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   /*
    * Copyright 2018 The Netty Project
    *
    * The Netty Project 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:
    *
    *   https://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 io.netty.resolver.dns;
  
  import java.net.UnknownHostException;
  import java.util.List;
  
  import io.netty.channel.Channel;
  import io.netty.channel.EventLoop;
  import io.netty.handler.codec.dns.DnsQuestion;
  import io.netty.handler.codec.dns.DnsRecord;
  import io.netty.handler.codec.dns.DnsRecordType;
  import io.netty.util.ReferenceCountUtil;
  import io.netty.util.concurrent.Future;
  import io.netty.util.concurrent.Promise;
  
  final class DnsRecordResolveContext extends DnsResolveContext<DnsRecord> {
  
      DnsRecordResolveContext(DnsNameResolver parent, Channel channel, Future<? extends Channel> channelReadyFuture,
                              Promise<?> originalPromise, DnsQuestion question, DnsRecord[] additionals,
                              DnsServerAddressStream nameServerAddrs, int allowedQueries) {
          this(parent, channel, channelReadyFuture, originalPromise, question.name(), question.dnsClass(),
               new DnsRecordType[] { question.type() },
               additionals, nameServerAddrs, allowedQueries);
      }
  
      private DnsRecordResolveContext(DnsNameResolver parent, Channel channel,
                                      Future<? extends Channel> channelReadyFuture, Promise<?> originalPromise,
                                      String hostname, int dnsClass, DnsRecordType[] expectedTypes,
                                      DnsRecord[] additionals,
                                      DnsServerAddressStream nameServerAddrs,
                                      int allowedQueries) {
          super(parent, channel, channelReadyFuture, originalPromise, hostname, dnsClass, expectedTypes,
                  additionals, nameServerAddrs, allowedQueries);
      }
  
      @Override
      DnsResolveContext<DnsRecord> newResolverContext(DnsNameResolver parent, Channel channel,
                                                      Future<? extends Channel> channelReadyFuture,
                                                      Promise<?> originalPromise,
                                                      String hostname,
                                                      int dnsClass, DnsRecordType[] expectedTypes,
                                                      DnsRecord[] additionals,
                                                      DnsServerAddressStream nameServerAddrs,
                                                      int allowedQueries) {
          return new DnsRecordResolveContext(parent, channel, channelReadyFuture, originalPromise, hostname, dnsClass,
                                             expectedTypes, additionals, nameServerAddrs, allowedQueries);
      }
  
      @Override
      DnsRecord convertRecord(DnsRecord record, String hostname, DnsRecord[] additionals, EventLoop eventLoop) {
          return ReferenceCountUtil.retain(record);
      }
  
      @Override
      List<DnsRecord> filterResults(List<DnsRecord> unfiltered) {
          return unfiltered;
      }
  
      @Override
      boolean isCompleteEarly(DnsRecord resolved) {
          return false;
      }
  
      @Override
      boolean isDuplicateAllowed() {
          return true;
      }
  
      @Override
      void cache(String hostname, DnsRecord[] additionals, DnsRecord result, DnsRecord convertedResult) {
          // Do not cache.
          // XXX: When we implement cache, we would need to retain the reference count of the result record.
      }
  
      @Override
      void cache(String hostname, DnsRecord[] additionals, UnknownHostException cause) {
          // Do not cache.
          // XXX: When we implement cache, we would need to retain the reference count of the result record.
      }
  
      @Override
      DnsCnameCache cnameCache() {
          // We don't use a cache here at all as we also don't cache if we end up using the DnsRecordResolverContext.
          return NoopDnsCnameCache.INSTANCE;
      }
 }