opendaylight/md-sal/sal-akka-raft/src/main/java/org/opendaylight/controller/cluster/raft/SnapshotManager.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.japi.Procedure;
  12 import akka.persistence.SnapshotSelectionCriteria;
  13 import com.google.common.annotations.VisibleForTesting;
  14 import java.util.List;
  15 import org.opendaylight.controller.cluster.raft.base.messages.ApplySnapshot;
  16 import org.opendaylight.controller.cluster.raft.base.messages.CaptureSnapshot;
  17 import org.opendaylight.controller.cluster.raft.base.messages.SendInstallSnapshot;
  18 import org.opendaylight.controller.cluster.raft.base.messages.SnapshotComplete;
  19 import org.opendaylight.controller.cluster.raft.behaviors.RaftActorBehavior;
  20 import org.slf4j.Logger;
  21
  22 public class SnapshotManager implements SnapshotState {
  23
  24     private final SnapshotState IDLE = new Idle();
  25     private final SnapshotState PERSISTING = new Persisting();
  26     private final SnapshotState CREATING = new Creating();
  27
  28     private final Logger LOG;
  29     private final RaftActorContext context;
  30     private final LastAppliedTermInformationReader lastAppliedTermInformationReader =
  31             new LastAppliedTermInformationReader();
  32     private final ReplicatedToAllTermInformationReader replicatedToAllTermInformationReader =
  33             new ReplicatedToAllTermInformationReader();
  34
  35
  36     private SnapshotState currentState = IDLE;
  37     private CaptureSnapshot captureSnapshot;
  38     private long lastSequenceNumber = -1;
  39
  40     private Procedure<Void> createSnapshotProcedure;
  41
  42     private ApplySnapshot applySnapshot;
  43     private Procedure<byte[]> applySnapshotProcedure;
  44
  45     public SnapshotManager(RaftActorContext context, Logger logger) {
  46         this.context = context;
  47         this.LOG = logger;
  48     }
  49
  50     public boolean isApplying() {
  51         return applySnapshot != null;
  52     }
  53
  54     @Override
  55     public boolean isCapturing() {
  56         return currentState.isCapturing();
  57     }
  58
  59     @Override
  60     public boolean captureToInstall(ReplicatedLogEntry lastLogEntry, long replicatedToAllIndex, String targetFollower) {
  61         return currentState.captureToInstall(lastLogEntry, replicatedToAllIndex, targetFollower);
  62     }
  63
  64     @Override
  65     public boolean capture(ReplicatedLogEntry lastLogEntry, long replicatedToAllIndex) {
  66         return currentState.capture(lastLogEntry, replicatedToAllIndex);
  67     }
  68
  69     @Override
  70     public void apply(ApplySnapshot snapshot) {
  71         currentState.apply(snapshot);
  72     }
  73
  74     @Override
  75     public void persist(byte[] snapshotBytes, RaftActorBehavior currentBehavior, long totalMemory) {
  76         currentState.persist(snapshotBytes, currentBehavior, totalMemory);
  77     }
  78
  79     @Override
  80     public void commit(long sequenceNumber, RaftActorBehavior currentBehavior) {
  81         currentState.commit(sequenceNumber, currentBehavior);
  82     }
  83
  84     @Override
  85     public void rollback() {
  86         currentState.rollback();
  87     }
  88
  89     @Override
  90     public long trimLog(long desiredTrimIndex, RaftActorBehavior currentBehavior) {
  91         return currentState.trimLog(desiredTrimIndex, currentBehavior);
  92     }
  93
  94     public void setCreateSnapshotCallable(Procedure<Void> createSnapshotProcedure) {
  95         this.createSnapshotProcedure = createSnapshotProcedure;
  96     }
  97
  98     public void setApplySnapshotProcedure(Procedure<byte[]> applySnapshotProcedure) {
  99         this.applySnapshotProcedure = applySnapshotProcedure;
 100     }
 101
 102     public long getLastSequenceNumber() {
 103         return lastSequenceNumber;
 104     }
 105
 106     @VisibleForTesting
 107     public CaptureSnapshot getCaptureSnapshot() {
 108         return captureSnapshot;
 109     }
 110
 111     private boolean hasFollowers(){
 112         return context.hasFollowers();
 113     }
 114
 115     private String persistenceId(){
 116         return context.getId();
 117     }
 118
 119     public CaptureSnapshot newCaptureSnapshot(ReplicatedLogEntry lastLogEntry, long replicatedToAllIndex,
 120             boolean installSnapshotInitiated) {
 121         TermInformationReader lastAppliedTermInfoReader =
 122                 lastAppliedTermInformationReader.init(context.getReplicatedLog(), context.getLastApplied(),
 123                         lastLogEntry, hasFollowers());
 124
 125         long lastAppliedIndex = lastAppliedTermInfoReader.getIndex();
 126         long lastAppliedTerm = lastAppliedTermInfoReader.getTerm();
 127
 128         TermInformationReader replicatedToAllTermInfoReader =
 129                 replicatedToAllTermInformationReader.init(context.getReplicatedLog(), replicatedToAllIndex);
 130
 131         long newReplicatedToAllIndex = replicatedToAllTermInfoReader.getIndex();
 132         long newReplicatedToAllTerm = replicatedToAllTermInfoReader.getTerm();
 133
 134         List<ReplicatedLogEntry> unAppliedEntries = context.getReplicatedLog().getFrom(lastAppliedIndex + 1);
 135
 136         long lastLogEntryIndex = lastAppliedIndex;
 137         long lastLogEntryTerm = lastAppliedTerm;
 138         if(lastLogEntry != null) {
 139             lastLogEntryIndex = lastLogEntry.getIndex();
 140             lastLogEntryTerm = lastLogEntry.getTerm();
 141         } else {
 142             LOG.warn("Capturing Snapshot : lastLogEntry is null. Using lastAppliedIndex {} and lastAppliedTerm {} instead.",
 143                 lastAppliedIndex, lastAppliedTerm);
 144         }
 145
 146         return new CaptureSnapshot(lastLogEntryIndex, lastLogEntryTerm, lastAppliedIndex, lastAppliedTerm,
 147                 newReplicatedToAllIndex, newReplicatedToAllTerm, unAppliedEntries, installSnapshotInitiated);
 148     }
 149
 150     private class AbstractSnapshotState implements SnapshotState {
 151
 152         @Override
 153         public boolean isCapturing() {
 154             return true;
 155         }
 156
 157         @Override
 158         public boolean capture(ReplicatedLogEntry lastLogEntry, long replicatedToAllIndex) {
 159             LOG.debug("capture should not be called in state {}", this);
 160             return false;
 161         }
 162
 163         @Override
 164         public boolean captureToInstall(ReplicatedLogEntry lastLogEntry, long replicatedToAllIndex, String targetFollower) {
 165             LOG.debug("captureToInstall should not be called in state {}", this);
 166             return false;
 167         }
 168
 169         @Override
 170         public void apply(ApplySnapshot snapshot) {
 171             LOG.debug("apply should not be called in state {}", this);
 172         }
 173
 174         @Override
 175         public void persist(byte[] snapshotBytes, RaftActorBehavior currentBehavior, long totalMemory) {
 176             LOG.debug("persist should not be called in state {}", this);
 177         }
 178
 179         @Override
 180         public void commit(long sequenceNumber, RaftActorBehavior currentBehavior) {
 181             LOG.debug("commit should not be called in state {}", this);
 182         }
 183
 184         @Override
 185         public void rollback() {
 186             LOG.debug("rollback should not be called in state {}", this);
 187         }
 188
 189         @Override
 190         public long trimLog(long desiredTrimIndex, RaftActorBehavior currentBehavior) {
 191             LOG.debug("trimLog should not be called in state {}", this);
 192             return -1;
 193         }
 194
 195         protected long doTrimLog(long desiredTrimIndex, RaftActorBehavior currentBehavior){
 196             //  we would want to keep the lastApplied as its used while capturing snapshots
 197             long lastApplied = context.getLastApplied();
 198             long tempMin = Math.min(desiredTrimIndex, (lastApplied > -1 ? lastApplied - 1 : -1));
 199
 200             if(LOG.isTraceEnabled()) {
 201                 LOG.trace("{}: performSnapshotWithoutCapture: desiredTrimIndex: {}, lastApplied: {}, tempMin: {}",
 202                         persistenceId(), desiredTrimIndex, lastApplied, tempMin);
 203             }
 204
 205             if (tempMin > -1 && context.getReplicatedLog().isPresent(tempMin)) {
 206                 LOG.debug("{}: fakeSnapshot purging log to {} for term {}", persistenceId(), tempMin,
 207                         context.getTermInformation().getCurrentTerm());
 208
 209                 //use the term of the temp-min, since we check for isPresent, entry will not be null
 210                 ReplicatedLogEntry entry = context.getReplicatedLog().get(tempMin);
 211                 context.getReplicatedLog().snapshotPreCommit(tempMin, entry.getTerm());
 212                 context.getReplicatedLog().snapshotCommit();
 213                 return tempMin;
 214             } else if(tempMin > currentBehavior.getReplicatedToAllIndex()) {
 215                 // It's possible a follower was lagging and an install snapshot advanced its match index past
 216                 // the current replicatedToAllIndex. Since the follower is now caught up we should advance the
 217                 // replicatedToAllIndex (to tempMin). The fact that tempMin wasn't found in the log is likely
 218                 // due to a previous snapshot triggered by the memory threshold exceeded, in that case we
 219                 // trim the log to the last applied index even if previous entries weren't replicated to all followers.
 220                 currentBehavior.setReplicatedToAllIndex(tempMin);
 221             }
 222             return -1;
 223         }
 224     }
 225
 226     private class Idle extends AbstractSnapshotState {
 227
 228         @Override
 229         public boolean isCapturing() {
 230             return false;
 231         }
 232
 233         private boolean capture(ReplicatedLogEntry lastLogEntry, long replicatedToAllIndex, String targetFollower) {
 234             captureSnapshot = newCaptureSnapshot(lastLogEntry, replicatedToAllIndex, targetFollower != null);
 235
 236             if(captureSnapshot.isInstallSnapshotInitiated()) {
 237                 LOG.info("{}: Initiating snapshot capture {} to install on {}",
 238                         persistenceId(), captureSnapshot, targetFollower);
 239             } else {
 240                 LOG.info("{}: Initiating snapshot capture {}", persistenceId(), captureSnapshot);
 241             }
 242
 243             lastSequenceNumber = context.getPersistenceProvider().getLastSequenceNumber();
 244
 245             LOG.debug("lastSequenceNumber prior to capture: {}", lastSequenceNumber);
 246
 247             SnapshotManager.this.currentState = CREATING;
 248
 249             try {
 250                 createSnapshotProcedure.apply(null);
 251             } catch (Exception e) {
 252                 SnapshotManager.this.currentState = IDLE;
 253                 LOG.error("Error creating snapshot", e);
 254                 return false;
 255             }
 256
 257             return true;
 258         }
 259
 260         @Override
 261         public boolean capture(ReplicatedLogEntry lastLogEntry, long replicatedToAllIndex) {
 262             return capture(lastLogEntry, replicatedToAllIndex, null);
 263         }
 264
 265         @Override
 266         public boolean captureToInstall(ReplicatedLogEntry lastLogEntry, long replicatedToAllIndex, String targetFollower) {
 267             return capture(lastLogEntry, replicatedToAllIndex, targetFollower);
 268         }
 269
 270         @Override
 271         public void apply(ApplySnapshot applySnapshot) {
 272             SnapshotManager.this.applySnapshot = applySnapshot;
 273
 274             lastSequenceNumber = context.getPersistenceProvider().getLastSequenceNumber();
 275
 276             LOG.debug("lastSequenceNumber prior to persisting applied snapshot: {}", lastSequenceNumber);
 277
 278             context.getPersistenceProvider().saveSnapshot(applySnapshot.getSnapshot());
 279
 280             SnapshotManager.this.currentState = PERSISTING;
 281         }
 282
 283         @Override
 284         public String toString() {
 285             return "Idle";
 286         }
 287
 288         @Override
 289         public long trimLog(long desiredTrimIndex, RaftActorBehavior currentBehavior) {
 290             return doTrimLog(desiredTrimIndex, currentBehavior);
 291         }
 292     }
 293
 294     private class Creating extends AbstractSnapshotState {
 295
 296         @Override
 297         public void persist(byte[] snapshotBytes, RaftActorBehavior currentBehavior, long totalMemory) {
 298             // create a snapshot object from the state provided and save it
 299             // when snapshot is saved async, SaveSnapshotSuccess is raised.
 300
 301             Snapshot snapshot = Snapshot.create(snapshotBytes,
 302                     captureSnapshot.getUnAppliedEntries(),
 303                     captureSnapshot.getLastIndex(), captureSnapshot.getLastTerm(),
 304                     captureSnapshot.getLastAppliedIndex(), captureSnapshot.getLastAppliedTerm(),
 305                     context.getTermInformation().getCurrentTerm(),
 306                     context.getTermInformation().getVotedFor());
 307
 308             context.getPersistenceProvider().saveSnapshot(snapshot);
 309
 310             LOG.info("{}: Persisting of snapshot done: {}", persistenceId(), snapshot);
 311
 312             long dataThreshold = totalMemory *
 313                     context.getConfigParams().getSnapshotDataThresholdPercentage() / 100;
 314             boolean dataSizeThresholdExceeded = context.getReplicatedLog().dataSize() > dataThreshold;
 315
 316             boolean logSizeExceededSnapshotBatchCount =
 317                     context.getReplicatedLog().size() >= context.getConfigParams().getSnapshotBatchCount();
 318
 319             if (dataSizeThresholdExceeded || logSizeExceededSnapshotBatchCount) {
 320                 if(LOG.isDebugEnabled()) {
 321                     if(dataSizeThresholdExceeded) {
 322                         LOG.debug("{}: log data size {} exceeds the memory threshold {} - doing snapshotPreCommit with index {}",
 323                                 context.getId(), context.getReplicatedLog().dataSize(), dataThreshold,
 324                                 captureSnapshot.getLastAppliedIndex());
 325                     } else {
 326                         LOG.debug("{}: log size {} exceeds the snapshot batch count {} - doing snapshotPreCommit with index {}",
 327                                 context.getId(), context.getReplicatedLog().size(),
 328                                 context.getConfigParams().getSnapshotBatchCount(), captureSnapshot.getLastAppliedIndex());
 329                     }
 330                 }
 331
 332                 // We either exceeded the memory threshold or the log size exceeded the snapshot batch
 333                 // count so, to keep the log memory footprint in check, clear the log based on lastApplied.
 334                 // This could/should only happen if one of the followers is down as normally we keep
 335                 // removing from the log as entries are replicated to all.
 336                 context.getReplicatedLog().snapshotPreCommit(captureSnapshot.getLastAppliedIndex(),
 337                         captureSnapshot.getLastAppliedTerm());
 338
 339                 // Don't reset replicatedToAllIndex to -1 as this may prevent us from trimming the log after an
 340                 // install snapshot to a follower.
 341                 if(captureSnapshot.getReplicatedToAllIndex() >= 0) {
 342                     currentBehavior.setReplicatedToAllIndex(captureSnapshot.getReplicatedToAllIndex());
 343                 }
 344
 345             } else if(captureSnapshot.getReplicatedToAllIndex() != -1){
 346                 // clear the log based on replicatedToAllIndex
 347                 context.getReplicatedLog().snapshotPreCommit(captureSnapshot.getReplicatedToAllIndex(),
 348                         captureSnapshot.getReplicatedToAllTerm());
 349
 350                 currentBehavior.setReplicatedToAllIndex(captureSnapshot.getReplicatedToAllIndex());
 351             } else {
 352                 // The replicatedToAllIndex was not found in the log
 353                 // This means that replicatedToAllIndex never moved beyond -1 or that it is already in the snapshot.
 354                 // In this scenario we may need to save the snapshot to the akka persistence
 355                 // snapshot for recovery but we do not need to do the replicated log trimming.
 356                 context.getReplicatedLog().snapshotPreCommit(context.getReplicatedLog().getSnapshotIndex(),
 357                         context.getReplicatedLog().getSnapshotTerm());
 358             }
 359
 360             LOG.info("{}: Removed in-memory snapshotted entries, adjusted snaphsotIndex: {} " +
 361                     "and term: {}", context.getId(), context.getReplicatedLog().getSnapshotIndex(),
 362                     context.getReplicatedLog().getSnapshotTerm());
 363
 364             if (context.getId().equals(currentBehavior.getLeaderId())
 365                     && captureSnapshot.isInstallSnapshotInitiated()) {
 366                 // this would be call straight to the leader and won't initiate in serialization
 367                 currentBehavior.handleMessage(context.getActor(), new SendInstallSnapshot(snapshot));
 368             }
 369
 370             captureSnapshot = null;
 371             SnapshotManager.this.currentState = PERSISTING;
 372         }
 373
 374         @Override
 375         public String toString() {
 376             return "Creating";
 377         }
 378
 379     }
 380
 381     private class Persisting extends AbstractSnapshotState {
 382
 383         @Override
 384         public void commit(long sequenceNumber, RaftActorBehavior currentBehavior) {
 385             LOG.debug("Snapshot success sequence number: {}", sequenceNumber);
 386
 387             if(applySnapshot != null) {
 388                 try {
 389                     Snapshot snapshot = applySnapshot.getSnapshot();
 390
 391                     //clears the followers log, sets the snapshot index to ensure adjusted-index works
 392                     context.setReplicatedLog(ReplicatedLogImpl.newInstance(snapshot, context, currentBehavior));
 393                     context.setLastApplied(snapshot.getLastAppliedIndex());
 394                     context.setCommitIndex(snapshot.getLastAppliedIndex());
 395                     context.getTermInformation().update(snapshot.getElectionTerm(), snapshot.getElectionVotedFor());
 396
 397                     if(snapshot.getState().length > 0 ) {
 398                         applySnapshotProcedure.apply(snapshot.getState());
 399                     }
 400
 401                     applySnapshot.getCallback().onSuccess();
 402                 } catch (Exception e) {
 403                     LOG.error("Error applying snapshot", e);
 404                 }
 405             } else {
 406                 context.getReplicatedLog().snapshotCommit();
 407             }
 408
 409             context.getPersistenceProvider().deleteSnapshots(new SnapshotSelectionCriteria(
 410                     sequenceNumber - context.getConfigParams().getSnapshotBatchCount(), 43200000));
 411
 412             context.getPersistenceProvider().deleteMessages(lastSequenceNumber);
 413
 414             snapshotComplete();
 415         }
 416
 417         @Override
 418         public void rollback() {
 419             // Nothing to rollback if we're applying a snapshot from the leader.
 420             if(applySnapshot == null) {
 421                 context.getReplicatedLog().snapshotRollback();
 422
 423                 LOG.info("{}: Replicated Log rolled back. Snapshot will be attempted in the next cycle." +
 424                         "snapshotIndex:{}, snapshotTerm:{}, log-size:{}", persistenceId(),
 425                         context.getReplicatedLog().getSnapshotIndex(),
 426                         context.getReplicatedLog().getSnapshotTerm(),
 427                         context.getReplicatedLog().size());
 428             } else {
 429                 applySnapshot.getCallback().onFailure();
 430             }
 431
 432             snapshotComplete();
 433         }
 434
 435         private void snapshotComplete() {
 436             lastSequenceNumber = -1;
 437             applySnapshot = null;
 438             SnapshotManager.this.currentState = IDLE;
 439
 440             context.getActor().tell(SnapshotComplete.INSTANCE, context.getActor());
 441         }
 442
 443         @Override
 444         public String toString() {
 445             return "Persisting";
 446         }
 447
 448     }
 449
 450     private static interface TermInformationReader {
 451         long getIndex();
 452         long getTerm();
 453     }
 454
 455     static class LastAppliedTermInformationReader implements TermInformationReader{
 456         private long index;
 457         private long term;
 458
 459         public LastAppliedTermInformationReader init(ReplicatedLog log, long originalIndex,
 460                                          ReplicatedLogEntry lastLogEntry, boolean hasFollowers){
 461             ReplicatedLogEntry entry = log.get(originalIndex);
 462             this.index = -1L;
 463             this.term = -1L;
 464             if (!hasFollowers) {
 465                 if(lastLogEntry != null) {
 466                     // since we have persisted the last-log-entry to persistent journal before the capture,
 467                     // we would want to snapshot from this entry.
 468                     index = lastLogEntry.getIndex();
 469                     term = lastLogEntry.getTerm();
 470                 }
 471             } else if (entry != null) {
 472                 index = entry.getIndex();
 473                 term = entry.getTerm();
 474             } else if(log.getSnapshotIndex() > -1){
 475                 index = log.getSnapshotIndex();
 476                 term = log.getSnapshotTerm();
 477             }
 478             return this;
 479         }
 480
 481         @Override
 482         public long getIndex(){
 483             return this.index;
 484         }
 485
 486         @Override
 487         public long getTerm(){
 488             return this.term;
 489         }
 490     }
 491
 492     private static class ReplicatedToAllTermInformationReader implements TermInformationReader{
 493         private long index;
 494         private long term;
 495
 496         ReplicatedToAllTermInformationReader init(ReplicatedLog log, long originalIndex){
 497             ReplicatedLogEntry entry = log.get(originalIndex);
 498             this.index = -1L;
 499             this.term = -1L;
 500
 501             if (entry != null) {
 502                 index = entry.getIndex();
 503                 term = entry.getTerm();
 504             }
 505
 506             return this;
 507         }
 508
 509         @Override
 510         public long getIndex(){
 511             return this.index;
 512         }
 513
 514         @Override
 515         public long getTerm(){
 516             return this.term;
 517         }
 518     }
 519 }