fonts: Store web fonts in the per-Layout FontContext

[mrobinson]

This moves mangement of web fonts to the per-Layout FontContext,
preventing web fonts from being available in different Documents.

Fixes #12920.

Co-authored-by: Mukilan Thiyagarajan mukilan@igalia.com
Signed-off-by: Martin Robinson mrobinson@igalia.com

---

• ./mach build -d does not report any errors
• ./mach test-tidy does not report any errors
• These changes fix Change keying of fonts in the font cache thread #12920.
• There are tests for these changes

[servo-wpt-sync]

🤖 Opened new upstream WPT pull request (web-platform-tests/wpt#46341) with upstreamable changes.

[servo-wpt-sync]

📝 Transplanted new upstreamable changes to existing upstream WPT pull request (web-platform-tests/wpt#46341).

[servo-wpt-sync]

📝 Transplanted new upstreamable changes to existing upstream WPT pull request (web-platform-tests/wpt#46341).

[mukilan]

We should be able to remove the Arc around font_source and resource_threads.

I'm able to compile and run servo with this patch:

diff --git a/components/gfx/font_context.rs b/components/gfx/font_context.rs
index 560247efe7..0aff4abde2 100644
--- a/components/gfx/font_context.rs
+++ b/components/gfx/font_context.rs
@@ -44,8 +44,8 @@ static SMALL_CAPS_SCALE_FACTOR: f32 = 0.8; // Matches FireFox (see gfxFont.h)
 /// paint code. It talks directly to the font cache thread where
 /// required.
 pub struct FontContext<S: FontSource> {
-    font_source: Arc<ReentrantMutex<S>>,
-    resource_threads: Arc<ReentrantMutex<CoreResourceThread>>,
+    font_source: ReentrantMutex<S>,
+    resource_threads: ReentrantMutex<CoreResourceThread>,
     cache: CachingFontSource<S>,
     web_fonts: CrossThreadFontStore,
     webrender_font_store: CrossThreadWebRenderFontStore,
@@ -60,11 +60,10 @@ impl<S: FontSource> MallocSizeOf for FontContext<S> {
 impl<S: FontSource> FontContext<S> {
     pub fn new(font_source: S, resource_threads: ResourceThreads) -> FontContext<S> {
         #[allow(clippy::default_constructed_unit_structs)]
-        let font_source = Arc::new(ReentrantMutex::new(font_source));
         FontContext {
-            font_source: font_source.clone(),
-            resource_threads: Arc::new(ReentrantMutex::new(resource_threads.core_thread)),
-            cache: CachingFontSource::new(font_source),
+            font_source: ReentrantMutex::new(font_source.clone()),
+            resource_threads: ReentrantMutex::new(resource_threads.core_thread.clone()),
+            cache: CachingFontSource::new(font_source.clone()),
             web_fonts: Arc::new(RwLock::default()),
             webrender_font_store: Arc::new(RwLock::default()),
         }
@@ -508,7 +507,7 @@ impl<FCT: FontSource + Send + 'static> RemoteWebFontDownloader<FCT> {
 
 #[derive(Default)]
 pub struct CachingFontSource<FCT: FontSource> {
-    font_cache_thread: Arc<ReentrantMutex<FCT>>,
+    font_cache_thread: ReentrantMutex<FCT>,
     fonts: RwLock<HashMap<FontCacheKey, Option<FontRef>>>,
     templates: RwLock<HashMap<FontTemplateCacheKey, Vec<FontTemplateRef>>>,
     resolved_font_groups:
@@ -516,9 +515,9 @@ pub struct CachingFontSource<FCT: FontSource> {
 }
 
 impl<FCT: FontSource> CachingFontSource<FCT> {
-    fn new(font_cache_thread: Arc<ReentrantMutex<FCT>>) -> Self {
+    fn new(font_cache_thread: FCT) -> Self {
         Self {
-            font_cache_thread,
+            font_cache_thread: ReentrantMutex::new(font_cache_thread),
             fonts: Default::default(),
             templates: Default::default(),
             resolved_font_groups: Default::default(),

[mrobinson]

Nice! I've gone ahead and integrated your changes.

[servo-wpt-sync]

📝 Transplanted new upstreamable changes to existing upstream WPT pull request (web-platform-tests/wpt#46341).

[servo-wpt-sync]

📝 Transplanted new upstreamable changes to existing upstream WPT pull request (web-platform-tests/wpt#46341).

[servo-wpt-sync]

📝 Transplanted new upstreamable changes to existing upstream WPT pull request (web-platform-tests/wpt#46341).

[servo-wpt-sync]

📝 Transplanted new upstreamable changes to existing upstream WPT pull request (web-platform-tests/wpt#46341).