Changeset 287802 in webkit

Timestamp:

Jan 7, 2022, 6:13:46 PM (5 years ago)

Author:

commit-queue@webkit.org

Message:

Don't dispatch "focusin" / "focusout" events if there are no listeners
​https://bugs.webkit.org/show_bug.cgi?id=234928

Patch by Alexey Shvayka <​ashvayka@apple.com> on 2022-01-07
Reviewed by Geoff Garen.

This patch avoids creating and dispatching "focusin" / "focusout" events if it's
guaranteed there are no registered listeners for them. These events are rather new
and not widely popular: according to Chrome stats, only 17% page loads use them [1],
which is even less than document.all.

Together with r287787, creation of four FocusEvent instances is now avoided when
focus is changed, advancing attached microbenchmark by 6%.

[1] ​https://chromestatus.com/metrics/feature/timeline/popularity/433

No new tests, no behavior change.

• dom/Document.cpp:

(WebCore::Document::setFocusedElement):
(WebCore::Document::addListenerTypeIfNeeded):

• dom/Document.h:
• dom/Element.cpp:

(WebCore::Element::dispatchFocusInEventIfNeeded):
(WebCore::Element::dispatchFocusOutEventIfNeeded):
(WebCore::Element::dispatchFocusInEvent): Deleted.
(WebCore::Element::dispatchFocusOutEvent): Deleted.

• dom/Element.h:

Location:

trunk/Source/WebCore

Files:

• ChangeLog (modified) (1 diff)
• dom/Document.cpp (modified) (3 diffs)
• dom/Document.h (modified) (1 diff)
• dom/Element.cpp (modified) (1 diff)
• dom/Element.h (modified) (1 diff)

trunk/Source/WebCore/ChangeLog

@@ +1 @@
+2022-01-07  Alexey Shvayka  <ashvayka@apple.com>
+
+        Don't dispatch "focusin" / "focusout" events if there are no listeners
+        https://bugs.webkit.org/show_bug.cgi?id=234928
+
+        Reviewed by Geoff Garen.
+
+        This patch avoids creating and dispatching "focusin" / "focusout" events if it's
+        guaranteed there are no registered listeners for them. These events are rather new
+        and not widely popular: according to Chrome stats, only 17% page loads use them [1],
+        which is even less than `document.all`.
+
+        Together with r287787, creation of four FocusEvent instances is now avoided when
+        focus is changed, advancing attached microbenchmark by 6%.
+
+        [1] https://chromestatus.com/metrics/feature/timeline/popularity/433
+
+        No new tests, no behavior change.
+
+        * dom/Document.cpp:
+        (WebCore::Document::setFocusedElement):
+        (WebCore::Document::addListenerTypeIfNeeded):
+        * dom/Document.h:
+        * dom/Element.cpp:
+        (WebCore::Element::dispatchFocusInEventIfNeeded):
+        (WebCore::Element::dispatchFocusOutEventIfNeeded):
+        (WebCore::Element::dispatchFocusInEvent): Deleted.
+        (WebCore::Element::dispatchFocusOutEvent): Deleted.
+        * dom/Element.h:
+
 2022-01-07  Alexey Shvayka  <ashvayka@apple.com>
 

trunk/Source/WebCore/dom/Document.cpp

@@ -4659 +4659 @@
             }
 
-            oldFocusedElement->dispatchFocusOutEvent(newFocusedElement.copyRef()); // DOM level 3 bubbling blur event.
+            oldFocusedElement->dispatchFocusOutEventIfNeeded(newFocusedElement.copyRef()); // DOM level 3 bubbling blur event.
 
             if (m_focusedElement) {
@@ -4724 +4724 @@
         }
 
-        m_focusedElement->dispatchFocusInEvent(oldFocusedElement.copyRef()); // DOM level 3 bubbling focus event.
+        m_focusedElement->dispatchFocusInEventIfNeeded(oldFocusedElement.copyRef()); // DOM level 3 bubbling focus event.
 
         if (m_focusedElement != newFocusedElement) {
@@ -5286 +5286 @@
     else if (eventType == eventNames().resizeEvent)
         addListenerType(RESIZE_LISTENER);
+    else if (eventType == eventNames().focusinEvent)
+        addListenerType(FOCUSIN_LISTENER);
+    else if (eventType == eventNames().focusoutEvent)
+        addListenerType(FOCUSOUT_LISTENER);
 }
 

trunk/Source/WebCore/dom/Document.h

@@ -907 +907 @@
         FORCEDOWN_LISTENER                   = 1 << 15,
         FORCEUP_LISTENER                     = 1 << 16,
-        RESIZE_LISTENER                      = 1 << 17
+        RESIZE_LISTENER                      = 1 << 17,
+        FOCUSIN_LISTENER                     = 1 << 18,
+        FOCUSOUT_LISTENER                    = 1 << 19,
     };
 

trunk/Source/WebCore/dom/Element.cpp

@@ -3183 +3183 @@
 }
 
-void Element::dispatchFocusInEvent(RefPtr<Element>&& oldFocusedElement)
-{
+void Element::dispatchFocusInEventIfNeeded(RefPtr<Element>&& oldFocusedElement)
+{
+    if (!document().hasListenerType(Document::FOCUSIN_LISTENER))
+        return;
     RELEASE_ASSERT_WITH_SECURITY_IMPLICATION(ScriptDisallowedScope::InMainThread::isScriptAllowed() || !isInWebProcess());
     dispatchScopedEvent(FocusEvent::create(eventNames().focusinEvent, Event::CanBubble::Yes, Event::IsCancelable::No, document().windowProxy(), 0, WTFMove(oldFocusedElement)));
 }
 
-void Element::dispatchFocusOutEvent(RefPtr<Element>&& newFocusedElement)
-{
+void Element::dispatchFocusOutEventIfNeeded(RefPtr<Element>&& newFocusedElement)
+{
+    if (!document().hasListenerType(Document::FOCUSOUT_LISTENER))
+        return;
     RELEASE_ASSERT_WITH_SECURITY_IMPLICATION(ScriptDisallowedScope::InMainThread::isScriptAllowed() || !isInWebProcess());
     dispatchScopedEvent(FocusEvent::create(eventNames().focusoutEvent, Event::CanBubble::Yes, Event::IsCancelable::No, document().windowProxy(), 0, WTFMove(newFocusedElement)));

trunk/Source/WebCore/dom/Element.h

@@ -572 +572 @@
 
     // FIXME: Consider changing signature to accept Element* because all callers perform copyRef().
-    void dispatchFocusInEvent(RefPtr<Element>&& oldFocusedElement);
-    void dispatchFocusOutEvent(RefPtr<Element>&& newFocusedElement);
+    void dispatchFocusInEventIfNeeded(RefPtr<Element>&& oldFocusedElement);
+    void dispatchFocusOutEventIfNeeded(RefPtr<Element>&& newFocusedElement);
     virtual void dispatchFocusEvent(RefPtr<Element>&& oldFocusedElement, FocusDirection);
     virtual void dispatchBlurEvent(RefPtr<Element>&& newFocusedElement);