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 javax.annotation.concurrent.ThreadSafe;
  15 import org.opendaylight.controller.cluster.access.client.BackendInfoResolver;
  16 import org.opendaylight.controller.cluster.access.concepts.ClientIdentifier;
  17 import org.opendaylight.controller.cluster.datastore.utils.ActorUtils;
  18 import org.slf4j.Logger;
  19 import org.slf4j.LoggerFactory;
  20
  21 /**
  22  * {@link BackendInfoResolver} implementation for static shard configuration based on ShardManager. Unlike the full
  23  * {@link ModuleShardBackendResolver}, this resolver is used in situations where the client corresponds exactly to one
  24  * backend shard, e.g. there is only one fixed cookie assigned and the operation path is not consulted at all.
  25  *
  26  * @author Robert Varga
  27  */
  28 @ThreadSafe
  29 final class SimpleShardBackendResolver extends AbstractShardBackendResolver {
  30     private static final Logger LOG = LoggerFactory.getLogger(SimpleShardBackendResolver.class);
  31
  32     private final String shardName;
  33
  34     private volatile ShardState state;
  35
  36     // FIXME: we really need just ActorContext.findPrimaryShardAsync()
  37     SimpleShardBackendResolver(final ClientIdentifier clientId, final ActorUtils actorUtils,
  38             final String shardName) {
  39         super(clientId, actorUtils);
  40         this.shardName = requireNonNull(shardName);
  41     }
  42
  43     private CompletionStage<ShardBackendInfo> getBackendInfo(final long cookie) {
  44         checkArgument(cookie == 0);
  45
  46         final ShardState existing = state;
  47         if (existing != null) {
  48             return existing.getStage();
  49         }
  50
  51         synchronized (this) {
  52             final ShardState recheck = state;
  53             if (recheck != null) {
  54                 return recheck.getStage();
  55             }
  56
  57             final ShardState newState = resolveBackendInfo(shardName, 0);
  58             state = newState;
  59
  60             final CompletionStage<ShardBackendInfo> stage = newState.getStage();
  61             stage.whenComplete((info, failure) -> {
  62                 if (failure != null) {
  63                     synchronized (SimpleShardBackendResolver.this) {
  64                         if (state == newState) {
  65                             state = null;
  66                         }
  67                     }
  68                 }
  69             });
  70
  71             return stage;
  72         }
  73     }
  74
  75     @Override
  76     public CompletionStage<ShardBackendInfo> getBackendInfo(final Long cookie) {
  77         return getBackendInfo(cookie.longValue());
  78     }
  79
  80     @Override
  81     public CompletionStage<? extends ShardBackendInfo> refreshBackendInfo(final Long cookie,
  82             final ShardBackendInfo staleInfo) {
  83
  84         final ShardState existing = state;
  85         if (existing != null) {
  86             if (!staleInfo.equals(existing.getResult())) {
  87                 return existing.getStage();
  88             }
  89
  90             synchronized (this) {
  91                 LOG.debug("Invalidating backend information {}", staleInfo);
  92                 flushCache(shardName);
  93                 LOG.trace("Invalidated cache {}", staleInfo);
  94                 state = null;
  95             }
  96         }
  97
  98         return getBackendInfo(cookie);
  99     }
 100
 101     @Override
 102     public String resolveCookieName(Long cookie) {
 103         return shardName;
 104     }
 105 }