tor-browser

commit 8ca067765f0d78cb542e121bfb1a52718ec83458
parent 9868f6c13635c8311585f6adc3e82d9bf4d0f71e
Author: Emilio Cobos Álvarez <emilio@crisal.io>
Date:   Mon,  1 Dec 2025 15:43:46 +0000

Bug 2003227 - Use unordered removal in StyleSheetInner. r=tlouw

The list of shared sheets is not order-dependent, neither is the
StyleSet set, so in order to avoid pathological performance with lots of
shared sheets, use unordered removal.

Differential Revision: https://phabricator.services.mozilla.com/D274597

Diffstat:
M
layout/style/StyleSheet.cpp
 | 
6
+++---
M
xpcom/ds/nsTArray.h
 | 
18
+++++++++++++++++-

2 files changed, 20 insertions(+), 4 deletions(-)
diff --git a/layout/style/StyleSheet.cpp b/layout/style/StyleSheet.cpp
@@ -407,7 +407,7 @@ void StyleSheetInfo::RemoveSheet(StyleSheet* aSheet) {
     return;
   }
 
-  mSheets.RemoveElement(aSheet);
+  mSheets.UnorderedRemoveElement(aSheet);
 }
 
 void StyleSheet::GetType(nsAString& aType) { aType.AssignLiteral("text/css"); }
@@ -454,7 +454,7 @@ void StyleSheet::AddStyleSet(ServoStyleSet* aStyleSet) {
 }
 
 void StyleSheet::DropStyleSet(ServoStyleSet* aStyleSet) {
-  bool found = mStyleSets.RemoveElement(aStyleSet);
+  bool found = mStyleSets.UnorderedRemoveElement(aStyleSet);
   MOZ_DIAGNOSTIC_ASSERT(found, "didn't find style set");
 #ifndef MOZ_DIAGNOSTIC_ASSERT_ENABLED
   (void)found;
@@ -467,7 +467,7 @@ void StyleSheet::DropStyleSet(ServoStyleSet* aStyleSet) {
   do {                                                                    \
     StyleSheet* current = this;                                           \
     do {                                                                  \
-      for (ServoStyleSet * set : current->mStyleSets) {                   \
+      for (ServoStyleSet* set : current->mStyleSets) {                    \
         set->function_ args_;                                             \
       }                                                                   \
       if (auto* docOrShadow = current->mDocumentOrShadowRoot) {           \
diff --git a/xpcom/ds/nsTArray.h b/xpcom/ds/nsTArray.h
@@ -1845,7 +1845,6 @@ class nsTArray_Impl
     if (i == NoIndex) {
       return false;
     }
-
     RemoveElementsAtUnsafe(i, 1);
     return true;
   }
@@ -1857,6 +1856,23 @@ class nsTArray_Impl
     return RemoveElement(aItem, nsDefaultComparator<value_type, Item>());
   }
 
+  // Variations for RemoveElement that uses unordered removal.
+  template <class Item, class Comparator>
+  bool UnorderedRemoveElement(const Item& aItem, const Comparator& aComp) {
+    index_type i = IndexOf(aItem, 0, aComp);
+    if (i == NoIndex) {
+      return false;
+    }
+    UnorderedRemoveElementAt(i);
+    return true;
+  }
+
+  template <class Item>
+  bool UnorderedRemoveElement(const Item& aItem) {
+    return UnorderedRemoveElement(aItem,
+                                  nsDefaultComparator<value_type, Item>());
+  }
+
   // This helper function combines IndexOfFirstElementGt with
   // RemoveElementAt to "search and destroy" the last element that
   // is equal to the given element.