Rework and improve the scheduling of the server lag check

Previously the server lag check was run by update_clock() if the number of
seconds since client startup was a multiple of 20 (unless it had already been
done this second).  This meant that if update_clock() was not being called
frequently (eg. if your IRC connection was very quiet), it might go a long
time between lag checks.

This commit adds a /set LAG_CHECK_INTERVAL (defaulting to 30).  For each
server, a lag check ping is scheduled for every LAG_CHECK_INTERVAL seconds
after the connection is finalised/registered.  Setting this value to 0
disables the lag check pings entirely.

The old code set the lag to 'unknown' immediately after sending out a ping,
which meant that it was quite unpredictable how long the lag value would
stay around for.  The new code only sets this once the current lag value
has become stale (ie. a ping reply is overdue based on the current lag
value).  If your lag is staying the same or reducing, you shouldn't see
the [Lag ??] at all.

Changelog

@@ -1,5 +1,8 @@
 [Changes 1.2.2]
 
+* Rework the lag check to make it simpler and more reliable.  This adds
+  a /set LAG_CHECK_INTERVAL to control the frequency of lag checks. (caf)
+
 * Wire up /set DOUBLE_STATUS_LINE (reported by presi). (caf)
 
 * Fix ignoring of nick changes. (caf)

include/config.h

@@ -561,7 +561,7 @@
 #define DEFAULT_XTERM "rxvt"
 #define DEFAULT_XTERM_OPTIONS "-bg black -fg white"
 #define DEFAULT_DCC_DLDIR "~"
-
+#define DEFAULT_LAG_CHECK_INTERVAL 30	/* Time between lag check pings, in seconds */
 #define DEFAULT_PAD_CHAR ' '
 #define DEFAULT_USERMODE "+iw"  /* change this to the default usermode */
 #define DEFAULT_OPERMODE "swfck"

include/server.h

@@ -94,7 +94,8 @@ typedef	struct
 	int	sent;			/* set if something has been sent,
 					 * used for redirect */
 	int	lag;			/* indication of lag from server CDE*/
-	time_t	lag_time;		/* time ping sent to server CDE */
+	struct timeval lag_sent;	/* time lag ping sent to server CDE */
+	struct timeval lag_recv;	/* time last lag ping reply was recieved */
 	unsigned long lag_cookie;	/* cookie to identify our lag check pings */
 	time_t	last_msg;		/* last mesg recieved from the server CDE */
 
@@ -237,9 +238,7 @@ extern	SGroup	*server_group_list;
 	
 	int	BX_get_server_lag (int);
 	void	BX_set_server_lag (int, int);
-	time_t	get_server_lagtime (int);
+	void server_lag_reply(int s, unsigned long cookie, struct timeval lag_recv, struct timeval lag_sent);
-	void	set_server_lagtime (int, time_t);
-	unsigned long get_server_lag_cookie(int gso_index);
 	
 	char	*BX_set_server_password (int, char *);
 	void	BX_set_server_nickname (int, char *);
@@ -365,7 +364,6 @@ ChannelList	*BX_get_server_channels		(int);
 	void reconnect_server(int *, int *, time_t *);
 	int finalize_server_connect(int, int, int);
 	int next_server(int);
-	int	check_serverlag (void);
 	void	do_idle_server (void);
 
 /* XXXXX ick, gross, bad.  XXXXX */

include/vars.h

@@ -163,6 +163,7 @@ enum VAR_TYPES {
 	KICK_ON_NICKFLOOD_VAR ,
 	KICK_ON_PUBFLOOD_VAR ,
 	KICK_OPS_VAR ,
+	LAG_CHECK_INTERVAL_VAR,
 	LAMEIDENT_VAR,
 	LAMELIST_VAR,
 	LASTLOG_VAR ,

source/irc.c

@@ -335,8 +335,6 @@ char	*BX_update_clock(int flag)
 			}
 			check_channel_limits();
 		}
-		if (!((hideous - start_time) % 20))
-			check_serverlag();
 		from_server = ofs;
 		if (flag != RESET_TIME || new_minute)
 			return time_str;

source/parse.c

@@ -856,35 +856,25 @@ static	void p_pong(char *from, char **ArgList)
 		char *p, *q;
 		unsigned long cookie;
 		struct timeval timenow, timethen;
-		int old_lag, new_lag;
 
+		get_time(&timenow);
 		p = strchr(ArgList[1], '.');
 		if (p)
 		{			
 			*p++ = 0;
 			cookie = strtoul(ArgList[1] + 4, NULL, 10);
 
-			if (cookie == get_server_lag_cookie(from_server))
+			q = strchr(p, '.');
+			if (q)
 			{
-				q = strchr(p, '.');
+				*q++ = 0;
-				if (q)
+				timethen.tv_usec = my_atol(q);
-				{
+			} else
-					*q++ = 0;
+				timethen.tv_usec = 0;
-					timethen.tv_usec = my_atol(q);
-				} else
-					timethen.tv_usec = 0;
 
-				timethen.tv_sec = my_atol(p);
+			timethen.tv_sec = my_atol(p);
-				get_time(&timenow);
 
-				old_lag = get_server_lag(from_server);
+			server_lag_reply(from_server, cookie, timenow, timethen);
-				new_lag = (int)(BX_time_diff(timethen, timenow) + 0.5);
-				if (old_lag != new_lag)
-				{
-					set_server_lag(from_server, new_lag);
-					status_update(1);
-				}
-			}
 		}
 	}
 	else if (!my_stricmp(ArgList[1], get_server_nickname(from_server)))

source/server.c

@@ -129,6 +129,7 @@ void	BX_close_server (int cs_index, char *message)
 	server_list[cs_index].server_change_pending = 0;
 	server_list[cs_index].operator = 0;
 	server_list[cs_index].connected = 0;
+	server_list[cs_index].lag = -1;
 	server_list[cs_index].buffer = NULL;
 	server_list[cs_index].link_look = 0;
 	server_list[cs_index].login_flags = 0;
@@ -241,6 +242,26 @@ void set_server_bits (fd_set *rd, fd_set *wr, struct timeval *wake_time)
 			if (time_cmp(wake_time, &connect_wake_time) > 0)
 				*wake_time = connect_wake_time;
 		}
+		if (is_server_connected(i))
+		{
+			/* Time to send another ping */
+			int lag_check_interval = get_int_var(LAG_CHECK_INTERVAL_VAR);
+			struct timeval lag_wake_time = server_list[i].lag_sent;
+			lag_wake_time.tv_sec += lag_check_interval;
+
+			if (lag_check_interval > 0 && time_cmp(wake_time, &lag_wake_time) > 0)
+				*wake_time = lag_wake_time;
+
+			if (server_list[i].lag != -1)
+			{
+				/* Time that previous lag value becomes stale */
+				lag_wake_time = server_list[i].lag_recv;
+				lag_wake_time.tv_sec += lag_check_interval + 1;
+
+				if (time_cmp(wake_time, &lag_wake_time) > 0)
+					*wake_time = lag_wake_time;
+			}
+		}
 
 		if (server_list[i].read > -1)
 			FD_SET(server_list[i].read, rd);
@@ -410,28 +431,6 @@ static void scan_nonblocking(void)
 }
 #endif
 
-int check_serverlag(void)
-{
-	int i;
-	struct timeval tv;
-
-	get_time(&tv);
-		
-	for (i = 0; i < server_list_size(); i++)
-	{
-		if (is_server_connected(i) && now != get_server_lagtime(i))
-		{
-			set_server_lagtime(i, now);
-			my_send_to_server(i, "PING LAG!%lu.%ld.%ld :%s", 
-					get_server_lag_cookie(i), 
-					(long)tv.tv_sec, (long)tv.tv_usec, get_server_itsname(i));
-			set_server_lag(i, -1);
-		}
-	}
-
-	return 0;
-}
-
 void	do_idle_server (void)
 {
 	int i;
@@ -445,7 +444,7 @@ void	do_idle_server (void)
 	for (i = 0; i < number_of_servers && i > -1; i++)
 	{
 		/* We were told to reconnect, to avoid recursion. */
-		if(get_server_reconnect(i) > 0)
+		if (get_server_reconnect(i) > 0)
 		{
 			int connect_delay = get_int_var(CONNECT_DELAY_VAR);
 
@@ -457,6 +456,29 @@ void	do_idle_server (void)
 				reconnect_server(&servernum, &times, &last_timeout);
 			}
 		}
+
+		if (is_server_connected(i))
+		{
+			int lag_check_interval = get_int_var(LAG_CHECK_INTERVAL_VAR);
+
+			if (lag_check_interval > 0 && 
+				time_since(&server_list[i].lag_sent) > lag_check_interval)
+			{
+				get_time(&server_list[i].lag_sent);
+				my_send_to_server(i, "PING LAG!%lu.%ld.%ld :%s", 
+					server_list[i].lag_cookie, 
+					(long)server_list[i].lag_sent.tv_sec, 
+					(long)server_list[i].lag_sent.tv_usec, 
+					get_server_itsname(i));
+			}
+			if (server_list[i].lag != -1 && 
+				time_since(&server_list[i].lag_recv) > lag_check_interval + 1)
+			{
+				/* Lag reply overdue */
+				set_server_lag(i, -1);
+				update_all_status(current_window, NULL, 0);
+			}
+		}
 	}
 }
 
@@ -475,29 +497,13 @@ void	do_server (fd_set *rd, fd_set *wr)
 	char	buffer[BIG_BUFFER_SIZE + 1];
 	int	des,
 		i;
-	static	int	times = 1;
 static	time_t	last_timeout = 0;
 
-#ifdef NON_BLOCKING_CONNECTS
+	/* Process server timeouts */
-	scan_nonblocking();
+	do_idle_server();
-#endif
 
 	for (i = 0; i < number_of_servers; i++)
 	{
-		/* We were told to reconnect, to avoid recursion. */
-		if(get_server_reconnect(i) > 0)
-		{
-			int connect_delay = get_int_var(CONNECT_DELAY_VAR);
-
-			if (time_since(&server_list[i].connect_time) > connect_delay)
-			{
-				int servernum = i;
-
-				set_server_reconnect(i, 0);
-				reconnect_server(&servernum, &times, &last_timeout);
-			}
-		}
-
 #ifdef NON_BLOCKING_CONNECTS
 		if (((des = server_list[i].write) > -1) && FD_ISSET(des, wr) && !(server_list[i].login_flags & LOGGED_IN))
 		{
@@ -638,6 +644,25 @@ static	time_t	last_timeout = 0;
 		window_check_servers(-1);
 }
 
+/* server_lag_reply()
+ *
+ * Called when a reply to a lag check ping has been recieved.
+ */
+void server_lag_reply(int s, unsigned long cookie, struct timeval lag_recv, struct timeval lag_sent)
+{
+	if (cookie == server_list[s].lag_cookie)
+	{
+		int new_lag = (int)(BX_time_diff(lag_sent, lag_recv) + 0.5);
+
+		server_list[s].lag_recv = lag_recv;
+		if (server_list[s].lag != new_lag)
+		{
+			server_list[s].lag = new_lag;
+			update_all_status(current_window, NULL, 0);
+		}
+	}
+}	
+
 /*
  * find_in_server_list: given a server name, this tries to match it against
  * names in the server list, returning the index into the list if found, or
@@ -2367,26 +2392,6 @@ void BX_set_server_lag (int gso_index, int secs)
 		server_list[gso_index].lag = secs;
 }
 
-time_t	get_server_lagtime (int gso_index)
-{
-	if ((gso_index < 0 || gso_index >= number_of_servers))
-		return 0;
-	return(server_list[gso_index].lag_time);
-}
-
-void set_server_lagtime (int gso_index, time_t secs)
-{
-	if ((gso_index != -1 && gso_index < number_of_servers))
-		server_list[gso_index].lag_time = secs;
-}
-
-unsigned long get_server_lag_cookie(int gso_index)
-{
-	if ((gso_index < 0 || gso_index >= number_of_servers))
-		return 0;
-	return server_list[gso_index].lag_cookie;
-}
-
 int 	BX_get_server_motd (int gsm_index)
 {
 	if (gsm_index != -1 && gsm_index < number_of_servers)
@@ -2401,7 +2406,10 @@ void 	BX_server_is_connected (int sic_index, int value)
 
 	server_list[sic_index].connected = value;
 	if (value)
+	{
 		server_list[sic_index].eof = 0;
+		get_time(&server_list[sic_index].lag_sent);
+	}
 }
 
 void	set_server_version_string (int servnum, const char *ver)

source/vars.c

@@ -266,6 +266,7 @@ static	IrcVariable irc_variable[] =
 	{ "KICK_ON_NICKFLOOD",0,	INT_TYPE_VAR,   DEFAULT_KICK_ON_NICKFLOOD, NULL, NULL, 0, VIF_BITCHX  },
 	{ "KICK_ON_PUBFLOOD",0,		INT_TYPE_VAR,   DEFAULT_KICK_ON_PUBFLOOD, NULL, NULL, 0, VIF_BITCHX  },
 	{ "KICK_OPS",0,			BOOL_TYPE_VAR,	DEFAULT_KICK_OPS, NULL, NULL, 0, VIF_BITCHX  },
+	{ "LAG_CHECK_INTERVAL",0,	INT_TYPE_VAR,	DEFAULT_LAG_CHECK_INTERVAL, NULL, NULL, 0, VIF_BITCHX },
 	{ "LAMEIDENT",0,		BOOL_TYPE_VAR,	DEFAULT_LAME_IDENT, NULL, NULL, 0, VIF_BITCHX },
 	{ "LAMELIST",0,			BOOL_TYPE_VAR,	DEFAULT_LAMELIST, NULL, NULL, 0, VIF_BITCHX },
 	{ "LASTLOG",0,			INT_TYPE_VAR,	DEFAULT_LASTLOG, NULL, set_lastlog_size, 0, 0 },