master 2fe4523518: Cache color lookup failures as well

[Po Lu]

branch: master
commit 2fe4523518db061067b62b004e619e91653bb36a
Author: Po Lu <luangruo@yahoo.com>
Commit: Po Lu <luangruo@yahoo.com>

    Cache color lookup failures as well
    
    * src/xterm.c (x_parse_color): Cache color lookup failures too.
    * src/xterm.h (struct color_name_cache_entry): New field
    `valid'.
---
 src/xterm.c | 45 +++++++++++++++++++++++++++++----------------
 src/xterm.h |  7 +++++++
 2 files changed, 36 insertions(+), 16 deletions(-)

diff --git a/src/xterm.c b/src/xterm.c
index 2141964c74..c841240a72 100644
--- a/src/xterm.c
+++ b/src/xterm.c
@@ -6933,11 +6933,12 @@ x_parse_color (struct frame *f, const char *color_name,
               XColor *color)
 {
   unsigned short r, g, b;
-  Display *dpy = FRAME_X_DISPLAY (f);
-  Colormap cmap = FRAME_X_COLORMAP (f);
+  Display *dpy;
+  Colormap cmap;
   struct x_display_info *dpyinfo;
   struct color_name_cache_entry *cache_entry;
   unsigned int hash, idx;
+  int rc;
 
   /* Don't pass #RGB strings directly to XParseColor, because that
      follows the X convention of zero-extending each channel
@@ -6949,37 +6950,49 @@ x_parse_color (struct frame *f, const char *color_name,
       color->red = r;
       color->green = g;
       color->blue = b;
+
       return 1;
     }
 
+  /* Some X servers send BadValue on empty color names.  */
+  if (!strlen (color_name))
+    return 0;
+
+  cmap = FRAME_X_COLORMAP (f);
+  dpy = FRAME_X_DISPLAY (f);
   dpyinfo = FRAME_DISPLAY_INFO (f);
+
   hash = x_hash_string_ignore_case (color_name);
   idx = hash % dpyinfo->color_names_size;
 
-  for (cache_entry = FRAME_DISPLAY_INFO (f)->color_names[idx];
+  for (cache_entry = dpyinfo->color_names[idx];
        cache_entry; cache_entry = cache_entry->next)
     {
       if (!xstrcasecmp (cache_entry->name, color_name))
        {
-         *color = cache_entry->rgb;
-         return 1;
+         if (cache_entry->valid)
+           *color = cache_entry->rgb;
+
+         return cache_entry->valid;
        }
     }
 
-  /* Some X servers send BadValue on empty color names.  */
-  if (!strlen (color_name))
-    return 0;
-
-  if (XParseColor (dpy, cmap, color_name, color) == 0)
-    /* No caching of negative results, currently.  */
-    return 0;
+  block_input ();
+  rc = XParseColor (dpy, cmap, color_name, color);
+  unblock_input ();
 
   cache_entry = xzalloc (sizeof *cache_entry);
-  cache_entry->rgb = *color;
+
+  if (rc)
+    cache_entry->rgb = *color;
+
+  cache_entry->valid = rc;
   cache_entry->name = xstrdup (color_name);
-  cache_entry->next = FRAME_DISPLAY_INFO (f)->color_names[idx];
-  FRAME_DISPLAY_INFO (f)->color_names[idx] = cache_entry;
-  return 1;
+  cache_entry->next = dpyinfo->color_names[idx];
+
+  dpyinfo->color_names[idx] = cache_entry;
+
+  return rc;
 }
 
 
diff --git a/src/xterm.h b/src/xterm.h
index 3e06564bee..66c4b17823 100644
--- a/src/xterm.h
+++ b/src/xterm.h
@@ -196,8 +196,15 @@ extern cairo_pattern_t *x_bitmap_stipple (struct frame *, 
Pixmap);
 struct color_name_cache_entry
 {
   struct color_name_cache_entry *next;
+
+  /* The color values of the cached color entry.  */
   XColor rgb;
+
+  /* The name of the cached color.  */
   char *name;
+
+  /* Whether or not RGB is valid (i.e. the color actually exists).  */
+  bool_bf valid : 1;
 };
 
 #ifdef HAVE_XINPUT2