Oilpan: Schedule a precise GC when a page navigates

Source/core/loader/FrameLoader.cpp

Index: Source/core/loader/FrameLoader.cpp
diff --git a/Source/core/loader/FrameLoader.cpp b/Source/core/loader/FrameLoader.cpp
index 3d8ab8b84bc46b42a5857b61572df491501f33b4..08ef3abe9caf37373ce569047d37e09b79181a24 100644
--- a/Source/core/loader/FrameLoader.cpp
+++ b/Source/core/loader/FrameLoader.cpp
@@ -1028,6 +1028,19 @@ bool FrameLoader::prepareForCommit()
     PluginScriptForbiddenScope forbidPluginDestructorScripting;
     RefPtrWillBeRawPtr<DocumentLoader> pdl = m_provisionalDocumentLoader;
 
+    if (m_frame->document()) {
+        unsigned nodeCount = 0;
+        for (Frame* frame = m_frame; frame; frame = frame->tree().traverseNext()) {
+            if (frame->isLocalFrame())
+                nodeCount += m_frame->domWindow()->document()->nodeCount();

[haraken, 2015/07/23 23:19:30]

If things happen in the order of:

1) User script removes all nodes from a document.
2) The document navigates away.

then the node count reported here would be underestimated. I think you were
saying that this is happening in Speedometer.

I guess what we really want to count here is (the number of nodes attached to
the document) + (the number of nodes that are not attached to any document).
Maybe we can count the number by hooking the following functions.

- Node's constructor  -- A
- Node's destructor  -- B
- Node::insertedInto  -- C(i)
- Node::removedFrom  -- D(i)

Then:

(the number of nodes attached to the document) + (the number of nodes that are
not attached to any document x) = (A - B - \sum (C(i) - D(i))) + (C(x) - D(x))

+        }
+        float ratio = static_cast<float>(nodeCount) / InstanceCounters::counterValue(InstanceCounters::NodeCounter);
+        if (ratio > 1)

[haraken, 2015/07/23 23:19:30]

When can this happen?

+            ratio = 1;
+        if (ThreadState::current()->shouldSchedulePreciseGCOnNavigation(ratio))
+            ThreadState::current()->schedulePreciseGC();
+    }
+
     if (m_documentLoader) {
         client()->dispatchWillClose();
         dispatchUnloadEvent();