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