IntersectionObserver: second cut.

third_party/WebKit/Source/core/dom/Document.cpp

Index: third_party/WebKit/Source/core/dom/Document.cpp
diff --git a/third_party/WebKit/Source/core/dom/Document.cpp b/third_party/WebKit/Source/core/dom/Document.cpp
index 5163577596583956aac44fb63d5c25e8caec1774..f2752b17856589f5e5f0caad0dcf468fee0b9c6f 100644
--- a/third_party/WebKit/Source/core/dom/Document.cpp
+++ b/third_party/WebKit/Source/core/dom/Document.cpp
@@ -76,6 +76,7 @@
 #include "core/dom/ExceptionCode.h"
 #include "core/dom/ExecutionContextTask.h"
 #include "core/dom/FrameRequestCallback.h"
+#include "core/dom/IntersectionObserverRegistry.h"
 #include "core/dom/LayoutTreeBuilderTraversal.h"
 #include "core/dom/MainThreadTaskRunner.h"
 #include "core/dom/Microtask.h"
@@ -433,6 +434,7 @@ Document::Document(const DocumentInit& initializer, DocumentClassFlags documentC
     , m_loadEventDelayCount(0)
     , m_loadEventDelayTimer(this, &Document::loadEventDelayTimerFired)
     , m_pluginLoadingTimer(this, &Document::pluginLoadingTimerFired)
+    , m_deliverIntersectionObservationsTimer(this, &Document::deliverIntersectionObservationsTimerFired)
     , m_documentTiming(*this)
     , m_writeRecursionIsTooDeep(false)
     , m_writeRecursionDepth(0)
@@ -602,6 +604,8 @@ void Document::dispose()
     if (svgExtensions())
         accessSVGExtensions().pauseAnimations();
 
+    m_deliverIntersectionObservationsTimer.stop();
+
     m_lifecycle.advanceTo(DocumentLifecycle::Disposed);
     DocumentLifecycleNotifier::notifyDocumentWasDisposed();
 
@@ -4482,11 +4486,7 @@ WeakPtrWillBeRawPtr<Document> Document::contextDocument()
     if (m_contextDocument)
         return m_contextDocument;
     if (m_frame) {
-#if ENABLE(OILPAN)
-        return this;
-#else
-        return m_weakFactory.createWeakPtr();
-#endif
+        return createWeakPtr();
     }
     return nullptr;
 }
@@ -4962,6 +4962,29 @@ void Document::parseDNSPrefetchControlHeader(const String& dnsPrefetchControl)
     m_haveExplicitlyDisabledDNSPrefetch = true;
 }
 
+WeakPtrWillBeRawPtr<Document> Document::createWeakPtr()

[dcheng, 2015/12/10 00:37:09]

Having look at the design doc and spec some more, I still feel pretty strongly
that we should not be exposing weak pointers to Document (more widely) and Node
(at all).

[szager1, 2015/12/10 22:38:54]

I understand your reticence, but I also spent two weeks trying to figure out a
better way to do this, without success.  I am open to concrete suggestions.  As
the design doc points out, there are some unusual lifetime constraints; namely:

- IntersectionObservers must remain alive even when there are no javascript
references to them.
- IntersectionObservers must not keep their root or target elements alive.

+{
+#if ENABLE(OILPAN)
+    return this;
+#else
+    return m_weakFactory.createWeakPtr();
+#endif
+}
+
+IntersectionObserverRegistry* Document::intersectionObserverRegistry()
+{
+    if (!m_intersectionObserverRegistry)
+        m_intersectionObserverRegistry = new IntersectionObserverRegistry(m_deliverIntersectionObservationsTimer);
+    return m_intersectionObserverRegistry.get();
+}
+
+void Document::deliverIntersectionObservationsTimerFired(Timer<Document>*)
+{
+    ASSERT(isMainThread());
+    ASSERT(m_intersectionObserverRegistry);
+    m_intersectionObserverRegistry->deliverIntersectionObservations();
+}
+
 void Document::reportBlockedScriptExecutionToInspector(const String& directiveText)
 {
     InspectorInstrumentation::scriptExecutionBlockedByCSP(this, directiveText);
@@ -5019,6 +5042,8 @@ void Document::tasksWereResumed()
         m_scriptedAnimationController->resume();
 
     MutationObserver::resumeSuspendedObservers();
+    if (m_intersectionObserverRegistry)
+        m_intersectionObserverRegistry->resumeSuspendedIntersectionObservers();
     if (m_domWindow)
         DOMWindowPerformance::performance(*m_domWindow)->resumeSuspendedObservers();
 }
@@ -5812,6 +5837,7 @@ DEFINE_TRACE(Document)
     visitor->trace(m_compositorPendingAnimations);
     visitor->trace(m_contextDocument);
     visitor->trace(m_canvasFontCache);
+    visitor->trace(m_intersectionObserverRegistry);
     WillBeHeapSupplementable<Document>::trace(visitor);
 #endif
     TreeScope::trace(visitor);