Fixing bug 406692. Speed up nsNodeSH::PreCreate(). r+sr=peterv@propagandism.org, a=jonas@sickin.cc

content/base/public/nsIDocument.h

@@ -92,11 +92,12 @@ class nsIDocumentObserver;
 class nsBindingManager;
 class nsIDOMNodeList;
 class mozAutoSubtreeModified;
+struct JSObject;
 
 // IID for the nsIDocument interface
 #define NS_IDOCUMENT_IID      \
-{ 0xc7f56e99, 0x5538, 0x4841, \
-  { 0x97, 0x39, 0x43, 0x6e, 0x6d, 0x26, 0x95, 0x12 } }
+{ 0xed21686d, 0x4e2f, 0x41f5, \
+  { 0x94, 0xaa, 0xcc, 0x1f, 0xbd, 0xfa, 0x1f, 0x84 } }
 
 
 // Flag for AddStyleSheet().
@@ -120,7 +121,8 @@ public:
       mNodeInfoManager(nsnull),
       mCompatMode(eCompatibility_FullStandards),
       mIsInitialDocumentInWindow(PR_FALSE),
-      mPartID(0)
+      mPartID(0),
+      mJSObject(nsnull)
   {
     mParentPtrBits |= PARENT_BIT_INDOCUMENT;
   }
@@ -895,6 +897,16 @@ public:
     return mLoadedAsData;
   }
 
+  JSObject* GetJSObject() const
+  {
+    return mJSObject;
+  }
+
+  void SetJSObject(JSObject *aJSObject)
+  {
+    mJSObject = aJSObject;
+  }
+
 protected:
   ~nsIDocument()
   {
@@ -983,6 +995,12 @@ protected:
 
   nsCOMArray<nsINode> mSubtreeModifiedTargets;
   PRUint32            mSubtreeModifiedDepth;
+
+private:
+  // JSObject cache. Only to be used for performance
+  // optimizations. This will be set once this document is touched
+  // from JS, and it will be unset once the JSObject is finalized.
+  JSObject *mJSObject;
 };
 
 NS_DEFINE_STATIC_IID_ACCESSOR(nsIDocument, NS_IDOCUMENT_IID)

dom/src/base/nsDOMClassInfo.cpp

@@ -492,7 +492,8 @@ static const char kDOMStringBundleURL[] =
    nsIXPCScriptable::WANT_ADDPROPERTY |                                       \
    nsIXPCScriptable::WANT_DELPROPERTY |                                       \
    nsIXPCScriptable::WANT_GETPROPERTY |                                       \
-   nsIXPCScriptable::WANT_POSTCREATE)
+   nsIXPCScriptable::WANT_POSTCREATE  |                                       \
+   nsIXPCScriptable::WANT_FINALIZE)
 
 #define ARRAY_SCRIPTABLE_FLAGS                                                \
   (DOM_DEFAULT_SCRIPTABLE_FLAGS       |                                       \
@@ -6506,6 +6507,10 @@ nsNodeSH::PreCreate(nsISupports *nativeObj, JSContext *cx, JSObject *globalObj,
   // to wrap here? But that's not always reachable, let's use
   // globalObj for now...
 
+  if (native_parent == doc && (*parentObj = doc->GetJSObject())) {
+    return NS_OK;
+  }
+
   jsval v;
   nsCOMPtr<nsIXPConnectJSObjectHolder> holder;
   nsresult rv = WrapNative(cx, globalObj, native_parent,
@@ -7536,9 +7541,6 @@ NS_IMETHODIMP
 nsDocumentSH::PostCreate(nsIXPConnectWrappedNative *wrapper, JSContext *cx,
                          JSObject *obj)
 {
-  nsresult rv = nsNodeSH::PostCreate(wrapper, cx, obj);
-  NS_ENSURE_SUCCESS(rv, rv);
-
   // If this is the current document for the window that's the script global
   // object of this document, then define this document object on the window.
   // That will make sure that the document is referenced (via window.document)
@@ -7548,6 +7550,13 @@ nsDocumentSH::PostCreate(nsIXPConnectWrappedNative *wrapper, JSContext *cx,
     return NS_ERROR_UNEXPECTED;
   }
 
+  // Cache the document's JSObject on the document so we can optimize
+  // nsNodeSH::PreCreate() to avoid nested WrapNative() calls.
+  doc->SetJSObject(obj);
+
+  nsresult rv = nsNodeSH::PostCreate(wrapper, cx, obj);
+  NS_ENSURE_SUCCESS(rv, rv);
+
   nsIScriptGlobalObject *sgo = doc->GetScriptGlobalObject();
   nsCOMPtr<nsPIDOMWindow> win = do_QueryInterface(sgo);
   if (!win) {
@@ -7587,6 +7596,20 @@ nsDocumentSH::PostCreate(nsIXPConnectWrappedNative *wrapper, JSContext *cx,
   return NS_OK;
 }
 
+NS_IMETHODIMP
+nsDocumentSH::Finalize(nsIXPConnectWrappedNative *wrapper, JSContext *cx,
+                       JSObject *obj)
+{
+  nsCOMPtr<nsIDocument> doc = do_QueryWrappedNative(wrapper);
+  if (!doc) {
+    return NS_ERROR_UNEXPECTED;
+  }
+
+  doc->SetJSObject(nsnull);
+
+  return NS_OK;
+}
+
 // HTMLDocument helper
 
 // static

dom/src/base/nsDOMClassInfo.h

@@ -798,6 +798,8 @@ public:
   NS_IMETHOD GetFlags(PRUint32* aFlags);
   NS_IMETHOD PostCreate(nsIXPConnectWrappedNative *wrapper, JSContext *cx,
                         JSObject *obj);
+  NS_IMETHOD Finalize(nsIXPConnectWrappedNative *wrapper, JSContext *cx,
+                      JSObject *obj);
 
   static nsIClassInfo *doCreate(nsDOMClassInfoData* aData)
   {