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gfx: Cache the last result of

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`TextRun::index_of_first_glyph_run_containing` in TLS.

This achieves a 40% or so hit rate on Wikipedia.
This commit is contained in:
Patrick Walton 2015-12-15 11:23:14 -08:00
parent 85c73deb78
commit 520c561d3d
1 changed files with 38 additions and 1 deletions
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39
components/gfx/text/text_run.rs
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@ -6,6 +6,7 @@ use app_units::Au;
use font::{Font, FontHandleMethods, FontMetrics, IS_WHITESPACE_SHAPING_FLAG, RunMetrics};
use font::{ShapingOptions};
use platform::font_template::FontTemplateData;
use std::cell::Cell;
use std::cmp::{Ordering, max};
use std::slice::Iter;
use std::sync::Arc;
@ -13,6 +14,11 @@ use text::glyph::{CharIndex, GlyphStore};
use util::range::Range;
use util::vec::{Comparator, FullBinarySearchMethods};
thread_local! {
static INDEX_OF_FIRST_GLYPH_RUN_CACHE: Cell<Option<(*const TextRun, CharIndex, usize)>> =
Cell::new(None)
}
/// A single "paragraph" of text in one font size and style.
#[derive(Clone, Deserialize, Serialize)]
pub struct TextRun {
@ -26,6 +32,19 @@ pub struct TextRun {
pub bidi_level: u8,
}
impl Drop for TextRun {
fn drop(&mut self) {
// Invalidate the glyph run cache if it was our text run that got freed.
INDEX_OF_FIRST_GLYPH_RUN_CACHE.with(|index_of_first_glyph_run_cache| {
if let Some((text_run_ptr, _, _)) = index_of_first_glyph_run_cache.get() {
if text_run_ptr == (self as *const TextRun) {
index_of_first_glyph_run_cache.set(None);
}
}
})
}
}
/// A single series of glyphs within a text run.
#[derive(Clone, Deserialize, Serialize)]
pub struct GlyphRun {
@ -248,6 +267,10 @@ impl<'a> TextRun {
}
pub fn advance_for_range(&self, range: &Range<CharIndex>) -> Au {
if range.is_empty() {
return Au(0)
}
// TODO(Issue #199): alter advance direction for RTL
// TODO(Issue #98): using inter-char and inter-word spacing settings when measuring text
self.natural_word_slices_in_range(range)
@ -279,7 +302,21 @@ impl<'a> TextRun {
/// Returns the index of the first glyph run containing the given character index.
fn index_of_first_glyph_run_containing(&self, index: CharIndex) -> Option<usize> {
(&**self.glyphs).binary_search_index_by(&index, CharIndexComparator)
let self_ptr = self as *const TextRun;
INDEX_OF_FIRST_GLYPH_RUN_CACHE.with(|index_of_first_glyph_run_cache| {
if let Some((last_text_run, last_index, last_result)) =
index_of_first_glyph_run_cache.get() {
if last_text_run == self_ptr && last_index == index {
return Some(last_result)
}
}
let result = (&**self.glyphs).binary_search_index_by(&index, CharIndexComparator);
if let Some(result) = result {
index_of_first_glyph_run_cache.set(Some((self_ptr, index, result)));
}
result
})
}
/// Returns an iterator that will iterate over all slices of glyphs that represent natural