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MINOR: acl: add fetch for server session rate

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Considering there is no option yet for maxconnrate for servers, I wrote
an ACL to check a backend server session rate which we use to send to an
"overflow" backend to prevent latency responses to our clients (very
sensitive latency requirements).
This commit is contained in:
Tait Clarridge 2012-12-05 21:39:31 -05:00 committed by Willy Tarreau
parent 4445502351
commit 7896d5293d
2 changed files with 29 additions and 0 deletions
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14
doc/configuration.txt
View file

@ -8021,6 +8021,20 @@ be_sess_rate(<backend>) <integer>
acl being_scanned be_sess_rate gt 100
redirect location /denied.html if being_scanned
srv_sess_rate(<backend>/<server>) <integer>
Returns true when the sessions creation rate on the server matches the
specified values or ranges, in number of new sessions per second. This is
used to switch to an alternate backend when an expensive or fragile one
reaches too high a session rate, or to limit abuse of service (eg. prevent
latent requests from overloading servers).
Example :
# Redirect to a separate back
acl srv1_full srv_sess_rate(be1/srv1) gt 50
acl srv2_full srv_sess_rate(be1/srv2) gt 50
use_backend be2 if srv1_full or srv2_full
connslots <integer>
connslots(<backend>) <integer>
The basic idea here is to be able to measure the number of connection "slots"

15
src/backend.c
View file

@ -1587,6 +1587,20 @@ acl_fetch_srv_conn(struct proxy *px, struct session *l4, void *l7, unsigned int
return 1;
}
/* set temp integer to the number of enabled servers on the proxy.
* Accepts exactly 1 argument. Argument is a server, other types will lead to
* undefined behaviour.
*/
static int
acl_fetch_srv_sess_rate(struct proxy *px, struct session *l4, void *l7, unsigned int opt,
const struct arg *args, struct sample *smp)
{
smp->flags = SMP_F_VOL_TEST;
smp->type = SMP_T_UINT;
smp->data.uint = read_freq_ctr(&args->data.srv->sess_per_sec);
return 1;
}
/* Note: must not be declared <const> as its list will be overwritten.
* Please take care of keeping this list alphabetically sorted.
*/
@ -1601,6 +1615,7 @@ static struct acl_kw_list acl_kws = {{ },{
{ "srv_conn", acl_parse_int, acl_fetch_srv_conn, acl_match_int, ACL_USE_NOTHING, ARG1(1,SRV) },
{ "srv_id", acl_parse_int, acl_fetch_srv_id, acl_match_int, ACL_USE_RTR_INTERNAL, 0 },
{ "srv_is_up", acl_parse_nothing, acl_fetch_srv_is_up, acl_match_nothing, ACL_USE_NOTHING, ARG1(1,SRV) },
{ "srv_sess_rate", acl_parse_int, acl_fetch_srv_sess_rate, acl_match_int, ACL_USE_NOTHING, ARG1(1,SRV) },
{ NULL, NULL, NULL, NULL },
}};