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