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

   1 /*
   2  * Copyright (c) 2014 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
   9 package org.opendaylight.controller.cluster.datastore;
  10
  11 import akka.actor.ActorPath;
  12 import akka.actor.ActorRef;
  13 import akka.actor.Address;
  14 import akka.actor.Props;
  15 import akka.event.Logging;
  16 import akka.event.LoggingAdapter;
  17 import akka.japi.Creator;
  18 import org.opendaylight.controller.cluster.datastore.messages.FindPrimary;
  19 import org.opendaylight.controller.cluster.datastore.messages.PrimaryFound;
  20 import org.opendaylight.controller.cluster.datastore.messages.PrimaryNotFound;
  21 import org.opendaylight.controller.cluster.datastore.messages.UpdateSchemaContext;
  22
  23 import java.util.HashMap;
  24 import java.util.List;
  25 import java.util.Map;
  26
  27 /**
  28  * The ShardManager has the following jobs,
  29  * <p>
  30  * <li> Create all the local shard replicas that belong on this cluster member
  31  * <li> Find the primary replica for any given shard
  32  * <li> Engage in shard replica elections which decide which replica should be the primary
  33  * </p>
  34  * <p/>
  35  * <h3>>Creation of Shard replicas</h3
  36  * <p>
  37  * When the ShardManager is constructed it reads the cluster configuration to find out which shard replicas
  38  * belong on this member. It finds out the name of the current cluster member from the Akka Clustering Service.
  39  * </p>
  40  * <p/>
  41  * <h3> Replica Elections </h3>
  42  * <p/>
  43  * <p>
  44  * The Shard Manager uses multiple cues to initiate election.
  45  * <li> When a member of the cluster dies
  46  * <li> When a local shard replica dies
  47  * <li> When a local shard replica comes alive
  48  * </p>
  49  */
  50 public class ShardManager extends AbstractUntypedActor {
  51
  52     // Stores a mapping between a shard name and the address of the current primary
  53     private final Map<String, Address> shardNameToPrimaryAddress =
  54         new HashMap<>();
  55
  56     // Stores a mapping between a member name and the address of the member
  57     private final Map<String, Address> memberNameToAddress = new HashMap<>();
  58
  59     // Stores a mapping between the shard name and all the members on which a replica of that shard are available
  60     private final Map<String, List<String>> shardNameToMembers =
  61         new HashMap<>();
  62
  63     private final LoggingAdapter log =
  64         Logging.getLogger(getContext().system(), this);
  65
  66
  67     private final Map<String, ActorPath> localShards = new HashMap<>();
  68
  69
  70     private final String type;
  71
  72     private final ClusterWrapper cluster;
  73
  74     private final Configuration configuration;
  75
  76     /**
  77      * @param type defines the kind of data that goes into shards created by this shard manager. Examples of type would be
  78      *             configuration or operational
  79      */
  80     private ShardManager(String type, ClusterWrapper cluster, Configuration configuration) {
  81         this.type = type;
  82         this.cluster = cluster;
  83         this.configuration = configuration;
  84         String memberName = cluster.getCurrentMemberName();
  85         List<String> memberShardNames =
  86             configuration.getMemberShardNames(memberName);
  87
  88         for(String shardName : memberShardNames){
  89             String shardActorName = getShardActorName(memberName, shardName);
  90             ActorRef actor = getContext()
  91                 .actorOf(Shard.props(shardActorName), shardActorName);
  92             ActorPath path = actor.path();
  93             localShards.put(shardName, path);
  94         }
  95     }
  96
  97     public static Props props(final String type,
  98         final ClusterWrapper cluster,
  99         final Configuration configuration) {
 100         return Props.create(new Creator<ShardManager>() {
 101
 102             @Override
 103             public ShardManager create() throws Exception {
 104                 return new ShardManager(type, cluster, configuration);
 105             }
 106         });
 107     }
 108
 109     @Override
 110     public void handleReceive(Object message) throws Exception {
 111         if (message instanceof FindPrimary) {
 112             FindPrimary msg = ((FindPrimary) message);
 113             String shardName = msg.getShardName();
 114
 115             List<String> members =
 116                 configuration.getMembersFromShardName(shardName);
 117
 118             for(String memberName : members) {
 119                 if (memberName.equals(cluster.getCurrentMemberName())) {
 120                     // This is a local shard
 121                     ActorPath shardPath = localShards.get(shardName);
 122                     // FIXME: This check may be redundant
 123                     if (shardPath == null) {
 124                         getSender()
 125                             .tell(new PrimaryNotFound(shardName), getSelf());
 126                         return;
 127                     }
 128                     getSender().tell(new PrimaryFound(shardPath.toString()),
 129                         getSelf());
 130                     return;
 131                 } else {
 132                     Address address = memberNameToAddress.get(shardName);
 133                     if(address != null){
 134                         String path =
 135                             address.toString() + "/user/" + getShardActorName(
 136                                 memberName, shardName);
 137                         getSender().tell(new PrimaryFound(path), getSelf());
 138                     }
 139
 140
 141                 }
 142             }
 143
 144             getSender().tell(new PrimaryNotFound(shardName), getSelf());
 145
 146         } else if (message instanceof UpdateSchemaContext) {
 147             for(ActorPath path : localShards.values()){
 148                 getContext().system().actorSelection(path)
 149                     .forward(message,
 150                         getContext());
 151             }
 152         }
 153     }
 154
 155     private String getShardActorName(String memberName, String shardName){
 156         return memberName + "-shard-" + shardName + "-" + this.type;
 157     }
 158
 159
 160 }