blob: 74fa659212ec85561fdd354b97159d4c7b55a03c [file] [log] [blame]
* Queue management functions.
* Copyright 2000-2009 Willy Tarreau <>
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; either version
* 2 of the License, or (at your option) any later version.
#include <common/config.h>
#include <common/memory.h>
#include <common/time.h>
#include <proto/queue.h>
#include <proto/server.h>
#include <proto/session.h>
#include <proto/stream_interface.h>
#include <proto/task.h>
struct pool_head *pool2_pendconn;
/* perform minimal intializations, report 0 in case of error, 1 if OK. */
int init_pendconn()
pool2_pendconn = create_pool("pendconn", sizeof(struct pendconn), MEM_F_SHARED);
return pool2_pendconn != NULL;
/* returns the effective dynamic maxconn for a server, considering the minconn
* and the proxy's usage relative to its dynamic connections limit. It is
* expected that 0 < s->minconn <= s->maxconn when this is called. If the
* server is currently warming up, the slowstart is also applied to the
* resulting value, which can be lower than minconn in this case, but never
* less than 1.
unsigned int srv_dynamic_maxconn(const struct server *s)
unsigned int max;
if (s->proxy->beconn >= s->proxy->fullconn)
/* no fullconn or proxy is full */
max = s->maxconn;
else if (s->minconn == s->maxconn)
/* static limit */
max = s->maxconn;
else max = MAX(s->minconn,
s->proxy->beconn * s->maxconn / s->proxy->fullconn);
if ((s->state == SRV_ST_STARTING) &&
now.tv_sec < s->last_change + s->slowstart &&
now.tv_sec >= s->last_change) {
unsigned int ratio;
ratio = 100 * (now.tv_sec - s->last_change) / s->slowstart;
max = MAX(1, max * ratio / 100);
return max;
* Manages a server's connection queue. This function will try to dequeue as
* many pending sessions as possible, and wake them up.
void process_srv_queue(struct server *s)
struct proxy *p = s->proxy;
int maxconn;
/* First, check if we can handle some connections queued at the proxy. We
* will take as many as we can handle.
maxconn = srv_dynamic_maxconn(s);
while (s->served < maxconn) {
struct session *sess = pendconn_get_next_sess(s, p);
if (sess == NULL)
task_wakeup(sess->task, TASK_WOKEN_RES);
/* Detaches the next pending connection from either a server or a proxy, and
* returns its associated session. If no pending connection is found, NULL is
* returned. Note that neither <srv> nor <px> may be NULL.
* Priority is given to the oldest request in the queue if both <srv> and <px>
* have pending requests. This ensures that no request will be left unserved.
* The <px> queue is not considered if the server (or a tracked server) is not
* RUNNING, is disabled, or has a null weight (server going down). The <srv>
* queue is still considered in this case, because if some connections remain
* there, it means that some requests have been forced there after it was seen
* down (eg: due to option persist).
* The session is immediately marked as "assigned", and both its <srv> and
* <srv_conn> are set to <srv>,
struct session *pendconn_get_next_sess(struct server *srv, struct proxy *px)
struct pendconn *ps, *pp;
struct session *sess;
struct server *rsrv;
rsrv = srv->track;
if (!rsrv)
rsrv = srv;
ps = pendconn_from_srv(srv);
pp = pendconn_from_px(px);
/* we want to get the definitive pendconn in <ps> */
if (!pp || !srv_is_usable(rsrv)) {
if (!ps)
return NULL;
} else {
/* pendconn exists in the proxy queue */
if (!ps || tv_islt(&pp->sess->logs.tv_request, &ps->sess->logs.tv_request))
ps = pp;
sess = ps->sess;
/* we want to note that the session has now been assigned a server */
sess->flags |= SN_ASSIGNED;
sess->target = &srv->obj_type;
session_add_srv_conn(sess, srv);
if (px->lbprm.server_take_conn)
return sess;
/* Adds the session <sess> to the pending connection list of server <sess>->srv
* or to the one of <sess>->proxy if srv is NULL. All counters and back pointers
* are updated accordingly. Returns NULL if no memory is available, otherwise the
* pendconn itself. If the session was already marked as served, its flag is
* cleared. It is illegal to call this function with a non-NULL sess->srv_conn.
struct pendconn *pendconn_add(struct session *sess)
struct pendconn *p;
struct server *srv;
p = pool_alloc2(pool2_pendconn);
if (!p)
return NULL;
sess->pend_pos = p;
p->sess = sess;
p->srv = srv = objt_server(sess->target);
if (sess->flags & SN_ASSIGNED && srv) {
LIST_ADDQ(&srv->pendconns, &p->list);
sess->logs.srv_queue_size += srv->nbpend;
if (srv->nbpend > srv->counters.nbpend_max)
srv->counters.nbpend_max = srv->nbpend;
} else {
LIST_ADDQ(&sess->be->pendconns, &p->list);
sess->logs.prx_queue_size += sess->be->nbpend;
if (sess->be->nbpend > sess->be->be_counters.nbpend_max)
sess->be->be_counters.nbpend_max = sess->be->nbpend;
return p;
/* Redistribute pending connections when a server goes down. The number of
* connections redistributed is returned.
int pendconn_redistribute(struct server *s)
struct pendconn *pc, *pc_bck;
int xferred = 0;
list_for_each_entry_safe(pc, pc_bck, &s->pendconns, list) {
struct session *sess = pc->sess;
if ((sess->be->options & (PR_O_REDISP|PR_O_PERSIST)) == PR_O_REDISP &&
!(sess->flags & SN_FORCE_PRST)) {
/* The REDISP option was specified. We will ignore
* cookie and force to balance or use the dispatcher.
/* it's left to the dispatcher to choose a server */
sess->flags &= ~(SN_DIRECT | SN_ASSIGNED | SN_ADDR_SET);
task_wakeup(sess->task, TASK_WOKEN_RES);
return xferred;
/* Check for pending connections at the backend, and assign some of them to
* the server coming up. The server's weight is checked before being assigned
* connections it may not be able to handle. The total number of transferred
* connections is returned.
int pendconn_grab_from_px(struct server *s)
int xferred;
if (!srv_is_usable(s))
return 0;
for (xferred = 0; !s->maxconn || xferred < srv_dynamic_maxconn(s); xferred++) {
struct session *sess;
struct pendconn *p;
p = pendconn_from_px(s->proxy);
if (!p)
p->sess->target = &s->obj_type;
sess = p->sess;
task_wakeup(sess->task, TASK_WOKEN_RES);
return xferred;
* Detaches pending connection <p>, decreases the pending count, and frees
* the pending connection. The connection might have been queued to a specific
* server as well as to the proxy. The session also gets marked unqueued.
void pendconn_free(struct pendconn *p)
p->sess->pend_pos = NULL;
if (p->srv)
pool_free2(pool2_pendconn, p);
* Local variables:
* c-indent-level: 8
* c-basic-offset: 8
* End: