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.Map;
  18 import javax.annotation.Nullable;
  19 import javax.annotation.concurrent.NotThreadSafe;
  20 import org.opendaylight.controller.cluster.access.commands.CreateLocalHistoryRequest;
  21 import org.opendaylight.controller.cluster.access.commands.DeadHistoryException;
  22 import org.opendaylight.controller.cluster.access.commands.DestroyLocalHistoryRequest;
  23 import org.opendaylight.controller.cluster.access.commands.LocalHistoryRequest;
  24 import org.opendaylight.controller.cluster.access.commands.LocalHistorySuccess;
  25 import org.opendaylight.controller.cluster.access.commands.OutOfSequenceEnvelopeException;
  26 import org.opendaylight.controller.cluster.access.commands.PurgeLocalHistoryRequest;
  27 import org.opendaylight.controller.cluster.access.commands.TransactionRequest;
  28 import org.opendaylight.controller.cluster.access.commands.TransactionSuccess;
  29 import org.opendaylight.controller.cluster.access.commands.UnknownHistoryException;
  30 import org.opendaylight.controller.cluster.access.concepts.ClientIdentifier;
  31 import org.opendaylight.controller.cluster.access.concepts.LocalHistoryIdentifier;
  32 import org.opendaylight.controller.cluster.access.concepts.RequestEnvelope;
  33 import org.opendaylight.controller.cluster.access.concepts.RequestException;
  34 import org.opendaylight.controller.cluster.access.concepts.UnsupportedRequestException;
  35 import org.opendaylight.yangtools.concepts.Identifiable;
  36 import org.slf4j.Logger;
  37 import org.slf4j.LoggerFactory;
  38
  39 /**
  40  * Frontend state as observed by the shard leader. This class is responsible for tracking generations and sequencing
  41  * in the frontend/backend conversation.
  42  *
  43  * @author Robert Varga
  44  */
  45 @NotThreadSafe
  46 final class LeaderFrontendState implements Identifiable<ClientIdentifier> {
  47     private static final Logger LOG = LoggerFactory.getLogger(LeaderFrontendState.class);
  48
  49     // Histories which have not been purged
  50     private final Map<LocalHistoryIdentifier, LocalFrontendHistory> localHistories;
  51
  52     // RangeSet performs automatic merging, hence we keep minimal state tracking information
  53     private final RangeSet<UnsignedLong> purgedHistories;
  54
  55     // Used for all standalone transactions
  56     private final AbstractFrontendHistory standaloneHistory;
  57     private final ShardDataTree tree;
  58     private final ClientIdentifier clientId;
  59     private final String persistenceId;
  60
  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, TreeRangeSet.create(), StandaloneFrontendHistory.create(persistenceId,
  75             clientId, tree), new HashMap<>());
  76     }
  77
  78     LeaderFrontendState(final String persistenceId, final ClientIdentifier clientId, final ShardDataTree tree,
  79         final RangeSet<UnsignedLong> purgedHistories, final AbstractFrontendHistory standaloneHistory,
  80         final Map<LocalHistoryIdentifier, LocalFrontendHistory> localHistories) {
  81         this.persistenceId = Preconditions.checkNotNull(persistenceId);
  82         this.clientId = Preconditions.checkNotNull(clientId);
  83         this.tree = Preconditions.checkNotNull(tree);
  84         this.purgedHistories = Preconditions.checkNotNull(purgedHistories);
  85         this.standaloneHistory = Preconditions.checkNotNull(standaloneHistory);
  86         this.localHistories = Preconditions.checkNotNull(localHistories);
  87     }
  88
  89     @Override
  90     public ClientIdentifier getIdentifier() {
  91         return clientId;
  92     }
  93
  94     private void checkRequestSequence(final RequestEnvelope envelope) throws OutOfSequenceEnvelopeException {
  95         if (expectedTxSequence != envelope.getTxSequence()) {
  96             throw new OutOfSequenceEnvelopeException(expectedTxSequence);
  97         }
  98     }
  99
 100     private void expectNextRequest() {
 101         expectedTxSequence++;
 102     }
 103
 104     @Nullable LocalHistorySuccess handleLocalHistoryRequest(final LocalHistoryRequest<?> request,
 105             final RequestEnvelope envelope, final long now) throws RequestException {
 106         checkRequestSequence(envelope);
 107
 108         try {
 109             if (request instanceof CreateLocalHistoryRequest) {
 110                 return handleCreateHistory((CreateLocalHistoryRequest) request, envelope, now);
 111             } else if (request instanceof DestroyLocalHistoryRequest) {
 112                 return handleDestroyHistory((DestroyLocalHistoryRequest) request, envelope, now);
 113             } else if (request instanceof PurgeLocalHistoryRequest) {
 114                 return handlePurgeHistory((PurgeLocalHistoryRequest)request, envelope, now);
 115             } else {
 116                 LOG.warn("{}: rejecting unsupported request {}", persistenceId, request);
 117                 throw new UnsupportedRequestException(request);
 118             }
 119         } finally {
 120             expectNextRequest();
 121         }
 122     }
 123
 124     private LocalHistorySuccess handleCreateHistory(final CreateLocalHistoryRequest request,
 125             final RequestEnvelope envelope, final long now) throws RequestException {
 126         final LocalHistoryIdentifier historyId = request.getTarget();
 127         final AbstractFrontendHistory existing = localHistories.get(historyId);
 128         if (existing != null) {
 129             // History already exists: report success
 130             LOG.debug("{}: history {} already exists", persistenceId, historyId);
 131             return new LocalHistorySuccess(historyId, request.getSequence());
 132         }
 133
 134         // We have not found the history. Before we create it we need to check history ID sequencing so that we do not
 135         // end up resurrecting a purged history.
 136         if (purgedHistories.contains(UnsignedLong.fromLongBits(historyId.getHistoryId()))) {
 137             LOG.debug("{}: rejecting purged request {}", persistenceId, request);
 138             throw new DeadHistoryException(purgedHistories);
 139         }
 140
 141         // Update last history we have seen
 142         if (lastSeenHistory == null || Long.compareUnsigned(lastSeenHistory, historyId.getHistoryId()) < 0) {
 143             lastSeenHistory = historyId.getHistoryId();
 144         }
 145
 146         // We have to send the response only after persistence has completed
 147         final ShardDataTreeTransactionChain chain = tree.ensureTransactionChain(historyId, () -> {
 148             LOG.debug("{}: persisted history {}", persistenceId, historyId);
 149             envelope.sendSuccess(new LocalHistorySuccess(historyId, request.getSequence()), tree.readTime() - now);
 150         });
 151
 152         localHistories.put(historyId, LocalFrontendHistory.create(persistenceId, tree, chain));
 153         LOG.debug("{}: created history {}", persistenceId, historyId);
 154         return null;
 155     }
 156
 157     private LocalHistorySuccess handleDestroyHistory(final DestroyLocalHistoryRequest request,
 158             final RequestEnvelope envelope, final long now)
 159             throws RequestException {
 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) throws RequestException {
 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(Range.singleton(UnsignedLong.fromLongBits(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(UnsignedLong.fromLongBits(lhId.getHistoryId()))) {
 199                         LOG.warn("{}: rejecting request {} to purged history", persistenceId, request);
 200                         throw new DeadHistoryException(purgedHistories);
 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     }
 219
 220     void retire() {
 221         // FIXME: flush all state
 222     }
 223
 224     @Override
 225     public String toString() {
 226         return MoreObjects.toStringHelper(LeaderFrontendState.class).add("clientId", clientId)
 227                 .add("purgedHistories", purgedHistories).toString();
 228     }
 229 }