content: /*
   * Licensed to the Apache Software Foundation (ASF) under one
   * or more contributor license agreements.  See the NOTICE file
   * distributed with this work for additional information
   * regarding copyright ownership.  The ASF licenses this file
   * to you 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.cassandra.service;
  
  import java.util.*;
  import java.util.concurrent.ConcurrentHashMap;
  import java.util.concurrent.ConcurrentMap;
  import java.util.concurrent.TimeUnit;
  
  import org.apache.cassandra.locator.InetAddressAndPort;
  import org.apache.cassandra.metrics.StorageMetrics;
  import org.slf4j.Logger;
  import org.slf4j.LoggerFactory;
  
  import org.apache.cassandra.concurrent.ScheduledExecutors;
  import org.apache.cassandra.gms.*;
  
  import static org.apache.cassandra.config.CassandraRelevantProperties.BROADCAST_INTERVAL_MS;
  
  public class LoadBroadcaster implements IEndpointStateChangeSubscriber
  {
      static final int BROADCAST_INTERVAL = BROADCAST_INTERVAL_MS.getInt();
  
      public static final LoadBroadcaster instance = new LoadBroadcaster();
  
      private static final Logger logger = LoggerFactory.getLogger(LoadBroadcaster.class);
  
      private ConcurrentMap<InetAddressAndPort, Double> loadInfo = new ConcurrentHashMap<>();
  
      private LoadBroadcaster()
      {
          Gossiper.instance.register(this);
      }
  
      public void onChange(InetAddressAndPort endpoint, ApplicationState state, VersionedValue value)
      {
          if (state != ApplicationState.LOAD)
              return;
          loadInfo.put(endpoint, Double.valueOf(value.value));
      }
  
      public void onJoin(InetAddressAndPort endpoint, EndpointState epState)
      {
          VersionedValue localValue = epState.getApplicationState(ApplicationState.LOAD);
          if (localValue != null)
          {
              onChange(endpoint, ApplicationState.LOAD, localValue);
          }
      }
  
      public void onRemove(InetAddressAndPort endpoint)
      {
          loadInfo.remove(endpoint);
      }
  
      public Map<InetAddressAndPort, Double> getLoadInfo()
      {
          return Collections.unmodifiableMap(loadInfo);
      }
  
      public void startBroadcasting()
      {
          // send the first broadcast "right away" (i.e., in 2 gossip heartbeats, when we should have someone to talk to);
          // after that send every BROADCAST_INTERVAL.
          Runnable runnable = new Runnable()
          {
              public void run()
              {
                  if (!Gossiper.instance.isEnabled())
                      return;
  
                  logger.trace("Disseminating load info ...");
                  Gossiper.instance.addLocalApplicationState(ApplicationState.LOAD,
                                                             StorageService.instance.valueFactory.load(StorageMetrics.load.getCount()));
              }
          };
          ScheduledExecutors.scheduledTasks.scheduleWithFixedDelay(runnable, 2 * Gossiper.intervalInMillis, BROADCAST_INTERVAL, TimeUnit.MILLISECONDS);
      }
  }
  
  