WebCore/bindings/v8/DOMData.h

/*
 * Copyright (C) 2009 Google Inc. All rights reserved.
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 * modification, are permitted provided that the following conditions are
 * met:
 *
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 * notice, this list of conditions and the following disclaimer.
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 * copyright notice, this list of conditions and the following disclaimer
 * in the documentation and/or other materials provided with the
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 * contributors may be used to endorse or promote products derived from
 * this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
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#ifndef DOMData_h
#define DOMData_h

#include "DOMDataStore.h"

namespace WebCore {

    // DOMData
    //
    // DOMData represents the all the DOM wrappers for a given thread.  In
    // particular, DOMData holds wrappers for all the isolated worlds in the
    // thread.  The DOMData for the main thread and the DOMData for child threads
    // use different subclasses.
    //
    class DOMData : public Noncopyable {
    public:
        DOMData();
        virtual ~DOMData();

        static DOMData* getCurrent();
        virtual DOMDataStore& getStore() = 0;

        template<typename T>
        static void handleWeakObject(DOMDataStore::DOMWrapperMapType, v8::Handle<v8::Object>, T* domObject);

        void forgetDelayedObject(void* object) { m_delayedObjectMap.take(object); }

        // This is to ensure that we will deref DOM objects from the owning thread,
        // not the GC thread. The helper function will be scheduled by the GC
        // thread to get called from the owning thread.
        static void derefDelayedObjectsInCurrentThread(void*);
        void derefDelayedObjects();

        template<typename T>
        static void removeObjectsFromWrapperMap(DOMWrapperMap<T>& domMap);

        ThreadIdentifier owningThread() const { return m_owningThread; }

    private:
        typedef WTF::HashMap<void*, V8ClassIndex::V8WrapperType> DelayedObjectMap;

        void ensureDeref(V8ClassIndex::V8WrapperType type, void* domObject);
        static void derefObject(V8ClassIndex::V8WrapperType type, void* domObject);

        // Stores all the DOM objects that are delayed to be processed when the
        // owning thread gains control.
        DelayedObjectMap m_delayedObjectMap;

        // The flag to indicate if the task to do the delayed process has
        // already been posted.
        bool m_delayedProcessingScheduled;

        bool m_isMainThread;
        ThreadIdentifier m_owningThread;
    };

    template<typename T>
    void DOMData::handleWeakObject(DOMDataStore::DOMWrapperMapType mapType, v8::Handle<v8::Object> v8Object, T* domObject)
    {
        ASSERT(WTF::isMainThread());
        DOMDataList& list = DOMDataStore::allStores();
        for (size_t i = 0; i < list.size(); ++i) {
            DOMDataStore* store = list[i];

            DOMDataStore::InternalDOMWrapperMap<T>* domMap = static_cast<DOMDataStore::InternalDOMWrapperMap<T>*>(store->getDOMWrapperMap(mapType));

            v8::Handle<v8::Object> wrapper = domMap->get(domObject);
            if (*wrapper == *v8Object) {
                // Clear the JS reference.
                domMap->forgetOnly(domObject);
                ASSERT(store->domData()->owningThread() == WTF::currentThread());
                store->domData()->derefObject(V8DOMWrapper::domWrapperType(v8Object), domObject);
            }
        }
    }

    template<typename T>
    void DOMData::removeObjectsFromWrapperMap(DOMWrapperMap<T>& domMap)
    {
        for (typename WTF::HashMap<T*, v8::Object*>::iterator iter(domMap.impl().begin()); iter != domMap.impl().end(); ++iter) {
            T* domObject = static_cast<T*>(iter->first);
            v8::Persistent<v8::Object> v8Object(iter->second);

            V8ClassIndex::V8WrapperType type = V8DOMWrapper::domWrapperType(v8::Handle<v8::Object>::Cast(v8Object));

            // Deref the DOM object.
            derefObject(type, domObject);

            // Clear the JS wrapper.
            v8Object.Dispose();
        }
        domMap.impl().clear();
    }

} // namespace WebCore

#endif // DOMData_h