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
47 = new InheritableThreadLocal<Map<String, String>>();
48
49 static boolean isJDK14() {
50 try {
51 String javaVersion = System.getProperty("java.version");
52 return javaVersion.startsWith("1.4");
53 } catch(SecurityException se) {
54 // punt and assume JDK 1.5 or later
55 return false;
56 }
57 }
58
59 static boolean IS_JDK14 = isJDK14();
60
61
62 /**
63 * Put a context value (the <code>val</code> parameter) as identified with
64 * the <code>key</code> parameter into the current thread's context map.
65 * Note that contrary to log4j, the <code>val</code> parameter can be null.
66 *
67 * <p>
68 * If the current thread does not have a context map it is created as a side
69 * effect of this call.
70 *
71 * @throws IllegalArgumentException
72 * in case the "key" parameter is null
73 */
74 public void put(String key, String val) {
75 if (key == null) {
76 throw new IllegalArgumentException("key cannot be null");
77 }
78 Map<String, String> map = (Map<String, String>) inheritableThreadLocal.get();
79 if (map == null) {
80 map = Collections.<String, String>synchronizedMap(new HashMap<String, String>());
81 inheritableThreadLocal.set(map);
82 }
83 map.put(key, val);
84 }
85
86 /**
87 * Get the context identified by the <code>key</code> parameter.
88 */
89 public String get(String key) {
90 Map<String, String> Map = (Map<String, String>) inheritableThreadLocal.get();
91 if ((Map != null) && (key != null)) {
92 return (String) Map.get(key);
93 } else {
94 return null;
95 }
96 }
97
98 /**
99 * Remove the the context identified by the <code>key</code> parameter.
100 */
101 public void remove(String key) {
102 Map<String, String> map = (Map<String, String>) inheritableThreadLocal.get();
103 if (map != null) {
104 map.remove(key);
105 }
106 }
107
108 /**
109 * Clear all entries in the MDC.
110 */
111 public void clear() {
112 Map<String, String> map = (Map<String, String>) inheritableThreadLocal.get();
113 if (map != null) {
114 map.clear();
115 // the InheritableThreadLocal.remove method was introduced in JDK 1.5
116 // Thus, invoking clear() on previous JDK 1.4 will fail
117 if(isJDK14()) {
118 inheritableThreadLocal.set(null);
119 } else {
120 inheritableThreadLocal.remove();
121 }
122 }
123 }
124
125 /**
126 * Returns the keys in the MDC as a {@link Set} of {@link String}s The
127 * returned value can be null.
128 *
129 * @return the keys in the MDC
130 */
131 public Set<String> getKeys() {
132 Map<String, String> map = (Map<String, String>) inheritableThreadLocal.get();
133 if (map != null) {
134 return map.keySet();
135 } else {
136 return null;
137 }
138 }
139 /**
140 * Return a copy of the current thread's context map.
141 * Returned value may be null.
142 *
143 */
144 public Map<String, String> getCopyOfContextMap() {
145 Map<String, String> oldMap = (Map<String, String>) inheritableThreadLocal.get();
146 if (oldMap != null) {
147 Map<String, String> newMap = Collections.<String, String>synchronizedMap(new HashMap<String, String>());
148 synchronized (oldMap) {
149 newMap.putAll(oldMap);
150 }
151 return newMap;
152 } else {
153 return null;
154 }
155 }
156
157 public void setContextMap(Map<String, String> contextMap) {
158 Map<String, String> map = Collections.<String, String>synchronizedMap(new HashMap<String, String>(contextMap));
159 inheritableThreadLocal.set(map);
160 }
161
162 }