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1   /*
2    * Copyright 2017 The Netty Project
3    *
4    * The Netty Project licenses this file to you under the Apache License,
5    * version 2.0 (the "License"); you may not use this file except in compliance
6    * with the License. You may obtain a copy of the License at:
7    *
8    *   http://www.apache.org/licenses/LICENSE-2.0
9    *
10   * Unless required by applicable law or agreed to in writing, software
11   * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
12   * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
13   * License for the specific language governing permissions and limitations
14   * under the License.
15   */
16  package io.netty.resolver.dns;
17  
18  import io.netty.handler.codec.dns.DnsQuestion;
19  import io.netty.util.internal.UnstableApi;
20  
21  import static io.netty.util.internal.ObjectUtil.checkNotNull;
22  
23  /**
24   * Combines two {@link DnsQueryLifecycleObserverFactory} into a single {@link DnsQueryLifecycleObserverFactory}.
25   */
26  @UnstableApi
27  public final class BiDnsQueryLifecycleObserverFactory implements DnsQueryLifecycleObserverFactory {
28      private final DnsQueryLifecycleObserverFactory a;
29      private final DnsQueryLifecycleObserverFactory b;
30  
31      /**
32       * Create a new instance.
33       * @param a The {@link DnsQueryLifecycleObserverFactory} that will receive events first.
34       * @param b The {@link DnsQueryLifecycleObserverFactory} that will receive events second.
35       */
36      public BiDnsQueryLifecycleObserverFactory(DnsQueryLifecycleObserverFactory a, DnsQueryLifecycleObserverFactory b) {
37          this.a = checkNotNull(a, "a");
38          this.b = checkNotNull(b, "b");
39      }
40  
41      @Override
42      public DnsQueryLifecycleObserver newDnsQueryLifecycleObserver(DnsQuestion question) {
43          return new BiDnsQueryLifecycleObserver(a.newDnsQueryLifecycleObserver(question),
44                                                 b.newDnsQueryLifecycleObserver(question));
45      }
46  }