haproxy/include/proto/queue.h
Willy Tarreau 922a806075 [BUG] do not dequeue the backend's pending connections on a dead server
Kai Krueger found that previous patch was incomplete, because there is
an unconditionnal call to process_srv_queue() in session_free() which
still causes a dead server to consume pending connections from the
backend.

This call was made unconditionnal so that we don't leave unserved
connections in the server queue, for instance connections coming
in with "option persist" which can bypass the server status check.
However, the server must not touch the backend's queue if it is down.

Another fear was that some connections might remain unserved when
the server is using a dynamic maxconn if the number of connections
to the backend is too low. Right now, srv_dynamic_maxconn() ensures
this cannot happen, so the call can remain conditionnal.

The fix consists in allowing a server to process it own queue whatever
its state, but not to touch the backend's queue if it is down. Its
queue should normally be empty when the server is down because it is
redistributed when the server goes down. The only remaining cases are
precisely the persistent connections with "option persist" set, coming
in after the queue has been redispatched. Those ones must still be
processed when a connection terminates.
(cherry picked from commit cd485c4480)
2008-12-07 23:51:12 +01:00

83 lines
2.4 KiB
C

/*
include/proto/queue.h
This file defines everything related to queues.
Copyright (C) 2000-2008 Willy Tarreau - w@1wt.eu
This library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public
License as published by the Free Software Foundation, version 2.1
exclusively.
This library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public
License along with this library; if not, write to the Free Software
Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*/
#ifndef _PROTO_QUEUE_H
#define _PROTO_QUEUE_H
#include <common/config.h>
#include <common/memory.h>
#include <common/mini-clist.h>
#include <types/proxy.h>
#include <types/queue.h>
#include <types/session.h>
#include <types/server.h>
#include <types/task.h>
extern struct pool_head *pool2_pendconn;
int init_pendconn();
struct session *pendconn_get_next_sess(struct server *srv, struct proxy *px);
struct pendconn *pendconn_add(struct session *sess);
void pendconn_free(struct pendconn *p);
void process_srv_queue(struct server *s);
unsigned int srv_dynamic_maxconn(const struct server *s);
/* Returns the first pending connection for server <s>, which may be NULL if
* nothing is pending.
*/
static inline struct pendconn *pendconn_from_srv(const struct server *s) {
if (!s->nbpend)
return NULL;
return LIST_ELEM(s->pendconns.n, struct pendconn *, list);
}
/* Returns the first pending connection for proxy <px>, which may be NULL if
* nothing is pending.
*/
static inline struct pendconn *pendconn_from_px(const struct proxy *px) {
if (!px->nbpend)
return NULL;
return LIST_ELEM(px->pendconns.n, struct pendconn *, list);
}
/* returns 0 if nothing has to be done for server <s> regarding queued connections,
* and non-zero otherwise. If the server is down, we only check its own queue. Suited
* for and if/else usage.
*/
static inline int may_dequeue_tasks(const struct server *s, const struct proxy *p) {
return (s && (s->nbpend || (p->nbpend && (s->state & SRV_RUNNING))) &&
(!s->maxconn || s->cur_sess < srv_dynamic_maxconn(s)));
}
#endif /* _PROTO_QUEUE_H */
/*
* Local variables:
* c-indent-level: 8
* c-basic-offset: 8
* End:
*/