From 9ec3c9374da70c4f96adb333b39f6f4f5e218f03 Mon Sep 17 00:00:00 2001
From: Glenn Watson <gw@intuitionlibrary.com>
Date: Fri, 12 Sep 2014 13:17:44 +1000
Subject: [PATCH] Reduce number of font instances and shaper structures
 created.

The font cache previously kept weak references to the fonts,
however in layout these fonts are dropped before they are
referenced again, so no caching was being used.

For now, just hold a strong reference in the cache, which means
that fonts will never be thrown out (this will need to be fixed
in the future).
---
 components/gfx/font_context.rs | 16 +++++++---------
 1 file changed, 7 insertions(+), 9 deletions(-)

diff --git a/components/gfx/font_context.rs b/components/gfx/font_context.rs
index 0a1ef69e0ce..d61ccf3055e 100644
--- a/components/gfx/font_context.rs
+++ b/components/gfx/font_context.rs
@@ -55,7 +55,7 @@ pub struct FontContext {
     font_cache_task: FontCacheTask,
 
     /// Weak reference as the layout FontContext is persistent.
-    layout_font_cache: Vec<Weak<RefCell<Font>>>,
+    layout_font_cache: Vec<Rc<RefCell<Font>>>,
 
     /// Strong reference as the render FontContext is (for now) recycled
     /// per frame. TODO: Make this weak when incremental redraw is done.
@@ -95,10 +95,8 @@ impl FontContext {
     /// a cached font if this font instance has already been used by
     /// this context.
     pub fn get_layout_font_group_for_style(&mut self, style: &SpecifiedFontStyle) -> FontGroup {
-        // Remove all weak pointers that have been dropped.
-        self.layout_font_cache.retain(|maybe_font| {
-            maybe_font.upgrade().is_some()
-        });
+        // TODO: The font context holds a strong ref to the cached fonts
+        // so they will never be released. Find out a good time to drop them.
 
         let mut fonts: Vec<Rc<RefCell<Font>>> = vec!();
 
@@ -107,9 +105,9 @@ impl FontContext {
 
             // GWTODO: Check on real pages if this is faster as Vec() or HashMap().
             let mut cache_hit = false;
-            for maybe_cached_font in self.layout_font_cache.iter() {
-                let cached_font = maybe_cached_font.upgrade().unwrap();
-                if cached_font.borrow().descriptor == desc {
+            for cached_font in self.layout_font_cache.iter() {
+                if cached_font.borrow().descriptor == desc &&
+                   cached_font.borrow().pt_size == style.pt_size {
                     fonts.push(cached_font.clone());
                     cache_hit = true;
                     break;
@@ -119,7 +117,7 @@ impl FontContext {
             if !cache_hit {
                 let font_template = self.font_cache_task.get_font_template(family.clone(), desc.clone());
                 let layout_font = Rc::new(RefCell::new(self.create_layout_font(font_template, desc.clone(), style.pt_size)));
-                self.layout_font_cache.push(layout_font.downgrade());
+                self.layout_font_cache.push(layout_font.clone());
                 fonts.push(layout_font);
             }
         }