1 | <?php |
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2 | /** |
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3 | * The Strangecode Codebase - a general application development framework for PHP |
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4 | * For details visit the project site: <http://trac.strangecode.com/codebase/> |
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5 | * Copyright 2001-2012 Strangecode, LLC |
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6 | * |
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7 | * This file is part of The Strangecode Codebase. |
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8 | * |
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9 | * The Strangecode Codebase is free software: you can redistribute it and/or |
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10 | * modify it under the terms of the GNU General Public License as published by the |
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11 | * Free Software Foundation, either version 3 of the License, or (at your option) |
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12 | * any later version. |
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13 | * |
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14 | * The Strangecode Codebase is distributed in the hope that it will be useful, but |
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15 | * WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or |
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16 | * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more |
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17 | * details. |
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18 | * |
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19 | * You should have received a copy of the GNU General Public License along with |
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20 | * The Strangecode Codebase. If not, see <http://www.gnu.org/licenses/>. |
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21 | */ |
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22 | |
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23 | /** |
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24 | * Cache.inc.php |
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25 | * |
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26 | * Provides an API for storing a limited amount of data |
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27 | * intended to have a short lifetime in a user's session. |
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28 | * |
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29 | * @author Quinn Comendant <quinn@strangecode.com> |
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30 | * @version 2.1 |
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31 | * @since 2001 |
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32 | */ |
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33 | |
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34 | class Cache { |
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35 | |
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36 | // A place to keep object instances for the singleton pattern. |
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37 | protected static $instances = array(); |
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38 | |
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39 | // Namespace of this instance of Prefs. |
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40 | protected $_ns; |
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41 | |
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42 | // Configuration parameters for this object. |
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43 | protected $_params = array( |
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44 | |
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45 | // Type of cache. Currently only 'session' is supported. |
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46 | 'type' => 'session', |
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47 | |
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48 | // If false nothing will be cached or retrieved. Useful for testing realtime data requests. |
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49 | 'enabled' => true, |
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50 | |
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51 | // The maximum size in bytes of any one variable. |
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52 | 'item_size_limit' => 4194304, // 4 MB |
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53 | |
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54 | // The maximum size in bytes before the cache will begin flushing out old items. |
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55 | 'stack_size_limit' => 4194304, // 4 MB |
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56 | |
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57 | // The minimum items to keep in the cache regardless of item or cache size. |
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58 | 'min_items' => 5, |
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59 | ); |
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60 | |
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61 | /* |
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62 | * Constructor. This is publically accessible for compatability with older implementations, |
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63 | * but the preferred method of instantiation is by use of the singleton pattern: |
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64 | * $cache =& Cache::getInstance('namespace'); |
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65 | * $cache->setParam(array('enabled' => true)); |
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66 | * |
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67 | * @access public |
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68 | * @param string $namespace This object will store data under this realm. |
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69 | * @author Quinn Comendant <quinn@strangecode.com> |
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70 | * @version 1.0 |
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71 | * @since 05 Jun 2006 23:14:21 |
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72 | */ |
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73 | public function __construct($namespace='') |
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74 | { |
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75 | $app =& App::getInstance(); |
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76 | |
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77 | $this->_ns = $namespace; |
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78 | |
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79 | if (true !== $app->getParam('enable_session')) { |
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80 | $app->logMsg('Cache disabled, enable_session is false.', LOG_DEBUG, __FILE__, __LINE__); |
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81 | $this->setParam(array('enabled' => false)); |
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82 | } |
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83 | |
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84 | if (!isset($_SESSION['_cache'][$this->_ns])) { |
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85 | $this->clear(); |
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86 | } |
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87 | } |
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88 | |
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89 | /** |
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90 | * This method enforces the singleton pattern for this class. |
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91 | * |
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92 | * @return object Reference to the global Cache object. |
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93 | * @access public |
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94 | * @static |
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95 | */ |
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96 | public static function &getInstance($namespace='') |
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97 | { |
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98 | if (!array_key_exists($namespace, self::$instances)) { |
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99 | self::$instances[$namespace] = new self($namespace); |
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100 | } |
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101 | return self::$instances[$namespace]; |
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102 | } |
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103 | |
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104 | /** |
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105 | * Set (or overwrite existing) parameters by passing an array of new parameters. |
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106 | * |
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107 | * @access public |
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108 | * @param array $params Array of parameters (key => val pairs). |
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109 | */ |
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110 | public function setParam($params) |
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111 | { |
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112 | $app =& App::getInstance(); |
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113 | |
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114 | if (isset($params) && is_array($params)) { |
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115 | // Merge new parameters with old overriding only those passed. |
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116 | $this->_params = array_merge($this->_params, $params); |
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117 | } else { |
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118 | $app->logMsg(sprintf('Parameters are not an array: %s', $params), LOG_ERR, __FILE__, __LINE__); |
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119 | } |
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120 | } |
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121 | |
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122 | /** |
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123 | * Return the value of a parameter, if it exists. |
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124 | * |
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125 | * @access public |
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126 | * @param string $param Which parameter to return. |
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127 | * @return mixed Configured parameter value. |
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128 | */ |
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129 | public function getParam($param) |
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130 | { |
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131 | $app =& App::getInstance(); |
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132 | |
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133 | if (array_key_exists($param, $this->_params)) { |
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134 | return $this->_params[$param]; |
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135 | } else { |
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136 | $app->logMsg(sprintf('Parameter is not set: %s', $param), LOG_DEBUG, __FILE__, __LINE__); |
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137 | return null; |
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138 | } |
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139 | } |
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140 | |
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141 | /** |
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142 | * Stores a new variable in the session cache. The $key should not be numeric |
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143 | * because the array_shift function will reset the key to the next largest |
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144 | * int key. Weird behavior I can't understand. For example $cache["123"] will become $cache[0] |
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145 | * |
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146 | * @param str $key An identifier for the cached object. |
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147 | * @param mixed $var The data to store in the session cache. |
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148 | * @param bool $allow_oversized If we have something really big that we still want to cache, setting this to true allows this. |
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149 | * @return bool True on success, false otherwise. |
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150 | */ |
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151 | public function set($key, $var, $allow_oversized=false) |
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152 | { |
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153 | $app =& App::getInstance(); |
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154 | |
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155 | if (true !== $this->getParam('enabled')) { |
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156 | $app->logMsg(sprintf('Cache disabled, not saving data.', null), LOG_DEBUG, __FILE__, __LINE__); |
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157 | return false; |
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158 | } |
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159 | |
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160 | if (is_numeric($key)) { |
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161 | $app->logMsg(sprintf('Cache::set key value should not be numeric (%s given)', $key), LOG_WARNING, __FILE__, __LINE__); |
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162 | } |
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163 | |
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164 | $var = serialize($var); |
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165 | $var_len = mb_strlen($var); |
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166 | |
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167 | if ($var_len >= $this->getParam('item_size_limit')) { |
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168 | $app->logMsg(sprintf('Serialized variable (%s bytes) more than item_size_limit (%s bytes).', $var_len, $this->getParam('item_size_limit')), LOG_NOTICE, __FILE__, __LINE__); |
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169 | return false; |
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170 | } |
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171 | |
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172 | if ($allow_oversized && $var_len >= $this->getParam('stack_size_limit')) { |
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173 | $app->logMsg(sprintf('Serialized variable (%s bytes) more than stack_size_limit (%s bytes).', $var_len, $this->getParam('stack_size_limit')), LOG_NOTICE, __FILE__, __LINE__); |
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174 | return false; |
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175 | } |
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176 | |
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177 | // Remove any value already stored under this key. |
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178 | unset($_SESSION['_cache'][$this->_ns][$key]); |
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179 | |
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180 | // Continue to prune the cache if its size is greater than stack_size_limit, but keep at least min_items. |
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181 | while (mb_strlen(serialize($_SESSION['_cache'][$this->_ns])) + $var_len >= $this->getParam('stack_size_limit') && sizeof($_SESSION['_cache'][$this->_ns]) >= $this->getParam('min_items')) { |
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182 | array_shift($_SESSION['_cache'][$this->_ns]); |
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183 | } |
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184 | |
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185 | // Save this value under the specified key. |
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186 | $_SESSION['_cache'][$this->_ns][$key] =& $var; |
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187 | |
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188 | if ($var_len >= 1024000) { |
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189 | $app->logMsg(sprintf('Successfully cached oversized variable (%s bytes).', $var_len), LOG_DEBUG, __FILE__, __LINE__); |
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190 | } |
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191 | |
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192 | return true; |
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193 | } |
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194 | |
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195 | /** |
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196 | * Retrieves an object from the session cache and returns it unserialized. |
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197 | * It also moves it to the top of the stack, which makes it such that the |
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198 | * cache flushing mechanism of putCache deletes the oldest referenced items |
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199 | * first. |
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200 | * |
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201 | * @param string $key The key for the datum to retrieve. |
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202 | * @return mixed The requested datum, or false on failure. |
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203 | */ |
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204 | public function get($key) |
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205 | { |
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206 | $app =& App::getInstance(); |
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207 | |
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208 | if (true !== $this->getParam('enabled')) { |
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209 | $app->logMsg(sprintf('Cache disabled, not getting data.', null), LOG_DEBUG, __FILE__, __LINE__); |
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210 | return false; |
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211 | } |
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212 | |
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213 | if (isset($_SESSION['_cache'][$this->_ns]) && array_key_exists($key, $_SESSION['_cache'][$this->_ns])) { |
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214 | $app->logMsg(sprintf('Retreiving %s from cache.', $key), LOG_DEBUG, __FILE__, __LINE__); |
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215 | // Move the accessed cached datum to the top of the stack. Maybe somebody knows a better way to do this? |
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216 | $tmp =& $_SESSION['_cache'][$this->_ns][$key]; |
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217 | unset($_SESSION['_cache'][$this->_ns][$key]); |
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218 | $_SESSION['_cache'][$this->_ns][$key] =& $tmp; |
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219 | // Return the unserialized datum. |
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220 | return unserialize($_SESSION['_cache'][$this->_ns][$key]); |
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221 | } else { |
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222 | $app->logMsg(sprintf('Missing %s from cache.', $key), LOG_DEBUG, __FILE__, __LINE__); |
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223 | return false; |
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224 | } |
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225 | } |
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226 | |
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227 | /** |
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228 | * Tells you if the object is cached. |
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229 | * |
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230 | * @param string $key The key of the object to check. |
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231 | * @return bool True if a value exists for the given key. |
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232 | */ |
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233 | public function exists($key) |
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234 | { |
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235 | $app =& App::getInstance(); |
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236 | |
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237 | if (true !== $this->getParam('enabled')) { |
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238 | $app->logMsg(sprintf('Cache disabled on exist assertion.', null), LOG_DEBUG, __FILE__, __LINE__); |
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239 | return false; |
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240 | } |
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241 | |
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242 | return (isset($_SESSION['_cache'][$this->_ns]) && array_key_exists($key, $_SESSION['_cache'][$this->_ns])); |
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243 | } |
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244 | |
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245 | /** |
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246 | * Removes a cached object. |
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247 | * |
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248 | * @param string $key The key of the object to check. |
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249 | * @return bool True if the value existed before being unset. |
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250 | */ |
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251 | public function delete($key) |
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252 | { |
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253 | if (isset($_SESSION['_cache'][$this->_ns]) && array_key_exists($key, $_SESSION['_cache'][$this->_ns])) { |
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254 | unset($_SESSION['_cache'][$this->_ns][$key]); |
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255 | return true; |
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256 | } else { |
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257 | return false; |
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258 | } |
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259 | } |
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260 | |
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261 | /* |
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262 | * Delete all existing items from the cache. |
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263 | * |
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264 | * @access public |
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265 | * @author Quinn Comendant <quinn@strangecode.com> |
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266 | * @version 1.0 |
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267 | * @since 05 Jun 2006 23:51:34 |
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268 | */ |
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269 | public function clear() |
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270 | { |
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271 | $_SESSION['_cache'][$this->_ns] = array(); |
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272 | } |
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273 | |
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274 | // END Cache |
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275 | } |
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276 | |
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