|
1
|
<?php
|
|
2
|
/**
|
|
3
|
* Licensed to the Apache Software Foundation (ASF) under one or more
|
|
4
|
* contributor license agreements. See the NOTICE file distributed with
|
|
5
|
* this work for additional information regarding copyright ownership.
|
|
6
|
* The ASF licenses this file to You under the Apache License, Version 2.0
|
|
7
|
* (the "License"); you may not use this file except in compliance with
|
|
8
|
* the License. You may obtain a copy of the License at
|
|
9
|
*
|
|
10
|
* http://www.apache.org/licenses/LICENSE-2.0
|
|
11
|
*
|
|
12
|
* Unless required by applicable law or agreed to in writing, software
|
|
13
|
* distributed under the License is distributed on an "AS IS" BASIS,
|
|
14
|
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
|
|
15
|
* See the License for the specific language governing permissions and
|
|
16
|
* limitations under the License.
|
|
17
|
*
|
|
18
|
* @package log4php
|
|
19
|
*/
|
|
20
|
|
|
21
|
/**
|
|
22
|
* The NDC class implements <i>nested diagnostic contexts</i>.
|
|
23
|
*
|
|
24
|
* NDC was defined by Neil Harrison in the article "Patterns for Logging
|
|
25
|
* Diagnostic Messages" part of the book <i>"Pattern Languages of
|
|
26
|
* Program Design 3"</i> edited by Martin et al.
|
|
27
|
*
|
|
28
|
* A Nested Diagnostic Context, or NDC in short, is an instrument
|
|
29
|
* to distinguish interleaved log output from different sources. Log
|
|
30
|
* output is typically interleaved when a server handles multiple
|
|
31
|
* clients near-simultaneously.
|
|
32
|
*
|
|
33
|
* This class is similar to the {@link LoggerMDC} class except that it is
|
|
34
|
* based on a stack instead of a map.
|
|
35
|
*
|
|
36
|
* Interleaved log output can still be meaningful if each log entry
|
|
37
|
* from different contexts had a distinctive stamp. This is where NDCs
|
|
38
|
* come into play.
|
|
39
|
*
|
|
40
|
* <b>Note that NDCs are managed on a per thread basis</b>.
|
|
41
|
*
|
|
42
|
* NDC operations such as {@link push()}, {@link pop()},
|
|
43
|
* {@link clear()}, {@link getDepth()} and {@link setMaxDepth()}
|
|
44
|
* affect the NDC of the <i>current</i> thread only. NDCs of other
|
|
45
|
* threads remain unaffected.
|
|
46
|
*
|
|
47
|
* For example, a servlet can build a per client request NDC
|
|
48
|
* consisting the clients host name and other information contained in
|
|
49
|
* the the request. <i>Cookies</i> are another source of distinctive
|
|
50
|
* information. To build an NDC one uses the {@link push()}
|
|
51
|
* operation.
|
|
52
|
*
|
|
53
|
* Simply put,
|
|
54
|
*
|
|
55
|
* - Contexts can be nested.
|
|
56
|
* - When entering a context, call <kbd>LoggerNDC::push()</kbd>
|
|
57
|
* As a side effect, if there is no nested diagnostic context for the
|
|
58
|
* current thread, this method will create it.
|
|
59
|
* - When leaving a context, call <kbd>LoggerNDC::pop()</kbd>
|
|
60
|
* - <b>When exiting a thread make sure to call {@link remove()}</b>
|
|
61
|
*
|
|
62
|
* There is no penalty for forgetting to match each
|
|
63
|
* <kbd>push</kbd> operation with a corresponding <kbd>pop</kbd>,
|
|
64
|
* except the obvious mismatch between the real application context
|
|
65
|
* and the context set in the NDC.
|
|
66
|
*
|
|
67
|
* If configured to do so, {@link LoggerPatternLayout} and {@link LoggerLayoutTTCC}
|
|
68
|
* instances automatically retrieve the nested diagnostic
|
|
69
|
* context for the current thread without any user intervention.
|
|
70
|
* Hence, even if a servlet is serving multiple clients
|
|
71
|
* simultaneously, the logs emanating from the same code (belonging to
|
|
72
|
* the same category) can still be distinguished because each client
|
|
73
|
* request will have a different NDC tag.
|
|
74
|
*
|
|
75
|
* Example:
|
|
76
|
*
|
|
77
|
* {@example ../../examples/php/ndc.php 19}<br>
|
|
78
|
*
|
|
79
|
* With the properties file:
|
|
80
|
*
|
|
81
|
* {@example ../../examples/resources/ndc.properties 18}<br>
|
|
82
|
*
|
|
83
|
* Will result in the following (notice the conn and client ids):
|
|
84
|
*
|
|
85
|
* <pre>
|
|
86
|
* 2009-09-13 19:04:27 DEBUG root conn=1234: just received a new connection in src/examples/php/ndc.php at 23
|
|
87
|
* 2009-09-13 19:04:27 DEBUG root conn=1234 client=ab23: some more messages that can in src/examples/php/ndc.php at 25
|
|
88
|
* 2009-09-13 19:04:27 DEBUG root conn=1234 client=ab23: now related to a client in src/examples/php/ndc.php at 26
|
|
89
|
* 2009-09-13 19:04:27 DEBUG root : back and waiting for new connections in src/examples/php/ndc.php at 29
|
|
90
|
* </pre>
|
|
91
|
*
|
|
92
|
* @version $Revision: 1166187 $
|
|
93
|
* @package log4php
|
|
94
|
* @since 0.3
|
|
95
|
*/
|
|
96
|
class LoggerNDC {
|
|
97
|
|
|
98
|
/** This is the repository of NDC stack */
|
|
99
|
private static $stack = array();
|
|
100
|
|
|
101
|
/**
|
|
102
|
* Clear any nested diagnostic information if any. This method is
|
|
103
|
* useful in cases where the same thread can be potentially used
|
|
104
|
* over and over in different unrelated contexts.
|
|
105
|
*
|
|
106
|
* <p>This method is equivalent to calling the {@link setMaxDepth()}
|
|
107
|
* method with a zero <var>maxDepth</var> argument.
|
|
108
|
*/
|
|
109
|
public static function clear() {
|
|
110
|
self::$stack = array();
|
|
111
|
}
|
|
112
|
|
|
113
|
/**
|
|
114
|
* Never use this method directly, use the {@link LoggerLoggingEvent::getNDC()} method instead.
|
|
115
|
* @return array
|
|
116
|
*/
|
|
117
|
public static function get() {
|
|
118
|
return implode(' ', self::$stack);
|
|
119
|
}
|
|
120
|
|
|
121
|
/**
|
|
122
|
* Get the current nesting depth of this diagnostic context.
|
|
123
|
*
|
|
124
|
* @see setMaxDepth()
|
|
125
|
* @return integer
|
|
126
|
*/
|
|
127
|
public static function getDepth() {
|
|
128
|
return count(self::$stack);
|
|
129
|
}
|
|
130
|
|
|
131
|
/**
|
|
132
|
* Clients should call this method before leaving a diagnostic
|
|
133
|
* context.
|
|
134
|
*
|
|
135
|
* <p>The returned value is the value that was pushed last. If no
|
|
136
|
* context is available, then the empty string "" is returned.</p>
|
|
137
|
*
|
|
138
|
* @return string The innermost diagnostic context.
|
|
139
|
*/
|
|
140
|
public static function pop() {
|
|
141
|
if(count(self::$stack) > 0) {
|
|
142
|
return array_pop(self::$stack);
|
|
143
|
} else {
|
|
144
|
return '';
|
|
145
|
}
|
|
146
|
}
|
|
147
|
|
|
148
|
/**
|
|
149
|
* Looks at the last diagnostic context at the top of this NDC
|
|
150
|
* without removing it.
|
|
151
|
*
|
|
152
|
* <p>The returned value is the value that was pushed last. If no
|
|
153
|
* context is available, then the empty string "" is returned.</p>
|
|
154
|
* @return string The innermost diagnostic context.
|
|
155
|
*/
|
|
156
|
public static function peek(){
|
|
157
|
if(count(self::$stack) > 0) {
|
|
158
|
return end(self::$stack);
|
|
159
|
} else {
|
|
160
|
return '';
|
|
161
|
}
|
|
162
|
}
|
|
163
|
|
|
164
|
/**
|
|
165
|
* Push new diagnostic context information for the current thread.
|
|
166
|
*
|
|
167
|
* <p>The contents of the <var>message</var> parameter is
|
|
168
|
* determined solely by the client.
|
|
169
|
*
|
|
170
|
* @param string $message The new diagnostic context information.
|
|
171
|
*/
|
|
172
|
public static function push($message) {
|
|
173
|
array_push(self::$stack, (string)$message);
|
|
174
|
}
|
|
175
|
|
|
176
|
/**
|
|
177
|
* Remove the diagnostic context for this thread.
|
|
178
|
*/
|
|
179
|
public static function remove() {
|
|
180
|
LoggerNDC::clear();
|
|
181
|
}
|
|
182
|
|
|
183
|
/**
|
|
184
|
* Set maximum depth of this diagnostic context. If the current
|
|
185
|
* depth is smaller or equal to <var>maxDepth</var>, then no
|
|
186
|
* action is taken.
|
|
187
|
*
|
|
188
|
* <p>This method is a convenient alternative to multiple
|
|
189
|
* {@link pop()} calls. Moreover, it is often the case that at
|
|
190
|
* the end of complex call sequences, the depth of the NDC is
|
|
191
|
* unpredictable. The {@link setMaxDepth()} method circumvents
|
|
192
|
* this problem.
|
|
193
|
*
|
|
194
|
* @param integer $maxDepth
|
|
195
|
* @see getDepth()
|
|
196
|
*/
|
|
197
|
public static function setMaxDepth($maxDepth) {
|
|
198
|
$maxDepth = (int)$maxDepth;
|
|
199
|
if(LoggerNDC::getDepth() > $maxDepth) {
|
|
200
|
self::$stack = array_slice(self::$stack, 0, $maxDepth);
|
|
201
|
}
|
|
202
|
}
|
|
203
|
}
|