/*
 * include/haproxy/backend.h
 * Functions prototypes for the backend.
 *
 * Copyright (C) 2000-2012 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 _HAPROXY_BACKEND_H
#define _HAPROXY_BACKEND_H

#include <haproxy/api.h>
#include <haproxy/backend-t.h>
#include <haproxy/clock.h>
#include <haproxy/proxy-t.h>
#include <haproxy/server-t.h>
#include <haproxy/stream-t.h>
#include <haproxy/time.h>

struct server *get_server_sh(struct proxy *px, const char *addr, int len, const struct server *avoid);
struct server *get_server_uh(struct proxy *px, char *uri, int uri_len, const struct server *avoid);
struct server *get_server_ph(struct proxy *px, const char *uri, int uri_len, const struct server *avoid);
struct server *get_server_ph_post(struct stream *s, const struct server *avoid);
struct server *get_server_hh(struct stream *s, const struct server *avoid);
struct server *get_server_rch(struct stream *s, const struct server *avoid);
struct server *get_server_expr(struct stream *s, const struct server *avoid);
struct server *get_server_rnd(struct stream *s, const struct server *avoid);

int assign_server(struct stream *s);
int assign_server_address(struct stream *s);
int assign_server_and_queue(struct stream *s);
int alloc_bind_address(struct sockaddr_storage **ss,
                       struct server *srv, struct proxy *be,
                       struct stream *s);

int be_reuse_mode(const struct proxy *be, const struct server *srv);

int64_t be_calculate_conn_hash(struct server *srv, struct stream *strm,
                               struct session *sess,
                               struct sockaddr_storage *src,
                               struct sockaddr_storage *dst,
                               struct ist name);
int be_reuse_connection(int64_t hash, struct session *sess,
                        struct proxy *be, struct server *srv,
                        struct stconn *sc, enum obj_type *target, int not_first_req);

int srv_redispatch_connect(struct stream *t);
void back_try_conn_req(struct stream *s);
void back_handle_st_req(struct stream *s);
void back_handle_st_con(struct stream *s);
void back_handle_st_rdy(struct stream *s);
void back_handle_st_cer(struct stream *s);

const char *backend_lb_algo_str(int algo);
int backend_parse_balance(const char **args, char **err, struct proxy *curproxy);
int tcp_persist_rdp_cookie(struct stream *s, struct channel *req, int an_bit);

int be_downtime(struct proxy *px);
int be_supports_dynamic_srv(struct proxy *px, char **msg);
void recount_servers(struct proxy *px);
void update_backend_weight(struct proxy *px);

/* Returns number of usable servers in backend */
static inline int be_usable_srv(struct proxy *be)
{
        if (be->flags & PR_FL_DISABLED)
                return 0;
        else if (be->srv_act)
                return be->srv_act;
        else if (be->lbprm.fbck)
                return 1;
        else
                return be->srv_bck;
}

/* Returns true if <be> backend can be used as target to a switching rules. */
static inline int be_is_eligible(const struct proxy *be)
{
	/* A disabled or unpublished backend cannot be selected for traffic.
	 * Note that STOPPED state is ignored as there is a risk of breaking
	 * requests during soft-stop.
	 */
	return !(be->flags & (PR_FL_DISABLED|PR_FL_BE_UNPUBLISHED));
}

/* set the time of last session on the backend */
static inline void be_set_sess_last(struct proxy *be)
{
	uint now_sec = ns_to_sec(now_ns);

	if (be->be_counters.shared.tg)
		if (HA_ATOMIC_LOAD(&be->be_counters.shared.tg[tgid - 1]->last_sess) != now_sec)
			HA_ATOMIC_STORE(&be->be_counters.shared.tg[tgid - 1]->last_sess, now_sec);
}

/* This function returns non-zero if the designated server will be
 * usable for LB according to pending weight and state.
 * Otherwise it returns 0.
 */
static inline int srv_willbe_usable(const struct server *srv)
{
	enum srv_state state = srv->next_state;

	if (!srv->next_eweight)
		return 0;
	if (srv->next_admin & SRV_ADMF_MAINT)
		return 0;
	if (srv->next_admin & SRV_ADMF_DRAIN)
		return 0;
	switch (state) {
	case SRV_ST_STARTING:
	case SRV_ST_RUNNING:
		return 1;
	case SRV_ST_STOPPING:
	case SRV_ST_STOPPED:
		return 0;
	}
	return 0;
}

/* This function returns non-zero if the designated server was usable for LB
 * according to its current weight and state. Otherwise it returns 0.
 */
static inline int srv_currently_usable(const struct server *srv)
{
	enum srv_state state = srv->cur_state;

	if (!srv->cur_eweight)
		return 0;
	if (srv->cur_admin & SRV_ADMF_MAINT)
		return 0;
	if (srv->cur_admin & SRV_ADMF_DRAIN)
		return 0;
	switch (state) {
	case SRV_ST_STARTING:
	case SRV_ST_RUNNING:
		return 1;
	case SRV_ST_STOPPING:
	case SRV_ST_STOPPED:
		return 0;
	}
	return 0;
}

/* This function commits the next server state and weight onto the current
 * ones in order to detect future changes. The server's lock is expected to
 * be held when calling this function.
 */
static inline void srv_lb_commit_status(struct server *srv)
{
	srv->cur_state = srv->next_state;
	srv->cur_admin = srv->next_admin;
	srv->cur_eweight = srv->next_eweight;
}

/* This function returns true when a server has experienced a change since last
 * commit on its state or weight, otherwise zero.
 */
static inline int srv_lb_status_changed(const struct server *srv)
{
	return (srv->next_state != srv->cur_state ||
		srv->next_admin != srv->cur_admin ||
		srv->next_eweight != srv->cur_eweight);
}

/* sends a log message when a backend goes down, and also sets last
 * change date.
 */
void set_backend_down(struct proxy *be);

unsigned int gen_hash(const struct proxy* px, const char* key, unsigned long len);

/* Returns true if connection reuse is supported by <be> backend. */
static inline int be_supports_conn_reuse(const struct proxy *be)
{
	return be->mode == PR_MODE_HTTP || be->mode == PR_MODE_SPOP;
}

#endif /* _HAPROXY_BACKEND_H */

/*
 * Local variables:
 *  c-indent-level: 8
 *  c-basic-offset: 8
 * End:
 */
