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

   1 /*
   2  * Copyright (c) 2015 Brocade Communications Systems, Inc. and others.  All rights reserved.
   3  * Copyright (c) 2015 Cisco Systems, Inc. and others.  All rights reserved.
   4  *
   5  * This program and the accompanying materials are made available under the
   6  * terms of the Eclipse Public License v1.0 which accompanies this distribution,
   7  * and is available at http://www.eclipse.org/legal/epl-v10.html
   8  */
   9 package org.opendaylight.controller.cluster.datastore;
  10
  11 import akka.actor.ActorSelection;
  12 import akka.dispatch.OnComplete;
  13 import akka.pattern.AskTimeoutException;
  14 import akka.util.Timeout;
  15 import com.google.common.base.Preconditions;
  16 import java.util.concurrent.TimeUnit;
  17 import org.opendaylight.controller.cluster.access.concepts.TransactionIdentifier;
  18 import org.opendaylight.controller.cluster.datastore.exceptions.NoShardLeaderException;
  19 import org.opendaylight.controller.cluster.datastore.exceptions.ShardLeaderNotRespondingException;
  20 import org.opendaylight.controller.cluster.datastore.messages.CreateTransaction;
  21 import org.opendaylight.controller.cluster.datastore.messages.CreateTransactionReply;
  22 import org.opendaylight.controller.cluster.datastore.messages.PrimaryShardInfo;
  23 import org.opendaylight.controller.cluster.datastore.utils.ActorContext;
  24 import org.slf4j.Logger;
  25 import org.slf4j.LoggerFactory;
  26 import scala.concurrent.Future;
  27 import scala.concurrent.duration.FiniteDuration;
  28
  29 /**
  30  * Handles creation of TransactionContext instances for remote transactions. This class creates
  31  * remote transactions, if necessary, by sending CreateTransaction messages with retries, up to a limit,
  32  * if the shard doesn't have a leader yet. This is done by scheduling a retry task after a short delay.
  33  * <p/>
  34  * The end result from a completed CreateTransaction message is a TransactionContext that is
  35  * used to perform transaction operations. Transaction operations that occur before the
  36  * CreateTransaction completes are cache via a TransactionContextWrapper and executed once the
  37  * CreateTransaction completes, successfully or not.
  38  */
  39 final class RemoteTransactionContextSupport {
  40     private static final Logger LOG = LoggerFactory.getLogger(RemoteTransactionContextSupport.class);
  41
  42     private static final long CREATE_TX_TRY_INTERVAL_IN_MS = 1000;
  43     private static final long MAX_CREATE_TX_MSG_TIMEOUT_IN_MS = 5000;
  44
  45     private final TransactionProxy parent;
  46     private final String shardName;
  47
  48     /**
  49      * The target primary shard.
  50      */
  51     private volatile PrimaryShardInfo primaryShardInfo;
  52
  53     /**
  54      * The total timeout for creating a tx on the primary shard.
  55      */
  56     private volatile long totalCreateTxTimeout;
  57
  58     private final Timeout createTxMessageTimeout;
  59
  60     private final TransactionContextWrapper transactionContextWrapper;
  61
  62     RemoteTransactionContextSupport(final TransactionContextWrapper transactionContextWrapper,
  63             final TransactionProxy parent, final String shardName) {
  64         this.parent = Preconditions.checkNotNull(parent);
  65         this.shardName = shardName;
  66         this.transactionContextWrapper = transactionContextWrapper;
  67
  68         // For the total create tx timeout, use 2 times the election timeout. This should be enough time for
  69         // a leader re-election to occur if we happen to hit it in transition.
  70         totalCreateTxTimeout = parent.getActorContext().getDatastoreContext().getShardRaftConfig()
  71                 .getElectionTimeOutInterval().toMillis() * 2;
  72
  73         // We'll use the operationTimeout for the the create Tx message timeout so it can be set appropriately
  74         // for unit tests but cap it at MAX_CREATE_TX_MSG_TIMEOUT_IN_MS. The operationTimeout could be set
  75         // larger than the totalCreateTxTimeout in production which we don't want.
  76         long operationTimeout = parent.getActorContext().getOperationTimeout().duration().toMillis();
  77         createTxMessageTimeout = new Timeout(Math.min(operationTimeout, MAX_CREATE_TX_MSG_TIMEOUT_IN_MS),
  78                 TimeUnit.MILLISECONDS);
  79     }
  80
  81     String getShardName() {
  82         return shardName;
  83     }
  84
  85     private TransactionType getTransactionType() {
  86         return parent.getType();
  87     }
  88
  89     private ActorContext getActorContext() {
  90         return parent.getActorContext();
  91     }
  92
  93     private TransactionIdentifier getIdentifier() {
  94         return parent.getIdentifier();
  95     }
  96
  97     /**
  98      * Sets the target primary shard and initiates a CreateTransaction try.
  99      */
 100     void setPrimaryShard(PrimaryShardInfo primaryShardInfo) {
 101         this.primaryShardInfo = primaryShardInfo;
 102
 103         if (getTransactionType() == TransactionType.WRITE_ONLY
 104                 && getActorContext().getDatastoreContext().isWriteOnlyTransactionOptimizationsEnabled()) {
 105             ActorSelection primaryShard = primaryShardInfo.getPrimaryShardActor();
 106
 107             LOG.debug("Tx {} Primary shard {} found - creating WRITE_ONLY transaction context",
 108                 getIdentifier(), primaryShard);
 109
 110             // For write-only Tx's we prepare the transaction modifications directly on the shard actor
 111             // to avoid the overhead of creating a separate transaction actor.
 112             transactionContextWrapper.executePriorTransactionOperations(createValidTransactionContext(
 113                     primaryShard, String.valueOf(primaryShard.path()), primaryShardInfo.getPrimaryShardVersion()));
 114         } else {
 115             tryCreateTransaction();
 116         }
 117     }
 118
 119     /**
 120       Performs a CreateTransaction try async.
 121      */
 122     private void tryCreateTransaction() {
 123         LOG.debug("Tx {} Primary shard {} found - trying create transaction", getIdentifier(),
 124                 primaryShardInfo.getPrimaryShardActor());
 125
 126         Object serializedCreateMessage = new CreateTransaction(getIdentifier(), getTransactionType().ordinal(),
 127                     primaryShardInfo.getPrimaryShardVersion()).toSerializable();
 128
 129         Future<Object> createTxFuture = getActorContext().executeOperationAsync(
 130                 primaryShardInfo.getPrimaryShardActor(), serializedCreateMessage, createTxMessageTimeout);
 131
 132         createTxFuture.onComplete(new OnComplete<Object>() {
 133             @Override
 134             public void onComplete(Throwable failure, Object response) {
 135                 onCreateTransactionComplete(failure, response);
 136             }
 137         }, getActorContext().getClientDispatcher());
 138     }
 139
 140     private void tryFindPrimaryShard() {
 141         LOG.debug("Tx {} Retrying findPrimaryShardAsync for shard {}", getIdentifier(), shardName);
 142
 143         this.primaryShardInfo = null;
 144         Future<PrimaryShardInfo> findPrimaryFuture = getActorContext().findPrimaryShardAsync(shardName);
 145         findPrimaryFuture.onComplete(new OnComplete<PrimaryShardInfo>() {
 146             @Override
 147             public void onComplete(final Throwable failure, final PrimaryShardInfo newPrimaryShardInfo) {
 148                 onFindPrimaryShardComplete(failure, newPrimaryShardInfo);
 149             }
 150         }, getActorContext().getClientDispatcher());
 151     }
 152
 153     private void onFindPrimaryShardComplete(final Throwable failure, final PrimaryShardInfo newPrimaryShardInfo) {
 154         if (failure == null) {
 155             this.primaryShardInfo = newPrimaryShardInfo;
 156             tryCreateTransaction();
 157         } else {
 158             LOG.debug("Tx {}: Find primary for shard {} failed", getIdentifier(), shardName, failure);
 159
 160             onCreateTransactionComplete(failure, null);
 161         }
 162     }
 163
 164     private void onCreateTransactionComplete(Throwable failure, Object response) {
 165         // An AskTimeoutException will occur if the local shard forwards to an unavailable remote leader or
 166         // the cached remote leader actor is no longer available.
 167         boolean retryCreateTransaction = primaryShardInfo != null
 168                 && (failure instanceof NoShardLeaderException || failure instanceof AskTimeoutException);
 169
 170         // Schedule a retry unless we're out of retries. Note: totalCreateTxTimeout is volatile as it may
 171         // be written by different threads however not concurrently, therefore decrementing it
 172         // non-atomically here is ok.
 173         if (retryCreateTransaction && totalCreateTxTimeout > 0) {
 174             long scheduleInterval = CREATE_TX_TRY_INTERVAL_IN_MS;
 175             if (failure instanceof AskTimeoutException) {
 176                 // Since we use the createTxMessageTimeout for the CreateTransaction request and it timed
 177                 // out, subtract it from the total timeout. Also since the createTxMessageTimeout period
 178                 // has already elapsed, we can immediately schedule the retry (10 ms is virtually immediate).
 179                 totalCreateTxTimeout -= createTxMessageTimeout.duration().toMillis();
 180                 scheduleInterval = 10;
 181             }
 182
 183             totalCreateTxTimeout -= scheduleInterval;
 184
 185             LOG.debug("Tx {}: create tx on shard {} failed with exception \"{}\" - scheduling retry in {} ms",
 186                     getIdentifier(), shardName, failure, scheduleInterval);
 187
 188             getActorContext().getActorSystem().scheduler().scheduleOnce(
 189                     FiniteDuration.create(scheduleInterval, TimeUnit.MILLISECONDS),
 190                     this::tryFindPrimaryShard, getActorContext().getClientDispatcher());
 191             return;
 192         }
 193
 194         createTransactionContext(failure, response);
 195     }
 196
 197     private void createTransactionContext(Throwable failure, Object response) {
 198         // Create the TransactionContext from the response or failure. Store the new
 199         // TransactionContext locally until we've completed invoking the
 200         // TransactionOperations. This avoids thread timing issues which could cause
 201         // out-of-order TransactionOperations. Eg, on a modification operation, if the
 202         // TransactionContext is non-null, then we directly call the TransactionContext.
 203         // However, at the same time, the code may be executing the cached
 204         // TransactionOperations. So to avoid thus timing, we don't publish the
 205         // TransactionContext until after we've executed all cached TransactionOperations.
 206         TransactionContext localTransactionContext;
 207         if (failure != null) {
 208             LOG.debug("Tx {} Creating NoOpTransaction because of error", getIdentifier(), failure);
 209
 210             Throwable resultingEx = failure;
 211             if (failure instanceof AskTimeoutException) {
 212                 resultingEx = new ShardLeaderNotRespondingException(String.format(
 213                         "Could not create a %s transaction on shard %s. The shard leader isn't responding.",
 214                         parent.getType(), shardName), failure);
 215             } else if (!(failure instanceof NoShardLeaderException)) {
 216                 resultingEx = new Exception(String.format(
 217                     "Error creating %s transaction on shard %s", parent.getType(), shardName), failure);
 218             }
 219
 220             localTransactionContext = new NoOpTransactionContext(resultingEx, getIdentifier());
 221         } else if (CreateTransactionReply.isSerializedType(response)) {
 222             localTransactionContext = createValidTransactionContext(
 223                     CreateTransactionReply.fromSerializable(response));
 224         } else {
 225             IllegalArgumentException exception = new IllegalArgumentException(String.format(
 226                     "Invalid reply type %s for CreateTransaction", response.getClass()));
 227
 228             localTransactionContext = new NoOpTransactionContext(exception, getIdentifier());
 229         }
 230
 231         transactionContextWrapper.executePriorTransactionOperations(localTransactionContext);
 232     }
 233
 234     private TransactionContext createValidTransactionContext(CreateTransactionReply reply) {
 235         LOG.debug("Tx {} Received {}", getIdentifier(), reply);
 236
 237         return createValidTransactionContext(getActorContext().actorSelection(reply.getTransactionPath()),
 238                 reply.getTransactionPath(), primaryShardInfo.getPrimaryShardVersion());
 239     }
 240
 241     private TransactionContext createValidTransactionContext(ActorSelection transactionActor, String transactionPath,
 242             short remoteTransactionVersion) {
 243         final TransactionContext ret = new RemoteTransactionContext(transactionContextWrapper.getIdentifier(),
 244                 transactionActor, getActorContext(), remoteTransactionVersion, transactionContextWrapper.getLimiter());
 245
 246         if (parent.getType() == TransactionType.READ_ONLY) {
 247             TransactionContextCleanup.track(parent, ret);
 248         }
 249
 250         return ret;
 251     }
 252 }
 253