MAJOR: servers: propagate server status changes asynchronously.

In order to prepare multi-thread development, code was re-worked
to propagate changes asynchronoulsy.

Servers with pending status changes are registered in a list
and this one is processed and emptied only once 'run poll' loop.

Operational status changes are performed before administrative
status changes.

In a case of multiple operational status change or admin status
change in the same 'run poll' loop iteration, those changes are
merged to reach only the targeted status.

include/proto/server.h

@@ -50,6 +50,9 @@ void srv_compute_all_admin_states(struct proxy *px);
 int srv_set_addr_via_libc(struct server *srv, int *err_code);
 int srv_init_addr(void);
 struct server *cli_find_server(struct appctx *appctx, char *arg);
+void servers_update_status(void);
+
+extern struct list updated_servers;
 
 /* functions related to server name resolution */
 int snr_update_srv_status(struct server *s, int has_no_ip);

include/types/server.h

@@ -299,6 +299,9 @@ struct server {
 		int nb_high;
 	} tmpl_info;
 	struct dns_srvrq *srvrq;		/* Pointer representing the DNS SRV requeest, if any */
+	struct list update_status;		/* to attach to list of servers chnaging status */
+	char op_st_chg_reason[48];		/* operational status change's reason */
+	char adm_st_chg_cause[48];		/* adminstrative status change's cause */
 };
 
 /* Descriptor for a "server" keyword. The ->parse() function returns 0 in case of

src/haproxy.c

@@ -2182,6 +2182,9 @@ static void run_poll_loop()
 		cur_poller.poll(&cur_poller, next);
 		fd_process_cached_events();
 		applet_run_active();
+
+		/* Commit server status changes */
+		servers_update_status();
 	}
 }