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 lastConnectTicks;
  61     private long lastSeenTicks;
  62     private long expectedTxSequence;
  63     private Long lastSeenHistory = null;
  64
  65     // TODO: explicit failover notification
  66     //       Record the ActorRef for the originating actor and when we switch to being a leader send a notification
  67     //       to the frontend client -- that way it can immediately start sending requests
  68
  69     // TODO: add statistics:
  70     // - number of requests processed
  71     // - number of histories processed
  72     // - per-RequestException throw counters
  73
  74     LeaderFrontendState(final String persistenceId, final ClientIdentifier clientId, final ShardDataTree tree) {
  75         this(persistenceId, clientId, tree, UnsignedLongRangeSet.create(),
  76             StandaloneFrontendHistory.create(persistenceId, clientId, tree), new HashMap<>());
  77     }
  78
  79     LeaderFrontendState(final String persistenceId, final ClientIdentifier clientId, final ShardDataTree tree,
  80         final UnsignedLongRangeSet purgedHistories, final AbstractFrontendHistory standaloneHistory,
  81         final Map<LocalHistoryIdentifier, LocalFrontendHistory> localHistories) {
  82         this.persistenceId = Preconditions.checkNotNull(persistenceId);
  83         this.clientId = Preconditions.checkNotNull(clientId);
  84         this.tree = Preconditions.checkNotNull(tree);
  85         this.purgedHistories = Preconditions.checkNotNull(purgedHistories);
  86         this.standaloneHistory = Preconditions.checkNotNull(standaloneHistory);
  87         this.localHistories = Preconditions.checkNotNull(localHistories);
  88         this.lastSeenTicks = tree.readTime();
  89     }
  90
  91     @Override
  92     public ClientIdentifier getIdentifier() {
  93         return clientId;
  94     }
  95
  96     private void checkRequestSequence(final RequestEnvelope envelope) throws OutOfSequenceEnvelopeException {
  97         if (expectedTxSequence != envelope.getTxSequence()) {
  98             throw new OutOfSequenceEnvelopeException(expectedTxSequence);
  99         }
 100     }
 101
 102     private void expectNextRequest() {
 103         expectedTxSequence++;
 104     }
 105
 106     @Nullable LocalHistorySuccess handleLocalHistoryRequest(final LocalHistoryRequest<?> request,
 107             final RequestEnvelope envelope, final long now) throws RequestException {
 108         checkRequestSequence(envelope);
 109
 110         try {
 111             if (request instanceof CreateLocalHistoryRequest) {
 112                 return handleCreateHistory((CreateLocalHistoryRequest) request, envelope, now);
 113             } else if (request instanceof DestroyLocalHistoryRequest) {
 114                 return handleDestroyHistory((DestroyLocalHistoryRequest) request, envelope, now);
 115             } else if (request instanceof PurgeLocalHistoryRequest) {
 116                 return handlePurgeHistory((PurgeLocalHistoryRequest)request, envelope, now);
 117             } else {
 118                 LOG.warn("{}: rejecting unsupported request {}", persistenceId, request);
 119                 throw new UnsupportedRequestException(request);
 120             }
 121         } finally {
 122             expectNextRequest();
 123         }
 124     }
 125
 126     private LocalHistorySuccess handleCreateHistory(final CreateLocalHistoryRequest request,
 127             final RequestEnvelope envelope, final long now) throws RequestException {
 128         final LocalHistoryIdentifier historyId = request.getTarget();
 129         final AbstractFrontendHistory existing = localHistories.get(historyId);
 130         if (existing != null) {
 131             // History already exists: report success
 132             LOG.debug("{}: history {} already exists", persistenceId, historyId);
 133             return new LocalHistorySuccess(historyId, request.getSequence());
 134         }
 135
 136         // We have not found the history. Before we create it we need to check history ID sequencing so that we do not
 137         // end up resurrecting a purged history.
 138         if (purgedHistories.contains(historyId.getHistoryId())) {
 139             LOG.debug("{}: rejecting purged request {}", persistenceId, request);
 140             throw new DeadHistoryException(purgedHistories.toImmutable());
 141         }
 142
 143         // Update last history we have seen
 144         if (lastSeenHistory == null || Long.compareUnsigned(lastSeenHistory, historyId.getHistoryId()) < 0) {
 145             lastSeenHistory = historyId.getHistoryId();
 146         }
 147
 148         // We have to send the response only after persistence has completed
 149         final ShardDataTreeTransactionChain chain = tree.ensureTransactionChain(historyId, () -> {
 150             LOG.debug("{}: persisted history {}", persistenceId, historyId);
 151             envelope.sendSuccess(new LocalHistorySuccess(historyId, request.getSequence()), tree.readTime() - now);
 152         });
 153
 154         localHistories.put(historyId, LocalFrontendHistory.create(persistenceId, tree, chain));
 155         LOG.debug("{}: created history {}", persistenceId, historyId);
 156         return null;
 157     }
 158
 159     private LocalHistorySuccess handleDestroyHistory(final DestroyLocalHistoryRequest request,
 160             final RequestEnvelope envelope, final long now)
 161             throws RequestException {
 162         final LocalHistoryIdentifier id = request.getTarget();
 163         final LocalFrontendHistory existing = localHistories.get(id);
 164         if (existing == null) {
 165             // History does not exist: report success
 166             LOG.debug("{}: history {} does not exist, nothing to destroy", persistenceId, id);
 167             return new LocalHistorySuccess(id, request.getSequence());
 168         }
 169
 170         existing.destroy(request.getSequence(), envelope, now);
 171         return null;
 172     }
 173
 174     private LocalHistorySuccess handlePurgeHistory(final PurgeLocalHistoryRequest request,
 175             final RequestEnvelope envelope, final long now) throws RequestException {
 176         final LocalHistoryIdentifier id = request.getTarget();
 177         final LocalFrontendHistory existing = localHistories.remove(id);
 178         if (existing == null) {
 179             LOG.debug("{}: history {} has already been purged", persistenceId, id);
 180             return new LocalHistorySuccess(id, request.getSequence());
 181         }
 182
 183         LOG.debug("{}: purging history {}", persistenceId, id);
 184         purgedHistories.add(id.getHistoryId());
 185         existing.purge(request.getSequence(), envelope, now);
 186         return null;
 187     }
 188
 189     @Nullable TransactionSuccess<?> handleTransactionRequest(final TransactionRequest<?> request,
 190             final RequestEnvelope envelope, final long now) throws RequestException {
 191         checkRequestSequence(envelope);
 192
 193         try {
 194             final LocalHistoryIdentifier lhId = request.getTarget().getHistoryId();
 195             final AbstractFrontendHistory history;
 196
 197             if (lhId.getHistoryId() != 0) {
 198                 history = localHistories.get(lhId);
 199                 if (history == null) {
 200                     if (purgedHistories.contains(lhId.getHistoryId())) {
 201                         LOG.warn("{}: rejecting request {} to purged history", persistenceId, request);
 202                         throw new DeadHistoryException(purgedHistories.toImmutable());
 203                     }
 204
 205                     LOG.warn("{}: rejecting unknown history request {}", persistenceId, request);
 206                     throw new UnknownHistoryException(lastSeenHistory);
 207                 }
 208             } else {
 209                 history = standaloneHistory;
 210             }
 211
 212             return history.handleTransactionRequest(request, envelope, now);
 213         } finally {
 214             expectNextRequest();
 215         }
 216     }
 217
 218     void reconnect() {
 219         expectedTxSequence = 0;
 220         lastConnectTicks = tree.readTime();
 221     }
 222
 223     void retire() {
 224         // Hunt down any transactions associated with this frontend
 225         final Iterator<SimpleShardDataTreeCohort> it = tree.cohortIterator();
 226         while (it.hasNext()) {
 227             final SimpleShardDataTreeCohort cohort = it.next();
 228             if (clientId.equals(cohort.getIdentifier().getHistoryId().getClientId())) {
 229                 if (cohort.getState() != State.COMMIT_PENDING) {
 230                     LOG.debug("{}: Retiring transaction {}", persistenceId, cohort.getIdentifier());
 231                     it.remove();
 232                 } else {
 233                     LOG.debug("{}: Transaction {} already committing, not retiring it", persistenceId,
 234                         cohort.getIdentifier());
 235                 }
 236             }
 237         }
 238
 239         // Clear out all transaction chains
 240         localHistories.values().forEach(AbstractFrontendHistory::retire);
 241         localHistories.clear();
 242         standaloneHistory.retire();
 243     }
 244
 245     long getLastConnectTicks() {
 246         return lastConnectTicks;
 247     }
 248
 249     long getLastSeenTicks() {
 250         return lastSeenTicks;
 251     }
 252
 253     void touch() {
 254         this.lastSeenTicks = tree.readTime();
 255     }
 256
 257     @Override
 258     public String toString() {
 259         return MoreObjects.toStringHelper(LeaderFrontendState.class)
 260                 .add("clientId", clientId)
 261                 .add("nanosAgo", tree.readTime() - lastSeenTicks)
 262                 .add("purgedHistories", purgedHistories)
 263                 .toString();
 264     }
 265 }