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 static com.google.common.base.Preconditions.checkArgument;
  11 import static java.util.Objects.requireNonNull;
  12
  13 import java.util.concurrent.CompletionStage;
  14 import org.opendaylight.controller.cluster.access.client.BackendInfoResolver;
  15 import org.opendaylight.controller.cluster.access.concepts.ClientIdentifier;
  16 import org.opendaylight.controller.cluster.datastore.utils.ActorUtils;
  17 import org.slf4j.Logger;
  18 import org.slf4j.LoggerFactory;
  19
  20 /**
  21  * {@link BackendInfoResolver} implementation for static shard configuration based on ShardManager. Unlike the full
  22  * {@link ModuleShardBackendResolver}, this resolver is used in situations where the client corresponds exactly to one
  23  * backend shard, e.g. there is only one fixed cookie assigned and the operation path is not consulted at all. This
  24  * class is thread-safe.
  25  *
  26  * @author Robert Varga
  27  */
  28 final class SimpleShardBackendResolver extends AbstractShardBackendResolver {
  29     private static final Logger LOG = LoggerFactory.getLogger(SimpleShardBackendResolver.class);
  30
  31     private final String shardName;
  32
  33     private volatile ShardState state;
  34
  35     // FIXME: we really need just ActorContext.findPrimaryShardAsync()
  36     SimpleShardBackendResolver(final ClientIdentifier clientId, final ActorUtils actorUtils,
  37             final String shardName) {
  38         super(clientId, actorUtils);
  39         this.shardName = requireNonNull(shardName);
  40     }
  41
  42     private CompletionStage<ShardBackendInfo> getBackendInfo(final long cookie) {
  43         checkArgument(cookie == 0);
  44
  45         final ShardState existing = state;
  46         if (existing != null) {
  47             return existing.getStage();
  48         }
  49
  50         synchronized (this) {
  51             final ShardState recheck = state;
  52             if (recheck != null) {
  53                 return recheck.getStage();
  54             }
  55
  56             final ShardState newState = resolveBackendInfo(shardName, 0);
  57             state = newState;
  58
  59             final CompletionStage<ShardBackendInfo> stage = newState.getStage();
  60             stage.whenComplete((info, failure) -> {
  61                 if (failure != null) {
  62                     synchronized (SimpleShardBackendResolver.this) {
  63                         if (state == newState) {
  64                             state = null;
  65                         }
  66                     }
  67                 }
  68             });
  69
  70             return stage;
  71         }
  72     }
  73
  74     @Override
  75     public CompletionStage<ShardBackendInfo> getBackendInfo(final Long cookie) {
  76         return getBackendInfo(cookie.longValue());
  77     }
  78
  79     @Override
  80     public CompletionStage<? extends ShardBackendInfo> refreshBackendInfo(final Long cookie,
  81             final ShardBackendInfo staleInfo) {
  82
  83         final ShardState existing = state;
  84         if (existing != null) {
  85             if (!staleInfo.equals(existing.getResult())) {
  86                 return existing.getStage();
  87             }
  88
  89             synchronized (this) {
  90                 LOG.debug("Invalidating backend information {}", staleInfo);
  91                 flushCache(shardName);
  92                 LOG.trace("Invalidated cache {}", staleInfo);
  93                 state = null;
  94             }
  95         }
  96
  97         return getBackendInfo(cookie);
  98     }
  99
 100     @Override
 101     public String resolveCookieName(Long cookie) {
 102         return shardName;
 103     }
 104 }