php curl 保持長鏈接

curl 擴展默認保持長鏈接，即沒有調用 curl_close()， 鏈接將保持打開狀態。

查看鏈接數：netstat -an|findstr 80 （for win）

private static $ch;
    public static function curlGet($url='', $keepalive=false, $ref='')
    {
        if (!extension_loaded('curl')) {
            exit('need curl extension!');
        }

        $useragent = 'Mozilla/5.0 (Windows NT 6.1; WOW64)';
        $header = [
            //
        ];

        try {
            if (!self::$ch) {
                self::$ch = curl_init();
            }

            
            $opts = [
                CURLOPT_URL => $url,
                CURLOPT_RETURNTRANSFER => true,
                CURLOPT_HTTPHEADER => $header,
                CURLOPT_REFERER => $ref,
                CURLOPT_USERAGENT => $useragent,
                CURLOPT_TIMEOUT => 10,
            ];

            curl_setopt_array(self::$ch, $opts);
            $html = curl_exec(self::$ch);

            if (!$keepalive) {
                curl_close(self::$ch);
            }

            return $html;
        } catch (\Exception $ex) {
            throw $ex;
        }
    }

http://stackoverflow.com/questions/972925/persistent-keepalive-http-with-the-php-curl-library