think\cache\driver\Memcached::__construct PHP Method

    public function __construct($options = [])
    {
        if (!extension_loaded('memcached')) {
            throw new \BadFunctionCallException('not support: memcached');
        }
        if (!empty($options)) {
            $this->options = array_merge($this->options, $options);
        }
        $this->handler = new \Memcached();
        if (!empty($this->options['option'])) {
            $this->handler->setOptions($this->options['option']);
        }
        // 设置连接超时时间（单位：毫秒）
        if ($this->options['timeout'] > 0) {
            $this->handler->setOption(\Memcached::OPT_CONNECT_TIMEOUT, $this->options['timeout']);
        }
        // 支持集群
        $hosts = explode(',', $this->options['host']);
        $ports = explode(',', $this->options['port']);
        if (empty($ports[0])) {
            $ports[0] = 11211;
        }
        // 建立连接
        $servers = [];
        foreach ((array) $hosts as $i => $host) {
            $servers[] = [$host, isset($ports[$i]) ? $ports[$i] : $ports[0], 1];
        }
        $this->handler->addServers($servers);
        if ('' != $this->options['username']) {
            $this->handler->setOption(\Memcached::OPT_BINARY_PROTOCOL, true);
            $this->handler->setSaslAuthData($this->options['username'], $this->options['password']);
        }
    }