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      1 /*
      2  * Copyright (C) 2009 Google Inc. All rights reserved.
      3  *
      4  * Redistribution and use in source and binary forms, with or without
      5  * modification, are permitted provided that the following conditions are
      6  * met:
      7  *
      8  *     * Redistributions of source code must retain the above copyright
      9  * notice, this list of conditions and the following disclaimer.
     10  *     * Redistributions in binary form must reproduce the above
     11  * copyright notice, this list of conditions and the following disclaimer
     12  * in the documentation and/or other materials provided with the
     13  * distribution.
     14  *     * Neither the name of Google Inc. nor the names of its
     15  * contributors may be used to endorse or promote products derived from
     16  * this software without specific prior written permission.
     17  *
     18  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
     19  * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
     20  * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
     21  * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
     22  * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
     23  * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
     24  * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
     25  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
     26  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
     27  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
     28  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
     29  */
     30 
     31 #ifndef V8DOMMap_h
     32 #define V8DOMMap_h
     33 
     34 #include <wtf/HashMap.h>
     35 #include <wtf/OwnPtr.h>
     36 #include <v8.h>
     37 
     38 namespace WebCore {
     39     class Node;
     40 #if ENABLE(SVG)
     41     class SVGElementInstance;
     42 #endif
     43 
     44     template <class KeyType, class ValueType> class AbstractWeakReferenceMap {
     45     public:
     46         AbstractWeakReferenceMap(v8::WeakReferenceCallback callback) : m_weakReferenceCallback(callback) { }
     47         virtual ~AbstractWeakReferenceMap() { }
     48 
     49         class Visitor {
     50         public:
     51             virtual void visitDOMWrapper(KeyType* key, v8::Persistent<ValueType> object) = 0;
     52         protected:
     53             virtual ~Visitor() { }
     54         };
     55 
     56         virtual v8::Persistent<ValueType> get(KeyType* obj) = 0;
     57         virtual void set(KeyType* obj, v8::Persistent<ValueType> wrapper) = 0;
     58         virtual bool contains(KeyType* obj) = 0;
     59         virtual void visit(Visitor* visitor) = 0;
     60         virtual bool removeIfPresent(KeyType* key, v8::Persistent<v8::Data> value) = 0;
     61         virtual void clear() = 0;
     62 
     63         v8::WeakReferenceCallback weakReferenceCallback() { return m_weakReferenceCallback; }
     64     private:
     65         v8::WeakReferenceCallback m_weakReferenceCallback;
     66     };
     67 
     68     typedef AbstractWeakReferenceMap<Node, v8::Object> DOMNodeMapping;
     69 
     70     // A table of wrappers with weak pointers.
     71     // This table allows us to avoid track wrapped objects for debugging
     72     // and for ensuring that we don't double wrap the same object.
     73     template<class KeyType, class ValueType> class WeakReferenceMap : public AbstractWeakReferenceMap<KeyType, ValueType> {
     74     public:
     75         typedef AbstractWeakReferenceMap<KeyType, ValueType> Parent;
     76         WeakReferenceMap(v8::WeakReferenceCallback callback) : Parent(callback) { }
     77         virtual ~WeakReferenceMap()
     78         {
     79     #ifndef NDEBUG
     80             if (m_map.size() > 0)
     81                 fprintf(stderr, "Leak %d JS wrappers.\n", m_map.size());
     82     #endif
     83         }
     84 
     85         // Get the JS wrapper object of an object.
     86         virtual v8::Persistent<ValueType> get(KeyType* obj)
     87         {
     88             ValueType* wrapper = m_map.get(obj);
     89             return wrapper ? v8::Persistent<ValueType>(wrapper) : v8::Persistent<ValueType>();
     90         }
     91 
     92         virtual void set(KeyType* obj, v8::Persistent<ValueType> wrapper)
     93         {
     94             ASSERT(!m_map.contains(obj));
     95             wrapper.MakeWeak(obj, Parent::weakReferenceCallback());
     96             m_map.set(obj, *wrapper);
     97         }
     98 
     99         virtual void forget(KeyType* obj)
    100         {
    101             ASSERT(obj);
    102             ValueType* wrapper = m_map.take(obj);
    103             if (!wrapper)
    104                 return;
    105 
    106             v8::Persistent<ValueType> handle(wrapper);
    107             handle.Dispose();
    108             handle.Clear();
    109         }
    110 
    111         bool removeIfPresent(KeyType* key, v8::Persistent<v8::Data> value)
    112         {
    113             typename HashMap<KeyType*, ValueType*>::iterator it = m_map.find(key);
    114             if (it == m_map.end() || it->second != *value)
    115                 return false;
    116 
    117             m_map.remove(it);
    118             value.Dispose();
    119             return true;
    120         }
    121 
    122         void clear()
    123         {
    124             m_map.clear();
    125         }
    126 
    127         bool contains(KeyType* obj) { return m_map.contains(obj); }
    128 
    129         virtual void visit(typename Parent::Visitor* visitor)
    130         {
    131             typename HashMap<KeyType*, ValueType*>::iterator it = m_map.begin();
    132             for (; it != m_map.end(); ++it)
    133                 visitor->visitDOMWrapper(it->first, v8::Persistent<ValueType>(it->second));
    134         }
    135 
    136     protected:
    137         HashMap<KeyType*, ValueType*> m_map;
    138         v8::WeakReferenceCallback m_weakReferenceCallback;
    139     };
    140 
    141     template <class KeyType> class DOMWrapperMap : public WeakReferenceMap<KeyType, v8::Object> {
    142     public:
    143         DOMWrapperMap(v8::WeakReferenceCallback callback) : WeakReferenceMap<KeyType, v8::Object>(callback) { }
    144     };
    145 
    146     // An opaque class that represents a set of DOM wrappers.
    147     class DOMDataStore;
    148 
    149     // A utility class to manage the lifetime of set of DOM wrappers.
    150     class DOMDataStoreHandle {
    151     public:
    152         DOMDataStoreHandle();
    153         ~DOMDataStoreHandle();
    154 
    155         DOMDataStore* getStore() const { return m_store.get(); }
    156 
    157     private:
    158         OwnPtr<DOMDataStore> m_store;
    159     };
    160 
    161     // A map from DOM node to its JS wrapper.
    162     DOMNodeMapping& getDOMNodeMap();
    163     void visitDOMNodesInCurrentThread(DOMWrapperMap<Node>::Visitor*);
    164 
    165     // A map from a DOM object (non-node) to its JS wrapper. This map does not contain the DOM objects which can have pending activity (active dom objects).
    166     DOMWrapperMap<void>& getDOMObjectMap();
    167     void visitDOMObjectsInCurrentThread(DOMWrapperMap<void>::Visitor*);
    168 
    169     // A map from a DOM object to its JS wrapper for DOM objects which can have pending activity.
    170     DOMWrapperMap<void>& getActiveDOMObjectMap();
    171     void visitActiveDOMObjectsInCurrentThread(DOMWrapperMap<void>::Visitor*);
    172 
    173     // This should be called to remove all DOM objects associated with the current thread when it is tearing down.
    174     void removeAllDOMObjectsInCurrentThread();
    175 
    176 #if ENABLE(SVG)
    177     // A map for SVGElementInstances to its JS wrapper.
    178     DOMWrapperMap<SVGElementInstance>& getDOMSVGElementInstanceMap();
    179     void visitSVGElementInstancesInCurrentThread(DOMWrapperMap<SVGElementInstance>::Visitor*);
    180 
    181     // Map of SVG objects with contexts to V8 objects.
    182     DOMWrapperMap<void>& getDOMSVGObjectWithContextMap();
    183     void visitDOMSVGObjectsInCurrentThread(DOMWrapperMap<void>::Visitor*);
    184 #endif
    185 
    186     void enableFasterDOMStoreAccess();
    187 } // namespace WebCore
    188 
    189 #endif // V8DOMMap_h
    190