Phalcon 框架，redis 如何切换库

<code>$di->set('modelsCache', function () use ($config) {
    $cache = new Phalcon\Cache\Backend\Redis(xx, xx);
    return $cache;
});</code>

<code>$this->modelsCache->save('data_in_db0','value');
$opt=$this->modelsCache->getOptions();
$opt['index']=1;
$this->modelsCache->setOptions($opt);
$this->modelsCache->save('data_in_db1','value');</code>

<code>$di->set('modelsCache', function () use ($config) {
    $cache = new Phalcon\Cache\Backend\Redis(xx, xx);
    return $cache;
});</code>

<code>$this->modelsCache->save('data_in_db0','value');
$opt=$this->modelsCache->getOptions();
$opt['index']=1;
$this->modelsCache->setOptions($opt);
$this->modelsCache->save('data_in_db1','value');</code>