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