opendaylight/md-sal/sal-distributed-datastore/src/main/java/org/opendaylight/controller/cluster/databroker/actors/dds/ModuleShardBackendResolver.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 akka.pattern.Patterns.ask;
  11
  12 import akka.dispatch.ExecutionContexts;
  13 import akka.dispatch.OnComplete;
  14 import akka.util.Timeout;
  15 import com.google.common.collect.BiMap;
  16 import com.google.common.collect.ImmutableBiMap;
  17 import com.google.common.collect.ImmutableBiMap.Builder;
  18 import java.util.concurrent.CompletionStage;
  19 import java.util.concurrent.ConcurrentHashMap;
  20 import java.util.concurrent.ConcurrentMap;
  21 import java.util.concurrent.TimeUnit;
  22 import javax.annotation.concurrent.GuardedBy;
  23 import javax.annotation.concurrent.ThreadSafe;
  24 import org.opendaylight.controller.cluster.access.client.BackendInfoResolver;
  25 import org.opendaylight.controller.cluster.access.concepts.ClientIdentifier;
  26 import org.opendaylight.controller.cluster.datastore.shardmanager.RegisterForShardAvailabilityChanges;
  27 import org.opendaylight.controller.cluster.datastore.shardstrategy.DefaultShardStrategy;
  28 import org.opendaylight.controller.cluster.datastore.utils.ActorContext;
  29 import org.opendaylight.yangtools.concepts.Registration;
  30 import org.opendaylight.yangtools.yang.data.api.YangInstanceIdentifier;
  31 import org.slf4j.Logger;
  32 import org.slf4j.LoggerFactory;
  33 import scala.concurrent.Future;
  34
  35 /**
  36  * {@link BackendInfoResolver} implementation for static shard configuration based on ShardManager. Each string-named
  37  * shard is assigned a single cookie and this mapping is stored in a bidirectional map. Information about corresponding
  38  * shard leader is resolved via {@link ActorContext}. The product of resolution is {@link ShardBackendInfo}.
  39  *
  40  * @author Robert Varga
  41  */
  42 @ThreadSafe
  43 final class ModuleShardBackendResolver extends AbstractShardBackendResolver {
  44     private static final Logger LOG = LoggerFactory.getLogger(ModuleShardBackendResolver.class);
  45
  46     private final ConcurrentMap<Long, ShardState> backends = new ConcurrentHashMap<>();
  47
  48     private final Future<Registration> shardAvailabilityChangesRegFuture;
  49
  50     @GuardedBy("this")
  51     private long nextShard = 1;
  52
  53     private volatile BiMap<String, Long> shards = ImmutableBiMap.of(DefaultShardStrategy.DEFAULT_SHARD, 0L);
  54
  55     // FIXME: we really need just ActorContext.findPrimaryShardAsync()
  56     ModuleShardBackendResolver(final ClientIdentifier clientId, final ActorContext actorContext) {
  57         super(clientId, actorContext);
  58
  59         shardAvailabilityChangesRegFuture = ask(actorContext.getShardManager(), new RegisterForShardAvailabilityChanges(
  60             this::onShardAvailabilityChange), Timeout.apply(60, TimeUnit.MINUTES))
  61                 .map(reply -> (Registration)reply, ExecutionContexts.global());
  62
  63         shardAvailabilityChangesRegFuture.onComplete(new OnComplete<Registration>() {
  64             @Override
  65             public void onComplete(Throwable failure, Registration reply) {
  66                 if (failure != null) {
  67                     LOG.error("RegisterForShardAvailabilityChanges failed", failure);
  68                 }
  69             }
  70         }, ExecutionContexts.global());
  71     }
  72
  73     private void onShardAvailabilityChange(String shardName) {
  74         LOG.debug("onShardAvailabilityChange for {}", shardName);
  75
  76         Long cookie = shards.get(shardName);
  77         if (cookie == null) {
  78             LOG.debug("No shard cookie found for {}", shardName);
  79             return;
  80         }
  81
  82         notifyStaleBackendInfoCallbacks(cookie);
  83     }
  84
  85     Long resolveShardForPath(final YangInstanceIdentifier path) {
  86         final String shardName = actorContext().getShardStrategyFactory().getStrategy(path).findShard(path);
  87         Long cookie = shards.get(shardName);
  88         if (cookie == null) {
  89             synchronized (this) {
  90                 cookie = shards.get(shardName);
  91                 if (cookie == null) {
  92                     cookie = nextShard++;
  93
  94                     Builder<String, Long> builder = ImmutableBiMap.builder();
  95                     builder.putAll(shards);
  96                     builder.put(shardName, cookie);
  97                     shards = builder.build();
  98                 }
  99             }
 100         }
 101
 102         return cookie;
 103     }
 104
 105     @Override
 106     public CompletionStage<ShardBackendInfo> getBackendInfo(final Long cookie) {
 107         /*
 108          * We cannot perform a simple computeIfAbsent() here because we need to control sequencing of when the state
 109          * is inserted into the map and retired from it (based on the stage result).
 110          *
 111          * We do not want to hook another stage one processing completes and hooking a removal on failure from a compute
 112          * method runs the inherent risk of stage completing before the insertion does (i.e. we have a removal of
 113          * non-existent element.
 114          */
 115         final ShardState existing = backends.get(cookie);
 116         if (existing != null) {
 117             return existing.getStage();
 118         }
 119
 120         final String shardName = shards.inverse().get(cookie);
 121         if (shardName == null) {
 122             LOG.warn("Failing request for non-existent cookie {}", cookie);
 123             throw new IllegalArgumentException("Cookie " + cookie + " does not have a shard assigned");
 124         }
 125
 126         LOG.debug("Resolving cookie {} to shard {}", cookie, shardName);
 127         final ShardState toInsert = resolveBackendInfo(shardName, cookie);
 128
 129         final ShardState raced = backends.putIfAbsent(cookie, toInsert);
 130         if (raced != null) {
 131             // We have had a concurrent insertion, return that
 132             LOG.debug("Race during insertion of state for cookie {} shard {}", cookie, shardName);
 133             return raced.getStage();
 134         }
 135
 136         // We have succeeded in populating the map, now we need to take care of pruning the entry if it fails to
 137         // complete
 138         final CompletionStage<ShardBackendInfo> stage = toInsert.getStage();
 139         stage.whenComplete((info, failure) -> {
 140             if (failure != null) {
 141                 LOG.debug("Resolution of cookie {} shard {} failed, removing state", cookie, shardName, failure);
 142                 backends.remove(cookie, toInsert);
 143
 144                 // Remove cache state in case someone else forgot to invalidate it
 145                 flushCache(shardName);
 146             }
 147         });
 148
 149         return stage;
 150     }
 151
 152     @Override
 153     public CompletionStage<ShardBackendInfo> refreshBackendInfo(final Long cookie,
 154             final ShardBackendInfo staleInfo) {
 155         final ShardState existing = backends.get(cookie);
 156         if (existing != null) {
 157             if (!staleInfo.equals(existing.getResult())) {
 158                 return existing.getStage();
 159             }
 160
 161             LOG.debug("Invalidating backend information {}", staleInfo);
 162             flushCache(staleInfo.getShardName());
 163
 164             LOG.trace("Invalidated cache {}", staleInfo);
 165             backends.remove(cookie, existing);
 166         }
 167
 168         return getBackendInfo(cookie);
 169     }
 170
 171     @Override
 172     public void close() {
 173         shardAvailabilityChangesRegFuture.onComplete(new OnComplete<Registration>() {
 174             @Override
 175             public void onComplete(Throwable failure, Registration reply) {
 176                 reply.close();
 177             }
 178         }, ExecutionContexts.global());
 179     }
 180 }