opendaylight/md-sal/sal-akka-raft/src/main/java/org/opendaylight/controller/cluster/raft/RaftActor.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.raft;
  10
  11 import akka.actor.ActorRef;
  12 import akka.actor.ActorSelection;
  13 import akka.event.Logging;
  14 import akka.event.LoggingAdapter;
  15 import akka.japi.Procedure;
  16 import akka.persistence.RecoveryCompleted;
  17 import akka.persistence.SaveSnapshotFailure;
  18 import akka.persistence.SaveSnapshotSuccess;
  19 import akka.persistence.SnapshotOffer;
  20 import akka.persistence.SnapshotSelectionCriteria;
  21 import com.google.common.annotations.VisibleForTesting;
  22 import com.google.common.base.Optional;
  23 import com.google.common.base.Stopwatch;
  24 import com.google.protobuf.ByteString;
  25 import java.io.Serializable;
  26 import java.util.Map;
  27 import org.opendaylight.controller.cluster.DataPersistenceProvider;
  28 import org.opendaylight.controller.cluster.common.actor.AbstractUntypedPersistentActor;
  29 import org.opendaylight.controller.cluster.notifications.RoleChanged;
  30 import org.opendaylight.controller.cluster.raft.base.messages.ApplyLogEntries;
  31 import org.opendaylight.controller.cluster.raft.base.messages.ApplySnapshot;
  32 import org.opendaylight.controller.cluster.raft.base.messages.ApplyState;
  33 import org.opendaylight.controller.cluster.raft.base.messages.CaptureSnapshot;
  34 import org.opendaylight.controller.cluster.raft.base.messages.CaptureSnapshotReply;
  35 import org.opendaylight.controller.cluster.raft.base.messages.Replicate;
  36 import org.opendaylight.controller.cluster.raft.base.messages.SendHeartBeat;
  37 import org.opendaylight.controller.cluster.raft.base.messages.SendInstallSnapshot;
  38 import org.opendaylight.controller.cluster.raft.behaviors.AbstractRaftActorBehavior;
  39 import org.opendaylight.controller.cluster.raft.behaviors.Follower;
  40 import org.opendaylight.controller.cluster.raft.behaviors.RaftActorBehavior;
  41 import org.opendaylight.controller.cluster.raft.client.messages.FindLeader;
  42 import org.opendaylight.controller.cluster.raft.client.messages.FindLeaderReply;
  43 import org.opendaylight.controller.cluster.raft.messages.AppendEntriesReply;
  44 import org.opendaylight.controller.cluster.raft.protobuff.client.messages.Payload;
  45 import org.opendaylight.controller.protobuff.messages.cluster.raft.AppendEntriesMessages;
  46
  47 /**
  48  * RaftActor encapsulates a state machine that needs to be kept synchronized
  49  * in a cluster. It implements the RAFT algorithm as described in the paper
  50  * <a href='https://ramcloud.stanford.edu/wiki/download/attachments/11370504/raft.pdf'>
  51  * In Search of an Understandable Consensus Algorithm</a>
  52  * <p/>
  53  * RaftActor has 3 states and each state has a certain behavior associated
  54  * with it. A Raft actor can behave as,
  55  * <ul>
  56  * <li> A Leader </li>
  57  * <li> A Follower (or) </li>
  58  * <li> A Candidate </li>
  59  * </ul>
  60  * <p/>
  61  * <p/>
  62  * A RaftActor MUST be a Leader in order to accept requests from clients to
  63  * change the state of it's encapsulated state machine. Once a RaftActor becomes
  64  * a Leader it is also responsible for ensuring that all followers ultimately
  65  * have the same log and therefore the same state machine as itself.
  66  * <p/>
  67  * <p/>
  68  * The current behavior of a RaftActor determines how election for leadership
  69  * is initiated and how peer RaftActors react to request for votes.
  70  * <p/>
  71  * <p/>
  72  * Each RaftActor also needs to know the current election term. It uses this
  73  * information for a couple of things. One is to simply figure out who it
  74  * voted for in the last election. Another is to figure out if the message
  75  * it received to update it's state is stale.
  76  * <p/>
  77  * <p/>
  78  * The RaftActor uses akka-persistence to store it's replicated log.
  79  * Furthermore through it's behaviors a Raft Actor determines
  80  * <p/>
  81  * <ul>
  82  * <li> when a log entry should be persisted </li>
  83  * <li> when a log entry should be applied to the state machine (and) </li>
  84  * <li> when a snapshot should be saved </li>
  85  * </ul>
  86  */
  87 public abstract class RaftActor extends AbstractUntypedPersistentActor {
  88     protected final LoggingAdapter LOG =
  89         Logging.getLogger(getContext().system(), this);
  90
  91     /**
  92      * The current state determines the current behavior of a RaftActor
  93      * A Raft Actor always starts off in the Follower State
  94      */
  95     private RaftActorBehavior currentBehavior;
  96
  97     /**
  98      * This context should NOT be passed directly to any other actor it is
  99      * only to be consumed by the RaftActorBehaviors
 100      */
 101     private final RaftActorContext context;
 102
 103     /**
 104      * The in-memory journal
 105      */
 106     private ReplicatedLogImpl replicatedLog = new ReplicatedLogImpl();
 107
 108     private CaptureSnapshot captureSnapshot = null;
 109
 110     private volatile boolean hasSnapshotCaptureInitiated = false;
 111
 112     private Stopwatch recoveryTimer;
 113
 114     private int currentRecoveryBatchCount;
 115
 116     public RaftActor(String id, Map<String, String> peerAddresses) {
 117         this(id, peerAddresses, Optional.<ConfigParams>absent());
 118     }
 119
 120     public RaftActor(String id, Map<String, String> peerAddresses,
 121          Optional<ConfigParams> configParams) {
 122
 123         context = new RaftActorContextImpl(this.getSelf(),
 124             this.getContext(), id, new ElectionTermImpl(),
 125             -1, -1, replicatedLog, peerAddresses,
 126             (configParams.isPresent() ? configParams.get(): new DefaultConfigParamsImpl()),
 127             LOG);
 128     }
 129
 130     private void initRecoveryTimer() {
 131         if(recoveryTimer == null) {
 132             recoveryTimer = new Stopwatch();
 133             recoveryTimer.start();
 134         }
 135     }
 136
 137     @Override
 138     public void preStart() throws Exception {
 139         LOG.info("Starting recovery for {} with journal batch size {}", persistenceId(),
 140                 context.getConfigParams().getJournalRecoveryLogBatchSize());
 141
 142         super.preStart();
 143     }
 144
 145     @Override
 146     public void handleRecover(Object message) {
 147         if(persistence().isRecoveryApplicable()) {
 148             if (message instanceof SnapshotOffer) {
 149                 onRecoveredSnapshot((SnapshotOffer) message);
 150             } else if (message instanceof ReplicatedLogEntry) {
 151                 onRecoveredJournalLogEntry((ReplicatedLogEntry) message);
 152             } else if (message instanceof ApplyLogEntries) {
 153                 onRecoveredApplyLogEntries((ApplyLogEntries) message);
 154             } else if (message instanceof DeleteEntries) {
 155                 replicatedLog.removeFrom(((DeleteEntries) message).getFromIndex());
 156             } else if (message instanceof UpdateElectionTerm) {
 157                 context.getTermInformation().update(((UpdateElectionTerm) message).getCurrentTerm(),
 158                         ((UpdateElectionTerm) message).getVotedFor());
 159             } else if (message instanceof RecoveryCompleted) {
 160                 onRecoveryCompletedMessage();
 161             }
 162         } else {
 163             if (message instanceof RecoveryCompleted) {
 164                 // Delete all the messages from the akka journal so that we do not end up with consistency issues
 165                 // Note I am not using the dataPersistenceProvider and directly using the akka api here
 166                 deleteMessages(lastSequenceNr());
 167
 168                 // Delete all the akka snapshots as they will not be needed
 169                 deleteSnapshots(new SnapshotSelectionCriteria(scala.Long.MaxValue(), scala.Long.MaxValue()));
 170
 171                 onRecoveryComplete();
 172
 173                 RaftActorBehavior oldBehavior = currentBehavior;
 174                 currentBehavior = new Follower(context);
 175                 handleBehaviorChange(oldBehavior, currentBehavior);
 176             }
 177         }
 178     }
 179
 180     private void onRecoveredSnapshot(SnapshotOffer offer) {
 181         if(LOG.isDebugEnabled()) {
 182             LOG.debug("SnapshotOffer called..");
 183         }
 184
 185         initRecoveryTimer();
 186
 187         Snapshot snapshot = (Snapshot) offer.snapshot();
 188
 189         // Create a replicated log with the snapshot information
 190         // The replicated log can be used later on to retrieve this snapshot
 191         // when we need to install it on a peer
 192         replicatedLog = new ReplicatedLogImpl(snapshot);
 193
 194         context.setReplicatedLog(replicatedLog);
 195         context.setLastApplied(snapshot.getLastAppliedIndex());
 196         context.setCommitIndex(snapshot.getLastAppliedIndex());
 197
 198         Stopwatch timer = new Stopwatch();
 199         timer.start();
 200
 201         // Apply the snapshot to the actors state
 202         applyRecoverySnapshot(ByteString.copyFrom(snapshot.getState()));
 203
 204         timer.stop();
 205         LOG.info("Recovery snapshot applied for {} in {}: snapshotIndex={}, snapshotTerm={}, journal-size=" +
 206                 replicatedLog.size(), persistenceId(), timer.toString(),
 207                 replicatedLog.snapshotIndex, replicatedLog.snapshotTerm);
 208     }
 209
 210     private void onRecoveredJournalLogEntry(ReplicatedLogEntry logEntry) {
 211         if(LOG.isDebugEnabled()) {
 212             LOG.debug("Received ReplicatedLogEntry for recovery: {}", logEntry.getIndex());
 213         }
 214
 215         replicatedLog.append(logEntry);
 216     }
 217
 218     private void onRecoveredApplyLogEntries(ApplyLogEntries ale) {
 219         if(LOG.isDebugEnabled()) {
 220             LOG.debug("Received ApplyLogEntries for recovery, applying to state: {} to {}",
 221                     context.getLastApplied() + 1, ale.getToIndex());
 222         }
 223
 224         for (long i = context.getLastApplied() + 1; i <= ale.getToIndex(); i++) {
 225             batchRecoveredLogEntry(replicatedLog.get(i));
 226         }
 227
 228         context.setLastApplied(ale.getToIndex());
 229         context.setCommitIndex(ale.getToIndex());
 230     }
 231
 232     private void batchRecoveredLogEntry(ReplicatedLogEntry logEntry) {
 233         initRecoveryTimer();
 234
 235         int batchSize = context.getConfigParams().getJournalRecoveryLogBatchSize();
 236         if(currentRecoveryBatchCount == 0) {
 237             startLogRecoveryBatch(batchSize);
 238         }
 239
 240         appendRecoveredLogEntry(logEntry.getData());
 241
 242         if(++currentRecoveryBatchCount >= batchSize) {
 243             endCurrentLogRecoveryBatch();
 244         }
 245     }
 246
 247     private void endCurrentLogRecoveryBatch() {
 248         applyCurrentLogRecoveryBatch();
 249         currentRecoveryBatchCount = 0;
 250     }
 251
 252     private void onRecoveryCompletedMessage() {
 253         if(currentRecoveryBatchCount > 0) {
 254             endCurrentLogRecoveryBatch();
 255         }
 256
 257         onRecoveryComplete();
 258
 259         String recoveryTime = "";
 260         if(recoveryTimer != null) {
 261             recoveryTimer.stop();
 262             recoveryTime = " in " + recoveryTimer.toString();
 263             recoveryTimer = null;
 264         }
 265
 266         LOG.info(
 267             "Recovery completed" + recoveryTime + " - Switching actor to Follower - " +
 268                 "Persistence Id =  " + persistenceId() +
 269                 " Last index in log={}, snapshotIndex={}, snapshotTerm={}, " +
 270                 "journal-size={}",
 271             replicatedLog.lastIndex(), replicatedLog.snapshotIndex,
 272             replicatedLog.snapshotTerm, replicatedLog.size());
 273
 274         RaftActorBehavior oldBehavior = currentBehavior;
 275         currentBehavior = new Follower(context);
 276         handleBehaviorChange(oldBehavior, currentBehavior);
 277     }
 278
 279     @Override public void handleCommand(Object message) {
 280         if (message instanceof ApplyState){
 281             ApplyState applyState = (ApplyState) message;
 282
 283             if(LOG.isDebugEnabled()) {
 284                 LOG.debug("Applying state for log index {} data {}",
 285                     applyState.getReplicatedLogEntry().getIndex(),
 286                     applyState.getReplicatedLogEntry().getData());
 287             }
 288
 289             applyState(applyState.getClientActor(), applyState.getIdentifier(),
 290                 applyState.getReplicatedLogEntry().getData());
 291
 292         } else if (message instanceof ApplyLogEntries){
 293             ApplyLogEntries ale = (ApplyLogEntries) message;
 294             if(LOG.isDebugEnabled()) {
 295                 LOG.debug("Persisting ApplyLogEntries with index={}", ale.getToIndex());
 296             }
 297             persistence().persist(new ApplyLogEntries(ale.getToIndex()), new Procedure<ApplyLogEntries>() {
 298                 @Override
 299                 public void apply(ApplyLogEntries param) throws Exception {
 300                 }
 301             });
 302
 303         } else if(message instanceof ApplySnapshot ) {
 304             Snapshot snapshot = ((ApplySnapshot) message).getSnapshot();
 305
 306             if(LOG.isDebugEnabled()) {
 307                 LOG.debug("ApplySnapshot called on Follower Actor " +
 308                         "snapshotIndex:{}, snapshotTerm:{}", snapshot.getLastAppliedIndex(),
 309                     snapshot.getLastAppliedTerm()
 310                 );
 311             }
 312             applySnapshot(ByteString.copyFrom(snapshot.getState()));
 313
 314             //clears the followers log, sets the snapshot index to ensure adjusted-index works
 315             replicatedLog = new ReplicatedLogImpl(snapshot);
 316             context.setReplicatedLog(replicatedLog);
 317             context.setLastApplied(snapshot.getLastAppliedIndex());
 318
 319         } else if (message instanceof FindLeader) {
 320             getSender().tell(
 321                 new FindLeaderReply(getLeaderAddress()),
 322                 getSelf()
 323             );
 324
 325         } else if (message instanceof SaveSnapshotSuccess) {
 326             SaveSnapshotSuccess success = (SaveSnapshotSuccess) message;
 327             LOG.info("SaveSnapshotSuccess received for snapshot");
 328
 329             long sequenceNumber = success.metadata().sequenceNr();
 330
 331             commitSnapshot(sequenceNumber);
 332
 333         } else if (message instanceof SaveSnapshotFailure) {
 334             SaveSnapshotFailure saveSnapshotFailure = (SaveSnapshotFailure) message;
 335
 336             LOG.info("saveSnapshotFailure.metadata():{}", saveSnapshotFailure.metadata().toString());
 337             LOG.error(saveSnapshotFailure.cause(), "SaveSnapshotFailure received for snapshot Cause:");
 338
 339             context.getReplicatedLog().snapshotRollback();
 340
 341             LOG.info("Replicated Log rollbacked. Snapshot will be attempted in the next cycle." +
 342                 "snapshotIndex:{}, snapshotTerm:{}, log-size:{}",
 343                 context.getReplicatedLog().getSnapshotIndex(),
 344                 context.getReplicatedLog().getSnapshotTerm(),
 345                 context.getReplicatedLog().size());
 346
 347         } else if (message instanceof CaptureSnapshot) {
 348             LOG.info("CaptureSnapshot received by actor");
 349             CaptureSnapshot cs = (CaptureSnapshot)message;
 350             captureSnapshot = cs;
 351             createSnapshot();
 352
 353         } else if (message instanceof CaptureSnapshotReply){
 354             LOG.info("CaptureSnapshotReply received by actor");
 355             CaptureSnapshotReply csr = (CaptureSnapshotReply) message;
 356
 357             ByteString stateInBytes = csr.getSnapshot();
 358             LOG.info("CaptureSnapshotReply stateInBytes size:{}", stateInBytes.size());
 359             handleCaptureSnapshotReply(stateInBytes);
 360
 361         } else {
 362             if (!(message instanceof AppendEntriesMessages.AppendEntries)
 363                 && !(message instanceof AppendEntriesReply) && !(message instanceof SendHeartBeat)) {
 364                 if(LOG.isDebugEnabled()) {
 365                     LOG.debug("onReceiveCommand: message: {}", message.getClass());
 366                 }
 367             }
 368
 369             RaftActorBehavior oldBehavior = currentBehavior;
 370             currentBehavior = currentBehavior.handleMessage(getSender(), message);
 371
 372             handleBehaviorChange(oldBehavior, currentBehavior);
 373         }
 374     }
 375
 376     private void handleBehaviorChange(RaftActorBehavior oldBehavior, RaftActorBehavior currentBehavior) {
 377         if (oldBehavior != currentBehavior){
 378             onStateChanged();
 379         }
 380
 381         String oldBehaviorLeaderId = oldBehavior == null? null : oldBehavior.getLeaderId();
 382         String oldBehaviorState = oldBehavior == null? null : oldBehavior.state().name();
 383
 384         // it can happen that the state has not changed but the leader has changed.
 385         onLeaderChanged(oldBehaviorLeaderId, currentBehavior.getLeaderId());
 386
 387         if (getRoleChangeNotifier().isPresent() &&
 388                 (oldBehavior == null || (oldBehavior.state() != currentBehavior.state()))) {
 389             getRoleChangeNotifier().get().tell(
 390                     new RoleChanged(getId(), oldBehaviorState , currentBehavior.state().name()),
 391                     getSelf());
 392         }
 393     }
 394
 395     /**
 396      * When a derived RaftActor needs to persist something it must call
 397      * persistData.
 398      *
 399      * @param clientActor
 400      * @param identifier
 401      * @param data
 402      */
 403     protected void persistData(ActorRef clientActor, String identifier,
 404         Payload data) {
 405
 406         ReplicatedLogEntry replicatedLogEntry = new ReplicatedLogImplEntry(
 407             context.getReplicatedLog().lastIndex() + 1,
 408             context.getTermInformation().getCurrentTerm(), data);
 409
 410         if(LOG.isDebugEnabled()) {
 411             LOG.debug("Persist data {}", replicatedLogEntry);
 412         }
 413
 414         replicatedLog
 415             .appendAndPersist(clientActor, identifier, replicatedLogEntry);
 416     }
 417
 418     protected String getId() {
 419         return context.getId();
 420     }
 421
 422     /**
 423      * Derived actors can call the isLeader method to check if the current
 424      * RaftActor is the Leader or not
 425      *
 426      * @return true it this RaftActor is a Leader false otherwise
 427      */
 428     protected boolean isLeader() {
 429         return context.getId().equals(currentBehavior.getLeaderId());
 430     }
 431
 432     /**
 433      * Derived actor can call getLeader if they need a reference to the Leader.
 434      * This would be useful for example in forwarding a request to an actor
 435      * which is the leader
 436      *
 437      * @return A reference to the leader if known, null otherwise
 438      */
 439     protected ActorSelection getLeader(){
 440         String leaderAddress = getLeaderAddress();
 441
 442         if(leaderAddress == null){
 443             return null;
 444         }
 445
 446         return context.actorSelection(leaderAddress);
 447     }
 448
 449     /**
 450      *
 451      * @return the current leader's id
 452      */
 453     protected String getLeaderId(){
 454         return currentBehavior.getLeaderId();
 455     }
 456
 457     protected RaftState getRaftState() {
 458         return currentBehavior.state();
 459     }
 460
 461     protected ReplicatedLogEntry getLastLogEntry() {
 462         return replicatedLog.last();
 463     }
 464
 465     protected Long getCurrentTerm(){
 466         return context.getTermInformation().getCurrentTerm();
 467     }
 468
 469     protected Long getCommitIndex(){
 470         return context.getCommitIndex();
 471     }
 472
 473     protected Long getLastApplied(){
 474         return context.getLastApplied();
 475     }
 476
 477     protected RaftActorContext getRaftActorContext() {
 478         return context;
 479     }
 480
 481     /**
 482      * setPeerAddress sets the address of a known peer at a later time.
 483      * <p>
 484      * This is to account for situations where a we know that a peer
 485      * exists but we do not know an address up-front. This may also be used in
 486      * situations where a known peer starts off in a different location and we
 487      * need to change it's address
 488      * <p>
 489      * Note that if the peerId does not match the list of peers passed to
 490      * this actor during construction an IllegalStateException will be thrown.
 491      *
 492      * @param peerId
 493      * @param peerAddress
 494      */
 495     protected void setPeerAddress(String peerId, String peerAddress){
 496         context.setPeerAddress(peerId, peerAddress);
 497     }
 498
 499     protected void commitSnapshot(long sequenceNumber) {
 500         context.getReplicatedLog().snapshotCommit();
 501
 502         // TODO: Not sure if we want to be this aggressive with trimming stuff
 503         trimPersistentData(sequenceNumber);
 504     }
 505
 506     /**
 507      * The applyState method will be called by the RaftActor when some data
 508      * needs to be applied to the actor's state
 509      *
 510      * @param clientActor A reference to the client who sent this message. This
 511      *                    is the same reference that was passed to persistData
 512      *                    by the derived actor. clientActor may be null when
 513      *                    the RaftActor is behaving as a follower or during
 514      *                    recovery.
 515      * @param identifier  The identifier of the persisted data. This is also
 516      *                    the same identifier that was passed to persistData by
 517      *                    the derived actor. identifier may be null when
 518      *                    the RaftActor is behaving as a follower or during
 519      *                    recovery
 520      * @param data        A piece of data that was persisted by the persistData call.
 521      *                    This should NEVER be null.
 522      */
 523     protected abstract void applyState(ActorRef clientActor, String identifier,
 524         Object data);
 525
 526     /**
 527      * This method is called during recovery at the start of a batch of state entries. Derived
 528      * classes should perform any initialization needed to start a batch.
 529      */
 530     protected abstract void startLogRecoveryBatch(int maxBatchSize);
 531
 532     /**
 533      * This method is called during recovery to append state data to the current batch. This method
 534      * is called 1 or more times after {@link #startLogRecoveryBatch}.
 535      *
 536      * @param data the state data
 537      */
 538     protected abstract void appendRecoveredLogEntry(Payload data);
 539
 540     /**
 541      * This method is called during recovery to reconstruct the state of the actor.
 542      *
 543      * @param snapshot A snapshot of the state of the actor
 544      */
 545     protected abstract void applyRecoverySnapshot(ByteString snapshot);
 546
 547     /**
 548      * This method is called during recovery at the end of a batch to apply the current batched
 549      * log entries. This method is called after {@link #appendRecoveredLogEntry}.
 550      */
 551     protected abstract void applyCurrentLogRecoveryBatch();
 552
 553     /**
 554      * This method is called when recovery is complete.
 555      */
 556     protected abstract void onRecoveryComplete();
 557
 558     /**
 559      * This method will be called by the RaftActor when a snapshot needs to be
 560      * created. The derived actor should respond with its current state.
 561      * <p/>
 562      * During recovery the state that is returned by the derived actor will
 563      * be passed back to it by calling the applySnapshot  method
 564      *
 565      * @return The current state of the actor
 566      */
 567     protected abstract void createSnapshot();
 568
 569     /**
 570      * This method can be called at any other point during normal
 571      * operations when the derived actor is out of sync with it's peers
 572      * and the only way to bring it in sync is by applying a snapshot
 573      *
 574      * @param snapshot A snapshot of the state of the actor
 575      */
 576     protected abstract void applySnapshot(ByteString snapshot);
 577
 578     /**
 579      * This method will be called by the RaftActor when the state of the
 580      * RaftActor changes. The derived actor can then use methods like
 581      * isLeader or getLeader to do something useful
 582      */
 583     protected abstract void onStateChanged();
 584
 585     protected abstract DataPersistenceProvider persistence();
 586
 587     /**
 588      * Notifier Actor for this RaftActor to notify when a role change happens
 589      * @return ActorRef - ActorRef of the notifier or Optional.absent if none.
 590      */
 591     protected abstract Optional<ActorRef> getRoleChangeNotifier();
 592
 593     protected void onLeaderChanged(String oldLeader, String newLeader){};
 594
 595     private void trimPersistentData(long sequenceNumber) {
 596         // Trim akka snapshots
 597         // FIXME : Not sure how exactly the SnapshotSelectionCriteria is applied
 598         // For now guessing that it is ANDed.
 599         persistence().deleteSnapshots(new SnapshotSelectionCriteria(
 600             sequenceNumber - context.getConfigParams().getSnapshotBatchCount(), 43200000));
 601
 602         // Trim akka journal
 603         persistence().deleteMessages(sequenceNumber);
 604     }
 605
 606     private String getLeaderAddress(){
 607         if(isLeader()){
 608             return getSelf().path().toString();
 609         }
 610         String leaderId = currentBehavior.getLeaderId();
 611         if (leaderId == null) {
 612             return null;
 613         }
 614         String peerAddress = context.getPeerAddress(leaderId);
 615         if(LOG.isDebugEnabled()) {
 616             LOG.debug("getLeaderAddress leaderId = {} peerAddress = {}",
 617                     leaderId, peerAddress);
 618         }
 619
 620         return peerAddress;
 621     }
 622
 623     private void handleCaptureSnapshotReply(ByteString stateInBytes) {
 624         // create a snapshot object from the state provided and save it
 625         // when snapshot is saved async, SaveSnapshotSuccess is raised.
 626
 627         Snapshot sn = Snapshot.create(stateInBytes.toByteArray(),
 628             context.getReplicatedLog().getFrom(captureSnapshot.getLastAppliedIndex() + 1),
 629             captureSnapshot.getLastIndex(), captureSnapshot.getLastTerm(),
 630             captureSnapshot.getLastAppliedIndex(), captureSnapshot.getLastAppliedTerm());
 631
 632         persistence().saveSnapshot(sn);
 633
 634         LOG.info("Persisting of snapshot done:{}", sn.getLogMessage());
 635
 636         //be greedy and remove entries from in-mem journal which are in the snapshot
 637         // and update snapshotIndex and snapshotTerm without waiting for the success,
 638
 639         context.getReplicatedLog().snapshotPreCommit(
 640             captureSnapshot.getLastAppliedIndex(),
 641             captureSnapshot.getLastAppliedTerm());
 642
 643         LOG.info("Removed in-memory snapshotted entries, adjusted snaphsotIndex:{} " +
 644             "and term:{}", captureSnapshot.getLastAppliedIndex(),
 645             captureSnapshot.getLastAppliedTerm());
 646
 647         if (isLeader() && captureSnapshot.isInstallSnapshotInitiated()) {
 648             // this would be call straight to the leader and won't initiate in serialization
 649             currentBehavior.handleMessage(getSelf(), new SendInstallSnapshot(stateInBytes));
 650         }
 651
 652         captureSnapshot = null;
 653         hasSnapshotCaptureInitiated = false;
 654     }
 655
 656     private class ReplicatedLogImpl extends AbstractReplicatedLogImpl {
 657
 658         public ReplicatedLogImpl(Snapshot snapshot) {
 659             super(snapshot.getLastAppliedIndex(), snapshot.getLastAppliedTerm(),
 660                 snapshot.getUnAppliedEntries());
 661         }
 662
 663         public ReplicatedLogImpl() {
 664             super();
 665         }
 666
 667         @Override public void removeFromAndPersist(long logEntryIndex) {
 668             int adjustedIndex = adjustedIndex(logEntryIndex);
 669
 670             if (adjustedIndex < 0) {
 671                 return;
 672             }
 673
 674             // FIXME: Maybe this should be done after the command is saved
 675             journal.subList(adjustedIndex , journal.size()).clear();
 676
 677             persistence().persist(new DeleteEntries(adjustedIndex), new Procedure<DeleteEntries>(){
 678
 679                 @Override public void apply(DeleteEntries param)
 680                     throws Exception {
 681                     //FIXME : Doing nothing for now
 682                     dataSize = 0;
 683                     for(ReplicatedLogEntry entry : journal){
 684                         dataSize += entry.size();
 685                     }
 686                 }
 687             });
 688         }
 689
 690         @Override public void appendAndPersist(
 691             final ReplicatedLogEntry replicatedLogEntry) {
 692             appendAndPersist(null, null, replicatedLogEntry);
 693         }
 694
 695         @Override
 696         public int dataSize() {
 697             return dataSize;
 698         }
 699
 700         public void appendAndPersist(final ActorRef clientActor,
 701             final String identifier,
 702             final ReplicatedLogEntry replicatedLogEntry) {
 703
 704             if(LOG.isDebugEnabled()) {
 705                 LOG.debug("Append log entry and persist {} ", replicatedLogEntry);
 706             }
 707
 708             // FIXME : By adding the replicated log entry to the in-memory journal we are not truly ensuring durability of the logs
 709             journal.add(replicatedLogEntry);
 710
 711             // When persisting events with persist it is guaranteed that the
 712             // persistent actor will not receive further commands between the
 713             // persist call and the execution(s) of the associated event
 714             // handler. This also holds for multiple persist calls in context
 715             // of a single command.
 716             persistence().persist(replicatedLogEntry,
 717                 new Procedure<ReplicatedLogEntry>() {
 718                     @Override
 719                     public void apply(ReplicatedLogEntry evt) throws Exception {
 720                         dataSize += replicatedLogEntry.size();
 721
 722                         long dataThreshold = Runtime.getRuntime().totalMemory() *
 723                                 getRaftActorContext().getConfigParams().getSnapshotDataThresholdPercentage() / 100;
 724
 725                         // when a snaphsot is being taken, captureSnapshot != null
 726                         if (hasSnapshotCaptureInitiated == false &&
 727                                 ( journal.size() % context.getConfigParams().getSnapshotBatchCount() == 0 ||
 728                                         dataSize > dataThreshold)) {
 729
 730                             LOG.info("Initiating Snapshot Capture..");
 731                             long lastAppliedIndex = -1;
 732                             long lastAppliedTerm = -1;
 733
 734                             ReplicatedLogEntry lastAppliedEntry = get(context.getLastApplied());
 735                             if (lastAppliedEntry != null) {
 736                                 lastAppliedIndex = lastAppliedEntry.getIndex();
 737                                 lastAppliedTerm = lastAppliedEntry.getTerm();
 738                             }
 739
 740                             if(LOG.isDebugEnabled()) {
 741                                 LOG.debug("Snapshot Capture logSize: {}", journal.size());
 742                                 LOG.debug("Snapshot Capture lastApplied:{} ",
 743                                     context.getLastApplied());
 744                                 LOG.debug("Snapshot Capture lastAppliedIndex:{}", lastAppliedIndex);
 745                                 LOG.debug("Snapshot Capture lastAppliedTerm:{}", lastAppliedTerm);
 746                             }
 747
 748                             // send a CaptureSnapshot to self to make the expensive operation async.
 749                             getSelf().tell(new CaptureSnapshot(
 750                                 lastIndex(), lastTerm(), lastAppliedIndex, lastAppliedTerm),
 751                                 null);
 752                             hasSnapshotCaptureInitiated = true;
 753                         }
 754                         // Send message for replication
 755                         if (clientActor != null) {
 756                             currentBehavior.handleMessage(getSelf(),
 757                                 new Replicate(clientActor, identifier,
 758                                     replicatedLogEntry)
 759                             );
 760                         }
 761                     }
 762                 }
 763             );
 764         }
 765
 766     }
 767
 768     static class DeleteEntries implements Serializable {
 769         private static final long serialVersionUID = 1L;
 770         private final int fromIndex;
 771
 772         public DeleteEntries(int fromIndex) {
 773             this.fromIndex = fromIndex;
 774         }
 775
 776         public int getFromIndex() {
 777             return fromIndex;
 778         }
 779     }
 780
 781
 782     private class ElectionTermImpl implements ElectionTerm {
 783         /**
 784          * Identifier of the actor whose election term information this is
 785          */
 786         private long currentTerm = 0;
 787         private String votedFor = null;
 788
 789         @Override
 790         public long getCurrentTerm() {
 791             return currentTerm;
 792         }
 793
 794         @Override
 795         public String getVotedFor() {
 796             return votedFor;
 797         }
 798
 799         @Override public void update(long currentTerm, String votedFor) {
 800             if(LOG.isDebugEnabled()) {
 801                 LOG.debug("Set currentTerm={}, votedFor={}", currentTerm, votedFor);
 802             }
 803             this.currentTerm = currentTerm;
 804             this.votedFor = votedFor;
 805         }
 806
 807         @Override
 808         public void updateAndPersist(long currentTerm, String votedFor){
 809             update(currentTerm, votedFor);
 810             // FIXME : Maybe first persist then update the state
 811             persistence().persist(new UpdateElectionTerm(this.currentTerm, this.votedFor), new Procedure<UpdateElectionTerm>(){
 812
 813                 @Override public void apply(UpdateElectionTerm param)
 814                     throws Exception {
 815
 816                 }
 817             });
 818         }
 819     }
 820
 821     static class UpdateElectionTerm implements Serializable {
 822         private static final long serialVersionUID = 1L;
 823         private final long currentTerm;
 824         private final String votedFor;
 825
 826         public UpdateElectionTerm(long currentTerm, String votedFor) {
 827             this.currentTerm = currentTerm;
 828             this.votedFor = votedFor;
 829         }
 830
 831         public long getCurrentTerm() {
 832             return currentTerm;
 833         }
 834
 835         public String getVotedFor() {
 836             return votedFor;
 837         }
 838     }
 839
 840     protected class NonPersistentRaftDataProvider extends NonPersistentDataProvider {
 841
 842         public NonPersistentRaftDataProvider(){
 843
 844         }
 845
 846         /**
 847          * The way snapshotting works is,
 848          * <ol>
 849          * <li> RaftActor calls createSnapshot on the Shard
 850          * <li> Shard sends a CaptureSnapshotReply and RaftActor then calls saveSnapshot
 851          * <li> When saveSnapshot is invoked on the akka-persistence API it uses the SnapshotStore to save the snapshot.
 852          * The SnapshotStore sends SaveSnapshotSuccess or SaveSnapshotFailure. When the RaftActor gets SaveSnapshot
 853          * success it commits the snapshot to the in-memory journal. This commitSnapshot is mimicking what is done
 854          * in SaveSnapshotSuccess.
 855          * </ol>
 856          * @param o
 857          */
 858         @Override
 859         public void saveSnapshot(Object o) {
 860             // Make saving Snapshot successful
 861             commitSnapshot(-1L);
 862         }
 863     }
 864
 865     @VisibleForTesting
 866     void setCurrentBehavior(AbstractRaftActorBehavior behavior) {
 867         currentBehavior = behavior;
 868     }
 869
 870     protected RaftActorBehavior getCurrentBehavior() {
 871         return currentBehavior;
 872     }
 873
 874 }