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 com.google.common.base.Verify.verifyNotNull;
  11
  12 import akka.dispatch.ExecutionContexts;
  13 import akka.dispatch.OnComplete;
  14 import akka.pattern.Patterns;
  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 = Patterns.ask(actorUtils.getShardManager(),
  62             new RegisterForShardAvailabilityChanges(this::onShardAvailabilityChange),
  63             Timeout.apply(60, TimeUnit.MINUTES))
  64                 .map(reply -> (Registration)reply, ExecutionContexts.global());
  65
  66         shardAvailabilityChangesRegFuture.onComplete(new OnComplete<Registration>() {
  67             @Override
  68             public void onComplete(final Throwable failure, final Registration reply) {
  69                 if (failure != null) {
  70                     LOG.error("RegisterForShardAvailabilityChanges failed", failure);
  71                 }
  72             }
  73         }, ExecutionContexts.global());
  74     }
  75
  76     private void onShardAvailabilityChange(final String shardName) {
  77         LOG.debug("onShardAvailabilityChange for {}", shardName);
  78
  79         Long cookie = shards.get(shardName);
  80         if (cookie == null) {
  81             LOG.debug("No shard cookie found for {}", shardName);
  82             return;
  83         }
  84
  85         notifyStaleBackendInfoCallbacks(cookie);
  86     }
  87
  88     Long resolveShardForPath(final YangInstanceIdentifier path) {
  89         return resolveCookie(actorUtils().getShardStrategyFactory().getStrategy(path).findShard(path));
  90     }
  91
  92     Stream<Long> resolveAllShards() {
  93         return actorUtils().getConfiguration().getAllShardNames().stream()
  94             .sorted()
  95             .map(this::resolveCookie);
  96     }
  97
  98     private @NonNull Long resolveCookie(final String shardName) {
  99         final Long cookie = shards.get(shardName);
 100         return cookie != null ? cookie : populateShard(shardName);
 101     }
 102
 103     private synchronized @NonNull Long populateShard(final String shardName) {
 104         Long cookie = shards.get(shardName);
 105         if (cookie == null) {
 106             cookie = nextShard++;
 107             shards = ImmutableBiMap.<String, Long>builder().putAll(shards).put(shardName, cookie).build();
 108         }
 109         return cookie;
 110     }
 111
 112     @Override
 113     public CompletionStage<ShardBackendInfo> getBackendInfo(final Long cookie) {
 114         /*
 115          * We cannot perform a simple computeIfAbsent() here because we need to control sequencing of when the state
 116          * is inserted into the map and retired from it (based on the stage result).
 117          *
 118          * We do not want to hook another stage one processing completes and hooking a removal on failure from a compute
 119          * method runs the inherent risk of stage completing before the insertion does (i.e. we have a removal of
 120          * non-existent element.
 121          */
 122         final ShardState existing = backends.get(cookie);
 123         if (existing != null) {
 124             return existing.getStage();
 125         }
 126
 127         final String shardName = shards.inverse().get(cookie);
 128         if (shardName == null) {
 129             LOG.warn("Failing request for non-existent cookie {}", cookie);
 130             throw new IllegalArgumentException("Cookie " + cookie + " does not have a shard assigned");
 131         }
 132
 133         LOG.debug("Resolving cookie {} to shard {}", cookie, shardName);
 134         final ShardState toInsert = resolveBackendInfo(shardName, cookie);
 135
 136         final ShardState raced = backends.putIfAbsent(cookie, toInsert);
 137         if (raced != null) {
 138             // We have had a concurrent insertion, return that
 139             LOG.debug("Race during insertion of state for cookie {} shard {}", cookie, shardName);
 140             return raced.getStage();
 141         }
 142
 143         // We have succeeded in populating the map, now we need to take care of pruning the entry if it fails to
 144         // complete
 145         final CompletionStage<ShardBackendInfo> stage = toInsert.getStage();
 146         stage.whenComplete((info, failure) -> {
 147             if (failure != null) {
 148                 LOG.debug("Resolution of cookie {} shard {} failed, removing state", cookie, shardName, failure);
 149                 backends.remove(cookie, toInsert);
 150
 151                 // Remove cache state in case someone else forgot to invalidate it
 152                 flushCache(shardName);
 153             }
 154         });
 155
 156         return stage;
 157     }
 158
 159     @Override
 160     public CompletionStage<ShardBackendInfo> refreshBackendInfo(final Long cookie,
 161             final ShardBackendInfo staleInfo) {
 162         final ShardState existing = backends.get(cookie);
 163         if (existing != null) {
 164             if (!staleInfo.equals(existing.getResult())) {
 165                 return existing.getStage();
 166             }
 167
 168             LOG.debug("Invalidating backend information {}", staleInfo);
 169             flushCache(staleInfo.getName());
 170
 171             LOG.trace("Invalidated cache {}", staleInfo);
 172             backends.remove(cookie, existing);
 173         }
 174
 175         return getBackendInfo(cookie);
 176     }
 177
 178     @Override
 179     public void close() {
 180         shardAvailabilityChangesRegFuture.onComplete(new OnComplete<Registration>() {
 181             @Override
 182             public void onComplete(final Throwable failure, final Registration reply) {
 183                 reply.close();
 184             }
 185         }, ExecutionContexts.global());
 186     }
 187
 188     @Override
 189     public String resolveCookieName(final Long cookie) {
 190         return verifyNotNull(shards.inverse().get(cookie), "Unexpected null cookie: %s", cookie);
 191     }
 192 }