Sync OpenBSD patchset 1072:

Add a simple form of output rate limiting by counting the number of
certain C0 sequences (linefeeds, backspaces, carriage returns) and if it
exceeds a threshold (current default 50/millisecond), start to redraw
the pane every 100 milliseconds instead of making each change as it
comes. Two configuration options - c0-change-trigger and
c0-change-interval.

This makes tmux much more responsive under very fast output (for example
yes(1) or accidentally cat'ing a large file) but may not be perfect on
all terminals and connections - feedback very welcome, particularly
where this change has a negative rather than positive effect (making it
off by default is a possibility).

After much experimentation based originally on a request Robin Lee
Powell (which ended with a completely different solution), this idea
from discussion with Ailin Nemui.

1 files changed, 40 insertions, 0 deletions

diff --git a/window.c b/window.c
index c585b2a3..73e08f6f 100644
--- a/window.c
+++ b/window.c
@@ -58,6 +58,7 @@ struct window_pane_tree all_window_panes;
 u_int	next_window_pane_id;
 u_int	next_window_id;
 
+void	window_pane_timer_callback(int, short, void *);
 void	window_pane_read_callback(struct bufferevent *, void *);
 void	window_pane_error_callback(struct bufferevent *, short, void *);
 
@@ -645,6 +646,8 @@ window_pane_destroy(struct window_pane *wp)
 {
 	window_pane_reset_mode(wp);
 
+	event_del(&wp->changes_timer);
+
 	if (wp->fd != -1) {
 		bufferevent_free(wp->event);
 		close(wp->fd);
@@ -765,6 +768,43 @@ window_pane_spawn(struct window_pane *wp, const char *cmd, const char *shell,
 	return (0);
 }
 
+void
+window_pane_timer_start(struct window_pane *wp)
+{
+	struct timeval	tv;
+
+	tv.tv_sec = 0;
+	tv.tv_usec = 1000;
+
+	evtimer_del(&wp->changes_timer);
+	evtimer_set(&wp->changes_timer, window_pane_timer_callback, wp);
+	evtimer_add(&wp->changes_timer, &tv);
+}
+
+void
+window_pane_timer_callback(unused int fd, unused short events, void *data)
+{
+	struct window_pane	*wp = data;
+	struct window		*w = wp->window;
+	u_int			 interval, trigger;
+
+	interval = options_get_number(&w->options, "c0-change-interval");
+	trigger = options_get_number(&w->options, "c0-change-trigger");
+
+	if (wp->changes_redraw++ == interval) {
+		wp->flags |= PANE_REDRAW;
+		wp->changes_redraw = 0;
+
+	}
+
+	if (trigger == 0 || wp->changes < trigger) {
+		wp->flags |= PANE_REDRAW;
+		wp->flags &= ~PANE_DROP;
+	} else
+		window_pane_timer_start(wp);
+	wp->changes = 0;
+}
+
 /* ARGSUSED */
 void
 window_pane_read_callback(unused struct bufferevent *bufev, void *data)