2006-06-26 00:48:02 +00:00
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/*
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include/proto/queue.h
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This file defines everything related to queues.
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[BUG] fix the dequeuing logic to ensure that all requests get served
The dequeuing logic was completely wrong. First, a task was assigned
to all servers to process the queue, but this task was never scheduled
and was only woken up on session free. Second, there was no reservation
of server entries when a task was assigned a server. This means that
as long as the task was not connected to the server, its presence was
not accounted for. This was causing trouble when detecting whether or
not a server had reached maxconn. Third, during a redispatch, a session
could lose its place at the server's and get blocked because another
session at the same moment would have stolen the entry. Fourth, the
redispatch option did not work when maxqueue was reached for a server,
and it was not possible to do so without indefinitely hanging a session.
The root cause of all those problems was the lack of pre-reservation of
connections at the server's, and the lack of tracking of servers during
a redispatch. Everything relied on combinations of flags which could
appear similarly in quite distinct situations.
This patch is a major rework but there was no other solution, as the
internal logic was deeply flawed. The resulting code is cleaner, more
understandable, uses less magics and is overall more robust.
As an added bonus, "option redispatch" now works when maxqueue has
been reached on a server.
2008-06-20 13:04:11 +00:00
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Copyright (C) 2000-2008 Willy Tarreau - w@1wt.eu
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2006-06-26 00:48:02 +00:00
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This library is free software; you can redistribute it and/or
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modify it under the terms of the GNU Lesser General Public
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License as published by the Free Software Foundation, version 2.1
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exclusively.
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This library is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public
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License along with this library; if not, write to the Free Software
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Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
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*/
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#ifndef _PROTO_QUEUE_H
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#define _PROTO_QUEUE_H
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2006-06-29 16:54:54 +00:00
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#include <common/config.h>
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2006-06-29 15:53:05 +00:00
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#include <common/memory.h>
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#include <common/mini-clist.h>
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2006-06-26 00:48:02 +00:00
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#include <types/proxy.h>
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#include <types/queue.h>
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#include <types/session.h>
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#include <types/server.h>
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#include <types/task.h>
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2007-05-13 18:19:55 +00:00
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extern struct pool_head *pool2_pendconn;
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int init_pendconn();
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2006-06-26 00:48:02 +00:00
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struct session *pendconn_get_next_sess(struct server *srv, struct proxy *px);
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struct pendconn *pendconn_add(struct session *sess);
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void pendconn_free(struct pendconn *p);
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[BUG] fix the dequeuing logic to ensure that all requests get served
The dequeuing logic was completely wrong. First, a task was assigned
to all servers to process the queue, but this task was never scheduled
and was only woken up on session free. Second, there was no reservation
of server entries when a task was assigned a server. This means that
as long as the task was not connected to the server, its presence was
not accounted for. This was causing trouble when detecting whether or
not a server had reached maxconn. Third, during a redispatch, a session
could lose its place at the server's and get blocked because another
session at the same moment would have stolen the entry. Fourth, the
redispatch option did not work when maxqueue was reached for a server,
and it was not possible to do so without indefinitely hanging a session.
The root cause of all those problems was the lack of pre-reservation of
connections at the server's, and the lack of tracking of servers during
a redispatch. Everything relied on combinations of flags which could
appear similarly in quite distinct situations.
This patch is a major rework but there was no other solution, as the
internal logic was deeply flawed. The resulting code is cleaner, more
understandable, uses less magics and is overall more robust.
As an added bonus, "option redispatch" now works when maxqueue has
been reached on a server.
2008-06-20 13:04:11 +00:00
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void process_srv_queue(struct server *s);
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2006-10-15 13:17:57 +00:00
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unsigned int srv_dynamic_maxconn(const struct server *s);
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2006-06-26 00:48:02 +00:00
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/* Returns the first pending connection for server <s>, which may be NULL if
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* nothing is pending.
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*/
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2006-10-15 13:17:57 +00:00
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static inline struct pendconn *pendconn_from_srv(const struct server *s) {
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2006-06-26 00:48:02 +00:00
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if (!s->nbpend)
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return NULL;
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return LIST_ELEM(s->pendconns.n, struct pendconn *, list);
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}
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/* Returns the first pending connection for proxy <px>, which may be NULL if
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* nothing is pending.
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*/
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2006-10-15 13:17:57 +00:00
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static inline struct pendconn *pendconn_from_px(const struct proxy *px) {
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2006-06-26 00:48:02 +00:00
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if (!px->nbpend)
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return NULL;
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return LIST_ELEM(px->pendconns.n, struct pendconn *, list);
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}
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/* returns 0 if nothing has to be done for server <s> regarding queued connections,
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2008-12-04 08:33:58 +00:00
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* and non-zero otherwise. If the server is down, we only check its own queue. Suited
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* for and if/else usage.
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2006-06-26 00:48:02 +00:00
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*/
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2006-10-15 13:17:57 +00:00
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static inline int may_dequeue_tasks(const struct server *s, const struct proxy *p) {
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2008-12-04 08:33:58 +00:00
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return (s && (s->nbpend || (p->nbpend && (s->state & SRV_RUNNING))) &&
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[BUG] fix the dequeuing logic to ensure that all requests get served
The dequeuing logic was completely wrong. First, a task was assigned
to all servers to process the queue, but this task was never scheduled
and was only woken up on session free. Second, there was no reservation
of server entries when a task was assigned a server. This means that
as long as the task was not connected to the server, its presence was
not accounted for. This was causing trouble when detecting whether or
not a server had reached maxconn. Third, during a redispatch, a session
could lose its place at the server's and get blocked because another
session at the same moment would have stolen the entry. Fourth, the
redispatch option did not work when maxqueue was reached for a server,
and it was not possible to do so without indefinitely hanging a session.
The root cause of all those problems was the lack of pre-reservation of
connections at the server's, and the lack of tracking of servers during
a redispatch. Everything relied on combinations of flags which could
appear similarly in quite distinct situations.
This patch is a major rework but there was no other solution, as the
internal logic was deeply flawed. The resulting code is cleaner, more
understandable, uses less magics and is overall more robust.
As an added bonus, "option redispatch" now works when maxqueue has
been reached on a server.
2008-06-20 13:04:11 +00:00
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(!s->maxconn || s->cur_sess < srv_dynamic_maxconn(s)));
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2006-06-26 00:48:02 +00:00
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}
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#endif /* _PROTO_QUEUE_H */
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/*
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* Local variables:
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* c-indent-level: 8
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* c-basic-offset: 8
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* End:
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*/
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