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