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   /*
    * Copyright 2017 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 io.netty.channel.ChannelFuture;
  import io.netty.handler.codec.dns.DnsQuestion;
  import io.netty.handler.codec.dns.DnsResponseCode;
  import io.netty.util.internal.logging.InternalLogLevel;
  import io.netty.util.internal.logging.InternalLogger;
  
  import java.net.InetSocketAddress;
  import java.util.List;
  
  import static io.netty.util.internal.ObjectUtil.checkNotNull;
  
  final class LoggingDnsQueryLifecycleObserver implements DnsQueryLifecycleObserver {
      private final InternalLogger logger;
      private final InternalLogLevel level;
      private final DnsQuestion question;
      private InetSocketAddress dnsServerAddress;
  
      LoggingDnsQueryLifecycleObserver(DnsQuestion question, InternalLogger logger, InternalLogLevel level) {
          this.question = checkNotNull(question, "question");
          this.logger = checkNotNull(logger, "logger");
          this.level = checkNotNull(level, "level");
      }
  
      @Override
      public void queryWritten(InetSocketAddress dnsServerAddress, ChannelFuture future) {
          this.dnsServerAddress = dnsServerAddress;
      }
  
      @Override
      public void queryCancelled(int queriesRemaining) {
          if (dnsServerAddress != null) {
              logger.log(level, "from {} : {} cancelled with {} queries remaining", dnsServerAddress, question,
                          queriesRemaining);
          } else {
              logger.log(level, "{} query never written and cancelled with {} queries remaining", question,
                          queriesRemaining);
          }
      }
  
      @Override
      public DnsQueryLifecycleObserver queryRedirected(List<InetSocketAddress> nameServers) {
          logger.log(level, "from {} : {} redirected", dnsServerAddress, question);
          return this;
      }
  
      @Override
      public DnsQueryLifecycleObserver queryCNAMEd(DnsQuestion cnameQuestion) {
          logger.log(level, "from {} : {} CNAME question {}", dnsServerAddress, question, cnameQuestion);
          return this;
      }
  
      @Override
      public DnsQueryLifecycleObserver queryNoAnswer(DnsResponseCode code) {
          logger.log(level, "from {} : {} no answer {}", dnsServerAddress, question, code);
          return this;
      }
  
      @Override
      public void queryFailed(Throwable cause) {
          if (dnsServerAddress != null) {
              logger.log(level, "from {} : {} failure", dnsServerAddress, question, cause);
          } else {
              logger.log(level, "{} query never written and failed", question, cause);
          }
      }
  
      @Override
      public void querySucceed() {
      }
  }