Add a way for control mode clients to subscribe to a format and be

notified of changes rather than having to poll. GitHub issue 2242.

5 files changed, 509 insertions, 13 deletions

diff --git a/cmd-refresh-client.c b/cmd-refresh-client.c
index f7b6269b..e55ce907 100644
--- a/cmd-refresh-client.c
+++ b/cmd-refresh-client.c
@@ -34,27 +34,62 @@ const struct cmd_entry cmd_refresh_client_entry = {
 	.name = "refresh-client",
 	.alias = "refresh",
 
-	.args = { "A:cC:Df:F:lLRSt:U", 0, 1 },
-	.usage = "[-cDlLRSU] [-A pane:state] [-C XxY] [-f flags] "
-		 CMD_TARGET_CLIENT_USAGE " [adjustment]",
+	.args = { "A:B:cC:Df:F:lLRSt:U", 0, 1 },
+	.usage = "[-cDlLRSU] [-A pane:state] [-B name:what:format] "
+		 "[-C XxY] [-f flags] " CMD_TARGET_CLIENT_USAGE " [adjustment]",
 
 	.flags = CMD_AFTERHOOK|CMD_CLIENT_TFLAG,
 	.exec = cmd_refresh_client_exec
 };
 
 static void
+cmd_refresh_client_update_subscription(struct client *tc, const char *value)
+{
+	char			*copy, *split, *name, *what;
+	enum control_sub_type	 subtype;
+	int			 subid = -1;
+
+	copy = name = xstrdup(value);
+	if ((split = strchr(copy, ':')) == NULL) {
+		control_remove_sub(tc, copy);
+		goto out;
+	}
+	*split++ = '\0';
+
+	what = split;
+	if ((split = strchr(what, ':')) == NULL)
+		goto out;
+	*split++ = '\0';
+
+	if (strcmp(what, "%*") == 0)
+		subtype = CONTROL_SUB_ALL_PANES;
+	else if (sscanf(what, "%%%d", &subid) == 1 && subid >= 0)
+		subtype = CONTROL_SUB_PANE;
+	else if (strcmp(what, "@*") == 0)
+		subtype = CONTROL_SUB_ALL_WINDOWS;
+	else if (sscanf(what, "@%d", &subid) == 1 && subid >= 0)
+		subtype = CONTROL_SUB_WINDOW;
+	else
+		subtype = CONTROL_SUB_SESSION;
+	control_add_sub(tc, name, subtype, subid, split);
+
+out:
+	free(copy);
+}
+
+static void
 cmd_refresh_client_update_offset(struct client *tc, const char *value)
 {
 	struct window_pane	*wp;
-	char			*copy, *colon;
+	char			*copy, *split;
 	u_int			 pane;
 
 	if (*value != '%')
 		return;
 	copy = xstrdup(value);
-	if ((colon = strchr(copy, ':')) == NULL)
+	if ((split = strchr(copy, ':')) == NULL)
 		goto out;
-	*colon++ = '\0';
+	*split++ = '\0';
 
 	if (sscanf(copy, "%%%u", &pane) != 1)
 		goto out;
@@ -62,13 +97,13 @@ cmd_refresh_client_update_offset(struct client *tc, const char *value)
 	if (wp == NULL)
 		goto out;
 
-	if (strcmp(colon, "on") == 0)
+	if (strcmp(split, "on") == 0)
 		control_set_pane_on(tc, wp);
-	else if (strcmp(colon, "off") == 0)
+	else if (strcmp(split, "off") == 0)
 		control_set_pane_off(tc, wp);
-	else if (strcmp(colon, "continue") == 0)
+	else if (strcmp(split, "continue") == 0)
 		control_continue_pane(tc, wp);
-	else if (strcmp(colon, "pause") == 0)
+	else if (strcmp(split, "pause") == 0)
 		control_pause_pane(tc, wp);
 
 out:
@@ -156,6 +191,16 @@ cmd_refresh_client_exec(struct cmd *self, struct cmdq_item *item)
 		}
 		return (CMD_RETURN_NORMAL);
 	}
+	if (args_has(args, 'B')) {
+		if (~tc->flags & CLIENT_CONTROL)
+			goto not_control_client;
+		value = args_first_value(args, 'B', &av);
+		while (value != NULL) {
+			cmd_refresh_client_update_subscription(tc, value);
+			value = args_next_value(&av);
+		}
+		return (CMD_RETURN_NORMAL);
+	}
 	if (args_has(args, 'C')) {
 		if (~tc->flags & CLIENT_CONTROL)
 			goto not_control_client;
diff --git a/control.c b/control.c
index 5681d2dc..c52f2020 100644
--- a/control.c
+++ b/control.c
@@ -76,6 +76,42 @@ struct control_pane {
 };
 RB_HEAD(control_panes, control_pane);
 
+/* Subscription pane. */
+struct control_sub_pane {
+	u_int				 pane;
+	u_int				 idx;
+	char				*last;
+
+	RB_ENTRY(control_sub_pane)	 entry;
+};
+RB_HEAD(control_sub_panes, control_sub_pane);
+
+/* Subscription window. */
+struct control_sub_window {
+	u_int				 window;
+	u_int				 idx;
+	char				*last;
+
+	RB_ENTRY(control_sub_window)	 entry;
+};
+RB_HEAD(control_sub_windows, control_sub_window);
+
+/* Control client subscription. */
+struct control_sub {
+	char				*name;
+	char				*format;
+
+	enum control_sub_type		 type;
+	u_int				 id;
+
+	char				*last;
+	struct control_sub_panes	 panes;
+	struct control_sub_windows	 windows;
+
+	RB_ENTRY(control_sub)		 entry;
+};
+RB_HEAD(control_subs, control_sub);
+
 /* Control client state. */
 struct control_state {
 	struct control_panes		 panes;
@@ -87,6 +123,9 @@ struct control_state {
 
 	struct bufferevent		*read_event;
 	struct bufferevent		*write_event;
+
+	struct control_subs		 subs;
+	struct event			 subs_timer;
 };
 
 /* Low and high watermarks. */
@@ -116,6 +155,73 @@ control_pane_cmp(struct control_pane *cp1, struct control_pane *cp2)
 }
 RB_GENERATE_STATIC(control_panes, control_pane, entry, control_pane_cmp);
 
+/* Compare client subs. */
+static int
+control_sub_cmp(struct control_sub *csub1, struct control_sub *csub2)
+{
+	return (strcmp(csub1->name, csub2->name));
+}
+RB_GENERATE_STATIC(control_subs, control_sub, entry, control_sub_cmp);
+
+/* Compare client subscription panes. */
+static int
+control_sub_pane_cmp(struct control_sub_pane *csp1,
+    struct control_sub_pane *csp2)
+{
+	if (csp1->pane < csp2->pane)
+		return (-1);
+	if (csp1->pane > csp2->pane)
+		return (1);
+	if (csp1->idx < csp2->idx)
+		return (-1);
+	if (csp1->idx > csp2->idx)
+		return (1);
+	return (0);
+}
+RB_GENERATE_STATIC(control_sub_panes, control_sub_pane, entry,
+    control_sub_pane_cmp);
+
+/* Compare client subscription windows. */
+static int
+control_sub_window_cmp(struct control_sub_window *csw1,
+    struct control_sub_window *csw2)
+{
+	if (csw1->window < csw2->window)
+		return (-1);
+	if (csw1->window > csw2->window)
+		return (1);
+	if (csw1->idx < csw2->idx)
+		return (-1);
+	if (csw1->idx > csw2->idx)
+		return (1);
+	return (0);
+}
+RB_GENERATE_STATIC(control_sub_windows, control_sub_window, entry,
+    control_sub_window_cmp);
+
+/* Free a subscription. */
+static void
+control_free_sub(struct control_state *cs, struct control_sub *csub)
+{
+	struct control_sub_pane		*csp, *csp1;
+	struct control_sub_window	*csw, *csw1;
+
+	RB_FOREACH_SAFE(csp, control_sub_panes, &csub->panes, csp1) {
+		RB_REMOVE(control_sub_panes, &csub->panes, csp);
+		free(csp);
+	}
+	RB_FOREACH_SAFE(csw, control_sub_windows, &csub->windows, csw1) {
+		RB_REMOVE(control_sub_windows, &csub->windows, csw);
+		free(csw);
+	}
+	free(csub->last);
+
+	RB_REMOVE(control_subs, &cs->subs, csub);
+	free(csub->name);
+	free(csub->format);
+	free(csub);
+}
+
 /* Free a block. */
 static void
 control_free_block(struct control_state *cs, struct control_block *cb)
@@ -666,6 +772,7 @@ control_start(struct client *c)
 	RB_INIT(&cs->panes);
 	TAILQ_INIT(&cs->pending_list);
 	TAILQ_INIT(&cs->all_blocks);
+	RB_INIT(&cs->subs);
 
 	cs->read_event = bufferevent_new(c->fd, control_read_callback,
 	    control_write_callback, control_error_callback, c);
@@ -704,14 +811,298 @@ control_stop(struct client *c)
 {
 	struct control_state	*cs = c->control_state;
 	struct control_block	*cb, *cb1;
+	struct control_sub	*csub, *csub1;
 
 	if (~c->flags & CLIENT_CONTROLCONTROL)
 		bufferevent_free(cs->write_event);
 	bufferevent_free(cs->read_event);
 
+	RB_FOREACH_SAFE(csub, control_subs, &cs->subs, csub1)
+		control_free_sub(cs, csub);
+	if (evtimer_initialized(&cs->subs_timer))
+		evtimer_del(&cs->subs_timer);
+
 	TAILQ_FOREACH_SAFE(cb, &cs->all_blocks, all_entry, cb1)
 		control_free_block(cs, cb);
 	control_reset_offsets(c);
 
 	free(cs);
 }
+
+/* Check session subscription. */
+static void
+control_check_subs_session(struct client *c, struct control_sub *csub)
+{
+	struct session		*s = c->session;
+	struct format_tree	*ft;
+	char			*value;
+
+	ft = format_create_defaults(NULL, c, s, NULL, NULL);
+	value = format_expand(ft, csub->format);
+	format_free(ft);
+
+	if (csub->last != NULL && strcmp(value, csub->last) == 0) {
+		free(value);
+		return;
+	}
+	control_write(c,
+	    "%%subscription-changed %s $%u - - - : %s",
+	    csub->name, s->id, value);
+	free(csub->last);
+	csub->last = value;
+}
+
+/* Check pane subscription. */
+static void
+control_check_subs_pane(struct client *c, struct control_sub *csub)
+{
+	struct session		*s = c->session;
+	struct window_pane	*wp;
+	struct window		*w;
+	struct winlink		*wl;
+	struct format_tree	*ft;
+	char			*value;
+	struct control_sub_pane	*csp, find;
+
+	wp = window_pane_find_by_id(csub->id);
+	if (wp == NULL)
+		return;
+	w = wp->window;
+
+	TAILQ_FOREACH(wl, &w->winlinks, wentry) {
+		if (wl->session != s)
+			continue;
+
+		ft = format_create_defaults(NULL, c, s, wl, wp);
+		value = format_expand(ft, csub->format);
+		format_free(ft);
+
+		find.pane = wp->id;
+		find.idx = wl->idx;
+
+		csp = RB_FIND(control_sub_panes, &csub->panes, &find);
+		if (csp == NULL) {
+			csp = xcalloc(1, sizeof *csp);
+			csp->pane = wp->id;
+			csp->idx = wl->idx;
+			RB_INSERT(control_sub_panes, &csub->panes, csp);
+		}
+
+		if (csp->last != NULL && strcmp(value, csp->last) == 0) {
+			free(value);
+			continue;
+		}
+		control_write(c,
+		    "%%subscription-changed %s $%u @%u %u %%%u : %s",
+		    csub->name, s->id, w->id, wl->idx, wp->id, value);
+		free(csp->last);
+		csp->last = value;
+	}
+}
+
+/* Check all panes subscription. */
+static void
+control_check_subs_all_panes(struct client *c, struct control_sub *csub)
+{
+	struct session		*s = c->session;
+	struct window_pane	*wp;
+	struct window		*w;
+	struct winlink		*wl;
+	struct format_tree	*ft;
+	char			*value;
+	struct control_sub_pane	*csp, find;
+
+	RB_FOREACH(wl, winlinks, &s->windows) {
+		w = wl->window;
+		TAILQ_FOREACH(wp, &w->panes, entry) {
+			ft = format_create_defaults(NULL, c, s, wl, wp);
+			value = format_expand(ft, csub->format);
+			format_free(ft);
+
+			find.pane = wp->id;
+			find.idx = wl->idx;
+
+			csp = RB_FIND(control_sub_panes, &csub->panes, &find);
+			if (csp == NULL) {
+				csp = xcalloc(1, sizeof *csp);
+				csp->pane = wp->id;
+				csp->idx = wl->idx;
+				RB_INSERT(control_sub_panes, &csub->panes, csp);
+			}
+
+			if (csp->last != NULL &&
+			    strcmp(value, csp->last) == 0) {
+				free(value);
+				continue;
+			}
+			control_write(c,
+			    "%%subscription-changed %s $%u @%u %u %%%u : %s",
+			    csub->name, s->id, w->id, wl->idx, wp->id, value);
+			free(csp->last);
+			csp->last = value;
+		}
+	}
+}
+
+/* Check window subscription. */
+static void
+control_check_subs_window(struct client *c, struct control_sub *csub)
+{
+	struct session			*s = c->session;
+	struct window			*w;
+	struct winlink			*wl;
+	struct format_tree		*ft;
+	char				*value;
+	struct control_sub_window	*csw, find;
+
+	w = window_find_by_id(csub->id);
+	if (w == NULL)
+		return;
+
+	TAILQ_FOREACH(wl, &w->winlinks, wentry) {
+		if (wl->session != s)
+			continue;
+
+		ft = format_create_defaults(NULL, c, s, wl, NULL);
+		value = format_expand(ft, csub->format);
+		format_free(ft);
+
+		find.window = w->id;
+		find.idx = wl->idx;
+
+		csw = RB_FIND(control_sub_windows, &csub->windows, &find);
+		if (csw == NULL) {
+			csw = xcalloc(1, sizeof *csw);
+			csw->window = w->id;
+			csw->idx = wl->idx;
+			RB_INSERT(control_sub_windows, &csub->windows, csw);
+		}
+
+		if (csw->last != NULL && strcmp(value, csw->last) == 0) {
+			free(value);
+			continue;
+		}
+		control_write(c,
+		    "%%subscription-changed %s $%u @%u %u - : %s",
+		    csub->name, s->id, w->id, wl->idx, value);
+		free(csw->last);
+		csw->last = value;
+	}
+}
+
+/* Check all windows subscription. */
+static void
+control_check_subs_all_windows(struct client *c, struct control_sub *csub)
+{
+	struct session			*s = c->session;
+	struct window			*w;
+	struct winlink			*wl;
+	struct format_tree		*ft;
+	char				*value;
+	struct control_sub_window	*csw, find;
+
+	RB_FOREACH(wl, winlinks, &s->windows) {
+		w = wl->window;
+
+		ft = format_create_defaults(NULL, c, s, wl, NULL);
+		value = format_expand(ft, csub->format);
+		format_free(ft);
+
+		find.window = w->id;
+		find.idx = wl->idx;
+
+		csw = RB_FIND(control_sub_windows, &csub->windows, &find);
+		if (csw == NULL) {
+			csw = xcalloc(1, sizeof *csw);
+			csw->window = w->id;
+			csw->idx = wl->idx;
+			RB_INSERT(control_sub_windows, &csub->windows, csw);
+		}
+
+		if (csw->last != NULL && strcmp(value, csw->last) == 0) {
+			free(value);
+			continue;
+		}
+		control_write(c,
+		    "%%subscription-changed %s $%u @%u %u - : %s",
+		    csub->name, s->id, w->id, wl->idx, value);
+		free(csw->last);
+		csw->last = value;
+	}
+}
+
+/* Check subscriptions timer. */
+static void
+control_check_subs_timer(__unused int fd, __unused short events, void *data)
+{
+	struct client		*c = data;
+	struct control_state	*cs = c->control_state;
+	struct control_sub	*csub, *csub1;
+	struct timeval		 tv = { .tv_sec = 1 };
+
+	log_debug("%s: timer fired", __func__);
+	evtimer_add(&cs->subs_timer, &tv);
+
+	RB_FOREACH_SAFE(csub, control_subs, &cs->subs, csub1) {
+		switch (csub->type) {
+		case CONTROL_SUB_SESSION:
+			control_check_subs_session(c, csub);
+			break;
+		case CONTROL_SUB_PANE:
+			control_check_subs_pane(c, csub);
+			break;
+		case CONTROL_SUB_ALL_PANES:
+			control_check_subs_all_panes(c, csub);
+			break;
+		case CONTROL_SUB_WINDOW:
+			control_check_subs_window(c, csub);
+			break;
+		case CONTROL_SUB_ALL_WINDOWS:
+			control_check_subs_all_windows(c, csub);
+			break;
+		}
+	}
+}
+
+/* Add a subscription. */
+void
+control_add_sub(struct client *c, const char *name, enum control_sub_type type,
+    int id, const char *format)
+{
+	struct control_state	*cs = c->control_state;
+	struct control_sub	*csub, find;
+	struct timeval		 tv = { .tv_sec = 1 };
+
+	find.name = (char *)name;
+	if ((csub = RB_FIND(control_subs, &cs->subs, &find)) != NULL)
+		control_free_sub(cs, csub);
+
+	csub = xcalloc(1, sizeof *csub);
+	csub->name = xstrdup(name);
+	csub->type = type;
+	csub->id = id;
+	csub->format = xstrdup(format);
+	RB_INSERT(control_subs, &cs->subs, csub);
+
+	RB_INIT(&csub->panes);
+	RB_INIT(&csub->windows);
+
+	if (!evtimer_initialized(&cs->subs_timer))
+		evtimer_set(&cs->subs_timer, control_check_subs_timer, c);
+	if (!evtimer_pending(&cs->subs_timer, NULL))
+		evtimer_add(&cs->subs_timer, &tv);
+}
+
+/* Remove a subscription. */
+void
+control_remove_sub(struct client *c, const char *name)
+{
+	struct control_state	*cs = c->control_state;
+	struct control_sub	*csub, find;
+
+	find.name = (char *)name;
+	if ((csub = RB_FIND(control_subs, &cs->subs, &find)) != NULL)
+		control_free_sub(cs, csub);
+	if (RB_EMPTY(&cs->subs))
+		evtimer_del(&cs->subs_timer);
+}
diff --git a/server-client.c b/server-client.c
index d86a9fb8..3a79a5d1 100644
--- a/server-client.c
+++ b/server-client.c
@@ -1474,11 +1474,13 @@ server_client_check_pane_resize(struct window_pane *wp)
 		 * Otherwise resize to the force size and start the timer.
 		 */
 		if (wp->flags & PANE_RESIZENOW) {
-			log_debug("%s: resizing %%%u after forced resize", __func__, wp->id);
+			log_debug("%s: resizing %%%u after forced resize",
+			    __func__, wp->id);
 			window_pane_send_resize(wp, 0);
 			wp->flags &= ~(PANE_RESIZE|PANE_RESIZEFORCE|PANE_RESIZENOW);
 		} else if (!evtimer_pending(&wp->force_timer, NULL)) {
-			log_debug("%s: forcing resize of %%%u", __func__, wp->id);
+			log_debug("%s: forcing resize of %%%u", __func__,
+			    wp->id);
 			window_pane_send_resize(wp, 1);
 			server_client_start_force_timer(wp);
 		}
diff --git a/tmux.1 b/tmux.1
index 4d079853..1c02bdda 100644
--- a/tmux.1
+++ b/tmux.1
@@ -1255,6 +1255,7 @@ specified multiple times.
 .It Xo Ic refresh-client
 .Op Fl cDlLRSU
 .Op Fl A Ar pane:state
+.Op Fl B Ar name:what:format
 .Op Fl C Ar XxY
 .Op Fl f Ar flags
 .Op Fl t Ar target-client
@@ -1328,6 +1329,31 @@ will pause the pane.
 .Fl A
 may be given multiple times for different panes.
 .Pp
+.Fl B
+sets a subscription to a format for a control mode client.
+The argument is split into three items by colons:
+.Ar name
+is a name for the subscription;
+.Ar what
+is a type of item to subscribe to;
+.Ar format
+is the format.
+After a subscription is added, changes to the format are reported with the
+.Ic %subscription-changed
+notification, at most once a second.
+If only the name is given, the subscription is removed.
+.Ar what
+may be empty to check the format only for the attached session, or one of:
+a pane ID such as
+.Ql %0 ;
+.Ql %*
+for all panes in the attached session;
+an window ID such as
+.Ql @0 ;
+or
+.Ql @*
+for all windows in the attached session.
+.Pp
 .Fl f
 sets a comma-separated list of client flags, see
 .Ic attach-session .
@@ -5932,7 +5958,7 @@ or an error occurred.
 If present,
 .Ar reason
 describes why the client exited.
-.It Ic %extended-output Ar pane-id Ar age Ar ... : Ar value
+.It Ic %extended-output Ar pane-id Ar age Ar ... \&  : Ar value
 New form of
 .Ic %output
 sent when the
@@ -5980,6 +6006,26 @@ changed its active window to the window with ID
 .Ar window-id .
 .It Ic %sessions-changed
 A session was created or destroyed.
+.It Xo Ic %subscription-changed
+.Ar name
+.Ar session-id
+.Ar window-id
+.Ar window-index
+.Ar pane-id ... \&  :
+.Ar value
+.Xc
+The value of the format associated with subscription
+.Ar name
+has changed to
+.Ar value .
+See
+.Ic refresh-client
+.Fl B .
+Any arguments after
+.Ar pane-id
+up until a single
+.Ql \&:
+are for future use and should be ignored.
 .It Ic %unlinked-window-add Ar window-id
 The window with ID
 .Ar window-id
diff --git a/tmux.h b/tmux.h
index a8c67051..07dfc0ae 100644
--- a/tmux.h
+++ b/tmux.h
@@ -1722,6 +1722,15 @@ struct client {
 };
 TAILQ_HEAD(clients, client);
 
+/* Control mode subscription type. */
+enum control_sub_type {
+	CONTROL_SUB_SESSION,
+	CONTROL_SUB_PANE,
+	CONTROL_SUB_ALL_PANES,
+	CONTROL_SUB_WINDOW,
+	CONTROL_SUB_ALL_WINDOWS
+};
+
 /* Key binding and key table. */
 struct key_binding {
 	key_code		 key;
@@ -2862,6 +2871,9 @@ void	control_reset_offsets(struct client *);
 void printflike(2, 3) control_write(struct client *, const char *, ...);
 void	control_write_output(struct client *, struct window_pane *);
 int	control_all_done(struct client *);
+void	control_add_sub(struct client *, const char *, enum control_sub_type,
+    	   int, const char *);
+void	control_remove_sub(struct client *, const char *);
 
 /* control-notify.c */
 void	control_notify_input(struct client *, struct window_pane *,