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