opendaylight/md-sal/sal-distributed-datastore/src/main/java/org/opendaylight/controller/cluster/datastore/FrontendTransaction.java

   1 /*
   2  * Copyright (c) 2016, 2017 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.base.Verify;
  13 import java.util.ArrayDeque;
  14 import java.util.Optional;
  15 import java.util.Queue;
  16 import org.eclipse.jdt.annotation.Nullable;
  17 import org.opendaylight.controller.cluster.access.commands.IncrementTransactionSequenceRequest;
  18 import org.opendaylight.controller.cluster.access.commands.IncrementTransactionSequenceSuccess;
  19 import org.opendaylight.controller.cluster.access.commands.OutOfOrderRequestException;
  20 import org.opendaylight.controller.cluster.access.commands.TransactionRequest;
  21 import org.opendaylight.controller.cluster.access.commands.TransactionSuccess;
  22 import org.opendaylight.controller.cluster.access.concepts.RequestEnvelope;
  23 import org.opendaylight.controller.cluster.access.concepts.RequestException;
  24 import org.opendaylight.controller.cluster.access.concepts.RuntimeRequestException;
  25 import org.opendaylight.controller.cluster.access.concepts.TransactionIdentifier;
  26 import org.opendaylight.yangtools.concepts.Identifiable;
  27 import org.slf4j.Logger;
  28 import org.slf4j.LoggerFactory;
  29
  30 /**
  31  * Frontend common transaction state as observed by the shard leader. This class is NOT thread-safe.
  32  *
  33  * @author Robert Varga
  34  */
  35 abstract class FrontendTransaction implements Identifiable<TransactionIdentifier> {
  36     private static final Logger LOG = LoggerFactory.getLogger(FrontendTransaction.class);
  37
  38     private final AbstractFrontendHistory history;
  39     private final TransactionIdentifier id;
  40
  41     /**
  42      * It is possible that after we process a request and send a response that response gets lost and the client
  43      * initiates a retry. Since subsequent requests can mutate transaction state we need to retain the response until
  44      * it is acknowledged by the client.
  45      */
  46     private final Queue<Object> replayQueue = new ArrayDeque<>();
  47     private long firstReplaySequence;
  48     private Long lastPurgedSequence;
  49     private long expectedSequence;
  50
  51     private RequestException previousFailure;
  52
  53     FrontendTransaction(final AbstractFrontendHistory history, final TransactionIdentifier id) {
  54         this.history = Preconditions.checkNotNull(history);
  55         this.id = Preconditions.checkNotNull(id);
  56     }
  57
  58     @Override
  59     public final TransactionIdentifier getIdentifier() {
  60         return id;
  61     }
  62
  63     final AbstractFrontendHistory history() {
  64         return history;
  65     }
  66
  67     final String persistenceId() {
  68         return history().persistenceId();
  69     }
  70
  71     final Optional<TransactionSuccess<?>> replaySequence(final long sequence) throws RequestException {
  72         // Fast path check: if the requested sequence is the next request, bail early
  73         if (expectedSequence == sequence) {
  74             return Optional.empty();
  75         }
  76
  77         // Check sequencing: we do not need to bother with future requests
  78         if (Long.compareUnsigned(expectedSequence, sequence) < 0) {
  79             throw new OutOfOrderRequestException(expectedSequence);
  80         }
  81
  82         // Sanity check: if we have purged sequences, this has to be newer
  83         if (lastPurgedSequence != null && Long.compareUnsigned(lastPurgedSequence.longValue(), sequence) >= 0) {
  84             // Client has sent a request sequence, which has already been purged. This is a hard error, which should
  85             // never occur. Throwing an IllegalArgumentException will cause it to be wrapped in a
  86             // RuntimeRequestException (which is not retriable) and report it back to the client.
  87             throw new IllegalArgumentException(String.format("Invalid purged sequence %s (last purged is %s)",
  88                 sequence, lastPurgedSequence));
  89         }
  90
  91         // At this point we have established that the requested sequence lies in the open interval
  92         // (lastPurgedSequence, expectedSequence). That does not actually mean we have a response, as the commit
  93         // machinery is asynchronous, hence a reply may be in the works and not available.
  94
  95         long replaySequence = firstReplaySequence;
  96         for (Object replay : replayQueue) {
  97             if (replaySequence == sequence) {
  98                 if (replay instanceof RequestException) {
  99                     throw (RequestException) replay;
 100                 }
 101
 102                 Verify.verify(replay instanceof TransactionSuccess);
 103                 return Optional.of((TransactionSuccess<?>) replay);
 104             }
 105
 106             replaySequence++;
 107         }
 108
 109         // Not found
 110         return Optional.empty();
 111     }
 112
 113     final void purgeSequencesUpTo(final long sequence) {
 114         // FIXME: implement this
 115
 116         lastPurgedSequence = sequence;
 117     }
 118
 119     // Request order has already been checked by caller and replaySequence()
 120     @SuppressWarnings("checkstyle:IllegalCatch")
 121     final @Nullable TransactionSuccess<?> handleRequest(final TransactionRequest<?> request,
 122             final RequestEnvelope envelope, final long now) throws RequestException {
 123         if (request instanceof IncrementTransactionSequenceRequest) {
 124             final IncrementTransactionSequenceRequest incr = (IncrementTransactionSequenceRequest) request;
 125             expectedSequence += incr.getIncrement();
 126
 127             return recordSuccess(incr.getSequence(),
 128                     new IncrementTransactionSequenceSuccess(incr.getTarget(), incr.getSequence()));
 129         }
 130
 131         if (previousFailure != null) {
 132             LOG.debug("{}: Rejecting request {} due to previous failure", persistenceId(), request, previousFailure);
 133             throw previousFailure;
 134         }
 135
 136         try {
 137             return doHandleRequest(request, envelope, now);
 138         } catch (RuntimeException e) {
 139             /*
 140              * The request failed to process, we should not attempt to ever
 141              * apply it again. Furthermore we cannot accept any further requests
 142              * from this connection, simply because the transaction state is
 143              * undefined.
 144              */
 145             LOG.debug("{}: Request {} failed to process", persistenceId(), request, e);
 146             previousFailure = new RuntimeRequestException("Request " + request + " failed to process", e);
 147             throw previousFailure;
 148         }
 149     }
 150
 151     abstract @Nullable TransactionSuccess<?> doHandleRequest(TransactionRequest<?> request, RequestEnvelope envelope,
 152             long now) throws RequestException;
 153
 154     abstract void retire();
 155
 156     private void recordResponse(final long sequence, final Object response) {
 157         if (replayQueue.isEmpty()) {
 158             firstReplaySequence = sequence;
 159         }
 160         replayQueue.add(response);
 161         expectedSequence++;
 162     }
 163
 164     final <T extends TransactionSuccess<?>> T recordSuccess(final long sequence, final T success) {
 165         recordResponse(sequence, success);
 166         return success;
 167     }
 168
 169     private long executionTime(final long startTime) {
 170         return history.readTime() - startTime;
 171     }
 172
 173     final void recordAndSendSuccess(final RequestEnvelope envelope, final long startTime,
 174             final TransactionSuccess<?> success) {
 175         recordResponse(success.getSequence(), success);
 176         envelope.sendSuccess(success, executionTime(startTime));
 177     }
 178
 179     final void recordAndSendFailure(final RequestEnvelope envelope, final long startTime,
 180             final RuntimeRequestException failure) {
 181         recordResponse(envelope.getMessage().getSequence(), failure);
 182         envelope.sendFailure(failure, executionTime(startTime));
 183     }
 184
 185     @Override
 186     public final String toString() {
 187         return MoreObjects.toStringHelper(this).omitNullValues().add("identifier", getIdentifier())
 188                 .add("expectedSequence", expectedSequence).add("firstReplaySequence", firstReplaySequence)
 189                 .add("lastPurgedSequence", lastPurgedSequence)
 190                 .toString();
 191     }
 192 }