public function setMulti(array $items, $expire = 0)
{
$keys = array_map(array($this, 'encodeKey'), array_keys($items));
$items = array_combine($keys, $items);
$success = $this->client->setMulti($items, $expire);
$keys = array_map(array($this, 'decodeKey'), array_keys($items));
return array_fill_keys($keys, $success);
}