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