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1   /*
2    * Copyright 2020 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    *   https://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.handler.logging.LogLevel;
20  import io.netty.util.internal.logging.InternalLogLevel;
21  import io.netty.util.internal.logging.InternalLogger;
22  import io.netty.util.internal.logging.InternalLoggerFactory;
23  
24  import static io.netty.util.internal.ObjectUtil.checkNotNull;
25  
26  /**
27   * A {@link DnsQueryLifecycleObserverFactory} that enables detailed logging in the {@link DnsNameResolver}.
28   * <p>
29   * When {@linkplain DnsNameResolverBuilder#dnsQueryLifecycleObserverFactory(DnsQueryLifecycleObserverFactory)
30   * configured on the resolver}, detailed trace information will be generated so that it is easier to understand the
31   * cause of resolution failure.
32   */
33  public final class LoggingDnsQueryLifeCycleObserverFactory implements DnsQueryLifecycleObserverFactory {
34      private static final InternalLogger DEFAULT_LOGGER =
35              InternalLoggerFactory.getInstance(LoggingDnsQueryLifeCycleObserverFactory.class);
36      private final InternalLogger logger;
37      private final InternalLogLevel level;
38  
39      /**
40       * Create {@link DnsQueryLifecycleObserver} instances that log events at the default {@link LogLevel#DEBUG} level.
41       */
42      public LoggingDnsQueryLifeCycleObserverFactory() {
43          this(LogLevel.DEBUG);
44      }
45  
46      /**
47       * Create {@link DnsQueryLifecycleObserver} instances that log events at the given log level.
48       * @param level The log level to use for logging resolver events.
49       */
50      public LoggingDnsQueryLifeCycleObserverFactory(LogLevel level) {
51          this.level = checkAndConvertLevel(level);
52          logger = DEFAULT_LOGGER;
53      }
54  
55      /**
56       * Create {@link DnsQueryLifecycleObserver} instances that log events to a logger with the given class context,
57       * at the given log level.
58       * @param classContext The class context for the logger to use.
59       * @param level The log level to use for logging resolver events.
60       */
61      public LoggingDnsQueryLifeCycleObserverFactory(Class<?> classContext, LogLevel level) {
62          this.level = checkAndConvertLevel(level);
63          logger = InternalLoggerFactory.getInstance(checkNotNull(classContext, "classContext"));
64      }
65  
66      /**
67       * Create {@link DnsQueryLifecycleObserver} instances that log events to a logger with the given name context,
68       * at the given log level.
69       * @param name The name for the logger to use.
70       * @param level The log level to use for logging resolver events.
71       */
72      public LoggingDnsQueryLifeCycleObserverFactory(String name, LogLevel level) {
73          this.level = checkAndConvertLevel(level);
74          logger = InternalLoggerFactory.getInstance(checkNotNull(name, "name"));
75      }
76  
77      private static InternalLogLevel checkAndConvertLevel(LogLevel level) {
78          return checkNotNull(level, "level").toInternalLevel();
79      }
80  
81      @Override
82      public DnsQueryLifecycleObserver newDnsQueryLifecycleObserver(DnsQuestion question) {
83          return new LoggingDnsQueryLifecycleObserver(question, logger, level);
84      }
85  }