[nginx] Limit req: "delay=" parameter.

[Maxim Dounin]

details: http://hg.nginx.org/nginx/rev/d6ca744c727e
branches:
changeset: 7399:d6ca744c727e
user: Maxim Dounin <***@mdounin.ru>
date: Wed Nov 21 18:56:50 2018 +0300
description:
Limit req: "delay=" parameter.

This parameter specifies an additional "soft" burst limit at which requests
become delayed (but not yet rejected as it happens if "burst=" limit is
exceeded). Defaults to 0, i.e., all excess requests are delayed.

Originally inspired by Vladislav Shabanov
(http://mailman.nginx.org/pipermail/nginx-devel/2016-April/008126.html).
Further improved based on a patch by Peter Shchuchkin
(http://mailman.nginx.org/pipermail/nginx-devel/2018-October/011522.html).

diffstat:

src/http/modules/ngx_http_limit_req_module.c | 32 +++++++++++++++++++--------
1 files changed, 22 insertions(+), 10 deletions(-)

diffs (93 lines):

diff --git a/src/http/modules/ngx_http_limit_req_module.c b/src/http/modules/ngx_http_limit_req_module.c
--- a/src/http/modules/ngx_http_limit_req_module.c
+++ b/src/http/modules/ngx_http_limit_req_module.c
@@ -44,7 +44,7 @@ typedef struct {
ngx_shm_zone_t *shm_zone;
/* integer value, 1 corresponds to 0.001 r/s */
ngx_uint_t burst;
- ngx_uint_t nodelay; /* unsigned nodelay:1 */
+ ngx_uint_t delay;
} ngx_http_limit_req_limit_t;


@@ -499,12 +499,12 @@ ngx_http_limit_req_account(ngx_http_limi

excess = *ep;

- if (excess == 0 || (*limit)->nodelay) {
+ if ((ngx_uint_t) excess <= (*limit)->delay) {
max_delay = 0;

} else {
ctx = (*limit)->shm_zone->data;
- max_delay = excess * 1000 / ctx->rate;
+ max_delay = (excess - (*limit)->delay) * 1000 / ctx->rate;
}

while (n--) {
@@ -544,11 +544,11 @@ ngx_http_limit_req_account(ngx_http_limi

ctx->node = NULL;

- if (limits[n].nodelay) {
+ if ((ngx_uint_t) excess <= limits[n].delay) {
continue;
}

- delay = excess * 1000 / ctx->rate;
+ delay = (excess - limits[n].delay) * 1000 / ctx->rate;

if (delay > max_delay) {
max_delay = delay;
@@ -875,9 +875,9 @@ ngx_http_limit_req(ngx_conf_t *cf, ngx_c
{
ngx_http_limit_req_conf_t *lrcf = conf;

- ngx_int_t burst;
+ ngx_int_t burst, delay;
ngx_str_t *value, s;
- ngx_uint_t i, nodelay;
+ ngx_uint_t i;
ngx_shm_zone_t *shm_zone;
ngx_http_limit_req_limit_t *limit, *limits;

@@ -885,7 +885,7 @@ ngx_http_limit_req(ngx_conf_t *cf, ngx_c

shm_zone = NULL;
burst = 0;
- nodelay = 0;
+ delay = 0;

for (i = 1; i < cf->args->nelts; i++) {

@@ -915,8 +915,20 @@ ngx_http_limit_req(ngx_conf_t *cf, ngx_c
continue;
}

+ if (ngx_strncmp(value[i].data, "delay=", 6) == 0) {
+
+ delay = ngx_atoi(value[i].data + 6, value[i].len - 6);
+ if (delay <= 0) {
+ ngx_conf_log_error(NGX_LOG_EMERG, cf, 0,
+ "invalid delay value \"%V\"", &value[i]);
+ return NGX_CONF_ERROR;
+ }
+
+ continue;
+ }
+
if (ngx_strcmp(value[i].data, "nodelay") == 0) {
- nodelay = 1;
+ delay = NGX_MAX_INT_T_VALUE / 1000;
continue;
}

@@ -956,7 +968,7 @@ ngx_http_limit_req(ngx_conf_t *cf, ngx_c

limit->shm_zone = shm_zone;
limit->burst = burst * 1000;
- limit->nodelay = nodelay;
+ limit->delay = delay * 1000;

return NGX_CONF_OK;
}