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             captureSnapshot = new CaptureSnapshot(lastLogEntry.getIndex(),
 215                     lastLogEntry.getTerm(), lastAppliedIndex, lastAppliedTerm,
 216                     newReplicatedToAllIndex, newReplicatedToAllTerm, unAppliedEntries, targetFollower != null);
 217
 218             if(captureSnapshot.isInstallSnapshotInitiated()) {
 219                 LOG.info("{}: Initiating snapshot capture {} to install on {}",
 220                         persistenceId(), captureSnapshot, targetFollower);
 221             } else {
 222                 LOG.info("{}: Initiating snapshot capture {}", persistenceId(), captureSnapshot);
 223             }
 224
 225             lastSequenceNumber = context.getPersistenceProvider().getLastSequenceNumber();
 226
 227             LOG.debug("lastSequenceNumber prior to capture: {}", lastSequenceNumber);
 228
 229             SnapshotManager.this.currentState = CREATING;
 230
 231             try {
 232                 createSnapshotProcedure.apply(null);
 233             } catch (Exception e) {
 234                 SnapshotManager.this.currentState = IDLE;
 235                 LOG.error("Error creating snapshot", e);
 236                 return false;
 237             }
 238
 239             return true;
 240         }
 241
 242         @Override
 243         public boolean capture(ReplicatedLogEntry lastLogEntry, long replicatedToAllIndex) {
 244             return capture(lastLogEntry, replicatedToAllIndex, null);
 245         }
 246
 247         @Override
 248         public boolean captureToInstall(ReplicatedLogEntry lastLogEntry, long replicatedToAllIndex, String targetFollower) {
 249             return capture(lastLogEntry, replicatedToAllIndex, targetFollower);
 250         }
 251
 252         @Override
 253         public void apply(Snapshot snapshot) {
 254             applySnapshot = snapshot;
 255
 256             lastSequenceNumber = context.getPersistenceProvider().getLastSequenceNumber();
 257
 258             LOG.debug("lastSequenceNumber prior to persisting applied snapshot: {}", lastSequenceNumber);
 259
 260             context.getPersistenceProvider().saveSnapshot(snapshot);
 261
 262             SnapshotManager.this.currentState = PERSISTING;
 263         }
 264
 265         @Override
 266         public String toString() {
 267             return "Idle";
 268         }
 269
 270         @Override
 271         public long trimLog(long desiredTrimIndex, RaftActorBehavior currentBehavior) {
 272             return doTrimLog(desiredTrimIndex, currentBehavior);
 273         }
 274     }
 275
 276     private class Creating extends AbstractSnapshotState {
 277
 278         @Override
 279         public void persist(byte[] snapshotBytes, RaftActorBehavior currentBehavior, long totalMemory) {
 280             // create a snapshot object from the state provided and save it
 281             // when snapshot is saved async, SaveSnapshotSuccess is raised.
 282
 283             Snapshot snapshot = Snapshot.create(snapshotBytes,
 284                     captureSnapshot.getUnAppliedEntries(),
 285                     captureSnapshot.getLastIndex(), captureSnapshot.getLastTerm(),
 286                     captureSnapshot.getLastAppliedIndex(), captureSnapshot.getLastAppliedTerm());
 287
 288             context.getPersistenceProvider().saveSnapshot(snapshot);
 289
 290             LOG.info("{}: Persisting of snapshot done: {}", persistenceId(), snapshot.getLogMessage());
 291
 292             long dataThreshold = totalMemory *
 293                     context.getConfigParams().getSnapshotDataThresholdPercentage() / 100;
 294             boolean dataSizeThresholdExceeded = context.getReplicatedLog().dataSize() > dataThreshold;
 295
 296             boolean logSizeExceededSnapshotBatchCount =
 297                     context.getReplicatedLog().size() >= context.getConfigParams().getSnapshotBatchCount();
 298 LOG.debug("Log size: {}, getSnapshotBatchCount: {}",context.getReplicatedLog().size(),context.getConfigParams().getSnapshotBatchCount());
 299             if (dataSizeThresholdExceeded || logSizeExceededSnapshotBatchCount) {
 300                 if(LOG.isDebugEnabled()) {
 301                     if(dataSizeThresholdExceeded) {
 302                         LOG.debug("{}: log data size {} exceeds the memory threshold {} - doing snapshotPreCommit with index {}",
 303                                 context.getId(), context.getReplicatedLog().dataSize(), dataThreshold,
 304                                 captureSnapshot.getLastAppliedIndex());
 305                     } else {
 306                         LOG.debug("{}: log size {} exceeds the snapshot batch count {} - doing snapshotPreCommit with index {}",
 307                                 context.getId(), context.getReplicatedLog().size(),
 308                                 context.getConfigParams().getSnapshotBatchCount(), captureSnapshot.getLastAppliedIndex());
 309                     }
 310                 }
 311
 312                 // We either exceeded the memory threshold or the log size exceeded the snapshot batch
 313                 // count so, to keep the log memory footprint in check, clear the log based on lastApplied.
 314                 // This could/should only happen if one of the followers is down as normally we keep
 315                 // removing from the log as entries are replicated to all.
 316                 context.getReplicatedLog().snapshotPreCommit(captureSnapshot.getLastAppliedIndex(),
 317                         captureSnapshot.getLastAppliedTerm());
 318
 319                 // Don't reset replicatedToAllIndex to -1 as this may prevent us from trimming the log after an
 320                 // install snapshot to a follower.
 321                 if(captureSnapshot.getReplicatedToAllIndex() >= 0) {
 322                     currentBehavior.setReplicatedToAllIndex(captureSnapshot.getReplicatedToAllIndex());
 323                 }
 324
 325             } else if(captureSnapshot.getReplicatedToAllIndex() != -1){
 326                 // clear the log based on replicatedToAllIndex
 327                 context.getReplicatedLog().snapshotPreCommit(captureSnapshot.getReplicatedToAllIndex(),
 328                         captureSnapshot.getReplicatedToAllTerm());
 329
 330                 currentBehavior.setReplicatedToAllIndex(captureSnapshot.getReplicatedToAllIndex());
 331             } else {
 332                 // The replicatedToAllIndex was not found in the log
 333                 // This means that replicatedToAllIndex never moved beyond -1 or that it is already in the snapshot.
 334                 // In this scenario we may need to save the snapshot to the akka persistence
 335                 // snapshot for recovery but we do not need to do the replicated log trimming.
 336                 context.getReplicatedLog().snapshotPreCommit(context.getReplicatedLog().getSnapshotIndex(),
 337                         context.getReplicatedLog().getSnapshotTerm());
 338             }
 339
 340             LOG.info("{}: Removed in-memory snapshotted entries, adjusted snaphsotIndex: {} " +
 341                     "and term: {}", context.getId(), context.getReplicatedLog().getSnapshotIndex(),
 342                     context.getReplicatedLog().getSnapshotTerm());
 343
 344             if (context.getId().equals(currentBehavior.getLeaderId())
 345                     && captureSnapshot.isInstallSnapshotInitiated()) {
 346                 // this would be call straight to the leader and won't initiate in serialization
 347                 currentBehavior.handleMessage(context.getActor(), new SendInstallSnapshot(snapshot));
 348             }
 349
 350             captureSnapshot = null;
 351             SnapshotManager.this.currentState = PERSISTING;
 352         }
 353
 354         @Override
 355         public String toString() {
 356             return "Creating";
 357         }
 358
 359     }
 360
 361     private class Persisting extends AbstractSnapshotState {
 362
 363         @Override
 364         public void commit(long sequenceNumber, RaftActorBehavior currentBehavior) {
 365             LOG.debug("Snapshot success sequence number:", sequenceNumber);
 366
 367             if(applySnapshot != null) {
 368                 try {
 369                     applySnapshotProcedure.apply(applySnapshot.getState());
 370
 371                     //clears the followers log, sets the snapshot index to ensure adjusted-index works
 372                     context.setReplicatedLog(ReplicatedLogImpl.newInstance(applySnapshot, context, currentBehavior));
 373                     context.setLastApplied(applySnapshot.getLastAppliedIndex());
 374                     context.setCommitIndex(applySnapshot.getLastAppliedIndex());
 375                 } catch (Exception e) {
 376                     LOG.error("Error applying snapshot", e);
 377                 }
 378             } else {
 379                 context.getReplicatedLog().snapshotCommit();
 380             }
 381
 382             context.getPersistenceProvider().deleteSnapshots(new SnapshotSelectionCriteria(
 383                     sequenceNumber - context.getConfigParams().getSnapshotBatchCount(), 43200000));
 384
 385             context.getPersistenceProvider().deleteMessages(lastSequenceNumber);
 386
 387             lastSequenceNumber = -1;
 388             applySnapshot = null;
 389             SnapshotManager.this.currentState = IDLE;
 390         }
 391
 392         @Override
 393         public void rollback() {
 394             // Nothing to rollback if we're applying a snapshot from the leader.
 395             if(applySnapshot == null) {
 396                 context.getReplicatedLog().snapshotRollback();
 397
 398                 LOG.info("{}: Replicated Log rolled back. Snapshot will be attempted in the next cycle." +
 399                         "snapshotIndex:{}, snapshotTerm:{}, log-size:{}", persistenceId(),
 400                         context.getReplicatedLog().getSnapshotIndex(),
 401                         context.getReplicatedLog().getSnapshotTerm(),
 402                         context.getReplicatedLog().size());
 403             }
 404
 405             lastSequenceNumber = -1;
 406             applySnapshot = null;
 407             SnapshotManager.this.currentState = IDLE;
 408         }
 409
 410         @Override
 411         public String toString() {
 412             return "Persisting";
 413         }
 414
 415     }
 416
 417     private static interface TermInformationReader {
 418         long getIndex();
 419         long getTerm();
 420     }
 421
 422     static class LastAppliedTermInformationReader implements TermInformationReader{
 423         private long index;
 424         private long term;
 425
 426         public LastAppliedTermInformationReader init(ReplicatedLog log, long originalIndex,
 427                                          ReplicatedLogEntry lastLogEntry, boolean hasFollowers){
 428             ReplicatedLogEntry entry = log.get(originalIndex);
 429             this.index = -1L;
 430             this.term = -1L;
 431             if (!hasFollowers) {
 432                 if(lastLogEntry != null) {
 433                     // since we have persisted the last-log-entry to persistent journal before the capture,
 434                     // we would want to snapshot from this entry.
 435                     index = lastLogEntry.getIndex();
 436                     term = lastLogEntry.getTerm();
 437                 }
 438             } else if (entry != null) {
 439                 index = entry.getIndex();
 440                 term = entry.getTerm();
 441             } else if(log.getSnapshotIndex() > -1){
 442                 index = log.getSnapshotIndex();
 443                 term = log.getSnapshotTerm();
 444             }
 445             return this;
 446         }
 447
 448         @Override
 449         public long getIndex(){
 450             return this.index;
 451         }
 452
 453         @Override
 454         public long getTerm(){
 455             return this.term;
 456         }
 457     }
 458
 459     private static class ReplicatedToAllTermInformationReader implements TermInformationReader{
 460         private long index;
 461         private long term;
 462
 463         ReplicatedToAllTermInformationReader init(ReplicatedLog log, long originalIndex){
 464             ReplicatedLogEntry entry = log.get(originalIndex);
 465             this.index = -1L;
 466             this.term = -1L;
 467
 468             if (entry != null) {
 469                 index = entry.getIndex();
 470                 term = entry.getTerm();
 471             }
 472
 473             return this;
 474         }
 475
 476         @Override
 477         public long getIndex(){
 478             return this.index;
 479         }
 480
 481         @Override
 482         public long getTerm(){
 483             return this.term;
 484         }
 485     }
 486 }