Create & use microtask work queue

Source/core/dom/MutationObserver.cpp

 /*
  * Copyright (C) 2011 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 18 matching lines @@
  */
 
 #include "config.h"
 #include "core/dom/MutationObserver.h"
 
 #include <algorithm>
 #include "bindings/v8/Dictionary.h"
 #include "bindings/v8/ExceptionState.h"
 #include "core/dom/Document.h"
 #include "core/dom/ExceptionCode.h"
+#include "core/dom/Microtask.h"
 #include "core/dom/MutationCallback.h"
 #include "core/dom/MutationObserverRegistration.h"
 #include "core/dom/MutationRecord.h"
 #include "core/dom/Node.h"
 #include "core/inspector/InspectorInstrumentation.h"
 #include "wtf/MainThread.h"
 
 namespace WebCore {
 
 static unsigned s_observerPriority = 0;
@@ skipping 126 matching lines @@
     DEFINE_STATIC_LOCAL(MutationObserverSet, activeObservers, ());
     return activeObservers;
 }
 
 static MutationObserverSet& suspendedMutationObservers()
 {
     DEFINE_STATIC_LOCAL(MutationObserverSet, suspendedObservers, ());
     return suspendedObservers;
 }
 
+static void activateObserver(PassRefPtr<MutationObserver> observer)
+{
+    MutationObserverSet& active = activeMutationObservers();

[adamk, 2014/01/29 22:58:24]

Nit: No need to save this into a local, you can just  inline this call into the
if statement.

[rafaelw, 2014/01/29 23:18:52]

Done.

+    if (active.isEmpty())
+        Microtask::enqueueMicrotask(&MutationObserver::deliverMutations);
+
+    activeMutationObservers().add(observer);
+}
+
 void MutationObserver::enqueueMutationRecord(PassRefPtr<MutationRecord> mutation)
 {
     ASSERT(isMainThread());
     m_records.append(mutation);
-    activeMutationObservers().add(this);
+    activateObserver(this);
     InspectorInstrumentation::didEnqueueMutationRecord(m_callback->executionContext(), this);
 }
 
 void MutationObserver::setHasTransientRegistration()
 {
     ASSERT(isMainThread());
-    activeMutationObservers().add(this);
+    activateObserver(this);
 }
 
 HashSet<Node*> MutationObserver::getObservedNodes() const
 {
     HashSet<Node*> observedNodes;
     for (HashSet<MutationObserverRegistration*>::const_iterator iter = m_registrations.begin(); iter != m_registrations.end(); ++iter)
         (*iter)->addRegistrationNodesToSet(observedNodes);
     return observedNodes;
 }
 
@@ skipping 20 matching lines @@
         return;
 
     Vector<RefPtr<MutationRecord> > records;
     records.swap(m_records);
 
     InspectorInstrumentation::willDeliverMutationRecords(m_callback->executionContext(), this);
     m_callback->call(records, this);
     InspectorInstrumentation::didDeliverMutationRecords(m_callback->executionContext());
 }
 
-void MutationObserver::deliverAllMutations()
+void MutationObserver::deliverMutations()
 {
     ASSERT(isMainThread());
     static bool deliveryInProgress = false;

[adamk, 2014/01/29 22:58:24]

Can you remove this bool while you're at it?

[rafaelw, 2014/01/29 23:18:52]

Sorry. Yes. Had this is my prototype, but failed to pull over into this patch.

On 2014/01/29 22:58:24, adamk wrote:

     if (deliveryInProgress)
         return;
     deliveryInProgress = true;
 
     if (!suspendedMutationObservers().isEmpty()) {
         Vector<RefPtr<MutationObserver> > suspended;
         copyToVector(suspendedMutationObservers(), suspended);
         for (size_t i = 0; i < suspended.size(); ++i) {
             if (!suspended[i]->canDeliver())
                 continue;
 
             suspendedMutationObservers().remove(suspended[i]);
-            activeMutationObservers().add(suspended[i]);
+            activateObserver(suspended[i]);
         }
     }
 
-    while (!activeMutationObservers().isEmpty()) {
-        Vector<RefPtr<MutationObserver> > observers;
-        copyToVector(activeMutationObservers(), observers);
-        activeMutationObservers().clear();
-        std::sort(observers.begin(), observers.end(), ObserverLessThan());
-        for (size_t i = 0; i < observers.size(); ++i) {
-            if (observers[i]->canDeliver())
-                observers[i]->deliver();
-            else
-                suspendedMutationObservers().add(observers[i]);
-        }
+    Vector<RefPtr<MutationObserver> > observers;
+    copyToVector(activeMutationObservers(), observers);
+    activeMutationObservers().clear();
+    std::sort(observers.begin(), observers.end(), ObserverLessThan());
+    for (size_t i = 0; i < observers.size(); ++i) {
+        if (observers[i]->canDeliver())
+            observers[i]->deliver();
+        else
+            suspendedMutationObservers().add(observers[i]);
     }
 
     deliveryInProgress = false;
 }
 
 } // namespace WebCore