opendaylight/md-sal/sal-distributed-datastore/src/main/java/org/opendaylight/controller/cluster/datastore/FrontendTransaction.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.base.Verify;
  13 import java.util.ArrayDeque;
  14 import java.util.Iterator;
  15 import java.util.Queue;
  16 import javax.annotation.Nullable;
  17 import javax.annotation.concurrent.NotThreadSafe;
  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 java.util.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 java.util.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         final Iterator<?> it = replayQueue.iterator();
  99         while (it.hasNext()) {
 100             final Object replay = it.next();
 101             if (replaySequence == sequence) {
 102                 if (replay instanceof RequestException) {
 103                     throw (RequestException) replay;
 104                 }
 105
 106                 Verify.verify(replay instanceof TransactionSuccess);
 107                 return java.util.Optional.of((TransactionSuccess<?>) replay);
 108             }
 109
 110             replaySequence++;
 111         }
 112
 113         // Not found
 114         return java.util.Optional.empty();
 115     }
 116
 117     final void purgeSequencesUpTo(final long sequence) {
 118         // FIXME: implement this
 119
 120         lastPurgedSequence = sequence;
 121     }
 122
 123     // Request order has already been checked by caller and replaySequence()
 124     @SuppressWarnings("checkstyle:IllegalCatch")
 125     final @Nullable TransactionSuccess<?> handleRequest(final TransactionRequest<?> request,
 126             final RequestEnvelope envelope, final long now) throws RequestException {
 127         if (request instanceof IncrementTransactionSequenceRequest) {
 128             final IncrementTransactionSequenceRequest incr = (IncrementTransactionSequenceRequest) request;
 129             expectedSequence += incr.getIncrement();
 130
 131             return recordSuccess(incr.getSequence(), new IncrementTransactionSequenceSuccess(incr.getTarget(),
 132                 incr.getSequence()));
 133         }
 134
 135         if (previousFailure != null) {
 136             LOG.debug("{}: Rejecting request {} due to previous failure", persistenceId(), request, previousFailure);
 137             throw previousFailure;
 138         }
 139
 140         try {
 141             return doHandleRequest(request, envelope, now);
 142         } catch (RuntimeException e) {
 143             /*
 144              * The request failed to process, we should not attempt to ever apply it again. Furthermore we cannot
 145              * accept any further requests from this connection, simply because the transaction state is 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     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
 193 }