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.tcm;
  
  import java.io.IOException;
  
  import org.slf4j.Logger;
  import org.slf4j.LoggerFactory;
  
  import org.apache.cassandra.io.IVersionedSerializer;
  import org.apache.cassandra.io.util.DataInputPlus;
  import org.apache.cassandra.io.util.DataOutputPlus;
  import org.apache.cassandra.metrics.TCMMetrics;
  import org.apache.cassandra.net.IVerbHandler;
  import org.apache.cassandra.net.Message;
  import org.apache.cassandra.net.MessagingService;
  import org.apache.cassandra.tcm.log.LogState;
  
  public class FetchPeerLog
  {
      public static final Serializer serializer = new Serializer();
  
      public final Epoch start;
  
      public FetchPeerLog(Epoch start)
      {
          this.start = start;
      }
  
      public String toString()
      {
          return "FetchPeerLog{" +
                 ", start=" + start +
                 '}';
      }
  
      static class Serializer implements IVersionedSerializer<FetchPeerLog>
      {
  
          public void serialize(FetchPeerLog t, DataOutputPlus out, int version) throws IOException
          {
              Epoch.serializer.serialize(t.start, out);
          }
  
          public FetchPeerLog deserialize(DataInputPlus in, int version) throws IOException
          {
              Epoch epoch = Epoch.serializer.deserialize(in);
              return new FetchPeerLog(epoch);
          }
  
          public long serializedSize(FetchPeerLog t, int version)
          {
              return Epoch.serializer.serializedSize(t.start);
          }
      }
  
      public static class Handler implements IVerbHandler<FetchPeerLog>
      {
          public static Handler instance = new Handler();
          private static final Logger logger = LoggerFactory.getLogger(Handler.class);
  
          public void doVerb(Message<FetchPeerLog> message) throws IOException
          {
              FetchPeerLog request = message.payload;
  
              ClusterMetadata metadata = ClusterMetadata.current();
              logger.info("Received peer log fetch request {} from {}: start = {}, current = {}", request, message.from(), message.payload.start, metadata.epoch);
              LogState delta = ClusterMetadataService.instance().log().storage().getLogState(message.payload.start);
              TCMMetrics.instance.peerLogEntriesServed(message.payload.start, delta.latestEpoch());
              logger.info("Responding with log delta: {}", delta);
              MessagingService.instance().send(message.responseWith(delta), message.from());
          }
      }
  }
  