symphony/lib/toolkit/cache/cache.database.php
<?php
/**
* @package core
*/
/**
* The CacheDatabase interface allows extensions to store data in Symphony's
* database table, `tbl_cache`. At the moment, it is mostly unused by the core,
* with the exception of the deprecated Dynamic XML datasource.
*
* This cache will be initialised by default if no other caches are specified
* in the install.
*
* @see ExtensionManager#getCacheProvider()
*/
class CacheDatabase implements iNamespacedCache
{
/**
* An instance of the Database class to communicate with `tbl_cache`
* which is where the cached data is stored.
*
* @var Database
*/
private $Database;
/**
* The constructor for the Cacheable takes an instance of the
* Database class and assigns it to `$this->Database`
*
* @param Database $Database
* An instance of the Database class to store the cached
* data in.
*/
public function __construct(Database $Database)
{
$this->Database = $Database;
}
/**
* Returns the human readable name of this cache type. This is
* displayed in the system preferences cache options.
*
* @return string
*/
public static function getName()
{
return 'Database';
}
/**
* This function returns all the settings of the current Cache
* instance.
*
* @return array
* An associative array of settings for this cache where the
* key is `getClass` and the value is an associative array of settings,
* key being the setting name, value being, the value
*/
public function settings()
{
}
/**
* Given the hash of a some data, check to see whether it exists in
* `tbl_cache`. If no cached object is found, this function will return
* false, otherwise the cached object will be returned as an array.
*
* @param string $hash
* The hash of the Cached object, as defined by the user
* @param string $namespace
* The namespace allows a group of data to be retrieved at once
* @return array|boolean
* An associative array of the cached object including the creation time,
* expiry time, the hash and the data. If the object is not found, false will
* be returned.
*/
public function read($hash, $namespace = null)
{
$data = false;
$query = $this->Database
->select()
->from('tbl_cache')
->where(['or' => [
['expiry' => 'null'],
['expiry' => ['>=' => 'UNIX_TIMESTAMP()']],
]]);
if (!$hash && !$namespace) {
return false;
}
// Check namespace first
if (!is_null($namespace) && is_null($hash)) {
$query->where(['namespace' => $namespace]);
}
// Then check hash
if (!is_null($hash)) {
$query->where(['hash' => $hash])->limit(1);
}
$data = $query->execute()->rows();
// If the data exists, see if it's still valid
if (!empty($data)) {
$data = array_map(function ($data) {
$data['data'] = Cacheable::decompressData($data['data']);
return $data;
}, $data);
$data = array_filter($data, function ($data) {
return $data['data'];
});
if (empty($data)) {
$this->delete($hash, $namespace);
return false;
}
if ($hash) {
return $data[0];
}
return $data;
}
return false;
}
/**
* This function will compress data for storage in `tbl_cache`.
* It is left to the user to define a unique hash for this data so that it can be
* retrieved in the future. Optionally, a `$ttl` parameter can
* be passed for this data. If this is omitted, it data is considered to be valid
* forever. This function utilizes the Mutex class to act as a crude locking
* mechanism.
*
* @see toolkit.Mutex
* @throws DatabaseException
* @param string $hash
* The hash of the Cached object, as defined by the user
* @param string $data
* The data to be cached, this will be compressed prior to saving.
* @param integer $ttl
* A integer representing how long the data should be valid for in minutes.
* By default this is null, meaning the data is valid forever
* @param string $namespace
* The namespace allows data to be grouped and saved so it can be
* retrieved later.
* @return boolean
* If an error occurs, this function will return false otherwise true
*/
public function write($hash, $data, $ttl = null, $namespace = null)
{
if (!Mutex::acquire($hash, 2, TMP)) {
return false;
}
$creation = time();
$expiry = null;
$ttl = intval($ttl);
if ($ttl > 0) {
$expiry = $creation + ($ttl * 60);
}
if (!$data = Cacheable::compressData($data)) {
return false;
}
$this->delete($hash, $namespace);
$this->Database->insert('tbl_cache')->values([
'hash' => $hash,
'creation' => $creation,
'expiry' => $expiry,
'data' => $data,
'namespace' => $namespace
])->execute();
Mutex::release($hash, TMP);
return true;
}
/**
* Given the hash of a cacheable object, remove it from `tbl_cache`
* regardless of if it has expired or not. If no $hash is given,
* this removes all cache objects from `tbl_cache` that have expired.
* After removing, the function uses the `__optimise` function
*
* @see core.Cacheable#optimise()
* @throws DatabaseException
* @param string $hash
* The hash of the Cached object, as defined by the user
* @param string $namespace
* The namespace allows similar data to be deleted quickly.
*/
public function delete($hash = null, $namespace = null)
{
$stm = $this->Database->delete('tbl_cache');
if (!is_null($hash)) {
$stm->where(['hash' => $hash])->execute();
} elseif (!is_null($namespace)) {
$stm->where(['namespace' => $namespace])->execute();
} else {
$stm->where(['expiry' => ['<' => 'UNIX_TIMESTAMP()']])->execute();
$this->__optimise();
}
}
/**
* Runs a MySQL OPTIMIZE query on `tbl_cache`
*/
private function __optimise()
{
$this->Database->optimize('tbl_cache')->execute();
}
}