content: /**
   * Licensed under the Apache License, Version 2.0 (the "License");
   * you may not use this file except in compliance with the License.
   * You may obtain a copy of the License at
   *
   *     http://www.apache.org/licenses/LICENSE-2.0
   *
   * Unless required by applicable law or agreed to in writing, software
   * distributed under the License is distributed on an "AS IS" BASIS,
   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   * See the License for the specific language governing permissions and
   * limitations under the License.
   */
  package org.apache.aurora.scheduler.state;
  
  import com.google.common.collect.HashMultimap;
  import com.google.common.collect.ImmutableSetMultimap;
  import com.google.common.collect.Multimap;
  import com.google.common.eventbus.Subscribe;
  
  import org.apache.aurora.scheduler.base.Tasks;
  import org.apache.aurora.scheduler.events.PubsubEvent;
  import org.apache.aurora.scheduler.events.PubsubEvent.TaskStateChange;
  import org.apache.aurora.scheduler.preemptor.PreemptionVictim;
  
  /**
   * A cached view of cluster state, kept up to date by pubsub notifications.
   */
  public class ClusterStateImpl implements ClusterState, PubsubEvent.EventSubscriber {
  
    private final Multimap<String, PreemptionVictim> victims = HashMultimap.create();
  
    @Override
    public Multimap<String, PreemptionVictim> getSlavesToActiveTasks() {
      synchronized (victims) {
        return ImmutableSetMultimap.copyOf(victims);
      }
    }
  
    @Subscribe
    public void taskChangedState(TaskStateChange stateChange) {
      synchronized (victims) {
        String slaveId = stateChange.getTask().getAssignedTask().getSlaveId();
        PreemptionVictim victim = PreemptionVictim.fromTask(stateChange.getTask().getAssignedTask());
        if (Tasks.SLAVE_ASSIGNED_STATES.contains(stateChange.getNewState())) {
          victims.put(slaveId, victim);
        } else {
          victims.remove(slaveId, victim);
        }
      }
    }
  }
  