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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 io.netty.channel.EventLoop;
  
  public final class NoopDnsCnameCache implements DnsCnameCache {
  
      public static final NoopDnsCnameCache INSTANCE = new NoopDnsCnameCache();
  
      private NoopDnsCnameCache() { }
  
      @Override
      public String get(String hostname) {
          return null;
      }
  
      @Override
      public void cache(String hostname, String cname, long originalTtl, EventLoop loop) {
          // NOOP
      }
  
      @Override
      public void clear() {
          // NOOP
      }
  
      @Override
      public boolean clear(String hostname) {
          return false;
      }
  }