diff options
Diffstat (limited to 'src/lb_ss.c')
| -rw-r--r-- | src/lb_ss.c | 183 |
1 files changed, 183 insertions, 0 deletions
diff --git a/src/lb_ss.c b/src/lb_ss.c new file mode 100644 index 0000000..4af031b --- /dev/null +++ b/src/lb_ss.c @@ -0,0 +1,183 @@ +/* + * sticky load-balancing + * + * Copyright 2024 HAProxy Technologies + * + * 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. + * + * This program 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 General Public License for more details. + * + * You should have received a copy of the GNU General Public License + * along with this program; if not, write to the Free Software + * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA + */ + +#include <haproxy/api.h> +#include <haproxy/backend.h> +#include <haproxy/lb_ss.h> +#include <haproxy/server-t.h> + +/* this function updates the stick server according to server <srv>'s new state. + * + * The server's lock must be held. The lbprm's lock will be used. + */ +static void ss_set_server_status_down(struct server *srv) +{ + struct proxy *p = srv->proxy; + + if (!srv_lb_status_changed(srv)) + return; + + if (srv_willbe_usable(srv)) + goto out_update_state; + + HA_RWLOCK_WRLOCK(LBPRM_LOCK, &p->lbprm.lock); + + if (!srv_currently_usable(srv)) + /* server was already down */ + goto out_update_backend; + + if (srv->flags & SRV_F_BACKUP) { + p->lbprm.tot_wbck -= srv->cur_eweight; + p->srv_bck--; + } else { + p->lbprm.tot_wact -= srv->cur_eweight; + p->srv_act--; + } + if (srv == p->lbprm.ss.srv) { + /* sticked server is down, elect a new server + * that we will be sticking on. + */ + recalc_server_ss(p); + } + + out_update_backend: + /* check/update tot_used, tot_weight */ + update_backend_weight(p); + HA_RWLOCK_WRUNLOCK(LBPRM_LOCK, &p->lbprm.lock); + + out_update_state: + srv_lb_commit_status(srv); +} + +/* This function updates the stick server according to server <srv>'s new state. + * + * The server's lock must be held. The lbprm's lock will be used. + */ +static void ss_set_server_status_up(struct server *srv) +{ + struct proxy *p = srv->proxy; + + if (!srv_lb_status_changed(srv)) + return; + + if (!srv_willbe_usable(srv)) + goto out_update_state; + + HA_RWLOCK_WRLOCK(LBPRM_LOCK, &p->lbprm.lock); + + if (srv_currently_usable(srv)) + /* server was already up */ + goto out_update_backend; + + if (srv->flags & SRV_F_BACKUP) { + p->lbprm.tot_wbck += srv->next_eweight; + p->srv_bck++; + } else { + p->lbprm.tot_wact += srv->next_eweight; + p->srv_act++; + } + if (!p->lbprm.ss.srv || + ((p->lbprm.ss.srv->flags & SRV_F_BACKUP) && !(srv->flags & SRV_F_BACKUP))) { + /* we didn't have a server or were sticking on a backup server, + * but now we have an active server, let's switch to it + */ + p->lbprm.ss.srv = srv; + } + + out_update_backend: + /* check/update tot_used, tot_weight */ + update_backend_weight(p); + HA_RWLOCK_WRUNLOCK(LBPRM_LOCK, &p->lbprm.lock); + + out_update_state: + srv_lb_commit_status(srv); +} + +/* This function elects a new stick server for proxy px. + * + * The lbprm's lock must be held. + */ +void recalc_server_ss(struct proxy *px) +{ + struct server *cur, *first; + int flag; + + if (!px->lbprm.tot_used) + return; /* no server */ + + /* here we *know* that we have some servers */ + if (px->srv_act) + flag = 0; + else + flag = SRV_F_BACKUP; + + first = NULL; + + for (cur = px->srv; cur; cur = cur->next) { + if ((cur->flags & SRV_F_BACKUP) == flag && + srv_willbe_usable(cur)) { + first = cur; + break; + } + } + px->lbprm.ss.srv = first; +} + +/* This function is responsible for preparing sticky LB algorithm. + * It should be called only once per proxy, at config time. + */ +void init_server_ss(struct proxy *p) +{ + struct server *srv; + + p->lbprm.set_server_status_up = ss_set_server_status_up; + p->lbprm.set_server_status_down = ss_set_server_status_down; + p->lbprm.update_server_eweight = NULL; + + if (!p->srv) + return; + + for (srv = p->srv; srv; srv = srv->next) { + srv->next_eweight = 1; /* ignore weights, all servers have the same weight */ + srv_lb_commit_status(srv); + } + + /* recounts servers and their weights */ + recount_servers(p); + update_backend_weight(p); + recalc_server_ss(p); +} + +/* + * This function returns the server that we're sticking on. If any server + * is found, it will be returned. If no valid server is found, NULL is + * returned. + * + * The lbprm's lock will be used. + */ +struct server *ss_get_server(struct proxy *px) +{ + struct server *srv = NULL; + + HA_RWLOCK_RDLOCK(LBPRM_LOCK, &px->lbprm.lock); + srv = px->lbprm.ss.srv; + HA_RWLOCK_RDUNLOCK(LBPRM_LOCK, &px->lbprm.lock); + return srv; +} |