opendaylight/md-sal/sal-distributed-datastore/src/main/java/org/opendaylight/controller/cluster/datastore/LeaderFrontendState.java

   1 /*
   2  * Copyright (c) 2016 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 package org.opendaylight.controller.cluster.datastore;
   9
  10 import com.google.common.base.MoreObjects;
  11 import com.google.common.base.Preconditions;
  12 import com.google.common.collect.Range;
  13 import com.google.common.collect.RangeSet;
  14 import com.google.common.collect.TreeRangeSet;
  15 import com.google.common.primitives.UnsignedLong;
  16 import java.util.HashMap;
  17 import java.util.Iterator;
  18 import java.util.Map;
  19 import javax.annotation.Nullable;
  20 import javax.annotation.concurrent.NotThreadSafe;
  21 import org.opendaylight.controller.cluster.access.commands.CreateLocalHistoryRequest;
  22 import org.opendaylight.controller.cluster.access.commands.DeadHistoryException;
  23 import org.opendaylight.controller.cluster.access.commands.DestroyLocalHistoryRequest;
  24 import org.opendaylight.controller.cluster.access.commands.LocalHistoryRequest;
  25 import org.opendaylight.controller.cluster.access.commands.LocalHistorySuccess;
  26 import org.opendaylight.controller.cluster.access.commands.OutOfSequenceEnvelopeException;
  27 import org.opendaylight.controller.cluster.access.commands.PurgeLocalHistoryRequest;
  28 import org.opendaylight.controller.cluster.access.commands.TransactionRequest;
  29 import org.opendaylight.controller.cluster.access.commands.TransactionSuccess;
  30 import org.opendaylight.controller.cluster.access.commands.UnknownHistoryException;
  31 import org.opendaylight.controller.cluster.access.concepts.ClientIdentifier;
  32 import org.opendaylight.controller.cluster.access.concepts.LocalHistoryIdentifier;
  33 import org.opendaylight.controller.cluster.access.concepts.RequestEnvelope;
  34 import org.opendaylight.controller.cluster.access.concepts.RequestException;
  35 import org.opendaylight.controller.cluster.access.concepts.UnsupportedRequestException;
  36 import org.opendaylight.controller.cluster.datastore.ShardDataTreeCohort.State;
  37 import org.opendaylight.yangtools.concepts.Identifiable;
  38 import org.slf4j.Logger;
  39 import org.slf4j.LoggerFactory;
  40
  41 /**
  42  * Frontend state as observed by the shard leader. This class is responsible for tracking generations and sequencing
  43  * in the frontend/backend conversation.
  44  *
  45  * @author Robert Varga
  46  */
  47 @NotThreadSafe
  48 final class LeaderFrontendState implements Identifiable<ClientIdentifier> {
  49     private static final Logger LOG = LoggerFactory.getLogger(LeaderFrontendState.class);
  50
  51     // Histories which have not been purged
  52     private final Map<LocalHistoryIdentifier, LocalFrontendHistory> localHistories;
  53
  54     // RangeSet performs automatic merging, hence we keep minimal state tracking information
  55     private final RangeSet<UnsignedLong> purgedHistories;
  56
  57     // Used for all standalone transactions
  58     private final AbstractFrontendHistory standaloneHistory;
  59     private final ShardDataTree tree;
  60     private final ClientIdentifier clientId;
  61     private final String persistenceId;
  62
  63     private long lastConnectTicks;
  64     private long lastSeenTicks;
  65     private long expectedTxSequence;
  66     private Long lastSeenHistory = null;
  67
  68     // TODO: explicit failover notification
  69     //       Record the ActorRef for the originating actor and when we switch to being a leader send a notification
  70     //       to the frontend client -- that way it can immediately start sending requests
  71
  72     // TODO: add statistics:
  73     // - number of requests processed
  74     // - number of histories processed
  75     // - per-RequestException throw counters
  76
  77     LeaderFrontendState(final String persistenceId, final ClientIdentifier clientId, final ShardDataTree tree) {
  78         this(persistenceId, clientId, tree, TreeRangeSet.create(), StandaloneFrontendHistory.create(persistenceId,
  79             clientId, tree), new HashMap<>());
  80     }
  81
  82     LeaderFrontendState(final String persistenceId, final ClientIdentifier clientId, final ShardDataTree tree,
  83         final RangeSet<UnsignedLong> purgedHistories, final AbstractFrontendHistory standaloneHistory,
  84         final Map<LocalHistoryIdentifier, LocalFrontendHistory> localHistories) {
  85         this.persistenceId = Preconditions.checkNotNull(persistenceId);
  86         this.clientId = Preconditions.checkNotNull(clientId);
  87         this.tree = Preconditions.checkNotNull(tree);
  88         this.purgedHistories = Preconditions.checkNotNull(purgedHistories);
  89         this.standaloneHistory = Preconditions.checkNotNull(standaloneHistory);
  90         this.localHistories = Preconditions.checkNotNull(localHistories);
  91         this.lastSeenTicks = tree.readTime();
  92     }
  93
  94     @Override
  95     public ClientIdentifier getIdentifier() {
  96         return clientId;
  97     }
  98
  99     private void checkRequestSequence(final RequestEnvelope envelope) throws OutOfSequenceEnvelopeException {
 100         if (expectedTxSequence != envelope.getTxSequence()) {
 101             throw new OutOfSequenceEnvelopeException(expectedTxSequence);
 102         }
 103     }
 104
 105     private void expectNextRequest() {
 106         expectedTxSequence++;
 107     }
 108
 109     @Nullable LocalHistorySuccess handleLocalHistoryRequest(final LocalHistoryRequest<?> request,
 110             final RequestEnvelope envelope, final long now) throws RequestException {
 111         checkRequestSequence(envelope);
 112
 113         try {
 114             if (request instanceof CreateLocalHistoryRequest) {
 115                 return handleCreateHistory((CreateLocalHistoryRequest) request, envelope, now);
 116             } else if (request instanceof DestroyLocalHistoryRequest) {
 117                 return handleDestroyHistory((DestroyLocalHistoryRequest) request, envelope, now);
 118             } else if (request instanceof PurgeLocalHistoryRequest) {
 119                 return handlePurgeHistory((PurgeLocalHistoryRequest)request, envelope, now);
 120             } else {
 121                 LOG.warn("{}: rejecting unsupported request {}", persistenceId, request);
 122                 throw new UnsupportedRequestException(request);
 123             }
 124         } finally {
 125             expectNextRequest();
 126         }
 127     }
 128
 129     private LocalHistorySuccess handleCreateHistory(final CreateLocalHistoryRequest request,
 130             final RequestEnvelope envelope, final long now) throws RequestException {
 131         final LocalHistoryIdentifier historyId = request.getTarget();
 132         final AbstractFrontendHistory existing = localHistories.get(historyId);
 133         if (existing != null) {
 134             // History already exists: report success
 135             LOG.debug("{}: history {} already exists", persistenceId, historyId);
 136             return new LocalHistorySuccess(historyId, request.getSequence());
 137         }
 138
 139         // We have not found the history. Before we create it we need to check history ID sequencing so that we do not
 140         // end up resurrecting a purged history.
 141         if (purgedHistories.contains(UnsignedLong.fromLongBits(historyId.getHistoryId()))) {
 142             LOG.debug("{}: rejecting purged request {}", persistenceId, request);
 143             throw new DeadHistoryException(purgedHistories);
 144         }
 145
 146         // Update last history we have seen
 147         if (lastSeenHistory == null || Long.compareUnsigned(lastSeenHistory, historyId.getHistoryId()) < 0) {
 148             lastSeenHistory = historyId.getHistoryId();
 149         }
 150
 151         // We have to send the response only after persistence has completed
 152         final ShardDataTreeTransactionChain chain = tree.ensureTransactionChain(historyId, () -> {
 153             LOG.debug("{}: persisted history {}", persistenceId, historyId);
 154             envelope.sendSuccess(new LocalHistorySuccess(historyId, request.getSequence()), tree.readTime() - now);
 155         });
 156
 157         localHistories.put(historyId, LocalFrontendHistory.create(persistenceId, tree, chain));
 158         LOG.debug("{}: created history {}", persistenceId, historyId);
 159         return null;
 160     }
 161
 162     private LocalHistorySuccess handleDestroyHistory(final DestroyLocalHistoryRequest request,
 163             final RequestEnvelope envelope, final long now)
 164             throws RequestException {
 165         final LocalHistoryIdentifier id = request.getTarget();
 166         final LocalFrontendHistory existing = localHistories.get(id);
 167         if (existing == null) {
 168             // History does not exist: report success
 169             LOG.debug("{}: history {} does not exist, nothing to destroy", persistenceId, id);
 170             return new LocalHistorySuccess(id, request.getSequence());
 171         }
 172
 173         existing.destroy(request.getSequence(), envelope, now);
 174         return null;
 175     }
 176
 177     private LocalHistorySuccess handlePurgeHistory(final PurgeLocalHistoryRequest request,
 178             final RequestEnvelope envelope, final long now) throws RequestException {
 179         final LocalHistoryIdentifier id = request.getTarget();
 180         final LocalFrontendHistory existing = localHistories.remove(id);
 181         if (existing == null) {
 182             LOG.debug("{}: history {} has already been purged", persistenceId, id);
 183             return new LocalHistorySuccess(id, request.getSequence());
 184         }
 185
 186         LOG.debug("{}: purging history {}", persistenceId, id);
 187         final UnsignedLong ul = UnsignedLong.fromLongBits(id.getHistoryId());
 188         purgedHistories.add(Range.closedOpen(ul, UnsignedLong.ONE.plus(ul)));
 189         existing.purge(request.getSequence(), envelope, now);
 190         return null;
 191     }
 192
 193     @Nullable TransactionSuccess<?> handleTransactionRequest(final TransactionRequest<?> request,
 194             final RequestEnvelope envelope, final long now) throws RequestException {
 195         checkRequestSequence(envelope);
 196
 197         try {
 198             final LocalHistoryIdentifier lhId = request.getTarget().getHistoryId();
 199             final AbstractFrontendHistory history;
 200
 201             if (lhId.getHistoryId() != 0) {
 202                 history = localHistories.get(lhId);
 203                 if (history == null) {
 204                     if (purgedHistories.contains(UnsignedLong.fromLongBits(lhId.getHistoryId()))) {
 205                         LOG.warn("{}: rejecting request {} to purged history", persistenceId, request);
 206                         throw new DeadHistoryException(purgedHistories);
 207                     }
 208
 209                     LOG.warn("{}: rejecting unknown history request {}", persistenceId, request);
 210                     throw new UnknownHistoryException(lastSeenHistory);
 211                 }
 212             } else {
 213                 history = standaloneHistory;
 214             }
 215
 216             return history.handleTransactionRequest(request, envelope, now);
 217         } finally {
 218             expectNextRequest();
 219         }
 220     }
 221
 222     void reconnect() {
 223         expectedTxSequence = 0;
 224         lastConnectTicks = tree.readTime();
 225     }
 226
 227     void retire() {
 228         // Hunt down any transactions associated with this frontend
 229         final Iterator<SimpleShardDataTreeCohort> it = tree.cohortIterator();
 230         while (it.hasNext()) {
 231             final SimpleShardDataTreeCohort cohort = it.next();
 232             if (clientId.equals(cohort.getIdentifier().getHistoryId().getClientId())) {
 233                 if (cohort.getState() != State.COMMIT_PENDING) {
 234                     LOG.debug("{}: Retiring transaction {}", persistenceId, cohort.getIdentifier());
 235                     it.remove();
 236                 } else {
 237                     LOG.debug("{}: Transaction {} already committing, not retiring it", persistenceId,
 238                         cohort.getIdentifier());
 239                 }
 240             }
 241         }
 242
 243         // Clear out all transaction chains
 244         localHistories.values().forEach(AbstractFrontendHistory::retire);
 245         localHistories.clear();
 246         standaloneHistory.retire();
 247     }
 248
 249     long getLastConnectTicks() {
 250         return lastConnectTicks;
 251     }
 252
 253     long getLastSeenTicks() {
 254         return lastSeenTicks;
 255     }
 256
 257     void touch() {
 258         this.lastSeenTicks = tree.readTime();
 259     }
 260
 261     @Override
 262     public String toString() {
 263         return MoreObjects.toStringHelper(LeaderFrontendState.class)
 264                 .add("clientId", clientId)
 265                 .add("nanosAgo", tree.readTime() - lastSeenTicks)
 266                 .add("purgedHistories", purgedHistories)
 267                 .toString();
 268     }
 269 }