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1   /*
2    * Licensed to the Apache Software Foundation (ASF) under one or more
3    * contributor license agreements. See the NOTICE file distributed with
4    * this work for additional information regarding copyright ownership.
5    * The ASF licenses this file to You under the Apache license, Version 2.0
6    * (the "License"); you may not use this file except in compliance with
7    * the License. You may obtain a copy of the License at
8    *
9    *      http://www.apache.org/licenses/LICENSE-2.0
10   *
11   * Unless required by applicable law or agreed to in writing, software
12   * distributed under the License is distributed on an "AS IS" BASIS,
13   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
14   * See the license for the specific language governing permissions and
15   * limitations under the license.
16   */
17  package org.apache.logging.log4j.spi;
18  
19  import java.util.Map;
20  
21  /**
22   * Service provider interface to implement custom MDC behavior for {@link org.apache.logging.log4j.ThreadContext}.
23   */
24  public interface ThreadContextMap {
25      /**
26       * Put a context value (the <code>o</code> parameter) as identified
27       * with the <code>key</code> parameter into the current thread's
28       * context map.
29       *
30       * <p>If the current thread does not have a context map it is
31       * created as a side effect.</p>
32       * @param key The key name.
33       * @param value The key value.
34       */
35      void put(final String key, final String value);
36  
37      /**
38       * Get the context identified by the <code>key</code> parameter.
39       *
40       * <p>This method has no side effects.</p>
41       * @param key The key to locate.
42       * @return The value associated with the key or null.
43       */
44      String get(final String key);
45  
46      /**
47       * Remove the the context identified by the <code>key</code>
48       * parameter.
49       * @param key The key to remove.
50       */
51      void remove(final String key);
52  
53      /**
54       * Clear the context.
55       */
56      void clear();
57  
58      /**
59       * Determine if the key is in the context.
60       * @param key The key to locate.
61       * @return True if the key is in the context, false otherwise.
62       */
63      boolean containsKey(final String key);
64  
65      /**
66       * Get a non-{@code null} mutable copy of current thread's context Map.
67       * @return a mutable copy of the context.
68       */
69      Map<String, String> getCopy();
70  
71      /**
72       * Return an immutable view on the context Map or {@code null} if the context map is empty.
73       * @return an immutable context Map or {@code null}.
74       */
75      Map<String, String> getImmutableMapOrNull();
76  
77      /**
78       * Returns true if the Map is empty.
79       * @return true if the Map is empty, false otherwise.
80       */
81      boolean isEmpty();
82  }