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.BiMap;
  17 import com.google.common.collect.ImmutableBiMap;
  18 import com.google.common.collect.ImmutableBiMap.Builder;
  19 import java.util.concurrent.CompletionStage;
  20 import java.util.concurrent.ConcurrentHashMap;
  21 import java.util.concurrent.ConcurrentMap;
  22 import java.util.concurrent.TimeUnit;
  23 import org.checkerframework.checker.lock.qual.GuardedBy;
  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 BiMap<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(Throwable failure, Registration reply) {
  68                 if (failure != null) {
  69                     LOG.error("RegisterForShardAvailabilityChanges failed", failure);
  70                 }
  71             }
  72         }, ExecutionContexts.global());
  73     }
  74
  75     private void onShardAvailabilityChange(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         final String shardName = actorUtils().getShardStrategyFactory().getStrategy(path).findShard(path);
  89         Long cookie = shards.get(shardName);
  90         if (cookie == null) {
  91             synchronized (this) {
  92                 cookie = shards.get(shardName);
  93                 if (cookie == null) {
  94                     cookie = nextShard++;
  95
  96                     Builder<String, Long> builder = ImmutableBiMap.builder();
  97                     builder.putAll(shards);
  98                     builder.put(shardName, cookie);
  99                     shards = builder.build();
 100                 }
 101             }
 102         }
 103
 104         return cookie;
 105     }
 106
 107     @Override
 108     public CompletionStage<ShardBackendInfo> getBackendInfo(final Long cookie) {
 109         /*
 110          * We cannot perform a simple computeIfAbsent() here because we need to control sequencing of when the state
 111          * is inserted into the map and retired from it (based on the stage result).
 112          *
 113          * We do not want to hook another stage one processing completes and hooking a removal on failure from a compute
 114          * method runs the inherent risk of stage completing before the insertion does (i.e. we have a removal of
 115          * non-existent element.
 116          */
 117         final ShardState existing = backends.get(cookie);
 118         if (existing != null) {
 119             return existing.getStage();
 120         }
 121
 122         final String shardName = shards.inverse().get(cookie);
 123         if (shardName == null) {
 124             LOG.warn("Failing request for non-existent cookie {}", cookie);
 125             throw new IllegalArgumentException("Cookie " + cookie + " does not have a shard assigned");
 126         }
 127
 128         LOG.debug("Resolving cookie {} to shard {}", cookie, shardName);
 129         final ShardState toInsert = resolveBackendInfo(shardName, cookie);
 130
 131         final ShardState raced = backends.putIfAbsent(cookie, toInsert);
 132         if (raced != null) {
 133             // We have had a concurrent insertion, return that
 134             LOG.debug("Race during insertion of state for cookie {} shard {}", cookie, shardName);
 135             return raced.getStage();
 136         }
 137
 138         // We have succeeded in populating the map, now we need to take care of pruning the entry if it fails to
 139         // complete
 140         final CompletionStage<ShardBackendInfo> stage = toInsert.getStage();
 141         stage.whenComplete((info, failure) -> {
 142             if (failure != null) {
 143                 LOG.debug("Resolution of cookie {} shard {} failed, removing state", cookie, shardName, failure);
 144                 backends.remove(cookie, toInsert);
 145
 146                 // Remove cache state in case someone else forgot to invalidate it
 147                 flushCache(shardName);
 148             }
 149         });
 150
 151         return stage;
 152     }
 153
 154     @Override
 155     public CompletionStage<ShardBackendInfo> refreshBackendInfo(final Long cookie,
 156             final ShardBackendInfo staleInfo) {
 157         final ShardState existing = backends.get(cookie);
 158         if (existing != null) {
 159             if (!staleInfo.equals(existing.getResult())) {
 160                 return existing.getStage();
 161             }
 162
 163             LOG.debug("Invalidating backend information {}", staleInfo);
 164             flushCache(staleInfo.getName());
 165
 166             LOG.trace("Invalidated cache {}", staleInfo);
 167             backends.remove(cookie, existing);
 168         }
 169
 170         return getBackendInfo(cookie);
 171     }
 172
 173     @Override
 174     public void close() {
 175         shardAvailabilityChangesRegFuture.onComplete(new OnComplete<Registration>() {
 176             @Override
 177             public void onComplete(Throwable failure, Registration reply) {
 178                 reply.close();
 179             }
 180         }, ExecutionContexts.global());
 181     }
 182
 183     @Override
 184     public String resolveCookieName(Long cookie) {
 185         return verifyNotNull(shards.inverse().get(cookie), "Unexpected null cookie: %s", cookie);
 186     }
 187 }