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.transport.messages;
  
  import java.util.ArrayList;
  import java.util.HashMap;
  import java.util.List;
  import java.util.Map;
  
  import io.netty.buffer.ByteBuf;
  
  import org.apache.cassandra.cql3.QueryProcessor;
  import org.apache.cassandra.service.QueryState;
  import org.apache.cassandra.transport.Compressor;
  import org.apache.cassandra.transport.Dispatcher;
  import org.apache.cassandra.transport.Message;
  import org.apache.cassandra.transport.ProtocolVersion;
  
  /**
   * Message to indicate that the server is ready to receive requests.
   */
  public class OptionsMessage extends Message.Request
  {
      public static final Message.Codec<OptionsMessage> codec = new Message.Codec<OptionsMessage>()
      {
          public OptionsMessage decode(ByteBuf body, ProtocolVersion version)
          {
              return new OptionsMessage();
          }
  
          public void encode(OptionsMessage msg, ByteBuf dest, ProtocolVersion version)
          {
          }
  
          public int encodedSize(OptionsMessage msg, ProtocolVersion version)
          {
              return 0;
          }
      };
  
      public OptionsMessage()
      {
          super(Message.Type.OPTIONS);
      }
  
      @Override
      protected Message.Response execute(QueryState state, Dispatcher.RequestTime requestTime, boolean traceRequest)
      {
          List<String> cqlVersions = new ArrayList<String>();
          cqlVersions.add(QueryProcessor.CQL_VERSION.toString());
  
          List<String> compressions = new ArrayList<String>();
          if (Compressor.SnappyCompressor.instance != null)
              compressions.add("snappy");
          // LZ4 is always available since worst case scenario it default to a pure JAVA implem.
          compressions.add("lz4");
  
          Map<String, List<String>> supported = new HashMap<String, List<String>>();
          supported.put(StartupMessage.CQL_VERSION, cqlVersions);
          supported.put(StartupMessage.COMPRESSION, compressions);
          supported.put(StartupMessage.PROTOCOL_VERSIONS, ProtocolVersion.supportedVersions());
  
          return new SupportedMessage(supported);
      }
  
      @Override
      public String toString()
      {
          return "OPTIONS";
      }
  }
  