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 javax.annotation.concurrent.GuardedBy;
  24 import javax.annotation.concurrent.ThreadSafe;
  25 import org.opendaylight.controller.cluster.access.client.BackendInfoResolver;
  26 import org.opendaylight.controller.cluster.access.concepts.ClientIdentifier;
  27 import org.opendaylight.controller.cluster.datastore.shardmanager.RegisterForShardAvailabilityChanges;
  28 import org.opendaylight.controller.cluster.datastore.shardstrategy.DefaultShardStrategy;
  29 import org.opendaylight.controller.cluster.datastore.utils.ActorContext;
  30 import org.opendaylight.yangtools.concepts.Registration;
  31 import org.opendaylight.yangtools.yang.data.api.YangInstanceIdentifier;
  32 import org.slf4j.Logger;
  33 import org.slf4j.LoggerFactory;
  34 import scala.concurrent.Future;
  35
  36 /**
  37  * {@link BackendInfoResolver} implementation for static shard configuration based on ShardManager. Each string-named
  38  * shard is assigned a single cookie and this mapping is stored in a bidirectional map. Information about corresponding
  39  * shard leader is resolved via {@link ActorContext}. The product of resolution is {@link ShardBackendInfo}.
  40  *
  41  * @author Robert Varga
  42  */
  43 @ThreadSafe
  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 BiMap<String, Long> shards = ImmutableBiMap.of(DefaultShardStrategy.DEFAULT_SHARD, 0L);
  55
  56     // FIXME: we really need just ActorContext.findPrimaryShardAsync()
  57     ModuleShardBackendResolver(final ClientIdentifier clientId, final ActorContext actorContext) {
  58         super(clientId, actorContext);
  59
  60         shardAvailabilityChangesRegFuture = ask(actorContext.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(Throwable failure, Registration reply) {
  67                 if (failure != null) {
  68                     LOG.error("RegisterForShardAvailabilityChanges failed", failure);
  69                 }
  70             }
  71         }, ExecutionContexts.global());
  72     }
  73
  74     private void onShardAvailabilityChange(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 = actorContext().getShardStrategyFactory().getStrategy(path).findShard(path);
  88         Long cookie = shards.get(shardName);
  89         if (cookie == null) {
  90             synchronized (this) {
  91                 cookie = shards.get(shardName);
  92                 if (cookie == null) {
  93                     cookie = nextShard++;
  94
  95                     Builder<String, Long> builder = ImmutableBiMap.builder();
  96                     builder.putAll(shards);
  97                     builder.put(shardName, cookie);
  98                     shards = builder.build();
  99                 }
 100             }
 101         }
 102
 103         return cookie;
 104     }
 105
 106     @Override
 107     public CompletionStage<ShardBackendInfo> getBackendInfo(final Long cookie) {
 108         /*
 109          * We cannot perform a simple computeIfAbsent() here because we need to control sequencing of when the state
 110          * is inserted into the map and retired from it (based on the stage result).
 111          *
 112          * We do not want to hook another stage one processing completes and hooking a removal on failure from a compute
 113          * method runs the inherent risk of stage completing before the insertion does (i.e. we have a removal of
 114          * non-existent element.
 115          */
 116         final ShardState existing = backends.get(cookie);
 117         if (existing != null) {
 118             return existing.getStage();
 119         }
 120
 121         final String shardName = shards.inverse().get(cookie);
 122         if (shardName == null) {
 123             LOG.warn("Failing request for non-existent cookie {}", cookie);
 124             throw new IllegalArgumentException("Cookie " + cookie + " does not have a shard assigned");
 125         }
 126
 127         LOG.debug("Resolving cookie {} to shard {}", cookie, shardName);
 128         final ShardState toInsert = resolveBackendInfo(shardName, cookie);
 129
 130         final ShardState raced = backends.putIfAbsent(cookie, toInsert);
 131         if (raced != null) {
 132             // We have had a concurrent insertion, return that
 133             LOG.debug("Race during insertion of state for cookie {} shard {}", cookie, shardName);
 134             return raced.getStage();
 135         }
 136
 137         // We have succeeded in populating the map, now we need to take care of pruning the entry if it fails to
 138         // complete
 139         final CompletionStage<ShardBackendInfo> stage = toInsert.getStage();
 140         stage.whenComplete((info, failure) -> {
 141             if (failure != null) {
 142                 LOG.debug("Resolution of cookie {} shard {} failed, removing state", cookie, shardName, failure);
 143                 backends.remove(cookie, toInsert);
 144
 145                 // Remove cache state in case someone else forgot to invalidate it
 146                 flushCache(shardName);
 147             }
 148         });
 149
 150         return stage;
 151     }
 152
 153     @Override
 154     public CompletionStage<ShardBackendInfo> refreshBackendInfo(final Long cookie,
 155             final ShardBackendInfo staleInfo) {
 156         final ShardState existing = backends.get(cookie);
 157         if (existing != null) {
 158             if (!staleInfo.equals(existing.getResult())) {
 159                 return existing.getStage();
 160             }
 161
 162             LOG.debug("Invalidating backend information {}", staleInfo);
 163             flushCache(staleInfo.getName());
 164
 165             LOG.trace("Invalidated cache {}", staleInfo);
 166             backends.remove(cookie, existing);
 167         }
 168
 169         return getBackendInfo(cookie);
 170     }
 171
 172     @Override
 173     public void close() {
 174         shardAvailabilityChangesRegFuture.onComplete(new OnComplete<Registration>() {
 175             @Override
 176             public void onComplete(Throwable failure, Registration reply) {
 177                 reply.close();
 178             }
 179         }, ExecutionContexts.global());
 180     }
 181
 182     @Override
 183     public String resolveCookieName(Long cookie) {
 184         return verifyNotNull(shards.inverse().get(cookie), "Unexpected null cookie: %s", cookie);
 185     }
 186 }