1 | <?php |
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2 | /** |
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3 | * Licensed to the Apache Software Foundation (ASF) under one or more |
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4 | * contributor license agreements. See the NOTICE file distributed with |
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5 | * this work for additional information regarding copyright ownership. |
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6 | * The ASF licenses this file to You under the Apache License, Version 2.0 |
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7 | * (the "License"); you may not use this file except in compliance with |
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8 | * the License. You may obtain a copy of the License at |
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9 | * |
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10 | * http://www.apache.org/licenses/LICENSE-2.0 |
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11 | * |
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12 | * Unless required by applicable law or agreed to in writing, software |
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13 | * distributed under the License is distributed on an "AS IS" BASIS, |
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14 | * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
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15 | * See the License for the specific language governing permissions and |
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16 | * limitations under the License. |
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17 | * |
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18 | * |
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19 | * @package log4php |
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20 | */ |
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21 | |
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22 | /** |
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23 | * @ignore |
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24 | */ |
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25 | if (!defined('LOG4PHP_DIR')) define('LOG4PHP_DIR', dirname(__FILE__)); |
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26 | |
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27 | /** |
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28 | */ |
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29 | require_once(LOG4PHP_DIR . '/LoggerLog.php'); |
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30 | |
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31 | define('LOGGER_NDC_HT_SIZE', 7); |
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32 | |
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33 | /** |
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34 | * This is the global repository of NDC stack |
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35 | */ |
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36 | $GLOBALS['log4php.LoggerNDC.ht'] = array(); |
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37 | |
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38 | /** |
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39 | * This is the max depth of NDC stack |
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40 | */ |
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41 | $GLOBALS['log4php.LoggerNDC.maxDepth'] = LOGGER_NDC_HT_SIZE; |
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42 | |
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43 | |
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44 | /** |
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45 | * The NDC class implements <i>nested diagnostic contexts</i> as |
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46 | * defined by Neil Harrison in the article "Patterns for Logging |
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47 | * Diagnostic Messages" part of the book "<i>Pattern Languages of |
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48 | * Program Design 3</i>" edited by Martin et al. |
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49 | * |
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50 | * <p>A Nested Diagnostic Context, or NDC in short, is an instrument |
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51 | * to distinguish interleaved log output from different sources. Log |
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52 | * output is typically interleaved when a server handles multiple |
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53 | * clients near-simultaneously. |
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54 | * |
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55 | * <p>Interleaved log output can still be meaningful if each log entry |
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56 | * from different contexts had a distinctive stamp. This is where NDCs |
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57 | * come into play. |
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58 | * |
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59 | * <p><i><b>Note that NDCs are managed on a per thread |
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60 | * basis</b></i>. NDC operations such as {@link push()}, {@link pop()}, |
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61 | * {@link clear()}, {@link getDepth()} and {@link setMaxDepth()} |
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62 | * affect the NDC of the <i>current</i> thread only. NDCs of other |
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63 | * threads remain unaffected. |
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64 | * |
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65 | * <p>For example, a servlet can build a per client request NDC |
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66 | * consisting the clients host name and other information contained in |
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67 | * the the request. <i>Cookies</i> are another source of distinctive |
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68 | * information. To build an NDC one uses the {@link push()} |
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69 | * operation.</p> |
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70 | * |
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71 | * Simply put, |
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72 | * |
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73 | * - Contexts can be nested. |
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74 | * - When entering a context, call |
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75 | * <code>LoggerNDC::push()</code> |
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76 | * As a side effect, if there is no nested diagnostic context for the |
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77 | * current thread, this method will create it. |
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78 | * - When leaving a context, call |
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79 | * <code>LoggerNDC::pop()</code> |
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80 | * - <b>When exiting a thread make sure to call {@link remove()}</b> |
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81 | * |
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82 | * <p>There is no penalty for forgetting to match each |
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83 | * <code>push</code> operation with a corresponding <code>pop</code>, |
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84 | * except the obvious mismatch between the real application context |
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85 | * and the context set in the NDC.</p> |
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86 | * |
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87 | * <p>If configured to do so, {@link LoggerPatternLayout} and {@link LoggerLayoutTTCC} |
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88 | * instances automatically retrieve the nested diagnostic |
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89 | * context for the current thread without any user intervention. |
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90 | * Hence, even if a servlet is serving multiple clients |
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91 | * simultaneously, the logs emanating from the same code (belonging to |
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92 | * the same category) can still be distinguished because each client |
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93 | * request will have a different NDC tag.</p> |
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94 | * |
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95 | * |
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96 | * @author Marco Vassura |
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97 | * @version $Revision: 635069 $ |
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98 | * @package log4php |
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99 | * @since 0.3 |
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100 | */ |
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101 | class LoggerNDC { |
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102 | |
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103 | /** |
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104 | * Clear any nested diagnostic information if any. This method is |
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105 | * useful in cases where the same thread can be potentially used |
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106 | * over and over in different unrelated contexts. |
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107 | * |
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108 | * <p>This method is equivalent to calling the {@link setMaxDepth()} |
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109 | * method with a zero <var>maxDepth</var> argument. |
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110 | * |
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111 | * @static |
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112 | */ |
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113 | public static function clear() |
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114 | { |
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115 | LoggerLog::debug("LoggerNDC::clear()"); |
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116 | |
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117 | $GLOBALS['log4php.LoggerNDC.ht'] = array(); |
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118 | } |
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119 | |
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120 | /** |
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121 | * Never use this method directly, use the {@link LoggerLoggingEvent::getNDC()} method instead. |
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122 | * @static |
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123 | * @return array |
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124 | */ |
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125 | public static function get() |
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126 | { |
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127 | LoggerLog::debug("LoggerNDC::get()"); |
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128 | |
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129 | return $GLOBALS['log4php.LoggerNDC.ht']; |
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130 | } |
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131 | |
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132 | /** |
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133 | * Get the current nesting depth of this diagnostic context. |
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134 | * |
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135 | * @see setMaxDepth() |
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136 | * @return integer |
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137 | * @static |
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138 | */ |
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139 | public static function getDepth() |
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140 | { |
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141 | LoggerLog::debug("LoggerNDC::getDepth()"); |
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142 | |
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143 | return sizeof($GLOBALS['log4php.LoggerNDC.ht']); |
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144 | } |
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145 | |
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146 | /** |
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147 | * Clients should call this method before leaving a diagnostic |
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148 | * context. |
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149 | * |
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150 | * <p>The returned value is the value that was pushed last. If no |
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151 | * context is available, then the empty string "" is returned.</p> |
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152 | * |
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153 | * @return string The innermost diagnostic context. |
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154 | * @static |
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155 | */ |
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156 | public static function pop() |
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157 | { |
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158 | LoggerLog::debug("LoggerNDC::pop()"); |
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159 | |
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160 | if (sizeof($GLOBALS['log4php.LoggerNDC.ht']) > 0) { |
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161 | return array_pop($GLOBALS['log4php.LoggerNDC.ht']); |
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162 | } else { |
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163 | return ''; |
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164 | } |
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165 | } |
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166 | |
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167 | /** |
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168 | * Looks at the last diagnostic context at the top of this NDC |
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169 | * without removing it. |
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170 | * |
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171 | * <p>The returned value is the value that was pushed last. If no |
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172 | * context is available, then the empty string "" is returned.</p> |
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173 | * @return string The innermost diagnostic context. |
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174 | * @static |
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175 | */ |
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176 | public static function peek() |
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177 | { |
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178 | LoggerLog::debug("LoggerNDC::peek()"); |
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179 | |
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180 | if (sizeof($GLOBALS['log4php.LoggerNDC.ht']) > 0) { |
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181 | return end($GLOBALS['log4php.LoggerNDC.ht']); |
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182 | } else { |
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183 | return ''; |
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184 | } |
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185 | } |
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186 | |
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187 | /** |
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188 | * Push new diagnostic context information for the current thread. |
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189 | * |
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190 | * <p>The contents of the <var>message</var> parameter is |
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191 | * determined solely by the client. |
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192 | * |
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193 | * @param string $message The new diagnostic context information. |
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194 | * @static |
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195 | */ |
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196 | public static function push($message) |
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197 | { |
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198 | LoggerLog::debug("LoggerNDC::push()"); |
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199 | |
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200 | array_push($GLOBALS['log4php.LoggerNDC.ht'], (string)$message); |
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201 | } |
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202 | |
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203 | /** |
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204 | * Remove the diagnostic context for this thread. |
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205 | * @static |
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206 | */ |
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207 | public static function remove() |
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208 | { |
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209 | LoggerLog::debug("LoggerNDC::remove()"); |
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210 | |
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211 | LoggerNDC::clear(); |
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212 | } |
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213 | |
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214 | /** |
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215 | * Set maximum depth of this diagnostic context. If the current |
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216 | * depth is smaller or equal to <var>maxDepth</var>, then no |
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217 | * action is taken. |
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218 | * |
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219 | * <p>This method is a convenient alternative to multiple |
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220 | * {@link pop()} calls. Moreover, it is often the case that at |
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221 | * the end of complex call sequences, the depth of the NDC is |
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222 | * unpredictable. The {@link setMaxDepth()} method circumvents |
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223 | * this problem. |
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224 | * |
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225 | * @param integer $maxDepth |
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226 | * @see getDepth() |
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227 | * @static |
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228 | */ |
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229 | public static function setMaxDepth($maxDepth) |
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230 | { |
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231 | LoggerLog::debug("LoggerNDC::setMaxDepth() maxDepth='$maxDepth'"); |
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232 | |
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233 | $maxDepth = (int)$maxDepth; |
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234 | if ($maxDepth <= LOGGER_NDC_HT_SIZE) { |
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235 | if (LoggerNDC::getDepth() > $maxDepth) { |
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236 | $GLOBALS['log4php.LoggerNDC.ht'] = array_slice($GLOBALS['log4php.LoggerNDC.ht'], $maxDepth); |
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237 | } |
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238 | $GLOBALS['log4php.LoggerNDC.maxDepth'] = $maxDepth; |
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239 | } |
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240 | } |
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241 | |
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242 | } |
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