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 expectedTxSequence;
  64     private Long lastSeenHistory = null;
  65
  66     // TODO: explicit failover notification
  67     //       Record the ActorRef for the originating actor and when we switch to being a leader send a notification
  68     //       to the frontend client -- that way it can immediately start sending requests
  69
  70     // TODO: add statistics:
  71     // - number of requests processed
  72     // - number of histories processed
  73     // - per-RequestException throw counters
  74
  75     LeaderFrontendState(final String persistenceId, final ClientIdentifier clientId, final ShardDataTree tree) {
  76         this(persistenceId, clientId, tree, TreeRangeSet.create(), StandaloneFrontendHistory.create(persistenceId,
  77             clientId, tree), new HashMap<>());
  78     }
  79
  80     LeaderFrontendState(final String persistenceId, final ClientIdentifier clientId, final ShardDataTree tree,
  81         final RangeSet<UnsignedLong> purgedHistories, final AbstractFrontendHistory standaloneHistory,
  82         final Map<LocalHistoryIdentifier, LocalFrontendHistory> localHistories) {
  83         this.persistenceId = Preconditions.checkNotNull(persistenceId);
  84         this.clientId = Preconditions.checkNotNull(clientId);
  85         this.tree = Preconditions.checkNotNull(tree);
  86         this.purgedHistories = Preconditions.checkNotNull(purgedHistories);
  87         this.standaloneHistory = Preconditions.checkNotNull(standaloneHistory);
  88         this.localHistories = Preconditions.checkNotNull(localHistories);
  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(UnsignedLong.fromLongBits(historyId.getHistoryId()))) {
 139             LOG.debug("{}: rejecting purged request {}", persistenceId, request);
 140             throw new DeadHistoryException(purgedHistories);
 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         final UnsignedLong ul = UnsignedLong.fromLongBits(id.getHistoryId());
 185         purgedHistories.add(Range.closedOpen(ul, UnsignedLong.ONE.plus(ul)));
 186         existing.purge(request.getSequence(), envelope, now);
 187         return null;
 188     }
 189
 190     @Nullable TransactionSuccess<?> handleTransactionRequest(final TransactionRequest<?> request,
 191             final RequestEnvelope envelope, final long now) throws RequestException {
 192         checkRequestSequence(envelope);
 193
 194         try {
 195             final LocalHistoryIdentifier lhId = request.getTarget().getHistoryId();
 196             final AbstractFrontendHistory history;
 197
 198             if (lhId.getHistoryId() != 0) {
 199                 history = localHistories.get(lhId);
 200                 if (history == null) {
 201                     if (purgedHistories.contains(UnsignedLong.fromLongBits(lhId.getHistoryId()))) {
 202                         LOG.warn("{}: rejecting request {} to purged history", persistenceId, request);
 203                         throw new DeadHistoryException(purgedHistories);
 204                     }
 205
 206                     LOG.warn("{}: rejecting unknown history request {}", persistenceId, request);
 207                     throw new UnknownHistoryException(lastSeenHistory);
 208                 }
 209             } else {
 210                 history = standaloneHistory;
 211             }
 212
 213             return history.handleTransactionRequest(request, envelope, now);
 214         } finally {
 215             expectNextRequest();
 216         }
 217     }
 218
 219     void reconnect() {
 220         expectedTxSequence = 0;
 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     @Override
 246     public String toString() {
 247         return MoreObjects.toStringHelper(LeaderFrontendState.class).add("clientId", clientId)
 248                 .add("purgedHistories", purgedHistories).toString();
 249     }
 250 }