opendaylight/md-sal/sal-distributed-datastore/src/main/java/org/opendaylight/controller/cluster/databroker/actors/dds/SimpleShardBackendResolver.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.databroker.actors.dds;
   9
  10 import com.google.common.base.Preconditions;
  11 import java.util.concurrent.CompletionStage;
  12 import javax.annotation.concurrent.ThreadSafe;
  13 import org.opendaylight.controller.cluster.access.client.BackendInfoResolver;
  14 import org.opendaylight.controller.cluster.access.concepts.ClientIdentifier;
  15 import org.opendaylight.controller.cluster.datastore.utils.ActorContext;
  16 import org.slf4j.Logger;
  17 import org.slf4j.LoggerFactory;
  18
  19 /**
  20  * {@link BackendInfoResolver} implementation for static shard configuration based on ShardManager. Unlike the full
  21  * {@link ModuleShardBackendResolver}, this resolver is used in situations where the client corresponds exactly to one
  22  * backend shard, e.g. there is only one fixed cookie assigned and the operation path is not consulted at all.
  23  *
  24  * @author Robert Varga
  25  */
  26 @ThreadSafe
  27 final class SimpleShardBackendResolver extends AbstractShardBackendResolver {
  28     private static final Logger LOG = LoggerFactory.getLogger(SimpleShardBackendResolver.class);
  29
  30     private final String shardName;
  31
  32     private volatile ShardState state;
  33
  34     // FIXME: we really need just ActorContext.findPrimaryShardAsync()
  35     SimpleShardBackendResolver(final ClientIdentifier clientId, final ActorContext actorContext,
  36             final String shardName) {
  37         super(clientId, actorContext);
  38         this.shardName = Preconditions.checkNotNull(shardName);
  39     }
  40
  41     private CompletionStage<ShardBackendInfo> getBackendInfo(final long cookie) {
  42         Preconditions.checkArgument(cookie == 0);
  43
  44         ShardState local = state;
  45         if (local == null) {
  46             synchronized (this) {
  47                 local = state;
  48                 if (local == null) {
  49                     local = resolveBackendInfo(shardName, 0);
  50                     state = local;
  51                 }
  52             }
  53         }
  54
  55         return local.getStage();
  56     }
  57
  58     @Override
  59     public CompletionStage<ShardBackendInfo> getBackendInfo(final Long cookie) {
  60         return getBackendInfo(cookie.longValue());
  61     }
  62
  63     @Override
  64     public CompletionStage<? extends ShardBackendInfo> refreshBackendInfo(final Long cookie,
  65             final ShardBackendInfo staleInfo) {
  66
  67         final ShardState existing = state;
  68         if (existing != null) {
  69             if (!staleInfo.equals(existing.getResult())) {
  70                 return existing.getStage();
  71             }
  72
  73             synchronized (this) {
  74                 LOG.debug("Invalidating backend information {}", staleInfo);
  75                 flushCache(shardName);
  76                 LOG.trace("Invalidated cache %s", staleInfo);
  77                 state = null;
  78             }
  79         }
  80
  81         return getBackendInfo(cookie);
  82     }
  83 }