hi, developers
Because of the modularity of nginx, I can extend the new function easily.
But there are some requirements which need to modify the original source
code.
For example:
I want to add a variable which records the count of requests sent to each
upstream. And I must add a variable into the struct
"ngx_http_upstream_rr_peer_t", when round robin get the upstream ,the
variable++ . This way, I shoud modify the source code of the upstream
module.
I think if the struct "ngx_http_upstream_rr_peer_t" have a reserved
pointer(void *), which reserved for others developing new modules.
Totally, I think the modularity of nginx just resolved the expansibility of
function. But if the I want to expand some import data like the struct
"ngx_http_request_t", I must modify the original source code. And if some
important struct adds a reserved pointer, I think the data of nginx will be
easily be extend.

thanks.