nginx proxy limit module development --2

Core algorithm of limit rate:

code:

if (u->limit_rate) {
excess = u->received - u->limit_rate_after
- u->limit_rate * (ngx_time() - r->start_sec + 1);

if (excess > 0) {
if (ngx_handle_read_event(r->connection->read, 0) != NGX_OK) {
return NGX_HTTP_INTERNAL_SERVER_ERROR;
}
delay = excess * 1000 /u->limit_rate;
if (delay > 0) {
c->read->delayed = 1;
ngx_add_timer(r->connection->read, delay);
return NGX_AGAIN;
}
}
}

Variable and description:

a. u->limit_rate

Description:

This variable can be set by user. The configure file include the phrase to set.

Limit the rate to upload file.

Example: proxy_limit_rate 10k;

b. u->limit_rate_after

Description:

This variable can be set by user. The configure file include the phrase to set.

Limit rate after 10k byte.

Example: proxy_limit_rate_after 10k;

Function and description:

ngx_add_timer(r->connection->read, delay);

http://blog.youkuaiyun.com/marcky/article/details/7623335

ngx_add_timer函数就是用来完成将一个新的定时事件加入定时器红黑树中，定时事件被执行后，就会从树中移除.

Summary:

After above, we only need to rewrite the 

ngx_http_read_client_request_body ==> ngx_http_proxy_read_client_request_body

Notice:

a. ngx_http_proxy_read_client_request_body_handler

This function should be modify. Because ngx_handle_read_event(rev, clcf->send_lowat) 

need to add for process read delay.

This code is important to deal read timeout. Or your code will be exit.

r->connection->read->timedout,   r->connection->read->delayed = 0;