1 /**
2 * Copyright (c) 2004-2011 QOS.ch
3 * All rights reserved.
4 *
5 * Permission is hereby granted, free of charge, to any person obtaining
6 * a copy of this software and associated documentation files (the
7 * "Software"), to deal in the Software without restriction, including
8 * without limitation the rights to use, copy, modify, merge, publish,
9 * distribute, sublicense, and/or sell copies of the Software, and to
10 * permit persons to whom the Software is furnished to do so, subject to
11 * the following conditions:
12 *
13 * The above copyright notice and this permission notice shall be
14 * included in all copies or substantial portions of the Software.
15 *
16 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
17 * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
18 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
19 * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
20 * LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
21 * OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
22 * WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
23 *
24 */
25 package org.slf4j.helpers;
26
27 import org.slf4j.spi.MDCAdapter;
28
29 import java.util.*;
30 import java.util.Map;
31
32 /**
33 * Basic MDC implementation, which can be used with logging systems that lack
34 * out-of-the-box MDC support.
35 *
36 * This code was initially inspired by logback's LogbackMDCAdapter. However,
37 * LogbackMDCAdapter has evolved and is now considerably more sophisticated.
38 *
39 * @author Ceki Gulcu
40 * @author Maarten Bosteels
41 *
42 * @since 1.5.0
43 */
44 public class BasicMDCAdapter implements MDCAdapter {
45
46 private InheritableThreadLocal<Map<String, String>> inheritableThreadLocal = new InheritableThreadLocal<Map<String, String>>();
47
48 static boolean isJDK14() {
49 try {
50 String javaVersion = System.getProperty("java.version");
51 return javaVersion.startsWith("1.4");
52 } catch (SecurityException se) {
53 // punt and assume JDK 1.5 or later
54 return false;
55 }
56 }
57
58 static boolean IS_JDK14 = isJDK14();
59
60 /**
61 * Put a context value (the <code>val</code> parameter) as identified with
62 * the <code>key</code> parameter into the current thread's context map.
63 * Note that contrary to log4j, the <code>val</code> parameter can be null.
64 *
65 * <p>
66 * If the current thread does not have a context map it is created as a side
67 * effect of this call.
68 *
69 * @throws IllegalArgumentException
70 * in case the "key" parameter is null
71 */
72 public void put(String key, String val) {
73 if (key == null) {
74 throw new IllegalArgumentException("key cannot be null");
75 }
76 Map<String, String> map = (Map<String, String>) inheritableThreadLocal.get();
77 if (map == null) {
78 map = Collections.<String, String> synchronizedMap(new HashMap<String, String>());
79 inheritableThreadLocal.set(map);
80 }
81 map.put(key, val);
82 }
83
84 /**
85 * Get the context identified by the <code>key</code> parameter.
86 */
87 public String get(String key) {
88 Map<String, String> Map = (Map<String, String>) inheritableThreadLocal.get();
89 if ((Map != null) && (key != null)) {
90 return (String) Map.get(key);
91 } else {
92 return null;
93 }
94 }
95
96 /**
97 * Remove the the context identified by the <code>key</code> parameter.
98 */
99 public void remove(String key) {
100 Map<String, String> map = (Map<String, String>) inheritableThreadLocal.get();
101 if (map != null) {
102 map.remove(key);
103 }
104 }
105
106 /**
107 * Clear all entries in the MDC.
108 */
109 public void clear() {
110 Map<String, String> map = (Map<String, String>) inheritableThreadLocal.get();
111 if (map != null) {
112 map.clear();
113 // the InheritableThreadLocal.remove method was introduced in JDK 1.5
114 // Thus, invoking clear() on previous JDK 1.4 will fail
115 if (isJDK14()) {
116 inheritableThreadLocal.set(null);
117 } else {
118 inheritableThreadLocal.remove();
119 }
120 }
121 }
122
123 /**
124 * Returns the keys in the MDC as a {@link Set} of {@link String}s The
125 * returned value can be null.
126 *
127 * @return the keys in the MDC
128 */
129 public Set<String> getKeys() {
130 Map<String, String> map = (Map<String, String>) inheritableThreadLocal.get();
131 if (map != null) {
132 return map.keySet();
133 } else {
134 return null;
135 }
136 }
137
138 /**
139 * Return a copy of the current thread's context map.
140 * Returned value may be null.
141 *
142 */
143 public Map<String, String> getCopyOfContextMap() {
144 Map<String, String> oldMap = (Map<String, String>) inheritableThreadLocal.get();
145 if (oldMap != null) {
146 Map<String, String> newMap = Collections.<String, String> synchronizedMap(new HashMap<String, String>());
147 synchronized (oldMap) {
148 newMap.putAll(oldMap);
149 }
150 return newMap;
151 } else {
152 return null;
153 }
154 }
155
156 public void setContextMap(Map<String, String> contextMap) {
157 Map<String, String> map = Collections.<String, String> synchronizedMap(new HashMap<String, String>(contextMap));
158 inheritableThreadLocal.set(map);
159 }
160
161 }