opendaylight/md-sal/sal-distributed-datastore/src/main/java/org/opendaylight/controller/cluster/datastore/jmx/mbeans/shard/OnDemandShardStateCache.java

   1 /*
   2  * Copyright (c) 2017 Inocybe Technologies 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.datastore.jmx.mbeans.shard;
   9
  10 import akka.actor.ActorRef;
  11 import akka.pattern.Patterns;
  12 import akka.util.Timeout;
  13 import com.google.common.base.Preconditions;
  14 import com.google.common.base.Stopwatch;
  15 import com.google.common.base.Throwables;
  16 import com.google.common.cache.Cache;
  17 import com.google.common.cache.CacheBuilder;
  18 import com.google.common.util.concurrent.ExecutionError;
  19 import com.google.common.util.concurrent.UncheckedExecutionException;
  20 import java.util.concurrent.ExecutionException;
  21 import java.util.concurrent.TimeUnit;
  22 import org.opendaylight.controller.cluster.datastore.messages.OnDemandShardState;
  23 import org.opendaylight.controller.cluster.raft.client.messages.GetOnDemandRaftState;
  24 import scala.concurrent.Await;
  25
  26 /**
  27  * Maintains a short-lived shared cache of OnDemandShardState.
  28  *
  29  * @author Thomas Pantelis
  30  */
  31 class OnDemandShardStateCache {
  32     private static final Cache<String, OnDemandShardState> ONDEMAND_SHARD_STATE_CACHE =
  33             CacheBuilder.newBuilder().expireAfterWrite(2, TimeUnit.SECONDS).build();
  34
  35     private final ActorRef shardActor;
  36     private final String shardName;
  37     private volatile String stateRetrievalTime;
  38
  39     OnDemandShardStateCache(String shardName, ActorRef shardActor) {
  40         this.shardName = Preconditions.checkNotNull(shardName);
  41         this.shardActor = shardActor;
  42     }
  43
  44     OnDemandShardState get() throws Exception {
  45         if (shardActor == null) {
  46             return OnDemandShardState.newBuilder().build();
  47         }
  48
  49         try {
  50             return ONDEMAND_SHARD_STATE_CACHE.get(shardName, this::retrieveState);
  51         } catch (ExecutionException | UncheckedExecutionException | ExecutionError e) {
  52             if (e.getCause() != null) {
  53                 Throwables.propagateIfPossible(e.getCause(), Exception.class);
  54                 throw new RuntimeException("unexpected", e.getCause());
  55             }
  56
  57             throw e;
  58         }
  59     }
  60
  61     String getStatRetrievaelTime() {
  62         return stateRetrievalTime;
  63     }
  64
  65     private OnDemandShardState retrieveState() throws Exception {
  66         stateRetrievalTime = null;
  67         Timeout timeout = new Timeout(10, TimeUnit.SECONDS);
  68         Stopwatch timer = Stopwatch.createStarted();
  69
  70         OnDemandShardState state = (OnDemandShardState) Await.result(Patterns.ask(shardActor,
  71                 GetOnDemandRaftState.INSTANCE, timeout), timeout.duration());
  72
  73         stateRetrievalTime = timer.stop().toString();
  74         return state;
  75     }
  76 }