request help: how ngx.timer.at get response set for ngx.arg[1] in body_filter?

[zhangweidongyyl]

Issue description

` local function push_data(premature, args)

    httpc, err = http:new()                                         -- 创建 http 连接对象
    httpc:set_timeout(time)                                         -- 注意名字里有一个下划线
    httpc:set_timeout(connect_timeout,                              -- 同上
            send_timeout, read_timeout)
    local res, err = httpc:request_uri(                             -- 发送 HTTP 请求，默认是 GET
            'http://www.baidu.com',                                     -- 指定 IP 地址
            {path = '/echo',                                        -- 指定具体路径
             query = {name = 'chrono'}}                              -- 请求的参数，使用 Lua 表
    )
    if not res then                                                 -- 检查请求是否成功
        core.log.error("failed to request : ", err)
        return
    end
    core.log.info("args:", type(args))
    core.log.info("res.body：",res.body)                                               -- 输出响应体
end
local resp = ""
local ok, err = ngx.timer.at(0, push_data, ngx.var.args)
if not ok then
    ngx.log(ngx.ERR, "failed to create timer: ", err)
    return
end
ngx.arg[1] = "success"
ngx.arg[2] = true`

how i set res.body for global

Environment

• apisix version (cmd: apisix version):
• OS (cmd: uname -a):
• OpenResty / Nginx version (cmd: nginx -V or openresty -V):
• etcd version, if have (cmd: run curl http://127.0.0.1:9090/v1/server_info to get the info from server-info API):
• apisix-dashboard version, if have:
• the plugin runner version, if the issue is about a plugin runner (cmd: depended on the kind of runner):
• luarocks version, if the issue is about installation (cmd: luarocks --version):

[tzssangglass]

the issue is not relevant to the project, I will turn it into a discussion.

[tzssangglass]

refer to: #4837 (comment)