serialize_precision
http://php.net/manual/en/ini.list.php
https://wiki.php.net/rfc/precise_float_value
https://segmentfault.com/a/1190000008737065
https://laravel-china.org/articles/5993/fix-the-overflow-problem-when-json-encode-deals-with-floatdouble-type-values-in-php7
