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 javax.annotation.concurrent.NotThreadSafe;
  17 import org.eclipse.jdt.annotation.Nullable;
  18 import org.opendaylight.controller.cluster.access.commands.IncrementTransactionSequenceRequest;
  19 import org.opendaylight.controller.cluster.access.commands.IncrementTransactionSequenceSuccess;
  20 import org.opendaylight.controller.cluster.access.commands.OutOfOrderRequestException;
  21 import org.opendaylight.controller.cluster.access.commands.TransactionRequest;
  22 import org.opendaylight.controller.cluster.access.commands.TransactionSuccess;
  23 import org.opendaylight.controller.cluster.access.concepts.RequestEnvelope;
  24 import org.opendaylight.controller.cluster.access.concepts.RequestException;
  25 import org.opendaylight.controller.cluster.access.concepts.RuntimeRequestException;
  26 import org.opendaylight.controller.cluster.access.concepts.TransactionIdentifier;
  27 import org.opendaylight.yangtools.concepts.Identifiable;
  28 import org.slf4j.Logger;
  29 import org.slf4j.LoggerFactory;
  30
  31 /**
  32  * Frontend common transaction state as observed by the shard leader.
  33  *
  34  * @author Robert Varga
  35  */
  36 @NotThreadSafe
  37 abstract class FrontendTransaction implements Identifiable<TransactionIdentifier> {
  38     private static final Logger LOG = LoggerFactory.getLogger(FrontendTransaction.class);
  39
  40     private final AbstractFrontendHistory history;
  41     private final TransactionIdentifier id;
  42
  43     /**
  44      * It is possible that after we process a request and send a response that response gets lost and the client
  45      * initiates a retry. Since subsequent requests can mutate transaction state we need to retain the response until
  46      * it is acknowledged by the client.
  47      */
  48     private final Queue<Object> replayQueue = new ArrayDeque<>();
  49     private long firstReplaySequence;
  50     private Long lastPurgedSequence;
  51     private long expectedSequence;
  52
  53     private RequestException previousFailure;
  54
  55     FrontendTransaction(final AbstractFrontendHistory history, final TransactionIdentifier id) {
  56         this.history = Preconditions.checkNotNull(history);
  57         this.id = Preconditions.checkNotNull(id);
  58     }
  59
  60     @Override
  61     public final TransactionIdentifier getIdentifier() {
  62         return id;
  63     }
  64
  65     final AbstractFrontendHistory history() {
  66         return history;
  67     }
  68
  69     final String persistenceId() {
  70         return history().persistenceId();
  71     }
  72
  73     final Optional<TransactionSuccess<?>> replaySequence(final long sequence) throws RequestException {
  74         // Fast path check: if the requested sequence is the next request, bail early
  75         if (expectedSequence == sequence) {
  76             return Optional.empty();
  77         }
  78
  79         // Check sequencing: we do not need to bother with future requests
  80         if (Long.compareUnsigned(expectedSequence, sequence) < 0) {
  81             throw new OutOfOrderRequestException(expectedSequence);
  82         }
  83
  84         // Sanity check: if we have purged sequences, this has to be newer
  85         if (lastPurgedSequence != null && Long.compareUnsigned(lastPurgedSequence.longValue(), sequence) >= 0) {
  86             // Client has sent a request sequence, which has already been purged. This is a hard error, which should
  87             // never occur. Throwing an IllegalArgumentException will cause it to be wrapped in a
  88             // RuntimeRequestException (which is not retriable) and report it back to the client.
  89             throw new IllegalArgumentException(String.format("Invalid purged sequence %s (last purged is %s)",
  90                 sequence, lastPurgedSequence));
  91         }
  92
  93         // At this point we have established that the requested sequence lies in the open interval
  94         // (lastPurgedSequence, expectedSequence). That does not actually mean we have a response, as the commit
  95         // machinery is asynchronous, hence a reply may be in the works and not available.
  96
  97         long replaySequence = firstReplaySequence;
  98         for (Object replay : replayQueue) {
  99             if (replaySequence == sequence) {
 100                 if (replay instanceof RequestException) {
 101                     throw (RequestException) replay;
 102                 }
 103
 104                 Verify.verify(replay instanceof TransactionSuccess);
 105                 return Optional.of((TransactionSuccess<?>) replay);
 106             }
 107
 108             replaySequence++;
 109         }
 110
 111         // Not found
 112         return Optional.empty();
 113     }
 114
 115     final void purgeSequencesUpTo(final long sequence) {
 116         // FIXME: implement this
 117
 118         lastPurgedSequence = sequence;
 119     }
 120
 121     // Request order has already been checked by caller and replaySequence()
 122     @SuppressWarnings("checkstyle:IllegalCatch")
 123     final @Nullable TransactionSuccess<?> handleRequest(final TransactionRequest<?> request,
 124             final RequestEnvelope envelope, final long now) throws RequestException {
 125         if (request instanceof IncrementTransactionSequenceRequest) {
 126             final IncrementTransactionSequenceRequest incr = (IncrementTransactionSequenceRequest) request;
 127             expectedSequence += incr.getIncrement();
 128
 129             return recordSuccess(incr.getSequence(),
 130                     new IncrementTransactionSequenceSuccess(incr.getTarget(), incr.getSequence()));
 131         }
 132
 133         if (previousFailure != null) {
 134             LOG.debug("{}: Rejecting request {} due to previous failure", persistenceId(), request, previousFailure);
 135             throw previousFailure;
 136         }
 137
 138         try {
 139             return doHandleRequest(request, envelope, now);
 140         } catch (RuntimeException e) {
 141             /*
 142              * The request failed to process, we should not attempt to ever
 143              * apply it again. Furthermore we cannot accept any further requests
 144              * from this connection, simply because the transaction state is
 145              * undefined.
 146              */
 147             LOG.debug("{}: Request {} failed to process", persistenceId(), request, e);
 148             previousFailure = new RuntimeRequestException("Request " + request + " failed to process", e);
 149             throw previousFailure;
 150         }
 151     }
 152
 153     abstract @Nullable TransactionSuccess<?> doHandleRequest(TransactionRequest<?> request, RequestEnvelope envelope,
 154             long now) throws RequestException;
 155
 156     abstract void retire();
 157
 158     private void recordResponse(final long sequence, final Object response) {
 159         if (replayQueue.isEmpty()) {
 160             firstReplaySequence = sequence;
 161         }
 162         replayQueue.add(response);
 163         expectedSequence++;
 164     }
 165
 166     final <T extends TransactionSuccess<?>> T recordSuccess(final long sequence, final T success) {
 167         recordResponse(sequence, success);
 168         return success;
 169     }
 170
 171     private long executionTime(final long startTime) {
 172         return history.readTime() - startTime;
 173     }
 174
 175     final void recordAndSendSuccess(final RequestEnvelope envelope, final long startTime,
 176             final TransactionSuccess<?> success) {
 177         recordResponse(success.getSequence(), success);
 178         envelope.sendSuccess(success, executionTime(startTime));
 179     }
 180
 181     final void recordAndSendFailure(final RequestEnvelope envelope, final long startTime,
 182             final RuntimeRequestException failure) {
 183         recordResponse(envelope.getMessage().getSequence(), failure);
 184         envelope.sendFailure(failure, executionTime(startTime));
 185     }
 186
 187     @Override
 188     public final String toString() {
 189         return MoreObjects.toStringHelper(this).omitNullValues().add("identifier", getIdentifier())
 190                 .add("expectedSequence", expectedSequence).add("firstReplaySequence", firstReplaySequence)
 191                 .add("lastPurgedSequence", lastPurgedSequence)
 192                 .toString();
 193     }
 194 }