Hi!

We use nginx rate limiting function but realized that it does not work for files smaller than the limit specified in limit_rate directive. Analyzing the source code it turned out that forcing the limit is second based. We modified the source to be able to rate limit more precisely and it also works for smaller files.

Here is the patch:
leki@szunyog:~/src/agwlimit/nginx-1.2.2$ diff -u src/http/ngx_http_write_filter_module.c{.old,}
--- src/http/ngx_http_write_filter_module.c.old 2012-07-30 08:32:13.155354399 +0200
+++ src/http/ngx_http_write_filter_module.c 2012-07-30 13:55:01.074823215 +0200
@@ -211,8 +211,15 @@
}

if (r->limit_rate) {
- limit = r->limit_rate * (ngx_time() - r->start_sec + 1)
- - (c->sent - clcf->limit_rate_after);
+ if (ngx_cached_time->msec < r->start_msec) {
+ limit = r->limit_rate * (ngx_time() - r->start_sec - 1)
+ + r->limit_rate * (ngx_cached_time->msec + 1000 - r->start_msec) / 1000
+ - (c->sent - clcf->limit_rate_after);
+ } else {
+ limit = r->limit_rate * (ngx_time() - r->start_sec)
+ + r->limit_rate * (ngx_cached_time->msec - r->start_msec) / 1000
+ - (c->sent - clcf->limit_rate_after);
+ }

if (limit <= 0) {
c->write->delayed = 1;

As we tested the pathced nginx it worked fine. Could we use it in production or do you see any mistakes we made? Is there any reason you don't count on milliseconds?

Regards,
Gabor

Regards,
Gabor Lekeny