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 static java.util.Objects.requireNonNull;
  11
  12 import akka.actor.ActorRef;
  13 import akka.pattern.Patterns;
  14 import akka.util.Timeout;
  15 import com.google.common.base.Stopwatch;
  16 import com.google.common.cache.Cache;
  17 import com.google.common.cache.CacheBuilder;
  18 import java.util.concurrent.TimeUnit;
  19 import org.opendaylight.controller.cluster.datastore.messages.OnDemandShardState;
  20 import org.opendaylight.controller.cluster.raft.client.messages.GetOnDemandRaftState;
  21 import scala.concurrent.Await;
  22
  23 /**
  24  * Maintains a short-lived shared cache of OnDemandShardState.
  25  *
  26  * @author Thomas Pantelis
  27  */
  28 class OnDemandShardStateCache {
  29     private static final Cache<String, OnDemandShardState> ONDEMAND_SHARD_STATE_CACHE =
  30             CacheBuilder.newBuilder().expireAfterWrite(2, TimeUnit.SECONDS).build();
  31
  32     private final ActorRef shardActor;
  33     private final String shardName;
  34     private volatile String stateRetrievalTime;
  35
  36     OnDemandShardStateCache(final String shardName, final ActorRef shardActor) {
  37         this.shardName = requireNonNull(shardName);
  38         this.shardActor = shardActor;
  39     }
  40
  41     OnDemandShardState get() throws Exception {
  42         if (shardActor == null) {
  43             return OnDemandShardState.newBuilder().build();
  44         }
  45
  46         return ONDEMAND_SHARD_STATE_CACHE.get(shardName, this::retrieveState);
  47     }
  48
  49     String getStatRetrievaelTime() {
  50         return stateRetrievalTime;
  51     }
  52
  53     private OnDemandShardState retrieveState() throws Exception {
  54         stateRetrievalTime = null;
  55         Timeout timeout = new Timeout(10, TimeUnit.SECONDS);
  56         Stopwatch timer = Stopwatch.createStarted();
  57
  58         OnDemandShardState state = (OnDemandShardState) Await.result(Patterns.ask(shardActor,
  59                 GetOnDemandRaftState.INSTANCE, timeout), timeout.duration());
  60
  61         stateRetrievalTime = timer.stop().toString();
  62         return state;
  63     }
  64 }