<?php
/**
* CakePHP(tm) : Rapid Development Framework (https://cakephp.org)
* Copyright (c) Cake Software Foundation, Inc. (https://cakefoundation.org)
*
* Licensed under The MIT License
* For full copyright and license information, please see the LICENSE.txt
* Redistributions of files must retain the above copyright notice.
*
* @copyright Copyright (c) Cake Software Foundation, Inc. (https://cakefoundation.org)
* @link https://cakephp.org CakePHP(tm) Project
* @since 3.0.0
* @license https://opensource.org/licenses/mit-license.php MIT License
*/
namespace Cake\Datasource;
use Cake\Cache\Cache;
use Cake\Cache\CacheEngine;
use RuntimeException;
use Traversable;
/**
* Handles caching queries and loading results from the cache.
*
* Used by Cake\Datasource\QueryTrait internally.
*
* @see \Cake\Datasource\QueryTrait::cache() for the public interface.
*/
class QueryCacher
{
/**
* The key or function to generate a key.
*
* @var string|callable
*/
protected $_key;
/**
* Config for cache engine.
*
* @var string|\Cake\Cache\CacheEngine
*/
protected $_config;
/**
* Constructor.
*
* @param string|\Closure $key The key or function to generate a key.
* @param string|\Cake\Cache\CacheEngine $config The cache config name or cache engine instance.
* @throws \RuntimeException
*/
public function __construct($key, $config)
{
if (!is_string($key) && !is_callable($key)) {
throw new RuntimeException('Cache keys must be strings or callables.');
}
$this->_key = $key;
if (!is_string($config) && !($config instanceof CacheEngine)) {
throw new RuntimeException('Cache configs must be strings or CacheEngine instances.');
}
$this->_config = $config;
}
/**
* Load the cached results from the cache or run the query.
*
* @param object $query The query the cache read is for.
* @return \Cake\Datasource\ResultSetInterface|null Either the cached results or null.
*/
public function fetch($query)
{
$key = $this->_resolveKey($query);
$storage = $this->_resolveCacher();
$result = $storage->read($key);
if (empty($result)) {
return null;
}
return $result;
}
/**
* Store the result set into the cache.
*
* @param object $query The query the cache read is for.
* @param \Traversable $results The result set to store.
* @return bool True if the data was successfully cached, false on failure
*/
public function store($query, Traversable $results)
{
$key = $this->_resolveKey($query);
$storage = $this->_resolveCacher();
return $storage->write($key, $results);
}
/**
* Get/generate the cache key.
*
* @param object $query The query to generate a key for.
* @return string
* @throws \RuntimeException
*/
protected function _resolveKey($query)
{
if (is_string($this->_key)) {
return $this->_key;
}
$func = $this->_key;
$key = $func($query);
if (!is_string($key)) {
$msg = sprintf('Cache key functions must return a string. Got %s.', var_export($key, true));
throw new RuntimeException($msg);
}
return $key;
}
/**
* Get the cache engine.
*
* @return \Cake\Cache\CacheEngine
*/
protected function _resolveCacher()
{
if (is_string($this->_config)) {
return Cache::engine($this->_config);
}
return $this->_config;
}
}