[1] | 1 | <?php |
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| 2 | /** |
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| 3 | * SessionCache.inc.php |
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| 4 | * Provides an API for storing a limited amount of data |
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| 5 | * intended to have a short lifetime in a user's session. |
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| 6 | * |
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| 7 | * Code by Strangecode :: www.strangecode.com :: This document contains copyrighted information. |
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| 8 | * @author Quinn Comendant <quinn@strangecode.com> |
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| 9 | * @version 1.2 |
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| 10 | * @since 2001 |
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| 11 | */ |
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| 12 | class SessionCache |
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| 13 | { |
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| 14 | var $_params = array( |
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[21] | 15 | 'enabled' => true, |
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[1] | 16 | 'soft_limit' => 204800, |
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| 17 | 'hard_limit' => 4194304, |
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| 18 | 'min_items' => 3, |
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| 19 | ); |
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| 20 | |
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| 21 | /** |
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| 22 | * This method enforces the singleton pattern for this class. |
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| 23 | * |
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| 24 | * @return object Reference to the global SessionCache object. |
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| 25 | * @access public |
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| 26 | * @static |
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| 27 | */ |
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| 28 | function &getInstance() { |
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| 29 | static $instance = null; |
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| 30 | |
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| 31 | if ($instance === null) { |
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| 32 | $instance = new SessionCache(); |
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| 33 | } |
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| 34 | |
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| 35 | return $instance; |
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| 36 | } |
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| 37 | |
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| 38 | /** |
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| 39 | * Set (or overwrite existing) parameters by passing an array of new parameters. |
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| 40 | * |
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| 41 | * @access public |
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| 42 | * @param array $params Array of parameters (key => val pairs). |
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| 43 | */ |
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| 44 | function setParam($params) |
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| 45 | { |
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[53] | 46 | if (!isset($this) || !is_a($this, 'SessionCache') && !is_subclass_of($this, 'SessionCache')) { |
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[21] | 47 | $this =& SessionCache::getInstance(); |
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| 48 | } |
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| 49 | |
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[1] | 50 | if (isset($params) && is_array($params)) { |
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| 51 | // Merge new parameters with old overriding only those passed. |
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| 52 | $this->_params = array_merge($this->_params, $params); |
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| 53 | } else { |
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| 54 | App::logMsg(sprintf('Parameters are not an array: %s', $params), LOG_ERR, __FILE__, __LINE__); |
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| 55 | } |
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| 56 | } |
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| 57 | |
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| 58 | /** |
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| 59 | * Return the value of a parameter, if it exists. |
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| 60 | * |
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| 61 | * @access public |
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| 62 | * @param string $param Which parameter to return. |
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| 63 | * @return mixed Configured parameter value. |
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| 64 | */ |
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| 65 | function getParam($param) |
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| 66 | { |
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[53] | 67 | if (!isset($this) || !is_a($this, 'SessionCache') && !is_subclass_of($this, 'SessionCache')) { |
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[21] | 68 | $this =& SessionCache::getInstance(); |
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| 69 | } |
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| 70 | |
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[1] | 71 | if (isset($this->_params[$param])) { |
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| 72 | return $this->_params[$param]; |
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| 73 | } else { |
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| 74 | App::logMsg(sprintf('Parameter is not set: %s', $param), LOG_DEBUG, __FILE__, __LINE__); |
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| 75 | return null; |
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| 76 | } |
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| 77 | } |
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| 78 | |
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| 79 | /** |
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| 80 | * Stores a new variable in the session cache. The $var_id is is md5'ed |
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| 81 | * because if a variable id is a very large integer, the array_shift function |
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| 82 | * will reset the key to the next largest int key. Weird behaviour I can't |
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| 83 | * understand. $session_cache[32341234123] will become $session_cache[0] |
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| 84 | * for example. Usage warning: if the variable is too big to fit, or is |
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| 85 | * old and discarded, you must provide alternative ways of accessing the data. |
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| 86 | * |
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| 87 | * @param mixed $var The var to store in the session cache. |
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| 88 | * @param str $var_id An identifyer for the cached object. |
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| 89 | * @param bool $force_it_in If we have something really big that we |
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[42] | 90 | * still want to cache, setting this true |
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[1] | 91 | * allows this. |
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| 92 | * |
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| 93 | * @return string The $var_id, or false if the object was too big to cache. |
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| 94 | */ |
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| 95 | function putCache($var, $var_id, $force_it_in=false) |
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| 96 | { |
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[53] | 97 | if (!isset($this) || !is_a($this, 'SessionCache') && !is_subclass_of($this, 'SessionCache')) { |
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[21] | 98 | $this =& SessionCache::getInstance(); |
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| 99 | } |
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[1] | 100 | |
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[21] | 101 | if (!$this->getParam('enabled')) { |
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[44] | 102 | App::logMsg(sprintf('SessionCache not enabled, not saving data.', null), LOG_DEBUG, __FILE__, __LINE__); |
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[21] | 103 | return false; |
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| 104 | } |
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| 105 | |
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[1] | 106 | $var_id = md5($var_id); |
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| 107 | $serialized_var = serialize($var); |
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| 108 | $serialized_var_len = strlen($serialized_var); |
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[42] | 109 | |
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[21] | 110 | if ($serialized_var_len >= $this->getParam('soft_limit') && !$force_it_in) { |
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| 111 | App::logMsg(sprintf('Serialized variable (%s bytes) more than soft_limit (%s bytes).', $serialized_var_len, $this->getParam('soft_limit')), LOG_NOTICE, __FILE__, __LINE__); |
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[1] | 112 | return false; |
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| 113 | } |
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[42] | 114 | |
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[21] | 115 | if ($serialized_var_len >= $this->getParam('hard_limit')) { |
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| 116 | App::logMsg(sprintf('Serialized variable (%s bytes) more than hard_limit (%s bytes).', $serialized_var_len, $this->getParam('hard_limit')), LOG_NOTICE, __FILE__, __LINE__); |
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[1] | 117 | return false; |
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| 118 | } |
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| 119 | |
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| 120 | if (!isset($_SESSION['_session_cache'])) { |
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| 121 | $_SESSION['_session_cache'] = array(); |
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| 122 | } else { |
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| 123 | unset($_SESSION['_session_cache'][$var_id]); |
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| 124 | // Continue to prune the cache if it's length is too long for the new variable to fit, but keep at least MIN_ITEMS at least. |
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[42] | 125 | while (strlen(serialize($_SESSION['_session_cache'])) + $serialized_var_len >= $this->getParam('soft_limit') |
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[21] | 126 | && sizeof($_SESSION['_session_cache']) >= $this->getParam('min_items')) { |
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[1] | 127 | array_shift($_SESSION['_session_cache']); |
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| 128 | } |
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| 129 | } |
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| 130 | $_SESSION['_session_cache'][$var_id] =& $serialized_var; |
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[42] | 131 | |
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[1] | 132 | if ($serialized_var_len >= 1024000) { |
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| 133 | App::logMsg(sprintf('Successfully cached oversized variable (%s bytes).', $serialized_var_len), LOG_DEBUG, __FILE__, __LINE__); |
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| 134 | } |
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[42] | 135 | |
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[1] | 136 | return $var_id; |
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| 137 | } |
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[42] | 138 | |
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[1] | 139 | /** |
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[42] | 140 | * Retrives an object from the session cache and returns it unserialized. |
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[1] | 141 | * It also moves it to the top of the stack, which makes it such that the |
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| 142 | * cache flushing mechanism of putCache deletes the oldest referenced items |
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| 143 | * first. |
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| 144 | * |
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| 145 | * @param string $var_id The identifyer for the datum to retrieve. |
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| 146 | * |
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| 147 | * @return mixed The requested datum, or false on failure. |
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| 148 | */ |
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| 149 | function getCache($var_id) |
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| 150 | { |
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[53] | 151 | if (!isset($this) || !is_a($this, 'SessionCache') && !is_subclass_of($this, 'SessionCache')) { |
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[21] | 152 | $this =& SessionCache::getInstance(); |
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| 153 | } |
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| 154 | |
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| 155 | if (!$this->getParam('enabled')) { |
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| 156 | return false; |
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| 157 | } |
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[42] | 158 | |
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[1] | 159 | $var_id = md5($var_id); |
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| 160 | if (isset($_SESSION['_session_cache'][$var_id])) { |
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| 161 | // Move the accessed cached datum to the top of the stack. Maybe somebody knows a better way to do this? |
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| 162 | $tmp =& $_SESSION['_session_cache'][$var_id]; |
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| 163 | unset($_SESSION['_session_cache'][$var_id]); |
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| 164 | $_SESSION['_session_cache'][$var_id] =& $tmp; |
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| 165 | // Return the unserialized datum. |
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| 166 | return unserialize($_SESSION['_session_cache'][$var_id]); |
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| 167 | } else { |
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| 168 | return false; |
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| 169 | } |
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| 170 | } |
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[42] | 171 | |
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[1] | 172 | /** |
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| 173 | * Tells you if the object is cached. |
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| 174 | * |
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| 175 | * @param string $var_id The ID of the object to check. |
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| 176 | * |
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| 177 | * @return bool The return from isset(). |
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| 178 | */ |
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| 179 | function isCached($var_id) |
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| 180 | { |
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[53] | 181 | if (!isset($this) || !is_a($this, 'SessionCache') && !is_subclass_of($this, 'SessionCache')) { |
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[21] | 182 | $this =& SessionCache::getInstance(); |
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| 183 | } |
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| 184 | |
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| 185 | if (!$this->getParam('enabled')) { |
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| 186 | return false; |
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| 187 | } |
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| 188 | |
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[1] | 189 | $var_id = md5($var_id); |
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| 190 | return isset($_SESSION['_session_cache'][$var_id]); |
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| 191 | } |
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[42] | 192 | |
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[1] | 193 | /** |
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| 194 | * Tells you if the object is cached. |
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| 195 | * |
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| 196 | * @param string $var_id The ID of the object to check. |
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| 197 | * |
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| 198 | * @return bool The return from isset(). |
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| 199 | */ |
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| 200 | function breakCache($var_id) |
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| 201 | { |
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| 202 | $var_id = md5($var_id); |
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| 203 | if (isset($_SESSION['_session_cache'][$var_id])) { |
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| 204 | unset($_SESSION['_session_cache'][$var_id]); |
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| 205 | } |
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| 206 | } |
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| 207 | |
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| 208 | // END SessionCache |
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| 209 | } |
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| 210 | |
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| 211 | ?> |
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