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.OutOfOrderRequestException;
  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 = new HashMap<>();
  51
  52     // RangeSet performs automatic merging, hence we keep minimal state tracking information
  53     private final RangeSet<UnsignedLong> purgedHistories = TreeRangeSet.create();
  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
  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 = Preconditions.checkNotNull(persistenceId);
  76         this.clientId = Preconditions.checkNotNull(clientId);
  77         this.tree = Preconditions.checkNotNull(tree);
  78         standaloneHistory = new StandaloneFrontendHistory(persistenceId, tree.ticker(), clientId, tree);
  79     }
  80
  81     @Override
  82     public ClientIdentifier getIdentifier() {
  83         return clientId;
  84     }
  85
  86     private void checkRequestSequence(final RequestEnvelope envelope) throws OutOfOrderRequestException {
  87         if (expectedTxSequence != envelope.getTxSequence()) {
  88             throw new OutOfOrderRequestException(expectedTxSequence);
  89         }
  90     }
  91
  92     private void expectNextRequest() {
  93         expectedTxSequence++;
  94     }
  95
  96     @Nullable LocalHistorySuccess handleLocalHistoryRequest(final LocalHistoryRequest<?> request,
  97             final RequestEnvelope envelope, final long now) throws RequestException {
  98         checkRequestSequence(envelope);
  99
 100         try {
 101             if (request instanceof CreateLocalHistoryRequest) {
 102                 return handleCreateHistory((CreateLocalHistoryRequest) request);
 103             } else if (request instanceof DestroyLocalHistoryRequest) {
 104                 return handleDestroyHistory((DestroyLocalHistoryRequest) request, now);
 105             } else if (request instanceof PurgeLocalHistoryRequest) {
 106                 return handlePurgeHistory((PurgeLocalHistoryRequest)request, now);
 107             } else {
 108                 throw new UnsupportedRequestException(request);
 109             }
 110         } finally {
 111             expectNextRequest();
 112         }
 113     }
 114
 115     private LocalHistorySuccess handleCreateHistory(final CreateLocalHistoryRequest request) throws RequestException {
 116         final LocalHistoryIdentifier id = request.getTarget();
 117         final AbstractFrontendHistory existing = localHistories.get(id);
 118         if (existing != null) {
 119             // History already exists: report success
 120             LOG.debug("{}: history {} already exists", persistenceId, id);
 121             return new LocalHistorySuccess(id, request.getSequence());
 122         }
 123
 124         // We have not found the history. Before we create it we need to check history ID sequencing so that we do not
 125         // end up resurrecting a purged history.
 126         if (purgedHistories.contains(UnsignedLong.fromLongBits(id.getHistoryId()))) {
 127             LOG.debug("{}: rejecting purged request {}", persistenceId, request);
 128             throw new DeadHistoryException(lastSeenHistory.longValue());
 129         }
 130
 131         // Update last history we have seen
 132         if (lastSeenHistory != null && Long.compareUnsigned(lastSeenHistory, id.getHistoryId()) < 0) {
 133             lastSeenHistory = id.getHistoryId();
 134         }
 135
 136         localHistories.put(id, new LocalFrontendHistory(persistenceId, tree.ticker(), tree.ensureTransactionChain(id)));
 137         LOG.debug("{}: created history {}", persistenceId, id);
 138         return new LocalHistorySuccess(id, request.getSequence());
 139     }
 140
 141     private LocalHistorySuccess handleDestroyHistory(final DestroyLocalHistoryRequest request, final long now)
 142             throws RequestException {
 143         final LocalHistoryIdentifier id = request.getTarget();
 144         final LocalFrontendHistory existing = localHistories.get(id);
 145         if (existing == null) {
 146             // History does not exist: report success
 147             LOG.debug("{}: history {} does not exist, nothing to destroy", persistenceId, id);
 148             return new LocalHistorySuccess(id, request.getSequence());
 149         }
 150
 151         return existing.destroy(request.getSequence(), now);
 152     }
 153
 154     private LocalHistorySuccess handlePurgeHistory(final PurgeLocalHistoryRequest request, final long now)
 155             throws RequestException {
 156         final LocalHistoryIdentifier id = request.getTarget();
 157         final LocalFrontendHistory existing = localHistories.remove(id);
 158         if (existing != null) {
 159             purgedHistories.add(Range.singleton(UnsignedLong.fromLongBits(id.getHistoryId())));
 160
 161             if (!existing.isDestroyed()) {
 162                 LOG.warn("{}: purging undestroyed history {}", persistenceId, id);
 163                 existing.destroy(request.getSequence(), now);
 164             }
 165
 166             // FIXME: record a PURGE tombstone in the journal
 167
 168             LOG.debug("{}: purged history {}", persistenceId, id);
 169         } else {
 170             LOG.debug("{}: history {} has already been purged", persistenceId, id);
 171         }
 172
 173         return new LocalHistorySuccess(id, request.getSequence());
 174     }
 175
 176     @Nullable TransactionSuccess<?> handleTransactionRequest(final TransactionRequest<?> request,
 177             final RequestEnvelope envelope, final long now) throws RequestException {
 178         checkRequestSequence(envelope);
 179
 180         try {
 181             final LocalHistoryIdentifier lhId = request.getTarget().getHistoryId();
 182             final AbstractFrontendHistory history;
 183
 184             if (lhId.getHistoryId() != 0) {
 185                 history = localHistories.get(lhId);
 186                 if (history == null) {
 187                     LOG.debug("{}: rejecting unknown history request {}", persistenceId, request);
 188                     throw new UnknownHistoryException(lastSeenHistory);
 189                 }
 190             } else {
 191                 history = standaloneHistory;
 192             }
 193
 194             return history.handleTransactionRequest(request, envelope, now);
 195         } finally {
 196             expectNextRequest();
 197         }
 198     }
 199
 200     void reconnect() {
 201         expectedTxSequence = 0;
 202     }
 203
 204     void retire() {
 205         // FIXME: flush all state
 206     }
 207
 208     @Override
 209     public String toString() {
 210         return MoreObjects.toStringHelper(LeaderFrontendState.class).add("clientId", clientId)
 211                 .add("purgedHistories", purgedHistories).toString();
 212     }
 213 }