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         final ShardState existing = state;
  45         if (existing != null) {
  46             return existing.getStage();
  47         }
  48
  49         synchronized (this) {
  50             final ShardState recheck = state;
  51             if (recheck != null) {
  52                 return recheck.getStage();
  53             }
  54
  55             final ShardState newState = resolveBackendInfo(shardName, 0);
  56             state = newState;
  57
  58             final CompletionStage<ShardBackendInfo> stage = newState.getStage();
  59             stage.whenComplete((info, failure) -> {
  60                 if (failure != null) {
  61                     synchronized (SimpleShardBackendResolver.this) {
  62                         if (state == newState) {
  63                             state = null;
  64                         }
  65                     }
  66                 }
  67             });
  68
  69             return stage;
  70         }
  71     }
  72
  73     @Override
  74     public CompletionStage<ShardBackendInfo> getBackendInfo(final Long cookie) {
  75         return getBackendInfo(cookie.longValue());
  76     }
  77
  78     @Override
  79     public CompletionStage<? extends ShardBackendInfo> refreshBackendInfo(final Long cookie,
  80             final ShardBackendInfo staleInfo) {
  81
  82         final ShardState existing = state;
  83         if (existing != null) {
  84             if (!staleInfo.equals(existing.getResult())) {
  85                 return existing.getStage();
  86             }
  87
  88             synchronized (this) {
  89                 LOG.debug("Invalidating backend information {}", staleInfo);
  90                 flushCache(shardName);
  91                 LOG.trace("Invalidated cache {}", staleInfo);
  92                 state = null;
  93             }
  94         }
  95
  96         return getBackendInfo(cookie);
  97     }
  98 }