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fonts: Make FontContext thread-safe and share it per-Layout (#32205)
This allows sharing font templates, fonts, and platform fonts across layout threads. It's the first step toward storing web fonts in the layout versus the shared `FontCacheThread`. Now fonts and font groups have some locking (especially on FreeType), which will probably affect performance. On the other hand, we measured memory usage and this saves roughly 40 megabytes of memory when loading servo.org based on data from the memory profiler. Signed-off-by: Martin Robinson <mrobinson@igalia.com> Co-authored-by: Mukilan Thiyagarajan <mukilan@igalia.com>
This commit is contained in:
Martin Robinson
GitHub
parent
8ec5344f70
commit
556bfb7dff
27 changed files with 437 additions and 500 deletions
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@ -2,17 +2,16 @@
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* License, v. 2.0. If a copy of the MPL was not distributed with this
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* file, You can obtain one at https://mozilla.org/MPL/2.0/. */
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use std::cell::RefCell;
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use std::collections::HashMap;
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use std::default::Default;
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use std::hash::{BuildHasherDefault, Hash, Hasher};
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use std::rc::Rc;
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use std::sync::atomic::{AtomicUsize, Ordering};
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use std::sync::Arc;
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use app_units::Au;
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use fnv::FnvHasher;
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use log::debug;
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use servo_arc::Arc;
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use parking_lot::{Mutex, RwLock};
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use servo_arc::Arc as ServoArc;
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use style::computed_values::font_variant_caps::T as FontVariantCaps;
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use style::properties::style_structs::Font as FontStyleStruct;
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use webrender_api::{FontInstanceFlags, FontInstanceKey};
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@ -25,10 +24,6 @@ use crate::platform::core_text_font_cache::CoreTextFontCache;
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static SMALL_CAPS_SCALE_FACTOR: f32 = 0.8; // Matches FireFox (see gfxFont.h)
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/// An epoch for the font context cache. The cache is flushed if the current epoch does not match
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/// this one.
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static FONT_CACHE_EPOCH: AtomicUsize = AtomicUsize::new(0);
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pub trait FontSource {
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fn get_font_instance(
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&mut self,
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@ -49,48 +44,48 @@ pub trait FontSource {
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/// required.
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#[derive(Debug)]
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pub struct FontContext<S: FontSource> {
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font_source: S,
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font_source: Mutex<S>,
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// TODO: The font context holds a strong ref to the cached fonts
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// so they will never be released. Find out a good time to drop them.
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// See bug https://github.com/servo/servo/issues/3300
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font_cache: HashMap<FontCacheKey, Option<FontRef>>,
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font_template_cache: HashMap<FontTemplateCacheKey, Vec<FontTemplateRef>>,
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font_cache: RwLock<HashMap<FontCacheKey, Option<FontRef>>>,
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font_template_cache: RwLock<HashMap<FontTemplateCacheKey, Vec<FontTemplateRef>>>,
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font_group_cache:
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HashMap<FontGroupCacheKey, Rc<RefCell<FontGroup>>, BuildHasherDefault<FnvHasher>>,
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epoch: usize,
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RwLock<HashMap<FontGroupCacheKey, Arc<RwLock<FontGroup>>, BuildHasherDefault<FnvHasher>>>,
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}
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impl<S: FontSource> FontContext<S> {
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pub fn new(font_source: S) -> FontContext<S> {
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#[allow(clippy::default_constructed_unit_structs)]
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FontContext {
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font_source,
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font_cache: HashMap::new(),
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font_template_cache: HashMap::new(),
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font_group_cache: HashMap::with_hasher(Default::default()),
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epoch: 0,
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font_source: Mutex::new(font_source),
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font_cache: RwLock::default(),
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font_template_cache: RwLock::default(),
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font_group_cache: RwLock::default(),
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}
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}
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fn expire_font_caches_if_necessary(&mut self) {
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let current_epoch = FONT_CACHE_EPOCH.load(Ordering::SeqCst);
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if current_epoch == self.epoch {
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return;
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}
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/// Invalidate all caches that this [`FontContext`] holds and any in-process platform-specific
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/// caches.
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///
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/// # Safety
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///
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/// This should never be called when more than one thread is using the [`FontContext`] or it
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/// may leave the context in an inconsistent state.
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pub fn invalidate_caches(&self) {
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#[cfg(target_os = "macos")]
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CoreTextFontCache::clear_core_text_font_cache();
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self.font_cache.clear();
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self.font_template_cache.clear();
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self.font_group_cache.clear();
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self.epoch = current_epoch
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self.font_cache.write().clear();
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self.font_template_cache.write().clear();
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self.font_group_cache.write().clear();
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}
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/// Returns a `FontGroup` representing fonts which can be used for layout, given the `style`.
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/// Font groups are cached, so subsequent calls with the same `style` will return a reference
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/// to an existing `FontGroup`.
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pub fn font_group(&mut self, style: Arc<FontStyleStruct>) -> Rc<RefCell<FontGroup>> {
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pub fn font_group(&self, style: ServoArc<FontStyleStruct>) -> Arc<RwLock<FontGroup>> {
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let font_size = style.font_size.computed_size().into();
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self.font_group_with_size(style, font_size)
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}
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@ -98,27 +93,27 @@ impl<S: FontSource> FontContext<S> {
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/// Like [`Self::font_group`], but overriding the size found in the [`FontStyleStruct`] with the given size
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/// in pixels.
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pub fn font_group_with_size(
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&mut self,
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style: Arc<FontStyleStruct>,
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&self,
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style: ServoArc<FontStyleStruct>,
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size: Au,
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) -> Rc<RefCell<FontGroup>> {
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self.expire_font_caches_if_necessary();
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) -> Arc<RwLock<FontGroup>> {
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let cache_key = FontGroupCacheKey { size, style };
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if let Some(font_group) = self.font_group_cache.get(&cache_key) {
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if let Some(font_group) = self.font_group_cache.read().get(&cache_key) {
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return font_group.clone();
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}
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let font_group = Rc::new(RefCell::new(FontGroup::new(&cache_key.style)));
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self.font_group_cache.insert(cache_key, font_group.clone());
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let font_group = Arc::new(RwLock::new(FontGroup::new(&cache_key.style)));
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self.font_group_cache
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.write()
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.insert(cache_key, font_group.clone());
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font_group
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}
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/// Returns a font matching the parameters. Fonts are cached, so repeated calls will return a
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/// reference to the same underlying `Font`.
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pub fn font(
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&mut self,
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&self,
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font_template: FontTemplateRef,
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font_descriptor: &FontDescriptor,
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) -> Option<FontRef> {
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@ -130,7 +125,7 @@ impl<S: FontSource> FontContext<S> {
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}
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fn get_font_maybe_synthesizing_small_caps(
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&mut self,
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&self,
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font_template: FontTemplateRef,
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font_descriptor: &FontDescriptor,
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synthesize_small_caps: bool,
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@ -157,27 +152,28 @@ impl<S: FontSource> FontContext<S> {
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font_descriptor: font_descriptor.clone(),
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};
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self.font_cache.get(&cache_key).cloned().unwrap_or_else(|| {
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debug!(
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"FontContext::font cache miss for font_template={:?} font_descriptor={:?}",
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font_template, font_descriptor
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);
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if let Some(font) = self.font_cache.read().get(&cache_key).cloned() {
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return font;
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}
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let font = self
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.create_font(
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font_template,
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font_descriptor.to_owned(),
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synthesized_small_caps_font,
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)
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.ok();
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self.font_cache.insert(cache_key, font.clone());
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debug!(
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"FontContext::font cache miss for font_template={:?} font_descriptor={:?}",
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font_template, font_descriptor
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);
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font
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})
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let font = self
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.create_font(
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font_template,
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font_descriptor.to_owned(),
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synthesized_small_caps_font,
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)
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.ok();
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self.font_cache.write().insert(cache_key, font.clone());
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font
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}
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pub fn matching_templates(
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&mut self,
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&self,
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descriptor_to_match: &FontDescriptor,
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family_descriptor: &FontFamilyDescriptor,
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) -> Vec<FontTemplateRef> {
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@ -186,27 +182,31 @@ impl<S: FontSource> FontContext<S> {
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family_descriptor: family_descriptor.clone(),
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};
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self.font_template_cache.get(&cache_key).cloned().unwrap_or_else(|| {
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debug!(
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"FontContext::font_template cache miss for template_descriptor={:?} family_descriptor={:?}",
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descriptor_to_match,
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family_descriptor
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);
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if let Some(templates) = self.font_template_cache.read().get(&cache_key).cloned() {
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return templates;
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}
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let template_info = self.font_source.find_matching_font_templates(
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descriptor_to_match,
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family_descriptor.clone(),
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);
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debug!(
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"FontContext::font_template cache miss for template_descriptor={:?} family_descriptor={:?}",
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descriptor_to_match,
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family_descriptor
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);
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self.font_template_cache.insert(cache_key, template_info.clone());
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template_info
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})
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let templates = self
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.font_source
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.lock()
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.find_matching_font_templates(descriptor_to_match, family_descriptor.clone());
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self.font_template_cache
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.write()
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.insert(cache_key, templates.clone());
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templates
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}
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/// Create a `Font` for use in layout calculations, from a `FontTemplateData` returned by the
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/// cache thread and a `FontDescriptor` which contains the styling parameters.
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fn create_font(
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&mut self,
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&self,
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font_template: FontTemplateRef,
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font_descriptor: FontDescriptor,
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synthesized_small_caps: Option<FontRef>,
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@ -216,13 +216,13 @@ impl<S: FontSource> FontContext<S> {
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font_descriptor.clone(),
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synthesized_small_caps,
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)?;
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font.font_key = self.font_source.get_font_instance(
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font.font_key = self.font_source.lock().get_font_instance(
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font_template.identifier(),
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font_descriptor.pt_size,
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font.webrender_font_instance_flags(),
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);
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Ok(Rc::new(RefCell::new(font)))
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Ok(Arc::new(font))
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}
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}
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@ -240,7 +240,7 @@ struct FontTemplateCacheKey {
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#[derive(Debug)]
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struct FontGroupCacheKey {
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style: Arc<FontStyleStruct>,
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style: ServoArc<FontStyleStruct>,
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size: Au,
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}
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@ -260,11 +260,3 @@ impl Hash for FontGroupCacheKey {
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self.style.hash.hash(hasher)
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}
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}
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#[inline]
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pub fn invalidate_font_caches() {
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FONT_CACHE_EPOCH.fetch_add(1, Ordering::SeqCst);
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#[cfg(target_os = "macos")]
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CoreTextFontCache::clear_core_text_font_cache();
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}
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