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