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.io.*;
  
  import org.apache.cassandra.db.TypeSizes;
  import org.apache.cassandra.io.IVersionedSerializer;
  import org.apache.cassandra.io.util.DataInputPlus;
  import org.apache.cassandra.io.util.DataOutputPlus;
  
  /**
   * HeartBeat State associated with any given endpoint.
   */
  public class HeartBeatState
  {
      public static final int EMPTY_VERSION = -1;
  
      public static final IVersionedSerializer<HeartBeatState> serializer = new HeartBeatStateSerializer();
  
      private final int generation;
      private final int version;
  
      HeartBeatState(int gen)
      {
          this(gen, 0);
      }
  
      public HeartBeatState(HeartBeatState other)
      {
          generation = other.generation;
          version = other.version;
      }
  
      public HeartBeatState(int gen, int ver)
      {
          generation = gen;
          version = ver;
      }
  
      public static HeartBeatState empty()
      {
          return new HeartBeatState(0, EMPTY_VERSION);
      }
  
      public boolean isEmpty()
      {
          // Instance I1 will update this value for I1's state, no other instance should.
          // It is also known that negative version isn't allowed, so can leverage this to
          // know that the state was not generated by I1 but rather than instance (normally
          // happens on startup, the peers are added to gossip with the empty state).
          return version == EMPTY_VERSION;
      }
  
      public int getGeneration()
      {
          return generation;
      }
  
      HeartBeatState updateHeartBeat()
      {
          return new HeartBeatState(generation, VersionGenerator.getNextVersion());
      }
  
      public int getHeartBeatVersion()
      {
          return version;
      }
  
      HeartBeatState forceNewerGenerationUnsafe()
      {
          return new HeartBeatState(generation + 1, version);
      }
  
      HeartBeatState forceHighestPossibleVersionUnsafe()
      {
          return new HeartBeatState(generation, Integer.MAX_VALUE);
      }
  
      public String toString()
      {
          return String.format("HeartBeat: generation = %d, version = %d", generation, version);
      }
  }
  
  class HeartBeatStateSerializer implements IVersionedSerializer<HeartBeatState>
  {
      public void serialize(HeartBeatState hbState, DataOutputPlus out, int version) throws IOException
      {
          out.writeInt(hbState.getGeneration());
          out.writeInt(hbState.getHeartBeatVersion());
      }
  
      public HeartBeatState deserialize(DataInputPlus in, int version) throws IOException
      {
          return new HeartBeatState(in.readInt(), in.readInt());
      }
  
      public long serializedSize(HeartBeatState state, int version)
      {
          return TypeSizes.sizeof(state.getGeneration()) + TypeSizes.sizeof(state.getHeartBeatVersion());
      }
  }
  