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.gms;
  
  import java.util.HashMap;
  import java.util.List;
  import java.util.Map;
  
  import org.slf4j.Logger;
  import org.slf4j.LoggerFactory;
  
  import org.apache.cassandra.locator.InetAddressAndPort;
  import org.apache.cassandra.net.Message;
  import org.apache.cassandra.net.MessagingService;
  
  import static org.apache.cassandra.net.Verb.GOSSIP_DIGEST_ACK2;
  import static org.apache.cassandra.utils.Clock.Global.nanoTime;
  
  public class GossipDigestAckVerbHandler extends GossipVerbHandler<GossipDigestAck>
  {
      public static final GossipDigestAckVerbHandler instance = new GossipDigestAckVerbHandler();
  
      private static final Logger logger = LoggerFactory.getLogger(GossipDigestAckVerbHandler.class);
  
      public void doVerb(Message<GossipDigestAck> message)
      {
          InetAddressAndPort from = message.from();
          logger.trace("Received a GossipDigestAckMessage from {}", from);
          if (!Gossiper.instance.isEnabled() && !NewGossiper.instance.isInShadowRound())
          {
              logger.trace("Ignoring GossipDigestAckMessage because gossip is disabled");
              return;
          }
  
          GossipDigestAck gDigestAckMessage = message.payload;
          List<GossipDigest> gDigestList = gDigestAckMessage.getGossipDigestList();
          Map<InetAddressAndPort, EndpointState> epStateMap = gDigestAckMessage.getEndpointStateMap();
          logger.trace("Received ack with {} digests and {} states", gDigestList.size(), epStateMap.size());
          if (NewGossiper.instance.isInShadowRound())
          {
              if (logger.isDebugEnabled())
                  logger.debug("Received an ack from {}, which may trigger exit from shadow round", from);
  
              NewGossiper.instance.onAck(epStateMap);
              return;
          }
          if (epStateMap.size() > 0)
          {
              // Ignore any GossipDigestAck messages that we handle before a regular GossipDigestSyn has been send.
              // This will prevent Acks from leaking over from the shadow round that are not actual part of
              // the regular gossip conversation.
              if ((nanoTime() - Gossiper.instance.firstSynSendAt) < 0 || Gossiper.instance.firstSynSendAt == 0)
              {
                  logger.trace("Ignoring unrequested GossipDigestAck from {}", from);
                  return;
              }
  
              /* Notify the Failure Detector */
              Gossiper.instance.notifyFailureDetector(epStateMap);
              Gossiper.instance.applyStateLocally(epStateMap);
          }
  
          /* Get the state required to send to this gossipee - construct GossipDigestAck2Message */
          Map<InetAddressAndPort, EndpointState> deltaEpStateMap = new HashMap<>();
          for (GossipDigest gDigest : gDigestList)
          {
              InetAddressAndPort addr = gDigest.getEndpoint();
              EndpointState localEpStatePtr = Gossiper.instance.getStateForVersionBiggerThan(addr, gDigest.getMaxVersion());
              if (localEpStatePtr != null)
                  deltaEpStateMap.put(addr, localEpStatePtr);
          }
  
          Message<GossipDigestAck2> gDigestAck2Message = Message.out(GOSSIP_DIGEST_ACK2, new GossipDigestAck2(deltaEpStateMap));
          logger.trace("Sending a GossipDigestAck2Message to {}", from);
          MessagingService.instance().send(gDigestAck2Message, from);
  
          super.doVerb(message);
      }
  }
  