123 lines
4.4 KiB
PHP
123 lines
4.4 KiB
PHP
<?php
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// $Id$
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/**
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* Return data from the persistent cache.
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*
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* @param $key
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* The cache ID of the data to retrieve.
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*/
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function cache_get($key) {
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global $user;
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// Garbage collection necessary when enforcing a minimum cache lifetime
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$cache_flush = variable_get('cache_flush', 0);
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if ($cache_flush && ($cache_flush + variable_get('cache_lifetime', 0) <= time())) {
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// Time to flush old cache data
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db_query("DELETE FROM {cache} WHERE expire != %d AND expire <= %d", CACHE_PERMANENT, $cache_flush);
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variable_set('cache_flush', 0);
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}
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$cache = db_fetch_object(db_query("SELECT data, created, headers, expire FROM {cache} WHERE cid = '%s'", $key));
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if (isset($cache->data)) {
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// If the data is permanent or we're not enforcing a minimum cache lifetime
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// always return the cached data.
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if ($cache->expire == CACHE_PERMANENT || !variable_get('cache_lifetime', 0)) {
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$cache->data = db_decode_blob($cache->data);
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}
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// If enforcing a minimum cache lifetime, validate that the data is
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// currently valid for this user before we return it by making sure the
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// cache entry was created before the timestamp in the current session's
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// cache timer. The cache variable is loaded into the $user object by
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// sess_read() in session.inc.
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else {
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if ($user->cache > $cache->created) {
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// This cache data is too old and thus not valid for us, ignore it.
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return 0;
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}
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else {
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$cache->data = db_decode_blob($cache->data);
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}
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}
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return $cache;
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}
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return 0;
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}
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/**
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* Store data in the persistent cache.
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*
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* @param $cid
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* The cache ID of the data to store.
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* @param $data
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* The data to store in the cache. Complex data types must be serialized first.
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* @param $expire
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* One of the following values:
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* - CACHE_PERMANENT: Indicates that the item should never be removed unless
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* explicitly told to using cache_clear_all() with a cache ID.
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* - CACHE_TEMPORARY: Indicates that the item should be removed at the next
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* general cache wipe.
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* - A Unix timestamp: Indicates that the item should be kept at least until
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* the given time, after which it behaves like CACHE_TEMPORARY.
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* @param $headers
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* A string containing HTTP header information for cached pages.
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*/
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function cache_set($cid, $data, $expire = CACHE_PERMANENT, $headers = NULL) {
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db_lock_table('cache');
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db_query("UPDATE {cache} SET data = %b, created = %d, expire = %d, headers = '%s' WHERE cid = '%s'", $data, time(), $expire, $headers, $cid);
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if (!db_affected_rows()) {
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@db_query("INSERT INTO {cache} (cid, data, created, expire, headers) VALUES ('%s', %b, %d, %d, '%s')", $cid, $data, time(), $expire, $headers);
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}
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db_unlock_tables();
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}
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/**
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* Expire data from the cache.
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*
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* @param $cid
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* If set, the cache ID to delete. Otherwise, all cache entries that can
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* expire are deleted.
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*
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* @param $wildcard
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* If set to true, the $cid is treated as a substring to match rather than a
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* complete ID.
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*/
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function cache_clear_all($cid = NULL, $wildcard = false) {
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global $user;
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if (empty($cid)) {
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if (variable_get('cache_lifetime', 0)) {
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// We store the time in the current user's $user->cache variable which
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// will be saved into the sessions table by sess_write(). We then
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// simulate that the cache was flushed for this user by not returning
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// cached data that was cached before the timestamp.
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$user->cache = time();
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$cache_flush = variable_get('cache_flush', 0);
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if ($cache_flush == 0) {
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// This is the first request to clear the cache, start a timer.
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variable_set('cache_flush', time());
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}
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else if (time() > ($cache_flush + variable_get('cache_lifetime', 0))) {
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// Clear the cache for everyone, cache_flush_delay seconds have
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// passed since the first request to clear the cache.
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db_query("DELETE FROM {cache} WHERE expire != %d AND expire < %d", CACHE_PERMANENT, time());
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variable_set('cache_flush', 0);
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}
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}
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else {
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// No minimum cache lifetime, flush all temporary cache entries now.
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db_query("DELETE FROM {cache} WHERE expire != %d AND expire < %d", CACHE_PERMANENT, time());
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}
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}
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else {
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if ($wildcard) {
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db_query("DELETE FROM {cache} WHERE cid LIKE '%%%s%%'", $cid);
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}
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else {
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db_query("DELETE FROM {cache} WHERE cid = '%s'", $cid);
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}
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}
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}
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