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 import static com.google.common.base.Verify.verifyNotNull;
  12
  13 import akka.dispatch.ExecutionContexts;
  14 import akka.dispatch.OnComplete;
  15 import akka.util.Timeout;
  16 import com.google.common.collect.ImmutableBiMap;
  17 import java.util.concurrent.CompletionStage;
  18 import java.util.concurrent.ConcurrentHashMap;
  19 import java.util.concurrent.ConcurrentMap;
  20 import java.util.concurrent.TimeUnit;
  21 import java.util.stream.Stream;
  22 import org.checkerframework.checker.lock.qual.GuardedBy;
  23 import org.eclipse.jdt.annotation.NonNull;
  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.ActorUtils;
  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 ActorUtils}. The product of resolution is {@link ShardBackendInfo}.
  39  *
  40  * <p>
  41  * This class is thread-safe.
  42  *
  43  * @author Robert Varga
  44  */
  45 final class ModuleShardBackendResolver extends AbstractShardBackendResolver {
  46     private static final Logger LOG = LoggerFactory.getLogger(ModuleShardBackendResolver.class);
  47
  48     private final ConcurrentMap<Long, ShardState> backends = new ConcurrentHashMap<>();
  49
  50     private final Future<Registration> shardAvailabilityChangesRegFuture;
  51
  52     @GuardedBy("this")
  53     private long nextShard = 1;
  54
  55     private volatile ImmutableBiMap<String, Long> shards = ImmutableBiMap.of(DefaultShardStrategy.DEFAULT_SHARD, 0L);
  56
  57     // FIXME: we really need just ActorContext.findPrimaryShardAsync()
  58     ModuleShardBackendResolver(final ClientIdentifier clientId, final ActorUtils actorUtils) {
  59         super(clientId, actorUtils);
  60
  61         shardAvailabilityChangesRegFuture = ask(actorUtils.getShardManager(), new RegisterForShardAvailabilityChanges(
  62             this::onShardAvailabilityChange), Timeout.apply(60, TimeUnit.MINUTES))
  63                 .map(reply -> (Registration)reply, ExecutionContexts.global());
  64
  65         shardAvailabilityChangesRegFuture.onComplete(new OnComplete<Registration>() {
  66             @Override
  67             public void onComplete(final Throwable failure, final Registration reply) {
  68                 if (failure != null) {
  69                     LOG.error("RegisterForShardAvailabilityChanges failed", failure);
  70                 }
  71             }
  72         }, ExecutionContexts.global());
  73     }
  74
  75     private void onShardAvailabilityChange(final String shardName) {
  76         LOG.debug("onShardAvailabilityChange for {}", shardName);
  77
  78         Long cookie = shards.get(shardName);
  79         if (cookie == null) {
  80             LOG.debug("No shard cookie found for {}", shardName);
  81             return;
  82         }
  83
  84         notifyStaleBackendInfoCallbacks(cookie);
  85     }
  86
  87     Long resolveShardForPath(final YangInstanceIdentifier path) {
  88         return resolveCookie(actorUtils().getShardStrategyFactory().getStrategy(path).findShard(path));
  89     }
  90
  91     Stream<Long> resolveAllShards() {
  92         return actorUtils().getConfiguration().getAllShardNames().stream()
  93             .sorted()
  94             .map(this::resolveCookie);
  95     }
  96
  97     private @NonNull Long resolveCookie(final String shardName) {
  98         final Long cookie = shards.get(shardName);
  99         return cookie != null ? cookie : populateShard(shardName);
 100     }
 101
 102     private synchronized @NonNull Long populateShard(final String shardName) {
 103         Long cookie = shards.get(shardName);
 104         if (cookie == null) {
 105             cookie = nextShard++;
 106             shards = ImmutableBiMap.<String, Long>builder().putAll(shards).put(shardName, cookie).build();
 107         }
 108         return cookie;
 109     }
 110
 111     @Override
 112     public CompletionStage<ShardBackendInfo> getBackendInfo(final Long cookie) {
 113         /*
 114          * We cannot perform a simple computeIfAbsent() here because we need to control sequencing of when the state
 115          * is inserted into the map and retired from it (based on the stage result).
 116          *
 117          * We do not want to hook another stage one processing completes and hooking a removal on failure from a compute
 118          * method runs the inherent risk of stage completing before the insertion does (i.e. we have a removal of
 119          * non-existent element.
 120          */
 121         final ShardState existing = backends.get(cookie);
 122         if (existing != null) {
 123             return existing.getStage();
 124         }
 125
 126         final String shardName = shards.inverse().get(cookie);
 127         if (shardName == null) {
 128             LOG.warn("Failing request for non-existent cookie {}", cookie);
 129             throw new IllegalArgumentException("Cookie " + cookie + " does not have a shard assigned");
 130         }
 131
 132         LOG.debug("Resolving cookie {} to shard {}", cookie, shardName);
 133         final ShardState toInsert = resolveBackendInfo(shardName, cookie);
 134
 135         final ShardState raced = backends.putIfAbsent(cookie, toInsert);
 136         if (raced != null) {
 137             // We have had a concurrent insertion, return that
 138             LOG.debug("Race during insertion of state for cookie {} shard {}", cookie, shardName);
 139             return raced.getStage();
 140         }
 141
 142         // We have succeeded in populating the map, now we need to take care of pruning the entry if it fails to
 143         // complete
 144         final CompletionStage<ShardBackendInfo> stage = toInsert.getStage();
 145         stage.whenComplete((info, failure) -> {
 146             if (failure != null) {
 147                 LOG.debug("Resolution of cookie {} shard {} failed, removing state", cookie, shardName, failure);
 148                 backends.remove(cookie, toInsert);
 149
 150                 // Remove cache state in case someone else forgot to invalidate it
 151                 flushCache(shardName);
 152             }
 153         });
 154
 155         return stage;
 156     }
 157
 158     @Override
 159     public CompletionStage<ShardBackendInfo> refreshBackendInfo(final Long cookie,
 160             final ShardBackendInfo staleInfo) {
 161         final ShardState existing = backends.get(cookie);
 162         if (existing != null) {
 163             if (!staleInfo.equals(existing.getResult())) {
 164                 return existing.getStage();
 165             }
 166
 167             LOG.debug("Invalidating backend information {}", staleInfo);
 168             flushCache(staleInfo.getName());
 169
 170             LOG.trace("Invalidated cache {}", staleInfo);
 171             backends.remove(cookie, existing);
 172         }
 173
 174         return getBackendInfo(cookie);
 175     }
 176
 177     @Override
 178     public void close() {
 179         shardAvailabilityChangesRegFuture.onComplete(new OnComplete<Registration>() {
 180             @Override
 181             public void onComplete(final Throwable failure, final Registration reply) {
 182                 reply.close();
 183             }
 184         }, ExecutionContexts.global());
 185     }
 186
 187     @Override
 188     public String resolveCookieName(final Long cookie) {
 189         return verifyNotNull(shards.inverse().get(cookie), "Unexpected null cookie: %s", cookie);
 190     }
 191 }