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.persistence.SnapshotSelectionCriteria;
  12 import com.google.common.annotations.VisibleForTesting;
  13 import com.google.common.io.ByteSource;
  14 import java.io.IOException;
  15 import java.io.OutputStream;
  16 import java.util.List;
  17 import java.util.Optional;
  18 import java.util.function.Consumer;
  19 import javax.annotation.Nonnull;
  20 import org.opendaylight.controller.cluster.io.FileBackedOutputStream;
  21 import org.opendaylight.controller.cluster.raft.base.messages.ApplySnapshot;
  22 import org.opendaylight.controller.cluster.raft.base.messages.CaptureSnapshot;
  23 import org.opendaylight.controller.cluster.raft.base.messages.SendInstallSnapshot;
  24 import org.opendaylight.controller.cluster.raft.base.messages.SnapshotComplete;
  25 import org.opendaylight.controller.cluster.raft.behaviors.RaftActorBehavior;
  26 import org.opendaylight.controller.cluster.raft.persisted.EmptyState;
  27 import org.opendaylight.controller.cluster.raft.persisted.Snapshot;
  28 import org.slf4j.Logger;
  29
  30 /**
  31  * Manages the capturing of snapshots for a RaftActor.
  32  *
  33  * @author Moiz Raja
  34  * @author Thomas Pantelis
  35  */
  36 public class SnapshotManager implements SnapshotState {
  37
  38     @SuppressWarnings("checkstyle:MemberName")
  39     private final SnapshotState IDLE = new Idle();
  40
  41     @SuppressWarnings({"checkstyle:MemberName", "checkstyle:AbbreviationAsWordInName"})
  42     private final SnapshotState PERSISTING = new Persisting();
  43
  44     @SuppressWarnings({"checkstyle:MemberName", "checkstyle:AbbreviationAsWordInName"})
  45     private final SnapshotState CREATING = new Creating();
  46
  47     private final Logger log;
  48     private final RaftActorContext context;
  49     private final LastAppliedTermInformationReader lastAppliedTermInformationReader =
  50             new LastAppliedTermInformationReader();
  51     private final ReplicatedToAllTermInformationReader replicatedToAllTermInformationReader =
  52             new ReplicatedToAllTermInformationReader();
  53
  54
  55     private SnapshotState currentState = IDLE;
  56     private CaptureSnapshot captureSnapshot;
  57     private long lastSequenceNumber = -1;
  58
  59     private Consumer<Optional<OutputStream>> createSnapshotProcedure;
  60
  61     private ApplySnapshot applySnapshot;
  62     private RaftActorSnapshotCohort snapshotCohort = NoopRaftActorSnapshotCohort.INSTANCE;
  63
  64     /**
  65      * Constructs an instance.
  66      *
  67      * @param context the RaftActorContext
  68      * @param logger the Logger
  69      */
  70     public SnapshotManager(final RaftActorContext context, final Logger logger) {
  71         this.context = context;
  72         this.log = logger;
  73     }
  74
  75     public boolean isApplying() {
  76         return applySnapshot != null;
  77     }
  78
  79     @Override
  80     public boolean isCapturing() {
  81         return currentState.isCapturing();
  82     }
  83
  84     @Override
  85     public boolean captureToInstall(final ReplicatedLogEntry lastLogEntry, final long replicatedToAllIndex,
  86             final String targetFollower) {
  87         return currentState.captureToInstall(lastLogEntry, replicatedToAllIndex, targetFollower);
  88     }
  89
  90     @Override
  91     public boolean capture(final ReplicatedLogEntry lastLogEntry, final long replicatedToAllIndex) {
  92         return currentState.capture(lastLogEntry, replicatedToAllIndex);
  93     }
  94
  95     @Override
  96     public void apply(final ApplySnapshot snapshot) {
  97         currentState.apply(snapshot);
  98     }
  99
 100     @Override
 101     public void persist(final Snapshot.State state, final Optional<OutputStream> installSnapshotStream,
 102             final long totalMemory) {
 103         currentState.persist(state, installSnapshotStream, totalMemory);
 104     }
 105
 106     @Override
 107     public void commit(final long sequenceNumber, final long timeStamp) {
 108         currentState.commit(sequenceNumber, timeStamp);
 109     }
 110
 111     @Override
 112     public void rollback() {
 113         currentState.rollback();
 114     }
 115
 116     @Override
 117     public long trimLog(final long desiredTrimIndex) {
 118         return currentState.trimLog(desiredTrimIndex);
 119     }
 120
 121     @SuppressWarnings("checkstyle:hiddenField")
 122     void setCreateSnapshotConsumer(final Consumer<Optional<OutputStream>> createSnapshotProcedure) {
 123         this.createSnapshotProcedure = createSnapshotProcedure;
 124     }
 125
 126     void setSnapshotCohort(final RaftActorSnapshotCohort snapshotCohort) {
 127         this.snapshotCohort = snapshotCohort;
 128     }
 129
 130     @Nonnull
 131     public Snapshot.State convertSnapshot(final ByteSource snapshotBytes) throws IOException {
 132         return snapshotCohort.deserializeSnapshot(snapshotBytes);
 133     }
 134
 135     public long getLastSequenceNumber() {
 136         return lastSequenceNumber;
 137     }
 138
 139     @VisibleForTesting
 140     public CaptureSnapshot getCaptureSnapshot() {
 141         return captureSnapshot;
 142     }
 143
 144     private boolean hasFollowers() {
 145         return context.hasFollowers();
 146     }
 147
 148     private String persistenceId() {
 149         return context.getId();
 150     }
 151
 152     /**
 153      * Constructs a CaptureSnapshot instance.
 154      *
 155      * @param lastLogEntry the last log entry for the snapshot.
 156      * @param replicatedToAllIndex the index of the last entry replicated to all followers.
 157      * @return a new CaptureSnapshot instance.
 158      */
 159     public CaptureSnapshot newCaptureSnapshot(final ReplicatedLogEntry lastLogEntry, final long replicatedToAllIndex) {
 160         TermInformationReader lastAppliedTermInfoReader =
 161                 lastAppliedTermInformationReader.init(context.getReplicatedLog(), context.getLastApplied(),
 162                         lastLogEntry, hasFollowers());
 163
 164         long lastAppliedIndex = lastAppliedTermInfoReader.getIndex();
 165         long lastAppliedTerm = lastAppliedTermInfoReader.getTerm();
 166
 167         TermInformationReader replicatedToAllTermInfoReader =
 168                 replicatedToAllTermInformationReader.init(context.getReplicatedLog(), replicatedToAllIndex);
 169
 170         long newReplicatedToAllIndex = replicatedToAllTermInfoReader.getIndex();
 171         long newReplicatedToAllTerm = replicatedToAllTermInfoReader.getTerm();
 172
 173         List<ReplicatedLogEntry> unAppliedEntries = context.getReplicatedLog().getFrom(lastAppliedIndex + 1);
 174
 175         long lastLogEntryIndex = lastAppliedIndex;
 176         long lastLogEntryTerm = lastAppliedTerm;
 177         if (lastLogEntry != null) {
 178             lastLogEntryIndex = lastLogEntry.getIndex();
 179             lastLogEntryTerm = lastLogEntry.getTerm();
 180         } else {
 181             log.debug("{}: Capturing Snapshot : lastLogEntry is null. Using lastAppliedIndex {} and "
 182                     + "lastAppliedTerm {} instead.", persistenceId(), lastAppliedIndex, lastAppliedTerm);
 183         }
 184
 185         return new CaptureSnapshot(lastLogEntryIndex, lastLogEntryTerm, lastAppliedIndex, lastAppliedTerm,
 186                 newReplicatedToAllIndex, newReplicatedToAllTerm, unAppliedEntries);
 187     }
 188
 189     private class AbstractSnapshotState implements SnapshotState {
 190
 191         @Override
 192         public boolean isCapturing() {
 193             return true;
 194         }
 195
 196         @Override
 197         public boolean capture(final ReplicatedLogEntry lastLogEntry, final long replicatedToAllIndex) {
 198             log.debug("capture should not be called in state {}", this);
 199             return false;
 200         }
 201
 202         @Override
 203         public boolean captureToInstall(final ReplicatedLogEntry lastLogEntry, final long replicatedToAllIndex,
 204                 final String targetFollower) {
 205             log.debug("captureToInstall should not be called in state {}", this);
 206             return false;
 207         }
 208
 209         @Override
 210         public void apply(final ApplySnapshot snapshot) {
 211             log.debug("apply should not be called in state {}", this);
 212         }
 213
 214         @Override
 215         public void persist(final Snapshot.State state, final Optional<OutputStream> installSnapshotStream,
 216                 final long totalMemory) {
 217             log.debug("persist should not be called in state {}", this);
 218         }
 219
 220         @Override
 221         public void commit(final long sequenceNumber, final long timeStamp) {
 222             log.debug("commit should not be called in state {}", this);
 223         }
 224
 225         @Override
 226         public void rollback() {
 227             log.debug("rollback should not be called in state {}", this);
 228         }
 229
 230         @Override
 231         public long trimLog(final long desiredTrimIndex) {
 232             log.debug("trimLog should not be called in state {}", this);
 233             return -1;
 234         }
 235
 236         protected long doTrimLog(final long desiredTrimIndex) {
 237             //  we would want to keep the lastApplied as its used while capturing snapshots
 238             long lastApplied = context.getLastApplied();
 239             long tempMin = Math.min(desiredTrimIndex, lastApplied > -1 ? lastApplied - 1 : -1);
 240
 241             if (log.isTraceEnabled()) {
 242                 log.trace("{}: performSnapshotWithoutCapture: desiredTrimIndex: {}, lastApplied: {}, tempMin: {}",
 243                         persistenceId(), desiredTrimIndex, lastApplied, tempMin);
 244             }
 245
 246             if (tempMin > -1 && context.getReplicatedLog().isPresent(tempMin)) {
 247                 log.debug("{}: fakeSnapshot purging log to {} for term {}", persistenceId(), tempMin,
 248                         context.getTermInformation().getCurrentTerm());
 249
 250                 //use the term of the temp-min, since we check for isPresent, entry will not be null
 251                 ReplicatedLogEntry entry = context.getReplicatedLog().get(tempMin);
 252                 context.getReplicatedLog().snapshotPreCommit(tempMin, entry.getTerm());
 253                 context.getReplicatedLog().snapshotCommit();
 254                 return tempMin;
 255             }
 256
 257             final RaftActorBehavior currentBehavior = context.getCurrentBehavior();
 258             if (tempMin > currentBehavior.getReplicatedToAllIndex()) {
 259                 // It's possible a follower was lagging and an install snapshot advanced its match index past
 260                 // the current replicatedToAllIndex. Since the follower is now caught up we should advance the
 261                 // replicatedToAllIndex (to tempMin). The fact that tempMin wasn't found in the log is likely
 262                 // due to a previous snapshot triggered by the memory threshold exceeded, in that case we
 263                 // trim the log to the last applied index even if previous entries weren't replicated to all followers.
 264                 currentBehavior.setReplicatedToAllIndex(tempMin);
 265             }
 266             return -1;
 267         }
 268     }
 269
 270     private class Idle extends AbstractSnapshotState {
 271
 272         @Override
 273         public boolean isCapturing() {
 274             return false;
 275         }
 276
 277         @SuppressWarnings("checkstyle:IllegalCatch")
 278         private boolean capture(final ReplicatedLogEntry lastLogEntry, final long replicatedToAllIndex,
 279                 final String targetFollower) {
 280             captureSnapshot = newCaptureSnapshot(lastLogEntry, replicatedToAllIndex);
 281
 282             OutputStream installSnapshotStream = null;
 283             if (targetFollower != null) {
 284                 installSnapshotStream = context.getFileBackedOutputStreamFactory().newInstance();
 285                 log.info("{}: Initiating snapshot capture {} to install on {}",
 286                         persistenceId(), captureSnapshot, targetFollower);
 287             } else {
 288                 log.info("{}: Initiating snapshot capture {}", persistenceId(), captureSnapshot);
 289             }
 290
 291             lastSequenceNumber = context.getPersistenceProvider().getLastSequenceNumber();
 292
 293             log.debug("{}: lastSequenceNumber prior to capture: {}", persistenceId(), lastSequenceNumber);
 294
 295             SnapshotManager.this.currentState = CREATING;
 296
 297             try {
 298                 createSnapshotProcedure.accept(Optional.ofNullable(installSnapshotStream));
 299             } catch (Exception e) {
 300                 SnapshotManager.this.currentState = IDLE;
 301                 log.error("Error creating snapshot", e);
 302                 return false;
 303             }
 304
 305             return true;
 306         }
 307
 308         @Override
 309         public boolean capture(final ReplicatedLogEntry lastLogEntry, final long replicatedToAllIndex) {
 310             return capture(lastLogEntry, replicatedToAllIndex, null);
 311         }
 312
 313         @Override
 314         public boolean captureToInstall(final ReplicatedLogEntry lastLogEntry, final long replicatedToAllIndex,
 315                 final String targetFollower) {
 316             return capture(lastLogEntry, replicatedToAllIndex, targetFollower);
 317         }
 318
 319         @Override
 320         public void apply(final ApplySnapshot toApply) {
 321             SnapshotManager.this.applySnapshot = toApply;
 322
 323             lastSequenceNumber = context.getPersistenceProvider().getLastSequenceNumber();
 324
 325             log.debug("lastSequenceNumber prior to persisting applied snapshot: {}", lastSequenceNumber);
 326
 327             context.getPersistenceProvider().saveSnapshot(toApply.getSnapshot());
 328
 329             SnapshotManager.this.currentState = PERSISTING;
 330         }
 331
 332         @Override
 333         public String toString() {
 334             return "Idle";
 335         }
 336
 337         @Override
 338         public long trimLog(final long desiredTrimIndex) {
 339             return doTrimLog(desiredTrimIndex);
 340         }
 341     }
 342
 343     private class Creating extends AbstractSnapshotState {
 344
 345         @Override
 346         public void persist(final Snapshot.State snapshotState, final Optional<OutputStream> installSnapshotStream,
 347                 final long totalMemory) {
 348             // create a snapshot object from the state provided and save it
 349             // when snapshot is saved async, SaveSnapshotSuccess is raised.
 350
 351             Snapshot snapshot = Snapshot.create(snapshotState,
 352                     captureSnapshot.getUnAppliedEntries(),
 353                     captureSnapshot.getLastIndex(), captureSnapshot.getLastTerm(),
 354                     captureSnapshot.getLastAppliedIndex(), captureSnapshot.getLastAppliedTerm(),
 355                     context.getTermInformation().getCurrentTerm(),
 356                     context.getTermInformation().getVotedFor(), context.getPeerServerInfo(true));
 357
 358             context.getPersistenceProvider().saveSnapshot(snapshot);
 359
 360             log.info("{}: Persisting of snapshot done: {}", persistenceId(), snapshot);
 361
 362             long dataThreshold = totalMemory * context.getConfigParams().getSnapshotDataThresholdPercentage() / 100;
 363             boolean dataSizeThresholdExceeded = context.getReplicatedLog().dataSize() > dataThreshold;
 364
 365             boolean logSizeExceededSnapshotBatchCount =
 366                     context.getReplicatedLog().size() >= context.getConfigParams().getSnapshotBatchCount();
 367
 368             final RaftActorBehavior currentBehavior = context.getCurrentBehavior();
 369             if (dataSizeThresholdExceeded || logSizeExceededSnapshotBatchCount) {
 370                 if (log.isDebugEnabled()) {
 371                     if (dataSizeThresholdExceeded) {
 372                         log.debug("{}: log data size {} exceeds the memory threshold {} - doing snapshotPreCommit "
 373                                 + "with index {}", context.getId(), context.getReplicatedLog().dataSize(),
 374                                 dataThreshold, captureSnapshot.getLastAppliedIndex());
 375                     } else {
 376                         log.debug("{}: log size {} exceeds the snapshot batch count {} - doing snapshotPreCommit with "
 377                                 + "index {}", context.getId(), context.getReplicatedLog().size(),
 378                                 context.getConfigParams().getSnapshotBatchCount(),
 379                                 captureSnapshot.getLastAppliedIndex());
 380                     }
 381                 }
 382
 383                 // We either exceeded the memory threshold or the log size exceeded the snapshot batch
 384                 // count so, to keep the log memory footprint in check, clear the log based on lastApplied.
 385                 // This could/should only happen if one of the followers is down as normally we keep
 386                 // removing from the log as entries are replicated to all.
 387                 context.getReplicatedLog().snapshotPreCommit(captureSnapshot.getLastAppliedIndex(),
 388                         captureSnapshot.getLastAppliedTerm());
 389
 390                 // Don't reset replicatedToAllIndex to -1 as this may prevent us from trimming the log after an
 391                 // install snapshot to a follower.
 392                 if (captureSnapshot.getReplicatedToAllIndex() >= 0) {
 393                     currentBehavior.setReplicatedToAllIndex(captureSnapshot.getReplicatedToAllIndex());
 394                 }
 395
 396             } else if (captureSnapshot.getReplicatedToAllIndex() != -1) {
 397                 // clear the log based on replicatedToAllIndex
 398                 context.getReplicatedLog().snapshotPreCommit(captureSnapshot.getReplicatedToAllIndex(),
 399                         captureSnapshot.getReplicatedToAllTerm());
 400
 401                 currentBehavior.setReplicatedToAllIndex(captureSnapshot.getReplicatedToAllIndex());
 402             } else {
 403                 // The replicatedToAllIndex was not found in the log
 404                 // This means that replicatedToAllIndex never moved beyond -1 or that it is already in the snapshot.
 405                 // In this scenario we may need to save the snapshot to the akka persistence
 406                 // snapshot for recovery but we do not need to do the replicated log trimming.
 407                 context.getReplicatedLog().snapshotPreCommit(context.getReplicatedLog().getSnapshotIndex(),
 408                         context.getReplicatedLog().getSnapshotTerm());
 409             }
 410
 411             log.info("{}: Removed in-memory snapshotted entries, adjusted snaphsotIndex: {} and term: {}",
 412                     context.getId(), context.getReplicatedLog().getSnapshotIndex(),
 413                     context.getReplicatedLog().getSnapshotTerm());
 414
 415             if (installSnapshotStream.isPresent()) {
 416                 if (context.getId().equals(currentBehavior.getLeaderId())) {
 417                     try {
 418                         ByteSource snapshotBytes = ((FileBackedOutputStream)installSnapshotStream.get()).asByteSource();
 419                         currentBehavior.handleMessage(context.getActor(),
 420                                 new SendInstallSnapshot(snapshot, snapshotBytes));
 421                     } catch (IOException e) {
 422                         log.error("{}: Snapshot install failed due to an unrecoverable streaming error",
 423                                 context.getId(), e);
 424                     }
 425                 } else {
 426                     ((FileBackedOutputStream)installSnapshotStream.get()).cleanup();
 427                 }
 428             }
 429
 430             captureSnapshot = null;
 431             SnapshotManager.this.currentState = PERSISTING;
 432         }
 433
 434         @Override
 435         public String toString() {
 436             return "Creating";
 437         }
 438
 439     }
 440
 441     private class Persisting extends AbstractSnapshotState {
 442
 443         @Override
 444         @SuppressWarnings("checkstyle:IllegalCatch")
 445         public void commit(final long sequenceNumber, final long timeStamp) {
 446             log.debug("{}: Snapshot success -  sequence number: {}", persistenceId(), sequenceNumber);
 447
 448             if (applySnapshot != null) {
 449                 try {
 450                     Snapshot snapshot = applySnapshot.getSnapshot();
 451
 452                     //clears the followers log, sets the snapshot index to ensure adjusted-index works
 453                     context.setReplicatedLog(ReplicatedLogImpl.newInstance(snapshot, context));
 454                     context.setLastApplied(snapshot.getLastAppliedIndex());
 455                     context.setCommitIndex(snapshot.getLastAppliedIndex());
 456                     context.getTermInformation().update(snapshot.getElectionTerm(), snapshot.getElectionVotedFor());
 457
 458                     if (snapshot.getServerConfiguration() != null) {
 459                         context.updatePeerIds(snapshot.getServerConfiguration());
 460                     }
 461
 462                     if (!(snapshot.getState() instanceof EmptyState)) {
 463                         snapshotCohort.applySnapshot(snapshot.getState());
 464                     }
 465
 466                     applySnapshot.getCallback().onSuccess();
 467                 } catch (Exception e) {
 468                     log.error("{}: Error applying snapshot", context.getId(), e);
 469                 }
 470             } else {
 471                 context.getReplicatedLog().snapshotCommit();
 472             }
 473
 474             context.getPersistenceProvider().deleteSnapshots(new SnapshotSelectionCriteria(sequenceNumber,
 475                     timeStamp - 1, 0L, 0L));
 476
 477             context.getPersistenceProvider().deleteMessages(lastSequenceNumber);
 478
 479             snapshotComplete();
 480         }
 481
 482         @Override
 483         public void rollback() {
 484             // Nothing to rollback if we're applying a snapshot from the leader.
 485             if (applySnapshot == null) {
 486                 context.getReplicatedLog().snapshotRollback();
 487
 488                 log.info("{}: Replicated Log rolled back. Snapshot will be attempted in the next cycle."
 489                         + "snapshotIndex:{}, snapshotTerm:{}, log-size:{}", persistenceId(),
 490                         context.getReplicatedLog().getSnapshotIndex(),
 491                         context.getReplicatedLog().getSnapshotTerm(),
 492                         context.getReplicatedLog().size());
 493             } else {
 494                 applySnapshot.getCallback().onFailure();
 495             }
 496
 497             snapshotComplete();
 498         }
 499
 500         private void snapshotComplete() {
 501             lastSequenceNumber = -1;
 502             applySnapshot = null;
 503             SnapshotManager.this.currentState = IDLE;
 504
 505             context.getActor().tell(SnapshotComplete.INSTANCE, context.getActor());
 506         }
 507
 508         @Override
 509         public String toString() {
 510             return "Persisting";
 511         }
 512
 513     }
 514
 515     private interface TermInformationReader {
 516         long getIndex();
 517
 518         long getTerm();
 519     }
 520
 521     static class LastAppliedTermInformationReader implements TermInformationReader {
 522         private long index;
 523         private long term;
 524
 525         LastAppliedTermInformationReader init(final ReplicatedLog log, final long originalIndex,
 526                 final ReplicatedLogEntry lastLogEntry, final boolean hasFollowers) {
 527             ReplicatedLogEntry entry = log.get(originalIndex);
 528             this.index = -1L;
 529             this.term = -1L;
 530             if (!hasFollowers) {
 531                 if (lastLogEntry != null) {
 532                     // since we have persisted the last-log-entry to persistent journal before the capture,
 533                     // we would want to snapshot from this entry.
 534                     index = lastLogEntry.getIndex();
 535                     term = lastLogEntry.getTerm();
 536                 }
 537             } else if (entry != null) {
 538                 index = entry.getIndex();
 539                 term = entry.getTerm();
 540             } else if (log.getSnapshotIndex() > -1) {
 541                 index = log.getSnapshotIndex();
 542                 term = log.getSnapshotTerm();
 543             }
 544             return this;
 545         }
 546
 547         @Override
 548         public long getIndex() {
 549             return this.index;
 550         }
 551
 552         @Override
 553         public long getTerm() {
 554             return this.term;
 555         }
 556     }
 557
 558     private static class ReplicatedToAllTermInformationReader implements TermInformationReader {
 559         private long index;
 560         private long term;
 561
 562         ReplicatedToAllTermInformationReader init(final ReplicatedLog log, final long originalIndex) {
 563             ReplicatedLogEntry entry = log.get(originalIndex);
 564             this.index = -1L;
 565             this.term = -1L;
 566
 567             if (entry != null) {
 568                 index = entry.getIndex();
 569                 term = entry.getTerm();
 570             }
 571
 572             return this;
 573         }
 574
 575         @Override
 576         public long getIndex() {
 577             return this.index;
 578         }
 579
 580         @Override
 581         public long getTerm() {
 582             return this.term;
 583         }
 584     }
 585 }