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

   1 /*
   2  * Copyright (c) 2015 Brocade Communications 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.entityownership;
   9
  10 import akka.actor.ActorRef;
  11 import akka.actor.Cancellable;
  12 import akka.actor.Status.Failure;
  13 import java.util.Iterator;
  14 import java.util.LinkedList;
  15 import java.util.Queue;
  16 import org.opendaylight.controller.cluster.datastore.DataStoreVersions;
  17 import org.opendaylight.controller.cluster.datastore.exceptions.NoShardLeaderException;
  18 import org.opendaylight.controller.cluster.datastore.identifiers.TransactionIdentifier;
  19 import org.opendaylight.controller.cluster.datastore.messages.BatchedModifications;
  20 import org.opendaylight.controller.cluster.datastore.messages.CommitTransactionReply;
  21 import org.opendaylight.controller.cluster.datastore.modification.Modification;
  22 import org.slf4j.Logger;
  23 import scala.concurrent.duration.FiniteDuration;
  24
  25 /**
  26  * Handles commits and retries for the EntityOwnershipShard.
  27  *
  28  * @author Thomas Pantelis
  29  */
  30 class EntityOwnershipShardCommitCoordinator {
  31     private static final Object COMMIT_RETRY_MESSAGE = "entityCommitRetry";
  32
  33     private final Logger log;
  34     private int transactionIDCounter = 0;
  35     private final String localMemberName;
  36     private final Queue<Modification> pendingModifications = new LinkedList<>();
  37     private BatchedModifications inflightCommit;
  38     private Cancellable retryCommitSchedule;
  39
  40     EntityOwnershipShardCommitCoordinator(String localMemberName, Logger log) {
  41         this.localMemberName = localMemberName;
  42         this.log = log;
  43     }
  44
  45     boolean handleMessage(Object message, EntityOwnershipShard shard) {
  46         boolean handled = true;
  47         if(CommitTransactionReply.SERIALIZABLE_CLASS.isInstance(message)) {
  48             // Successful reply from a local commit.
  49             inflightCommitSucceeded(shard);
  50         } else if(message instanceof akka.actor.Status.Failure) {
  51             // Failure reply from a local commit.
  52             inflightCommitFailure(((Failure)message).cause(), shard);
  53         } else if(message.equals(COMMIT_RETRY_MESSAGE)) {
  54             retryInflightCommit(shard);
  55         } else {
  56             handled = false;
  57         }
  58
  59         return handled;
  60     }
  61
  62     private void retryInflightCommit(EntityOwnershipShard shard) {
  63         // Shouldn't be null happen but verify anyway
  64         if(inflightCommit == null) {
  65             return;
  66         }
  67
  68         if(shard.hasLeader()) {
  69             log.debug("Retrying commit for BatchedModifications {}", inflightCommit.getTransactionID());
  70
  71             shard.tryCommitModifications(inflightCommit);
  72         } else {
  73             scheduleInflightCommitRetry(shard);
  74         }
  75     }
  76
  77     void inflightCommitFailure(Throwable cause, EntityOwnershipShard shard) {
  78         // This should've originated from a failed inflight commit but verify anyway
  79         if(inflightCommit == null) {
  80             return;
  81         }
  82
  83         log.debug("Inflight BatchedModifications {} commit failed", inflightCommit.getTransactionID(), cause);
  84
  85         if(!(cause instanceof NoShardLeaderException)) {
  86             // If the failure is other than NoShardLeaderException the commit may have been partially
  87             // processed so retry with a new transaction ID to be safe.
  88             newInflightCommitWithDifferentTransactionID();
  89         }
  90
  91         scheduleInflightCommitRetry(shard);
  92     }
  93
  94     private void scheduleInflightCommitRetry(EntityOwnershipShard shard) {
  95         FiniteDuration duration = shard.getDatastoreContext().getShardRaftConfig().getElectionTimeOutInterval();
  96
  97         log.debug("Scheduling retry for BatchedModifications commit {} in {}",
  98                 inflightCommit.getTransactionID(), duration);
  99
 100         retryCommitSchedule = shard.getContext().system().scheduler().scheduleOnce(duration, shard.getSelf(),
 101                 COMMIT_RETRY_MESSAGE, shard.getContext().dispatcher(), ActorRef.noSender());
 102     }
 103
 104     void inflightCommitSucceeded(EntityOwnershipShard shard) {
 105         // Shouldn't be null but verify anyway
 106         if(inflightCommit == null) {
 107             return;
 108         }
 109
 110         if(retryCommitSchedule != null) {
 111             retryCommitSchedule.cancel();
 112         }
 113
 114         log.debug("BatchedModifications commit {} succeeded", inflightCommit.getTransactionID());
 115
 116         inflightCommit = null;
 117         commitNextBatch(shard);
 118     }
 119
 120     void commitNextBatch(EntityOwnershipShard shard) {
 121         if(inflightCommit != null || pendingModifications.isEmpty() || !shard.hasLeader()) {
 122             return;
 123         }
 124
 125         inflightCommit = newBatchedModifications();
 126         Iterator<Modification> iter = pendingModifications.iterator();
 127         while(iter.hasNext()) {
 128             inflightCommit.addModification(iter.next());
 129             iter.remove();
 130             if(inflightCommit.getModifications().size() >=
 131                     shard.getDatastoreContext().getShardBatchedModificationCount()) {
 132                 break;
 133             }
 134         }
 135
 136         log.debug("Committing next BatchedModifications {}, size {}", inflightCommit.getTransactionID(),
 137                 inflightCommit.getModifications().size());
 138
 139         shard.tryCommitModifications(inflightCommit);
 140     }
 141
 142     void commitModification(Modification modification, EntityOwnershipShard shard) {
 143         boolean hasLeader = shard.hasLeader();
 144         if(inflightCommit != null || !hasLeader) {
 145             if(log.isDebugEnabled()) {
 146                 log.debug("{} - adding modification to pending",
 147                         (inflightCommit != null ? "A commit is inflight" : "No shard leader"));
 148             }
 149
 150             pendingModifications.add(modification);
 151         } else {
 152             inflightCommit = newBatchedModifications();
 153             inflightCommit.addModification(modification);
 154
 155             shard.tryCommitModifications(inflightCommit);
 156         }
 157     }
 158
 159     void onStateChanged(EntityOwnershipShard shard, boolean isLeader) {
 160         if(!isLeader && inflightCommit != null) {
 161             // We're no longer the leader but we have an inflight local commit. This likely means we didn't get
 162             // consensus for the commit and switched to follower due to another node with a higher term. We
 163             // can't be sure if the commit was replicated to any node so we retry it here with a new
 164             // transaction ID.
 165             if(retryCommitSchedule != null) {
 166                 retryCommitSchedule.cancel();
 167             }
 168
 169             newInflightCommitWithDifferentTransactionID();
 170             retryInflightCommit(shard);
 171         } else {
 172             commitNextBatch(shard);
 173         }
 174     }
 175
 176     private void newInflightCommitWithDifferentTransactionID() {
 177         BatchedModifications newBatchedModifications = newBatchedModifications();
 178         newBatchedModifications.getModifications().addAll(inflightCommit.getModifications());
 179         inflightCommit = newBatchedModifications;
 180     }
 181
 182     private BatchedModifications newBatchedModifications() {
 183         BatchedModifications modifications = new BatchedModifications(
 184                 TransactionIdentifier.create(localMemberName, ++transactionIDCounter).toString(),
 185                 DataStoreVersions.CURRENT_VERSION, "");
 186         modifications.setDoCommitOnReady(true);
 187         modifications.setReady(true);
 188         modifications.setTotalMessagesSent(1);
 189         return modifications;
 190     }
 191 }