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