From df0334d3b397de03a81411f1101a8e82a55b9be9 Mon Sep 17 00:00:00 2001
From: nicm <nicm>
Date: Wed, 28 Aug 2019 07:34:32 +0000
Subject: [PATCH] The resize event was never deciding to actually resize the
 pane if there was output in the pane faster than the timer would fire, so
 change how it works to only defer the timer again if the pane was actually
 resized within the last timer period. Reported by James Tai in GitHub issue
 1880.

---
 server-client.c | 75 +++++++++++++++++++++++++++++--------------------
 tmux.h          |  1 +
 window.c        |  2 +-
 3 files changed, 46 insertions(+), 32 deletions(-)

diff --git a/server-client.c b/server-client.c
index d5d88717..4b60f5c0 100644
--- a/server-client.c
+++ b/server-client.c
@@ -44,6 +44,7 @@ static void	server_client_set_title(struct client *);
 static void	server_client_reset_state(struct client *);
 static int	server_client_assume_paste(struct session *);
 static void	server_client_clear_overlay(struct client *);
+static void	server_client_resize_event(int, short, void *);
 
 static void	server_client_dispatch(struct imsg *, void *);
 static void	server_client_dispatch_command(struct client *, struct imsg *);
@@ -1319,19 +1320,11 @@ server_client_resize_force(struct window_pane *wp)
 	return (1);
 }
 
-/* Resize timer event. */
+/* Resize a pane. */
 static void
-server_client_resize_event(__unused int fd, __unused short events, void *data)
+server_client_resize_pane(struct window_pane *wp)
 {
-	struct window_pane	*wp = data;
-	struct winsize		 ws;
-
-	evtimer_del(&wp->resize_timer);
-
-	if (!(wp->flags & PANE_RESIZE))
-		return;
-	if (server_client_resize_force(wp))
-		return;
+	struct winsize	ws;
 
 	memset(&ws, 0, sizeof ws);
 	ws.ws_col = wp->sx;
@@ -1346,35 +1339,55 @@ server_client_resize_event(__unused int fd, __unused short events, void *data)
 	wp->osy = wp->sy;
 }
 
+/* Start the resize timer. */
+static void
+server_client_start_resize_timer(struct window_pane *wp)
+{
+	struct timeval	tv = { .tv_usec = 250000 };
+
+	if (!evtimer_pending(&wp->resize_timer, NULL))
+		evtimer_add(&wp->resize_timer, &tv);
+}
+
+/* Resize timer event. */
+static void
+server_client_resize_event(__unused int fd, __unused short events, void *data)
+{
+	struct window_pane	*wp = data;
+
+	evtimer_del(&wp->resize_timer);
+
+	if (~wp->flags & PANE_RESIZE)
+		return;
+	log_debug("%s: %%%u timer fired (was%s resized)", __func__, wp->id,
+	    (wp->flags & PANE_RESIZED) ? "" : " not");
+
+	if (wp->saved_grid == NULL && (wp->flags & PANE_RESIZED)) {
+		log_debug("%s: %%%u deferring timer", __func__, wp->id);
+		server_client_start_resize_timer(wp);
+	} else if (!server_client_resize_force(wp)) {
+		log_debug("%s: %%%u resizing pane", __func__, wp->id);
+		server_client_resize_pane(wp);
+	}
+	wp->flags &= ~PANE_RESIZED;
+}
+
 /* Check if pane should be resized. */
 static void
 server_client_check_resize(struct window_pane *wp)
 {
-	struct timeval	 tv = { .tv_usec = 250000 };
-
-	if (!(wp->flags & PANE_RESIZE))
+	if (~wp->flags & PANE_RESIZE)
 		return;
-	log_debug("%s: %%%u resize to %u,%u", __func__, wp->id, wp->sx, wp->sy);
 
 	if (!event_initialized(&wp->resize_timer))
 		evtimer_set(&wp->resize_timer, server_client_resize_event, wp);
 
-	/*
-	 * The first resize should happen immediately, so if the timer is not
-	 * running, do it now.
-	 */
-	if (!evtimer_pending(&wp->resize_timer, NULL))
-		server_client_resize_event(-1, 0, wp);
-
-	/*
-	 * If the pane is in the alternate screen, let the timer expire and
-	 * resize to give the application a chance to redraw. If not, keep
-	 * pushing the timer back.
-	 */
-	if (wp->saved_grid != NULL && evtimer_pending(&wp->resize_timer, NULL))
-		return;
-	evtimer_del(&wp->resize_timer);
-	evtimer_add(&wp->resize_timer, &tv);
+	if (!evtimer_pending(&wp->resize_timer, NULL)) {
+		log_debug("%s: %%%u starting timer", __func__, wp->id);
+		server_client_resize_pane(wp);
+		server_client_start_resize_timer(wp);
+	} else
+		log_debug("%s: %%%u timer running", __func__, wp->id);
 }
 
 /* Check whether pane should be focused. */
diff --git a/tmux.h b/tmux.h
index 0cd2708d..2b69b002 100644
--- a/tmux.h
+++ b/tmux.h
@@ -843,6 +843,7 @@ struct window_pane {
 #define PANE_STATUSDRAWN 0x400
 #define PANE_EMPTY 0x800
 #define PANE_STYLECHANGED 0x1000
+#define PANE_RESIZED 0x2000
 
 	int		 argc;
 	char	       **argv;
diff --git a/window.c b/window.c
index bf4fbb70..0b691197 100644
--- a/window.c
+++ b/window.c
@@ -953,7 +953,7 @@ window_pane_resize(struct window_pane *wp, u_int sx, u_int sy)
 	if (wme != NULL && wme->mode->resize != NULL)
 		wme->mode->resize(wme, sx, sy);
 
-	wp->flags |= PANE_RESIZE;
+	wp->flags |= (PANE_RESIZE|PANE_RESIZED);
 }
 
 /*