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LibWeb: Avoid unnecessary JS::Handles in Node::queue_mutation_record()

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We don't need to make a list of the target node's ancestors before
iterating over them, since nothing happens while iterating them that
can disturb the list anyway (no arbitrary JS execution etc).

The incessant construction and destruction of handles here was showing
up in profiles of basically every website that uses JavaScript to build
some or all of their DOM tree.
This commit is contained in:
Andreas Kling 2023-11-02 07:48:51 +01:00
parent aa6c008450
commit e4621704ce
1 changed files with 2 additions and 8 deletions
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10
Userland/Libraries/LibWeb/DOM/Node.cpp
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@ -1544,14 +1544,8 @@ void Node::queue_mutation_record(FlyString const& type, Optional<DeprecatedStrin
OrderedHashMap<MutationObserver*, Optional<DeprecatedString>> interested_observers;
// 2. Let nodes be the inclusive ancestors of target.
Vector<JS::Handle<Node const>> nodes;
nodes.append(JS::make_handle(*this));
for (auto* parent_node = parent(); parent_node; parent_node = parent_node->parent())
nodes.append(JS::make_handle(*parent_node));
// 3. For each node in nodes, and then for each registered of node’s registered observer list:
for (auto& node : nodes) {
for (auto* node = this; node; node = node->parent()) {
for (auto& registered_observer : node->m_registered_observer_list) {
// 1. Let options be registered’s options.
auto& options = registered_observer->options();
@ -1563,7 +1557,7 @@ void Node::queue_mutation_record(FlyString const& type, Optional<DeprecatedStrin
// - type is "characterData" and options["characterData"] either does not exist or is false
// - type is "childList" and options["childList"] is false
// then:
if (!(node.ptr() != this && !options.subtree)
if (!(node != this && !options.subtree)
&& !(type == MutationType::attributes && (!options.attributes.has_value() || !options.attributes.value()))
&& !(type == MutationType::attributes && options.attribute_filter.has_value() && (attribute_namespace.has_value() || !options.attribute_filter->contains_slow(attribute_name.value_or("").view())))
&& !(type == MutationType::characterData && (!options.character_data.has_value() || !options.character_data.value()))