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 org.checkerframework.checker.lock.qual.GuardedBy;
  22 import org.eclipse.jdt.annotation.NonNull;
  23 import org.opendaylight.controller.cluster.access.client.BackendInfoResolver;
  24 import org.opendaylight.controller.cluster.access.concepts.ClientIdentifier;
  25 import org.opendaylight.controller.cluster.datastore.shardmanager.RegisterForShardAvailabilityChanges;
  26 import org.opendaylight.controller.cluster.datastore.shardstrategy.DefaultShardStrategy;
  27 import org.opendaylight.controller.cluster.datastore.utils.ActorUtils;
  28 import org.opendaylight.yangtools.concepts.Registration;
  29 import org.opendaylight.yangtools.yang.data.api.YangInstanceIdentifier;
  30 import org.slf4j.Logger;
  31 import org.slf4j.LoggerFactory;
  32 import scala.concurrent.Future;
  33
  34 /**
  35  * {@link BackendInfoResolver} implementation for static shard configuration based on ShardManager. Each string-named
  36  * shard is assigned a single cookie and this mapping is stored in a bidirectional map. Information about corresponding
  37  * shard leader is resolved via {@link ActorUtils}. The product of resolution is {@link ShardBackendInfo}.
  38  *
  39  * <p>
  40  * This class is thread-safe.
  41  *
  42  * @author Robert Varga
  43  */
  44 final class ModuleShardBackendResolver extends AbstractShardBackendResolver {
  45     private static final Logger LOG = LoggerFactory.getLogger(ModuleShardBackendResolver.class);
  46
  47     private final ConcurrentMap<Long, ShardState> backends = new ConcurrentHashMap<>();
  48
  49     private final Future<Registration> shardAvailabilityChangesRegFuture;
  50
  51     @GuardedBy("this")
  52     private long nextShard = 1;
  53
  54     private volatile ImmutableBiMap<String, Long> shards = ImmutableBiMap.of(DefaultShardStrategy.DEFAULT_SHARD, 0L);
  55
  56     // FIXME: we really need just ActorContext.findPrimaryShardAsync()
  57     ModuleShardBackendResolver(final ClientIdentifier clientId, final ActorUtils actorUtils) {
  58         super(clientId, actorUtils);
  59
  60         shardAvailabilityChangesRegFuture = ask(actorUtils.getShardManager(), new RegisterForShardAvailabilityChanges(
  61             this::onShardAvailabilityChange), Timeout.apply(60, TimeUnit.MINUTES))
  62                 .map(reply -> (Registration)reply, ExecutionContexts.global());
  63
  64         shardAvailabilityChangesRegFuture.onComplete(new OnComplete<Registration>() {
  65             @Override
  66             public void onComplete(final Throwable failure, final Registration reply) {
  67                 if (failure != null) {
  68                     LOG.error("RegisterForShardAvailabilityChanges failed", failure);
  69                 }
  70             }
  71         }, ExecutionContexts.global());
  72     }
  73
  74     private void onShardAvailabilityChange(final String shardName) {
  75         LOG.debug("onShardAvailabilityChange for {}", shardName);
  76
  77         Long cookie = shards.get(shardName);
  78         if (cookie == null) {
  79             LOG.debug("No shard cookie found for {}", shardName);
  80             return;
  81         }
  82
  83         notifyStaleBackendInfoCallbacks(cookie);
  84     }
  85
  86     Long resolveShardForPath(final YangInstanceIdentifier path) {
  87         final String shardName = actorUtils().getShardStrategyFactory().getStrategy(path).findShard(path);
  88         final Long cookie = shards.get(shardName);
  89         return cookie != null ? cookie : populateShard(shardName);
  90     }
  91
  92     private synchronized @NonNull Long populateShard(final String shardName) {
  93         Long cookie = shards.get(shardName);
  94         if (cookie == null) {
  95             cookie = nextShard++;
  96             shards = ImmutableBiMap.<String, Long>builder().putAll(shards).put(shardName, cookie).build();
  97         }
  98         return cookie;
  99     }
 100
 101     @Override
 102     public CompletionStage<ShardBackendInfo> getBackendInfo(final Long cookie) {
 103         /*
 104          * We cannot perform a simple computeIfAbsent() here because we need to control sequencing of when the state
 105          * is inserted into the map and retired from it (based on the stage result).
 106          *
 107          * We do not want to hook another stage one processing completes and hooking a removal on failure from a compute
 108          * method runs the inherent risk of stage completing before the insertion does (i.e. we have a removal of
 109          * non-existent element.
 110          */
 111         final ShardState existing = backends.get(cookie);
 112         if (existing != null) {
 113             return existing.getStage();
 114         }
 115
 116         final String shardName = shards.inverse().get(cookie);
 117         if (shardName == null) {
 118             LOG.warn("Failing request for non-existent cookie {}", cookie);
 119             throw new IllegalArgumentException("Cookie " + cookie + " does not have a shard assigned");
 120         }
 121
 122         LOG.debug("Resolving cookie {} to shard {}", cookie, shardName);
 123         final ShardState toInsert = resolveBackendInfo(shardName, cookie);
 124
 125         final ShardState raced = backends.putIfAbsent(cookie, toInsert);
 126         if (raced != null) {
 127             // We have had a concurrent insertion, return that
 128             LOG.debug("Race during insertion of state for cookie {} shard {}", cookie, shardName);
 129             return raced.getStage();
 130         }
 131
 132         // We have succeeded in populating the map, now we need to take care of pruning the entry if it fails to
 133         // complete
 134         final CompletionStage<ShardBackendInfo> stage = toInsert.getStage();
 135         stage.whenComplete((info, failure) -> {
 136             if (failure != null) {
 137                 LOG.debug("Resolution of cookie {} shard {} failed, removing state", cookie, shardName, failure);
 138                 backends.remove(cookie, toInsert);
 139
 140                 // Remove cache state in case someone else forgot to invalidate it
 141                 flushCache(shardName);
 142             }
 143         });
 144
 145         return stage;
 146     }
 147
 148     @Override
 149     public CompletionStage<ShardBackendInfo> refreshBackendInfo(final Long cookie,
 150             final ShardBackendInfo staleInfo) {
 151         final ShardState existing = backends.get(cookie);
 152         if (existing != null) {
 153             if (!staleInfo.equals(existing.getResult())) {
 154                 return existing.getStage();
 155             }
 156
 157             LOG.debug("Invalidating backend information {}", staleInfo);
 158             flushCache(staleInfo.getName());
 159
 160             LOG.trace("Invalidated cache {}", staleInfo);
 161             backends.remove(cookie, existing);
 162         }
 163
 164         return getBackendInfo(cookie);
 165     }
 166
 167     @Override
 168     public void close() {
 169         shardAvailabilityChangesRegFuture.onComplete(new OnComplete<Registration>() {
 170             @Override
 171             public void onComplete(final Throwable failure, final Registration reply) {
 172                 reply.close();
 173             }
 174         }, ExecutionContexts.global());
 175     }
 176
 177     @Override
 178     public String resolveCookieName(final Long cookie) {
 179         return verifyNotNull(shards.inverse().get(cookie), "Unexpected null cookie: %s", cookie);
 180     }
 181 }