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1 <?php |
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2 // $Id: cache.inc,v 1.17.2.2 2009/05/26 08:10:33 goba Exp $ |
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3 |
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4 /** |
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5 * Return data from the persistent cache. Data may be stored as either plain text or as serialized data. |
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6 * cache_get will automatically return unserialized objects and arrays. |
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7 * |
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8 * @param $cid |
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9 * The cache ID of the data to retrieve. |
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10 * @param $table |
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11 * The table $table to store the data in. Valid core values are 'cache_filter', |
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12 * 'cache_menu', 'cache_page', or 'cache' for the default cache. |
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13 */ |
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14 function cache_get($cid, $table = 'cache') { |
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15 global $user; |
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16 |
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17 // Garbage collection necessary when enforcing a minimum cache lifetime |
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18 $cache_flush = variable_get('cache_flush_'. $table, 0); |
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19 if ($cache_flush && ($cache_flush + variable_get('cache_lifetime', 0) <= time())) { |
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20 // Reset the variable immediately to prevent a meltdown in heavy load situations. |
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21 variable_set('cache_flush_'. $table, 0); |
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22 // Time to flush old cache data |
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23 db_query("DELETE FROM {". $table ."} WHERE expire != %d AND expire <= %d", CACHE_PERMANENT, $cache_flush); |
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24 } |
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25 |
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26 $cache = db_fetch_object(db_query("SELECT data, created, headers, expire, serialized FROM {". $table ."} WHERE cid = '%s'", $cid)); |
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27 if (isset($cache->data)) { |
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28 // If the data is permanent or we're not enforcing a minimum cache lifetime |
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29 // always return the cached data. |
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30 if ($cache->expire == CACHE_PERMANENT || !variable_get('cache_lifetime', 0)) { |
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31 $cache->data = db_decode_blob($cache->data); |
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32 if ($cache->serialized) { |
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33 $cache->data = unserialize($cache->data); |
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34 } |
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35 } |
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36 // If enforcing a minimum cache lifetime, validate that the data is |
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37 // currently valid for this user before we return it by making sure the |
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38 // cache entry was created before the timestamp in the current session's |
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39 // cache timer. The cache variable is loaded into the $user object by |
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40 // sess_read() in session.inc. |
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41 else { |
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42 if ($user->cache > $cache->created) { |
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43 // This cache data is too old and thus not valid for us, ignore it. |
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44 return 0; |
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45 } |
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46 else { |
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47 $cache->data = db_decode_blob($cache->data); |
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48 if ($cache->serialized) { |
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49 $cache->data = unserialize($cache->data); |
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50 } |
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51 } |
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52 } |
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53 return $cache; |
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54 } |
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55 return 0; |
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56 } |
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57 |
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58 /** |
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59 * Store data in the persistent cache. |
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60 * |
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61 * The persistent cache is split up into four database |
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62 * tables. Contributed modules can add additional tables. |
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63 * |
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64 * 'cache_page': This table stores generated pages for anonymous |
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65 * users. This is the only table affected by the page cache setting on |
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66 * the administrator panel. |
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67 * |
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68 * 'cache_menu': Stores the cachable part of the users' menus. |
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69 * |
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70 * 'cache_filter': Stores filtered pieces of content. This table is |
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71 * periodically cleared of stale entries by cron. |
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72 * |
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73 * 'cache': Generic cache storage table. |
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74 * |
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75 * The reasons for having several tables are as follows: |
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76 * |
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77 * - smaller tables allow for faster selects and inserts |
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78 * - we try to put fast changing cache items and rather static |
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79 * ones into different tables. The effect is that only the fast |
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80 * changing tables will need a lot of writes to disk. The more |
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81 * static tables will also be better cachable with MySQL's query cache |
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82 * |
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83 * @param $cid |
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84 * The cache ID of the data to store. |
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85 * @param $data |
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86 * The data to store in the cache. Complex data types will be automatically serialized before insertion. |
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87 * Strings will be stored as plain text and not serialized. |
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88 * @param $table |
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89 * The table $table to store the data in. Valid core values are 'cache_filter', |
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90 * 'cache_menu', 'cache_page', or 'cache'. |
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91 * @param $expire |
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92 * One of the following values: |
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93 * - CACHE_PERMANENT: Indicates that the item should never be removed unless |
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94 * explicitly told to using cache_clear_all() with a cache ID. |
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95 * - CACHE_TEMPORARY: Indicates that the item should be removed at the next |
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96 * general cache wipe. |
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97 * - A Unix timestamp: Indicates that the item should be kept at least until |
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98 * the given time, after which it behaves like CACHE_TEMPORARY. |
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99 * @param $headers |
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100 * A string containing HTTP header information for cached pages. |
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101 */ |
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102 function cache_set($cid, $data, $table = 'cache', $expire = CACHE_PERMANENT, $headers = NULL) { |
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103 $serialized = 0; |
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104 if (is_object($data) || is_array($data)) { |
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105 $data = serialize($data); |
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106 $serialized = 1; |
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107 } |
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108 $created = time(); |
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109 db_query("UPDATE {". $table ."} SET data = %b, created = %d, expire = %d, headers = '%s', serialized = %d WHERE cid = '%s'", $data, $created, $expire, $headers, $serialized, $cid); |
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110 if (!db_affected_rows()) { |
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111 @db_query("INSERT INTO {". $table ."} (cid, data, created, expire, headers, serialized) VALUES ('%s', %b, %d, %d, '%s', %d)", $cid, $data, $created, $expire, $headers, $serialized); |
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112 } |
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113 } |
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114 |
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115 /** |
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116 * |
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117 * Expire data from the cache. If called without arguments, expirable |
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118 * entries will be cleared from the cache_page and cache_block tables. |
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119 * |
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120 * @param $cid |
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121 * If set, the cache ID to delete. Otherwise, all cache entries that can |
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122 * expire are deleted. |
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123 * |
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124 * @param $table |
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125 * If set, the table $table to delete from. Mandatory |
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126 * argument if $cid is set. |
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127 * |
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128 * @param $wildcard |
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129 * If set to TRUE, the $cid is treated as a substring |
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130 * to match rather than a complete ID. The match is a right hand |
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131 * match. If '*' is given as $cid, the table $table will be emptied. |
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132 */ |
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133 function cache_clear_all($cid = NULL, $table = NULL, $wildcard = FALSE) { |
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134 global $user; |
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135 |
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136 if (!isset($cid) && !isset($table)) { |
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137 // Clear the block cache first, so stale data will |
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138 // not end up in the page cache. |
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139 cache_clear_all(NULL, 'cache_block'); |
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140 cache_clear_all(NULL, 'cache_page'); |
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141 return; |
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142 } |
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143 |
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144 if (empty($cid)) { |
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145 if (variable_get('cache_lifetime', 0)) { |
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146 // We store the time in the current user's $user->cache variable which |
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147 // will be saved into the sessions table by sess_write(). We then |
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148 // simulate that the cache was flushed for this user by not returning |
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149 // cached data that was cached before the timestamp. |
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150 $user->cache = time(); |
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151 |
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152 $cache_flush = variable_get('cache_flush_'. $table, 0); |
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153 if ($cache_flush == 0) { |
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154 // This is the first request to clear the cache, start a timer. |
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155 variable_set('cache_flush_'. $table, time()); |
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156 } |
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157 else if (time() > ($cache_flush + variable_get('cache_lifetime', 0))) { |
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158 // Clear the cache for everyone, cache_lifetime seconds have |
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159 // passed since the first request to clear the cache. |
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160 db_query("DELETE FROM {". $table ."} WHERE expire != %d AND expire < %d", CACHE_PERMANENT, time()); |
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161 variable_set('cache_flush_'. $table, 0); |
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162 } |
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163 } |
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164 else { |
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165 // No minimum cache lifetime, flush all temporary cache entries now. |
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166 db_query("DELETE FROM {". $table ."} WHERE expire != %d AND expire < %d", CACHE_PERMANENT, time()); |
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167 } |
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168 } |
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169 else { |
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170 if ($wildcard) { |
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171 if ($cid == '*') { |
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172 db_query("DELETE FROM {". $table ."}"); |
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173 } |
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174 else { |
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175 db_query("DELETE FROM {". $table ."} WHERE cid LIKE '%s%%'", $cid); |
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176 } |
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177 } |
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178 else { |
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179 db_query("DELETE FROM {". $table ."} WHERE cid = '%s'", $cid); |
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180 } |
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181 } |
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182 } |
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183 |