Cache XParseColor results in the X display info structure.

With repeated lookups of foreground and background colors for multiple
faces per frame, we issue a lot of redundant color name lookups to the
X server, waiting every time for the response.  On a remote network
with, say, 30ms round-trip time, this can add nearly a full second to
creation of a new frame.

* src/gtkutil.c (xg_check_special_colors): Call x_parse_color.
* src/image.c (get_spec_bg_or_alpha_as_argb):
(xpm_init_color_cache, xpm_lookup_color):
* src/xfns.c (x_defined_color):
* src/xterm.c (x_parse_color): New function; caches color names not
starting with "#" in the display-info structure.
(x_delete_display): Delete the cache content.
* src/xterm.h (struct color_name_cache_entry): New type.
(x_parse_color): Declare.
(struct x_display_info): Add a new field for the cache.

1 files changed, 56 insertions, 0 deletions

diff --git a/src/xterm.c b/src/xterm.c
index dd54552510c..6065f964063 100644
--- a/src/xterm.c
+++ b/src/xterm.c
@@ -2223,6 +2223,52 @@ x_query_color (struct frame *f, XColor *color)
 }
 
 
+/* On frame F, translate the color name to RGB values.  Use cached
+   information, if possible.
+
+   Note that there is currently no way to clean old entries out of the
+   cache.  However, it is limited to names in the server's database,
+   and names we've actually looked up; list-colors-display is probably
+   the most color-intensive case we're likely to hit.  */
+
+Status x_parse_color (struct frame *f, const char *color_name,
+                      XColor *color)
+{
+  Display *dpy = FRAME_X_DISPLAY (f);
+  Colormap cmap = FRAME_X_COLORMAP (f);
+  Status status;
+  struct color_name_cache_entry *cache_entry;
+
+  if (color_name[0] == '#')
+    {
+      /* The hex form is parsed directly by XParseColor without
+         talking to the X server.  No need for caching.  */
+      return XParseColor (dpy, cmap, color_name, color);
+    }
+
+  for (cache_entry = FRAME_DISPLAY_INFO (f)->color_names; cache_entry;
+       cache_entry = cache_entry->next)
+    {
+      if (!xstrcasecmp(cache_entry->name, color_name))
+        {
+          *color = cache_entry->rgb;
+          return 1;
+        }
+    }
+
+  if (XParseColor (dpy, cmap, color_name, color) == 0)
+    /* No caching of negative results, currently.  */
+    return 0;
+
+  cache_entry = xzalloc (sizeof *cache_entry);
+  cache_entry->rgb = *color;
+  cache_entry->name = xstrdup (color_name);
+  cache_entry->next = FRAME_DISPLAY_INFO (f)->color_names;
+  FRAME_DISPLAY_INFO (f)->color_names = cache_entry;
+  return 1;
+}
+
+
 /* Allocate the color COLOR->pixel on DISPLAY, colormap CMAP.  If an
    exact match can't be allocated, try the nearest color available.
    Value is true if successful.  Set *COLOR to the color
@@ -12119,6 +12165,7 @@ static void
 x_delete_display (struct x_display_info *dpyinfo)
 {
   struct terminal *t;
+  struct color_name_cache_entry *color_entry, *next_color_entry;
 
   /* Close all frames and delete the generic struct terminal for this
      X display.  */
@@ -12148,6 +12195,15 @@ x_delete_display (struct x_display_info *dpyinfo)
           tail->next = tail->next->next;
     }
 
+  for (color_entry = dpyinfo->color_names;
+       color_entry;
+       color_entry = next_color_entry)
+    {
+      next_color_entry = color_entry->next;
+      xfree (color_entry->name);
+      xfree (color_entry);
+    }
+
   xfree (dpyinfo->x_id_name);
   xfree (dpyinfo->x_dnd_atoms);
   xfree (dpyinfo->color_cells);