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