gistfile1.nginxconf

    location /t {
        access_log off;
        content_by_lua '
            local mysql = require "mysql2"
            local query = mysql.query
            local db = {
                _max_packet_size = 10240
            }
            local sub = string.sub

            local f, err = io.open("/tmp/packet2", "r")
            if not f then
                ngx.log(ngx.ERR, "failed to open file for reading: ", err)
                return ngx.exit(500)
            end

            local offset
            local packet_data = f:read("*a")
            f:close()
    
            db.sock = {
                receive = function (sock, len)
                    local data = sub(packet_data, offset, offset + len - 1)
                    offset = offset + len
                    if data == nil then
                        return nil, "eof already"
                    end
                    coroutine.yield()
                    return data
                end,

                send = function (data)
                    return #data
                end
            }

            offset = 1
            local res, err, errno, sqlstate
            for j = 1, 10 do
                -- offset = 1
                db.state = 1
                res, err, errno, sqlstate = query(db, "select * from City order by ID limit 50", 50)
                if not res then
                    ngx.log(ngx.ERR, "bad result #1: ", err, ": ", errno, ": ", sqlstate, ".")
                    return ngx.exit(500)
                end
            end

            for _, row in ipairs(res) do
                local ncols = 0
                for k, v in pairs(row) do
                    ncols = ncols + 1
                end
                ngx.say("ncols: ", ncols)
            end
        ';
    }