bindings: Supports reentrance to ScriptWrappable::wrap through V8DOMWrapper::createWrapper.

Source/core/dom/Node.cpp

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  *           (C) 1999 Antti Koivisto (koivisto@kde.org)
  *           (C) 2001 Dirk Mueller (mueller@kde.org)
  * Copyright (C) 2004, 2005, 2006, 2007, 2008, 2009, 2010, 2011 Apple Inc. All rights reserved.
  * Copyright (C) 2008 Nokia Corporation and/or its subsidiary(-ies)
  * Copyright (C) 2009 Torch Mobile Inc. All rights reserved. (http://www.torchmobile.com/)
  *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Library General Public
@@ skipping 2395 matching lines @@
     case Node::DOCUMENT_FRAGMENT_NODE:
         return toContainerNode(this)->countChildren();
     case Node::ATTRIBUTE_NODE:
     case Node::DOCUMENT_TYPE_NODE:
         return 0;
     }
     ASSERT_NOT_REACHED();
     return 0;
 }
 
 v8::Local<v8::Object> Node::wrap(v8::Isolate* isolate, v8::Local<v8::Object> creationContext)

[haraken, 2015/06/29 12:00:30]

Not related to this CL, but why do we need the custom wrap for Node::wrap? This
looks like the same as ScriptWrappable::wrap.

[Yuki, 2015/06/29 12:42:41]

The code looks completely the same, but we have two versions of
DOMDataStore::getWrapper(), one takes ScriptWrappable* and the other takes
Node*.  The latter version has Node-specific optimization.  We'd like to
propagate type information.

 {
     // It's possible that no one except for the new wrapper owns this object at
     // this moment, so we have to prevent GC to collect this object until the
     // object gets associated with the wrapper.
     RefPtrWillBeRawPtr<Node> protect(this);
 
     ASSERT(!DOMDataStore::containsWrapper(this, isolate));
 
     const WrapperTypeInfo* wrapperType = wrapperTypeInfo();
 
     v8::Local<v8::Object> wrapper = V8DOMWrapper::createWrapper(isolate, creationContext, wrapperType, this);
+    // V8DOMWrapper::createWrapper may run an arbitrary script and it may result
+    // in creating a new wrapper and associating it with |this|.  If so, the
+    // wrapper already created and associated must be used.
+    v8::Local<v8::Object> associatedWrapper = DOMDataStore::getWrapper(this, isolate);
+    if (UNLIKELY(!associatedWrapper.IsEmpty()))
+        return associatedWrapper;
     if (UNLIKELY(wrapper.IsEmpty()))
         return wrapper;
 
     wrapperType->installConditionallyEnabledProperties(wrapper, isolate);
     return associateWithWrapper(isolate, wrapperType, wrapper);
 }
 
 v8::Local<v8::Object> Node::associateWithWrapper(v8::Isolate* isolate, const WrapperTypeInfo* wrapperType, v8::Local<v8::Object> wrapper)
 {
     return V8DOMWrapper::associateObjectWithWrapper(isolate, this, wrapperType, wrapper);
@@ skipping 21 matching lines @@
 
 void showNodePath(const blink::Node* node)
 {
     if (node)
         node->showNodePathForThis();
     else
         fprintf(stderr, "Cannot showNodePath for (nil)\n");
 }
 
 #endif