Changeset 102721 in webkit

Timestamp:

Dec 13, 2011 5:03:01 PM (12 years ago)

Author:

adamk@chromium.org

Message:

[MutationObservers] Avoid allocations if no observers are present
​https://bugs.webkit.org/show_bug.cgi?id=74423

Patch by Rafael Weinstein <​rafaelw@chromium.org> on 2011-12-13
Reviewed by Ojan Vafai.

This patch adds Node::mayHaveMutationObserversOfType which can be used to check
if there are any observers at all which could receive a give type of mutation.
MutationObserverInterestGroup uses this to possibly exit early (returning
null) if no observers are present.

No tests needed. This patch is just a refactor.

• css/CSSMutableStyleDeclaration.cpp:
• dom/CharacterData.cpp:

(WebCore::CharacterData::dispatchModifiedEvent):

• dom/ChildListMutationScope.cpp:

(WebCore::ChildListMutationAccumulator::MutationAccumulationRouter::incrementScopingLevel):

• dom/Element.cpp:

(WebCore::enqueueAttributesMutationRecord):

• dom/Node.cpp:

(WebCore::Node::mayHaveMutationObserversOfType):

• dom/Node.h:
• dom/WebKitMutationObserver.cpp:

(WebCore::MutationObserverInterestGroup::createIfNeeded):
(WebCore::MutationObserverInterestGroup::createForChildListMutation):
(WebCore::MutationObserverInterestGroup::createForCharacterDataMutation):
(WebCore::MutationObserverInterestGroup::createForAttributesMutation):
(WebCore::MutationObserverInterestGroup::MutationObserverInterestGroup):
(WebCore::MutationObserverInterestGroup::enqueueMutationRecord):

• dom/WebKitMutationObserver.h:

Location:

trunk/Source/WebCore

Files:

• ChangeLog (modified) (1 diff)
• css/CSSMutableStyleDeclaration.cpp (modified) (1 diff)
• dom/CharacterData.cpp (modified) (1 diff)
• dom/ChildListMutationScope.cpp (modified) (3 diffs)
• dom/Element.cpp (modified) (1 diff)
• dom/Node.cpp (modified) (1 diff)
• dom/Node.h (modified) (1 diff)
• dom/WebKitMutationObserver.cpp (modified) (2 diffs)
• dom/WebKitMutationObserver.h (modified) (1 diff)

trunk/Source/WebCore/ChangeLog

@@ +1 @@
+2011-12-13  Rafael Weinstein  <rafaelw@chromium.org>
+
+        [MutationObservers] Avoid allocations if no observers are present
+        https://bugs.webkit.org/show_bug.cgi?id=74423
+
+        Reviewed by Ojan Vafai.
+
+        This patch adds Node::mayHaveMutationObserversOfType which can be used to check
+        if there are any observers at all which could receive a give type of mutation.
+        MutationObserverInterestGroup uses this to possibly exit early (returning
+        null) if no observers are present.
+
+        No tests needed. This patch is just a refactor.
+
+        * css/CSSMutableStyleDeclaration.cpp:
+        * dom/CharacterData.cpp:
+        (WebCore::CharacterData::dispatchModifiedEvent):
+        * dom/ChildListMutationScope.cpp:
+        (WebCore::ChildListMutationAccumulator::MutationAccumulationRouter::incrementScopingLevel):
+        * dom/Element.cpp:
+        (WebCore::enqueueAttributesMutationRecord):
+        * dom/Node.cpp:
+        (WebCore::Node::mayHaveMutationObserversOfType):
+        * dom/Node.h:
+        * dom/WebKitMutationObserver.cpp:
+        (WebCore::MutationObserverInterestGroup::createIfNeeded):
+        (WebCore::MutationObserverInterestGroup::createForChildListMutation):
+        (WebCore::MutationObserverInterestGroup::createForCharacterDataMutation):
+        (WebCore::MutationObserverInterestGroup::createForAttributesMutation):
+        (WebCore::MutationObserverInterestGroup::MutationObserverInterestGroup):
+        (WebCore::MutationObserverInterestGroup::enqueueMutationRecord):
+        * dom/WebKitMutationObserver.h:
+
 2011-12-13  Robin Dunn  <robin@alldunn.com>
 

trunk/Source/WebCore/css/CSSMutableStyleDeclaration.cpp

@@ -72 +72 @@
 
         m_mutationRecipients = MutationObserverInterestGroup::createForAttributesMutation(inlineDecl->element(), HTMLNames::styleAttr);
-        if (m_mutationRecipients->isEmpty()) {
-            m_mutationRecipients.clear();
+        if (!m_mutationRecipients)
             return;
-        }
 
         AtomicString oldValue = m_mutationRecipients->isOldValueRequested() ? inlineDecl->element()->getAttribute(HTMLNames::styleAttr) : nullAtom;

trunk/Source/WebCore/dom/CharacterData.cpp

@@ -192 +192 @@
 {
 #if ENABLE(MUTATION_OBSERVERS)
-    OwnPtr<MutationObserverInterestGroup> mutationRecipients = MutationObserverInterestGroup::createForCharacterDataMutation(this);
-    mutationRecipients->enqueueMutationRecord(MutationRecord::createCharacterData(this, oldData));
+    if (OwnPtr<MutationObserverInterestGroup> mutationRecipients = MutationObserverInterestGroup::createForCharacterDataMutation(this))
+        mutationRecipients->enqueueMutationRecord(MutationRecord::createCharacterData(this, oldData));
 #endif
     if (parentNode())

trunk/Source/WebCore/dom/ChildListMutationScope.cpp

@@ -219 +219 @@
     HashMap<Node*, OwnPtr<ChildListMutationAccumulator> >::iterator iter = m_accumulations.find(target);
     ASSERT(iter != m_accumulations.end());
-
-    if (iter->second)
-        iter->second->childAdded(child);
+    if (iter == m_accumulations.end() || !iter->second)
+        return;
+
+    iter->second->childAdded(child);
 }
 
@@ -228 +229 @@
     HashMap<Node*, OwnPtr<ChildListMutationAccumulator> >::iterator iter = m_accumulations.find(target);
     ASSERT(iter != m_accumulations.end());
-
-    if (iter->second)
-        iter->second->willRemoveChild(child);
+    if (iter == m_accumulations.end() || !iter->second)
+        return;
+
+    iter->second->willRemoveChild(child);
 }
 
@@ -241 +243 @@
     }
 
-    OwnPtr<MutationObserverInterestGroup> observers = MutationObserverInterestGroup::createForChildListMutation(target);
-    if (observers->isEmpty())
+    if (OwnPtr<MutationObserverInterestGroup> observers = MutationObserverInterestGroup::createForChildListMutation(target))
+        m_accumulations.set(target, adoptPtr(new ChildListMutationAccumulator(target, observers.release())));
+#ifndef NDEBUG
+    else
         m_accumulations.set(target, nullptr);
-    else
-        m_accumulations.set(target, adoptPtr(new ChildListMutationAccumulator(target, observers.release())));
+#endif
 }
 

trunk/Source/WebCore/dom/Element.cpp

@@ -184 +184 @@
 static void enqueueAttributesMutationRecord(Element* target, const QualifiedName& attributeName, const AtomicString& oldValue)
 {
-    OwnPtr<MutationObserverInterestGroup> mutationRecipients = MutationObserverInterestGroup::createForAttributesMutation(target, attributeName);
-    mutationRecipients->enqueueMutationRecord(MutationRecord::createAttributes(target, attributeName, oldValue));
+    if (OwnPtr<MutationObserverInterestGroup> mutationRecipients = MutationObserverInterestGroup::createForAttributesMutation(target, attributeName))
+        mutationRecipients->enqueueMutationRecord(MutationRecord::createAttributes(target, attributeName, oldValue));
 }
 #endif

trunk/Source/WebCore/dom/Node.cpp

@@ -2715 +2715 @@
 }
 
+bool Node::mayHaveMutationObserversOfType(WebKitMutationObserver::MutationType type)
+{
+    return document()->hasSubtreeMutationObserverOfType(type) || (hasRareData() && (rareData()->mutationObserverRegistry() || rareData()->transientMutationObserverRegistry()));
+}
+
 void Node::getRegisteredMutationObserversOfType(HashMap<WebKitMutationObserver*, MutationRecordDeliveryOptions>& observers, WebKitMutationObserver::MutationType type, const AtomicString& attributeName)
 {

trunk/Source/WebCore/dom/Node.h

@@ -600 +600 @@
 #if ENABLE(MUTATION_OBSERVERS)
     void getRegisteredMutationObserversOfType(HashMap<WebKitMutationObserver*, MutationRecordDeliveryOptions>&, WebKitMutationObserver::MutationType, const AtomicString& attributeName = nullAtom);
+    bool mayHaveMutationObserversOfType(WebKitMutationObserver::MutationType);
     MutationObserverRegistration* registerMutationObserver(PassRefPtr<WebKitMutationObserver>);
     void unregisterMutationObserver(MutationObserverRegistration*);

trunk/Source/WebCore/dom/WebKitMutationObserver.cpp

@@ -150 +150 @@
 }
 
+PassOwnPtr<MutationObserverInterestGroup> MutationObserverInterestGroup::createIfNeeded(Node* target, WebKitMutationObserver::MutationType type, const AtomicString& attributeName, MutationRecordDeliveryOptions oldValueFlag)
+{
+    if (!target->mayHaveMutationObserversOfType(type))
+        return nullptr;
+
+    HashMap<WebKitMutationObserver*, MutationRecordDeliveryOptions> observers;
+    target->getRegisteredMutationObserversOfType(observers, type, attributeName);
+    if (observers.isEmpty())
+        return nullptr;
+
+    return adoptPtr(new MutationObserverInterestGroup(observers, oldValueFlag));
+}
+
 PassOwnPtr<MutationObserverInterestGroup> MutationObserverInterestGroup::createForChildListMutation(Node* target)
 {
-    return adoptPtr(new MutationObserverInterestGroup(target, WebKitMutationObserver::ChildList));
+    MutationRecordDeliveryOptions oldValueFlag = 0;
+    return createIfNeeded(target, WebKitMutationObserver::ChildList, nullAtom, oldValueFlag);
 }
 
 PassOwnPtr<MutationObserverInterestGroup> MutationObserverInterestGroup::createForCharacterDataMutation(Node* target)
 {
-    return adoptPtr(new MutationObserverInterestGroup(target, WebKitMutationObserver::CharacterData));
+    return createIfNeeded(target, WebKitMutationObserver::CharacterData, nullAtom, WebKitMutationObserver::CharacterDataOldValue);
 }
 
 PassOwnPtr<MutationObserverInterestGroup> MutationObserverInterestGroup::createForAttributesMutation(Node* target, const QualifiedName& attributeName)
 {
-    return adoptPtr(new MutationObserverInterestGroup(target, WebKitMutationObserver::Attributes, attributeName.localName()));
-}
-
-MutationObserverInterestGroup::MutationObserverInterestGroup(Node* target, WebKitMutationObserver::MutationType type, const AtomicString& attributeName)
-{
-    target->getRegisteredMutationObserversOfType(m_observers, type, attributeName);
-    if (type & WebKitMutationObserver::Attributes)
-        m_oldValueFlag = WebKitMutationObserver::AttributeOldValue;
-    else if (type & WebKitMutationObserver::CharacterData)
-        m_oldValueFlag = WebKitMutationObserver::CharacterDataOldValue;
+    return createIfNeeded(target, WebKitMutationObserver::Attributes, attributeName.localName(), WebKitMutationObserver::AttributeOldValue);
+}
+
+MutationObserverInterestGroup::MutationObserverInterestGroup(HashMap<WebKitMutationObserver*, MutationRecordDeliveryOptions> observers, MutationRecordDeliveryOptions oldValueFlag)
+    : m_oldValueFlag(oldValueFlag)
+{
+    ASSERT(!observers.isEmpty());
+    m_observers.swap(observers);
 }
 
@@ -185 +197 @@
 void MutationObserverInterestGroup::enqueueMutationRecord(PassRefPtr<MutationRecord> prpMutation)
 {
-    if (m_observers.isEmpty())
-        return;
-
     RefPtr<MutationRecord> mutation = prpMutation;
     RefPtr<MutationRecord> mutationWithNullOldValue;

trunk/Source/WebCore/dom/WebKitMutationObserver.h

@@ -104 +104 @@
 
     bool isOldValueRequested();
-    bool isEmpty() { return m_observers.isEmpty(); }
     void enqueueMutationRecord(PassRefPtr<MutationRecord>);
 private:
-    MutationObserverInterestGroup(Node* target, WebKitMutationObserver::MutationType, const AtomicString& attributeName = nullAtom);
+    static PassOwnPtr<MutationObserverInterestGroup> createIfNeeded(Node* target, WebKitMutationObserver::MutationType, const AtomicString& attributeName, MutationRecordDeliveryOptions oldValueFlag);
+    MutationObserverInterestGroup(HashMap<WebKitMutationObserver*, MutationRecordDeliveryOptions> observers, MutationRecordDeliveryOptions oldValueFlag);
 
     inline bool hasOldValue(MutationRecordDeliveryOptions options) { return options & m_oldValueFlag; }
 
     HashMap<WebKitMutationObserver*, MutationRecordDeliveryOptions> m_observers;
-    WebKitMutationObserver::DeliveryFlags m_oldValueFlag;
+    MutationRecordDeliveryOptions m_oldValueFlag;
 };