1 | <?php |
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2 | /** |
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3 | * SessionCache.inc.php |
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4 | * Code by Strangecode :: www.strangecode.com :: This document contains copyrighted information |
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5 | */ |
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6 | |
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7 | /** |
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8 | * The maximum byte size that the session cache will hold. |
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9 | * @const SESSION_CACHE_SIZE_BYTES |
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10 | */ |
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11 | if (!defined('SESSION_CACHE_SIZE_BYTES')) { |
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12 | define('SESSION_CACHE_SIZE_BYTES', 32768); // 32 Kilobytes. |
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13 | } |
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14 | |
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15 | /** |
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16 | * The cache will never flush out all the items, it will leave this many in. |
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17 | * This is in case you cache a very large item and expect it to stay a little |
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18 | * longer than having if dumped the next time something goes into the cache. |
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19 | * @const SESSION_CACHE_MIN_ITEMS |
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20 | */ |
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21 | define('SESSION_CACHE_MIN_ITEMS', 3); // 3 items. |
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22 | |
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23 | |
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24 | /** |
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25 | * SessionCache:: provides an API for storing a limited amount of data |
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26 | * intended to have a short lifetime in a user's session. |
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27 | * |
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28 | * @inspiration Horde 2.0's SessionCache class. |
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29 | * @author Quinn Comendant <quinn@strangecode.com> |
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30 | * @version 1.0 |
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31 | */ |
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32 | class SessionCache |
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33 | { |
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34 | |
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35 | /** |
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36 | * Stores a new variable in the session cache. The $var_id is is md5'ed |
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37 | * because if a variable id is a very large integer, the array_shift function |
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38 | * will reset the key to the next largest int key. Weird behaviour I can't |
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39 | * understand. $session_cache[32341234123] will become $session_cache[0] |
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40 | * for example. Usage warning: if the variable is too big to fit, or is |
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41 | * old and discarded, you must provide alternative ways of accessing the data. |
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42 | * |
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43 | * @param mixed $var The var to store in the session cache. |
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44 | * @param str $var_id An identifyer for the cached object. |
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45 | * @param bool $force_it_in If we have something really big that we |
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46 | * still want to cache, setting this true |
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47 | * allows this. |
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48 | * |
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49 | * @return string The $var_id, or false if the object was too big to cache. |
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50 | */ |
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51 | function putCache($var, $var_id, $force_it_in=false) |
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52 | { |
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53 | $var_id = md5($var_id); |
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54 | $serialized_var = serialize($var); |
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55 | $serialized_var_len = strlen($serialized_var); |
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56 | |
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57 | if ($serialized_var_len >= 1024000) { |
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58 | logMsg(sprintf('Attempting to cache oversized variable at %s bytes.', $serialized_var_len), LOG_NOTICE, __FILE__, __LINE__); |
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59 | } |
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60 | |
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61 | if ($serialized_var_len >= SESSION_CACHE_SIZE_BYTES && !$force_it_in) { |
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62 | return false; |
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63 | } |
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64 | |
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65 | if (!isset($_SESSION['_session_cache'])) { |
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66 | $_SESSION['_session_cache'] = array(); |
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67 | } else { |
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68 | unset($_SESSION['_session_cache'][$var_id]); |
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69 | // Continue to prune the cache if it's length is too long for the new variable to fit, but keep at least MIN_ITEMS at least. |
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70 | while (strlen(serialize($_SESSION['_session_cache'])) + $serialized_var_len >= SESSION_CACHE_SIZE_BYTES |
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71 | && sizeof($_SESSION['_session_cache']) >= SESSION_CACHE_MIN_ITEMS) { |
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72 | array_shift($_SESSION['_session_cache']); |
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73 | } |
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74 | } |
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75 | $_SESSION['_session_cache'][$var_id] =& $serialized_var; |
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76 | |
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77 | return $var_id; |
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78 | } |
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79 | |
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80 | /** |
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81 | * Retrives an object from the session cache and returns it unserialized. |
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82 | * It also moves it to the top of the stack, which makes it such that the |
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83 | * cache flushing mechanism of putCache deletes the oldest referenced items |
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84 | * first. |
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85 | * |
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86 | * @param string $var_id The identifyer for the datum to retrieve. |
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87 | * |
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88 | * @return mixed The requested datum, or false on failure. |
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89 | */ |
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90 | function getCache($var_id) |
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91 | { |
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92 | $var_id = md5($var_id); |
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93 | if (isset($_SESSION['_session_cache'][$var_id])) { |
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94 | // Move the accessed cached datum to the top of the stack. Maybe somebody knows a better way to do this? |
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95 | $tmp =& $_SESSION['_session_cache'][$var_id]; |
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96 | unset($_SESSION['_session_cache'][$var_id]); |
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97 | $_SESSION['_session_cache'][$var_id] =& $tmp; |
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98 | // Return the unserialized datum. |
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99 | return unserialize($_SESSION['_session_cache'][$var_id]); |
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100 | } else { |
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101 | return false; |
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102 | } |
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103 | } |
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104 | |
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105 | /** |
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106 | * Tells you if the object is cached. |
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107 | * |
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108 | * @param string $var_id The ID of the object to check. |
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109 | * |
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110 | * @return bool The return from isset(). |
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111 | */ |
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112 | function isCached($var_id) |
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113 | { |
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114 | $var_id = md5($var_id); |
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115 | return isset($_SESSION['_session_cache'][$var_id]); |
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116 | } |
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117 | |
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118 | /** |
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119 | * Tells you if the object is cached. |
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120 | * |
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121 | * @param string $var_id The ID of the object to check. |
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122 | * |
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123 | * @return bool The return from isset(). |
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124 | */ |
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125 | function breakCache($var_id) |
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126 | { |
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127 | $var_id = md5($var_id); |
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128 | unset($_SESSION['_session_cache'][$var_id]); |
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129 | } |
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130 | |
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131 | // END SessionCache |
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132 | } |
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133 | |
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134 | ?> |
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