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 import org.apache.logging.log4j.ThreadContext;
22
23 /**
24 * Service provider interface to implement custom MDC behavior for {@link org.apache.logging.log4j.ThreadContext}.
25 * <p>
26 * Since 2.8, {@code ThreadContextMap} implementations that implement the {@link ReadOnlyThreadContextMap} interface
27 * are accessible to applications via the {@link ThreadContext#getThreadContextMap()} method.
28 * </p>
29 */
30 public interface ThreadContextMap {
31
32 /**
33 * Clears the context.
34 */
35 void clear();
36
37 /**
38 * Determines if the key is in the context.
39 * @param key The key to locate.
40 * @return True if the key is in the context, false otherwise.
41 */
42 boolean containsKey(final String key);
43
44 /**
45 * Gets the context identified by the <code>key</code> parameter.
46 *
47 * <p>This method has no side effects.</p>
48 * @param key The key to locate.
49 * @return The value associated with the key or null.
50 */
51 String get(final String key);
52
53 /**
54 * Gets a non-{@code null} mutable copy of current thread's context Map.
55 * @return a mutable copy of the context.
56 */
57 Map<String, String> getCopy();
58
59 /**
60 * Returns an immutable view on the context Map or {@code null} if the context map is empty.
61 * @return an immutable context Map or {@code null}.
62 */
63 Map<String, String> getImmutableMapOrNull();
64
65 /**
66 * Returns true if the Map is empty.
67 * @return true if the Map is empty, false otherwise.
68 */
69 boolean isEmpty();
70
71 /**
72 * Puts a context value (the <code>o</code> parameter) as identified
73 * with the <code>key</code> parameter into the current thread's
74 * context map.
75 *
76 * <p>If the current thread does not have a context map it is
77 * created as a side effect.</p>
78 * @param key The key name.
79 * @param value The key value.
80 */
81 void put(final String key, final String value);
82
83 /**
84 * Removes the the context identified by the <code>key</code>
85 * parameter.
86 * @param key The key to remove.
87 */
88 void remove(final String key);
89 }