From 70bc07a35831d653f83395cc351066a5a7c1256d Mon Sep 17 00:00:00 2001
From: nicm <nicm>
Date: Sun, 10 Sep 2017 14:36:12 +0000
Subject: [PATCH] Previously, extended cell data was never reduced in size even
 when the cell was overwritten. With a large history this can be a substantial
 amount of memory. To reduce this, compact each extended cell list to only
 cells in use as it is scrolled off the visible screen into the history. From
 Dan Aloni in GitHub issue 1062.

---
 grid.c | 43 +++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 43 insertions(+)

diff --git a/grid.c b/grid.c
index 62ec3f1c..c26db476 100644
--- a/grid.c
+++ b/grid.c
@@ -94,6 +94,48 @@ grid_need_extended_cell(const struct grid_cell_entry *gce,
 	return (0);
 }
 
+/* Free up unused extended cells. */
+static void
+grid_compact_line(struct grid_line *gl)
+{
+	int			 new_extdsize = 0;
+	struct grid_cell	*new_extddata;
+	struct grid_cell_entry	*gce;
+	struct grid_cell	*gc;
+	u_int			 px, idx;
+
+	if (gl->extdsize == 0)
+		return;
+
+	for (px = 0; px < gl->cellsize; px++) {
+		gce = &gl->celldata[px];
+		if (gce->flags & GRID_FLAG_EXTENDED)
+			new_extdsize++;
+	}
+
+	if (new_extdsize == 0) {
+		free(gl->extddata);
+		gl->extddata = NULL;
+		gl->extdsize = 0;
+		return;
+	}
+	new_extddata = xreallocarray(NULL, new_extdsize, sizeof *gl->extddata);
+
+	idx = 0;
+	for (px = 0; px < gl->cellsize; px++) {
+		gce = &gl->celldata[px];
+		if (gce->flags & GRID_FLAG_EXTENDED) {
+			gc = &gl->extddata[gce->offset];
+			memcpy(&new_extddata[idx], gc, sizeof *gc);
+			gce->offset = idx++;
+		}
+	}
+
+	free(gl->extddata);
+	gl->extddata = new_extddata;
+	gl->extdsize = new_extdsize;
+}
+
 /* Set cell as extended. */
 static struct grid_cell *
 grid_extended_cell(struct grid_line *gl, struct grid_cell_entry *gce,
@@ -285,6 +327,7 @@ grid_scroll_history(struct grid *gd, u_int bg)
 	grid_empty_line(gd, yy, bg);
 
 	gd->hscrolled++;
+	grid_compact_line(&gd->linedata[gd->hsize]);
 	gd->hsize++;
 }