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<?php defined("SYSPATH") or die("No direct script access.");
/**
* Gallery - a web based photo album viewer and editor
* Copyright (C) 2000-2009 Bharat Mediratta
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or (at
* your option) any later version.
*
* This program is distributed in the hope that it will be useful, but
* WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street - Fifth Floor, Boston, MA 02110-1301, USA.
*/
/*
* Based on the Cache_Sqlite_Driver developed by the Kohana Team
*/
class Cache_Database_Driver implements Cache_Driver {
// Kohana database instance
protected $db;
/**
* Tests that the storage location is a directory and is writable.
*/
public function __construct() {
// Open up an instance of the database
$this->db = Database::instance();
if (!$this->db->table_exists("caches")) {
throw new Exception("@todo Cache table is not defined");
}
}
/**
* Checks if a cache id is already set.
*
* @param string cache id
* @return boolean
*/
public function exists($id) {
$count = $this->db->count_records("caches", array("key" => $id, "expiration >=" => time()));
return $count > 0;
}
/**
* Sets a cache item to the given data, tags, and lifetime.
*
* @param string cache id to set
* @param string data in the cache
* @param array cache tags
* @param integer lifetime
* @return bool
*/
public function set($id, $data, array $tags = NULL, $lifetime) {
if (!empty($tags)) {
// Escape the tags, adding brackets so the tag can be explicitly matched
$tags = "<" . implode(">,<", $tags) . ">";
}
// Cache Database driver expects unix timestamp
if ($lifetime !== 0) {
$lifetime += time();
}
if ($this->exists($id)) {
$status = $this->db->update(
"caches",
array("tags" => $tags, "expiration" => $lifetime, "cache" => serialize($data)), array("key" => $id));
} else {
$status = $this->db->insert(
"caches",
array("key" => $id, "tags" => $tags, "expiration" => $lifetime, "cache" => serialize($data)));
}
return count($status) > 0;
}
/**
* Finds an array of ids for a given tag.
*
* @param string tag name
* @return array of ids that match the tag
*/
public function find($tag) {
$db_result = $this->db->from("caches")
->like("tags", "<$tag>")
->get()
->result(true);
// An array will always be returned
$result = array();
if ($db_result->count() > 0) {
// Disable notices for unserializing
$ER = error_reporting(~E_NOTICE);
foreach ($db_result as $row) {
// Add each cache to the array
$result[$row->key] = unserialize($row->cache);
}
// Turn notices back on
error_reporting($ER);
}
return $result;
}
/**
* Fetches a cache item. This will delete the item if it is expired or if
* the hash does not match the stored hash.
*
* @param string cache id
* @return mixed|NULL
*/
public function get($id) {
$data = null;
$result = $this->db->getwhere("caches", array("key" => $id));
if (count($result) > 0) {
$cache = $result->current();
// Make sure the expiration is valid and that the hash matches
if ($cache->expiration != 0 && $cache->expiration <= time()) {
// Cache is not valid, delete it now
$this->delete($cache->id);
} else {
// Disable notices for unserializing
$ER = error_reporting(~E_NOTICE);
// Return the valid cache data
$data = unserialize($cache->cache);
// Turn notices back on
error_reporting($ER);
}
}
return $data;
}
/**
* Deletes a cache item by id or tag
*
* @param string cache id or tag, or true for "all items"
* @param bool delete a tag
* @return bool
*/
public function delete($id, $tag = false) {
$this->db->from("caches");
if ($id === true) {
$this->db->where(1);
// Delete all caches
} else if ($tag === true) {
$this->db->like("tags", "<$id>");
} else {
$this->db->where("key", $id);
}
$status = $this->db->delete();
return count($status) > 0;
}
/**
* Deletes all cache files that are older than the current time.
*/
public function delete_expired() {
// Delete all expired caches
$status = $this->db->from("caches")
->where(array("expiration !=" => 0, "expiration <=" => time()))
->delete();
return count($status) > 0;
}
} // End Cache Database Driver
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