1271
1272     private void onSaveSnapshotSuccess (SaveSnapshotSuccess successMessage) {
1273         LOG.debug ("{} saved ShardManager snapshot successfully. Deleting the prev snapshot if available",
1274             persistenceId());
1275         deleteSnapshots(new SnapshotSelectionCriteria(scala.Long.MaxValue(), successMessage.metadata().timestamp() - 1,
1276             0, 0));
1277     }
1278
1279     private static class ForwardedAddServerReply {
1280         ShardInformation shardInfo;
1281         AddServerReply addServerReply;
1282         String leaderPath;
1283         boolean removeShardOnFailure;
1284
1285         ForwardedAddServerReply(ShardInformation shardInfo, AddServerReply addServerReply, String leaderPath,
1286                 boolean removeShardOnFailure) {
1287             this.shardInfo = shardInfo;
1288             this.addServerReply = addServerReply;
1289             this.leaderPath = leaderPath;
1290             this.removeShardOnFailure = removeShardOnFailure;
1291         }
1292     }
1293
1294     private static class ForwardedAddServerFailure {
1295         String shardName;
1296         String failureMessage;
1297         Throwable failure;
1298         boolean removeShardOnFailure;
1299
1300         ForwardedAddServerFailure(String shardName, String failureMessage, Throwable failure,
1301                 boolean removeShardOnFailure) {
1302             this.shardName = shardName;
1303             this.failureMessage = failureMessage;
1304             this.failure = failure;
1305             this.removeShardOnFailure = removeShardOnFailure;
1306         }
1307     }
1308
1309     @VisibleForTesting
1310     protected static class ShardInformation {
1311         private final ShardIdentifier shardId;
1312         private final String shardName;
1313         private ActorRef actor;
1314         private final Map<String, String> initialPeerAddresses;
1315         private Optional<DataTree> localShardDataTree;
1316         private boolean leaderAvailable = false;
1317
1318         // flag that determines if the actor is ready for business
1319         private boolean actorInitialized = false;
1320
1321         private boolean followerSyncStatus = false;
1322
1323         private final Set<OnShardInitialized> onShardInitializedSet = Sets.newHashSet();
1324         private String role ;
1325         private String leaderId;
1326         private short leaderVersion;
1327
1328         private DatastoreContext datastoreContext;
1329         private Shard.AbstractBuilder<?, ?> builder;
1330         private final ShardPeerAddressResolver addressResolver;
1331         private boolean isActiveMember = true;
1332
1333         private ShardInformation(String shardName, ShardIdentifier shardId,
1334                 Map<String, String> initialPeerAddresses, DatastoreContext datastoreContext,
1335                 Shard.AbstractBuilder<?, ?> builder, ShardPeerAddressResolver addressResolver) {
1336             this.shardName = shardName;
1337             this.shardId = shardId;
1338             this.initialPeerAddresses = initialPeerAddresses;
1339             this.datastoreContext = datastoreContext;
1340             this.builder = builder;
1341             this.addressResolver = addressResolver;
1342         }
1343
1344         Props newProps(SchemaContext schemaContext) {
1345             Preconditions.checkNotNull(builder);
1346             Props props = builder.id(shardId).peerAddresses(initialPeerAddresses).datastoreContext(datastoreContext).
1347                     schemaContext(schemaContext).props();
1348             builder = null;
1349             return props;
1350         }
1351
1352         String getShardName() {
1353             return shardName;
1354         }
1355
1356         @Nullable
1357         ActorRef getActor(){
1358             return actor;
1359         }
1360
1361         void setActor(ActorRef actor) {
1362             this.actor = actor;
1363         }
1364
1365         ShardIdentifier getShardId() {
1366             return shardId;
1367         }
1368
1369         void setLocalDataTree(Optional<DataTree> localShardDataTree) {
1370             this.localShardDataTree = localShardDataTree;
1371         }
1372
1373         Optional<DataTree> getLocalShardDataTree() {
1374             return localShardDataTree;
1375         }
1376
1377         DatastoreContext getDatastoreContext() {
1378             return datastoreContext;
1379         }
1380
1381         void setDatastoreContext(DatastoreContext datastoreContext, ActorRef sender) {
1382             this.datastoreContext = datastoreContext;
1383             if (actor != null) {
1384                 LOG.debug ("Sending new DatastoreContext to {}", shardId);
1385                 actor.tell(this.datastoreContext, sender);
1386             }
1387         }
1388
1389         void updatePeerAddress(String peerId, String peerAddress, ActorRef sender){
1390             LOG.info("updatePeerAddress for peer {} with address {}", peerId, peerAddress);
1391
1392             if(actor != null) {
1393                 if(LOG.isDebugEnabled()) {
1394                     LOG.debug("Sending PeerAddressResolved for peer {} with address {} to {}",
1395                             peerId, peerAddress, actor.path());
1396                 }
1397
1398                 actor.tell(new PeerAddressResolved(peerId, peerAddress), sender);
1399             }
1400
1401             notifyOnShardInitializedCallbacks();
1402         }
1403
1404         void peerDown(String memberName, String peerId, ActorRef sender) {
1405             if(actor != null) {
1406                 actor.tell(new PeerDown(memberName, peerId), sender);
1407             }
1408         }
1409
1410         void peerUp(String memberName, String peerId, ActorRef sender) {
1411             if(actor != null) {
1412                 actor.tell(new PeerUp(memberName, peerId), sender);
1413             }
1414         }
1415
1416         boolean isShardReady() {
1417             return !RaftState.Candidate.name().equals(role) && !Strings.isNullOrEmpty(role);
1418         }
1419
1420         boolean isShardReadyWithLeaderId() {
1421             return leaderAvailable && isShardReady() && !RaftState.IsolatedLeader.name().equals(role) &&
1422                     (isLeader() || addressResolver.resolve(leaderId) != null);
1423         }
1424
1425         boolean isShardInitialized() {
1426             return getActor() != null && actorInitialized;
1427         }
1428
1429         boolean isLeader() {
1430             return Objects.equal(leaderId, shardId.toString());
1431         }
1432
1433         String getSerializedLeaderActor() {
1434             if(isLeader()) {
1435                 return Serialization.serializedActorPath(getActor());
1436             } else {
1437                 return addressResolver.resolve(leaderId);
1438             }
1439         }
1440
1441         void setActorInitialized() {
1442             LOG.debug("Shard {} is initialized", shardId);
1443
1444             this.actorInitialized = true;
1445
1446             notifyOnShardInitializedCallbacks();
1447         }
1448
1449         private void notifyOnShardInitializedCallbacks() {
1450             if(onShardInitializedSet.isEmpty()) {
1451                 return;
1452             }
1453
1454             boolean ready = isShardReadyWithLeaderId();
1455
1456             if(LOG.isDebugEnabled()) {
1457                 LOG.debug("Shard {} is {} - notifying {} OnShardInitialized callbacks", shardId,
1458                         ready ? "ready" : "initialized", onShardInitializedSet.size());
1459             }
1460
1461             Iterator<OnShardInitialized> iter = onShardInitializedSet.iterator();
1462             while(iter.hasNext()) {
1463                 OnShardInitialized onShardInitialized = iter.next();
1464                 if(!(onShardInitialized instanceof OnShardReady) || ready) {
1465                     iter.remove();
1466                     onShardInitialized.getTimeoutSchedule().cancel();
1467                     onShardInitialized.getReplyRunnable().run();
1468                 }
1469             }
1470         }
1471
1472         void addOnShardInitialized(OnShardInitialized onShardInitialized) {
1473             onShardInitializedSet.add(onShardInitialized);
1474         }
1475
1476         void removeOnShardInitialized(OnShardInitialized onShardInitialized) {
1477             onShardInitializedSet.remove(onShardInitialized);
1478         }
1479
1480         void setRole(String newRole) {
1481             this.role = newRole;
1482
1483             notifyOnShardInitializedCallbacks();
1484         }
1485
1486         void setFollowerSyncStatus(boolean syncStatus){
1487             this.followerSyncStatus = syncStatus;
1488         }
1489
1490         boolean isInSync(){
1491             if(RaftState.Follower.name().equals(this.role)){
1492                 return followerSyncStatus;
1493             } else if(RaftState.Leader.name().equals(this.role)){
1494                 return true;
1495             }
1496
1497             return false;
1498         }
1499
1500         boolean setLeaderId(String leaderId) {
1501             boolean changed = !Objects.equal(this.leaderId, leaderId);
1502             this.leaderId = leaderId;
1503             if(leaderId != null) {
1504                 this.leaderAvailable = true;
1505             }
1506             notifyOnShardInitializedCallbacks();
1507
1508             return changed;
1509         }
1510
1511         String getLeaderId() {
1512             return leaderId;
1513         }
1514
1515         void setLeaderAvailable(boolean leaderAvailable) {
1516             this.leaderAvailable = leaderAvailable;
1517
1518             if(leaderAvailable) {
1519                 notifyOnShardInitializedCallbacks();
1520             }
1521         }
1522
1523         short getLeaderVersion() {
1524             return leaderVersion;
1525         }
1526
1527         void setLeaderVersion(short leaderVersion) {
1528             this.leaderVersion = leaderVersion;
1529         }
1530
1531         boolean isActiveMember() {
1532             return isActiveMember;
1533         }
1534
1535         void setActiveMember(boolean isActiveMember) {
1536             this.isActiveMember = isActiveMember;
1537         }
1538     }
1539
1540     private static class OnShardInitialized {
1541         private final Runnable replyRunnable;
1542         private Cancellable timeoutSchedule;
1543
1544         OnShardInitialized(Runnable replyRunnable) {
1545             this.replyRunnable = replyRunnable;
1546         }
1547
1548         Runnable getReplyRunnable() {
1549             return replyRunnable;
1550         }
1551
1552         Cancellable getTimeoutSchedule() {
1553             return timeoutSchedule;
1554         }
1555
1556         void setTimeoutSchedule(Cancellable timeoutSchedule) {
1557             this.timeoutSchedule = timeoutSchedule;
1558         }
1559     }
1560
1561     private static class OnShardReady extends OnShardInitialized {
1562         OnShardReady(Runnable replyRunnable) {
1563             super(replyRunnable);
1564         }
1565     }
1566
1567     private static class ShardNotInitializedTimeout {
1568         private final ActorRef sender;
1569         private final ShardInformation shardInfo;
1570         private final OnShardInitialized onShardInitialized;
1571
1572         ShardNotInitializedTimeout(ShardInformation shardInfo, OnShardInitialized onShardInitialized, ActorRef sender) {
1573             this.sender = sender;
1574             this.shardInfo = shardInfo;
1575             this.onShardInitialized = onShardInitialized;
1576         }
1577
1578         ActorRef getSender() {
1579             return sender;
1580         }
1581
1582         ShardInformation getShardInfo() {
1583             return shardInfo;
1584         }
1585
1586         OnShardInitialized getOnShardInitialized() {
1587             return onShardInitialized;
1588         }
1589     }
1590
1591     private void findPrimary(final String shardName, final FindPrimaryResponseHandler handler) {
1592         Timeout findPrimaryTimeout = new Timeout(datastoreContextFactory.getBaseDatastoreContext().
1593                 getShardInitializationTimeout().duration().$times(2));
1594
1595
1596         Future<Object> futureObj = ask(getSelf(), new FindPrimary(shardName, true), findPrimaryTimeout);
1597         futureObj.onComplete(new OnComplete<Object>() {
1598             @Override
1599             public void onComplete(Throwable failure, Object response) {
1600                 if (failure != null) {
1601                     handler.onFailure(failure);
1602                 } else {
1603                     if(response instanceof RemotePrimaryShardFound) {
1604                         handler.onRemotePrimaryShardFound((RemotePrimaryShardFound) response);
1605                     } else if(response instanceof LocalPrimaryShardFound) {
1606                         handler.onLocalPrimaryFound((LocalPrimaryShardFound) response);
1607                     } else {
1608                         handler.onUnknownResponse(response);
1609                     }
1610                 }
1611             }
1612         }, new Dispatchers(context().system().dispatchers()).getDispatcher(Dispatchers.DispatcherType.Client));
1613     }
1614
1615     /**
1616      * The FindPrimaryResponseHandler provides specific callback methods which are invoked when a response to the
1617      * a remote or local find primary message is processed
1618      */
1619     private static interface FindPrimaryResponseHandler {
1620         /**
1621          * Invoked when a Failure message is received as a response
1622          *
1623          * @param failure
1624          */
1625         void onFailure(Throwable failure);
1626
1627         /**
1628          * Invoked when a RemotePrimaryShardFound response is received
1629          *
1630          * @param response
1631          */
1632         void onRemotePrimaryShardFound(RemotePrimaryShardFound response);
1633
1634         /**
1635          * Invoked when a LocalPrimaryShardFound response is received
1636          * @param response
1637          */
1638         void onLocalPrimaryFound(LocalPrimaryShardFound response);
1639
1640         /**
1641          * Invoked when an unknown response is received. This is another type of failure.
1642          *
1643          * @param response
1644          */
1645         void onUnknownResponse(Object response);
1646     }
1647
1648     /**
1649      * The AutoFindPrimaryFailureResponseHandler automatically processes Failure responses when finding a primary
1650      * replica and sends a wrapped Failure response to some targetActor
1651      */
1652     private static abstract class AutoFindPrimaryFailureResponseHandler implements FindPrimaryResponseHandler {
1653         private final ActorRef targetActor;
1654         private final String shardName;
1655         private final String persistenceId;
1656         private final ActorRef shardManagerActor;
1657
1658         /**
1659          * @param targetActor The actor to whom the Failure response should be sent when a FindPrimary failure occurs
1660          * @param shardName The name of the shard for which the primary replica had to be found
1661          * @param persistenceId The persistenceId for the ShardManager
1662          * @param shardManagerActor The ShardManager actor which triggered the call to FindPrimary
1663          */
1664         protected AutoFindPrimaryFailureResponseHandler(ActorRef targetActor, String shardName, String persistenceId, ActorRef shardManagerActor){
1665             this.targetActor = Preconditions.checkNotNull(targetActor);
1666             this.shardName = Preconditions.checkNotNull(shardName);
1667             this.persistenceId = Preconditions.checkNotNull(persistenceId);
1668             this.shardManagerActor = Preconditions.checkNotNull(shardManagerActor);
1669         }
1670
1671         public ActorRef getTargetActor() {
1672             return targetActor;
1673         }
1674
1675         public String getShardName() {
1676             return shardName;
1677         }
1678
1679         @Override
1680         public void onFailure(Throwable failure) {
1681             LOG.debug ("{}: Received failure from FindPrimary for shard {}", persistenceId, shardName, failure);
1682             targetActor.tell(new akka.actor.Status.Failure(new RuntimeException(
1683                     String.format("Failed to find leader for shard %s", shardName), failure)), shardManagerActor);
1684         }
1685
1686         @Override
1687         public void onUnknownResponse(Object response) {
1688             String msg = String.format("Failed to find leader for shard %s: received response: %s",
1689                     shardName, response);
1690             LOG.debug ("{}: {}", persistenceId, msg);
1691             targetActor.tell(new akka.actor.Status.Failure(response instanceof Throwable ? (Throwable) response :
1692                     new RuntimeException(msg)), shardManagerActor);
1693         }
1694     }
1695
1696
1697     /**
1698      * The PrimaryShardFoundForContext is a DTO which puts together a message (aka 'Context' message) which needs to be
1699      * forwarded to the primary replica of a shard and the message (aka 'PrimaryShardFound' message) that is received
1700      * as a successful response to find primary.
1701      */
1702     private static class PrimaryShardFoundForContext {
1703         private final String shardName;
1704         private final Object contextMessage;
1705         private final RemotePrimaryShardFound remotePrimaryShardFound;
1706         private final LocalPrimaryShardFound localPrimaryShardFound;
1707
1708         public PrimaryShardFoundForContext(@Nonnull String shardName, @Nonnull Object contextMessage,
1709                 @Nonnull Object primaryFoundMessage) {
1710             this.shardName = Preconditions.checkNotNull(shardName);
1711             this.contextMessage = Preconditions.checkNotNull(contextMessage);
1712             Preconditions.checkNotNull(primaryFoundMessage);
1713             this.remotePrimaryShardFound = (primaryFoundMessage instanceof RemotePrimaryShardFound) ?
1714                     (RemotePrimaryShardFound) primaryFoundMessage : null;
1715             this.localPrimaryShardFound = (primaryFoundMessage instanceof LocalPrimaryShardFound) ?
1716                     (LocalPrimaryShardFound) primaryFoundMessage : null;
1717         }
1718
1719         @Nonnull
1720         String getPrimaryPath(){
1721             if(remotePrimaryShardFound != null) {
1722                 return remotePrimaryShardFound.getPrimaryPath();
1723             }
1724             return localPrimaryShardFound.getPrimaryPath();
1725         }
1726
1727         @Nonnull
1728         Object getContextMessage() {
1729             return contextMessage;
1730         }
1731
1732         @Nullable
1733         RemotePrimaryShardFound getRemotePrimaryShardFound() {
1734             return remotePrimaryShardFound;
1735         }
1736
1737         @Nonnull
1738         String getShardName() {
1739             return shardName;
1740         }
1741     }
1742
1743     /**
1744      * The WrappedShardResponse class wraps a response from a Shard.
1745      */
1746     private static class WrappedShardResponse {
1747         private final ShardIdentifier shardId;
1748         private final Object response;
1749         private final String leaderPath;
1750
1751         private WrappedShardResponse(ShardIdentifier shardId, Object response, String leaderPath) {
1752             this.shardId = shardId;
1753             this.response = response;
1754             this.leaderPath = leaderPath;
1755         }
1756
1757         ShardIdentifier getShardId() {
1758             return shardId;
1759         }
1760
1761         Object getResponse() {
1762             return response;
1763         }
1764
1765         String getLeaderPath() {
1766             return leaderPath;
1767         }
1768     }
1769 }
1770
1771
1772