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|
<?php
namespace Studip\Cache;
use DBManager;
use Psr\Cache\CacheItemInterface;
/**
* StudipCache implementation using database table
*
* @author Elmar Ludwig <elmar.ludwig@uos.de>
*/
class DbCache extends Cache
{
/**
* @return string A display name (that can be translated) for this cache class.
*/
public static function getDisplayName(): string
{
return _('Datenbank');
}
/**
* Expire item from the cache.
*
* @param string $arg a single key
*/
public function expire($arg)
{
$db = DBManager::get();
$stmt = $db->prepare('DELETE FROM cache WHERE cache_key = ?');
$stmt->execute([$arg]);
}
/**
* Expire all items from the cache.
*/
public function flush()
{
$db = DBManager::get();
$db->exec('TRUNCATE TABLE cache');
}
/**
* Delete all expired items from the cache.
*/
public function purge()
{
$db = DBManager::get();
$stmt = $db->prepare('DELETE FROM cache WHERE expires < ?');
$stmt->execute([time()]);
}
/**
* Return statistics.
*
* @return array|array[]
*@see Cache::getStats()
*
*/
public function getStats(): array
{
return [
__CLASS__ => [
'name' => _('Anzahl Einträge'),
'value' => DBManager::get()->fetchColumn("SELECT COUNT(*) FROM `cache`")
]
];
}
/**
* Return the Vue component name and props that handle configuration.
*
* @return array
*@see Cache::getConfig()
*
*/
public static function getConfig(): array
{
return [
'component' => null,
'props' => []
];
}
/**
* @inheritDoc
*/
public function getItem(string $key): CacheItemInterface
{
$query = "SELECT `content`, `expires`
FROM `cache`
WHERE `cache_key` = :key
AND `expires` > UNIX_TIMESTAMP()";
$result = DBManager::get()->fetchOne($query, [':key' => $key]);
$item = new Item($key);
if (!empty($result)) {
$item->setHit();
if ($result['content']) {
$item->set(unserialize($result['content']));
}
if ($result['expires']) {
$expiration = new \DateTime();
$expiration->setTimestamp($result['expires']);
$item->expiresAt($expiration);
}
}
return $item;
}
/**
* @inheritDoc
*/
public function hasItem(string $key): bool
{
$query = "SELECT 1
FROM `cache`
WHERE `cache_key` = :key
AND `expires` > UNIX_TIMESTAMP()";
return (bool) DBManager::get()->fetchColumn($query, [':key' => $key]);
}
/**
* @inheritDoc
*/
public function save(CacheItemInterface $item): bool
{
$expiration = $this->getExpiration($item);
if ($expiration < 1) {
// The item would expire immediately.
return false;
}
return DBManager::get()->execute(
'REPLACE INTO `cache` VALUES (?, ?, ?)',
[$item->getKey(), serialize($item->get()), $expiration]
);
}
}
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