yii\caching\MemCache::getMemcache PHP Method

    public function getMemcache()
    {
        if ($this->_cache === null) {
            $extension = $this->useMemcached ? 'memcached' : 'memcache';
            if (!extension_loaded($extension)) {
                throw new InvalidConfigException("MemCache requires PHP {$extension} extension to be loaded.");
            }
            if ($this->useMemcached) {
                $this->_cache = $this->persistentId !== null ? new \Memcached($this->persistentId) : new \Memcached();
                if ($this->username !== null || $this->password !== null) {
                    $this->_cache->setOption(\Memcached::OPT_BINARY_PROTOCOL, true);
                    $this->_cache->setSaslAuthData($this->username, $this->password);
                }
                if (!empty($this->options)) {
                    $this->_cache->setOptions($this->options);
                }
            } else {
                $this->_cache = new \Memcache();
            }
        }
        return $this->_cache;
    }