| Code Coverage
| Classes and Traits | Functions and Methods | Lines
Total |  | 100.00% | 1 / 1 |  | 100.00% | 8 / 8 | CRAP |  | 100.00% | 19 / 19
LoggerNDC |  | 100.00% | 1 / 1 |  | 100.00% | 8 / 8 | 11 |  | 100.00% | 19 / 19
clear() |  | 100.00% | 1 / 1 | 1 |  | 100.00% | 2 / 2
get() |  | 100.00% | 1 / 1 | 1 |  | 100.00% | 1 / 1
getDepth() |  | 100.00% | 1 / 1 | 1 |  | 100.00% | 1 / 1
pop() |  | 100.00% | 1 / 1 | 2 |  | 100.00% | 3 / 3
peek() |  | 100.00% | 1 / 1 | 2 |  | 100.00% | 3 / 3
push($message) |  | 100.00% | 1 / 1 | 1 |  | 100.00% | 2 / 2
remove() |  | 100.00% | 1 / 1 | 1 |  | 100.00% | 2 / 2
setMaxDepth($maxDepth) |  | 100.00% | 1 / 1 | 2 |  | 100.00% | 5 / 5

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: 1350602 $
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 | }