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/*
* Copyright (C) 2010 Google Inc. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are
* met:
*
* * Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* * Redistributions in binary form must reproduce the above
* copyright notice, this list of conditions and the following disclaimer
* in the documentation and/or other materials provided with the
* distribution.
* * Neither the name of Google Inc. nor the names of its
* 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
* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
* A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
* OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
* LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
#ifndef ScriptWrappable_h
#define ScriptWrappable_h
#include "bindings/core/v8/WrapperTypeInfo.h"
#include "platform/heap/Handle.h"
#include "wtf/Noncopyable.h"
#include <v8.h>
namespace blink {
/**
* ScriptWrappable wraps a V8 object and its WrapperTypeInfo.
*
* ScriptWrappable acts much like a v8::Persistent<> in that it keeps a
* V8 object alive.
*
* The state transitions are:
* - new: an empty ScriptWrappable.
* - setWrapper: install a v8::Persistent (or empty)
* - disposeWrapper (via setWeakCallback, triggered by V8 garbage collecter):
* remove v8::Persistent and become empty.
*/
class ScriptWrappable {
WTF_MAKE_NONCOPYABLE(ScriptWrappable);
public:
ScriptWrappable() { }
template<typename T>
T* toImpl()
{
// Check if T* is castable to ScriptWrappable*, which means T doesn't
// have two or more ScriptWrappable as superclasses. If T has two
// ScriptWrappable as superclasses, conversions from T* to
// ScriptWrappable* are ambiguous.
ASSERT(static_cast<ScriptWrappable*>(static_cast<T*>(this)));
return static_cast<T*>(this);
}
// Returns the WrapperTypeInfo of the instance.
//
// This method must be overridden by DEFINE_WRAPPERTYPEINFO macro.
virtual const WrapperTypeInfo* wrapperTypeInfo() const = 0;
// Creates and returns a new wrapper object.
virtual v8::Handle<v8::Object> wrap(v8::Handle<v8::Object> creationContext, v8::Isolate*);
// Associates the instance with the existing wrapper. Returns |wrapper|.
virtual v8::Handle<v8::Object> associateWithWrapper(v8::Isolate*, const WrapperTypeInfo*, v8::Handle<v8::Object> wrapper);
void setWrapper(v8::Handle<v8::Object> wrapper, v8::Isolate* isolate, const WrapperTypeInfo* wrapperTypeInfo)
{
ASSERT(!containsWrapper());
if (!*wrapper)
return;
RELEASE_ASSERT_WITH_SECURITY_IMPLICATION(toScriptWrappable(wrapper) == this);
m_wrapper.Reset(isolate, wrapper);
wrapperTypeInfo->configureWrapper(&m_wrapper);
m_wrapper.SetWeak(this, &setWeakCallback);
ASSERT(containsWrapper());
}
v8::Local<v8::Object> newLocalWrapper(v8::Isolate* isolate) const
{
return v8::Local<v8::Object>::New(isolate, m_wrapper);
}
bool isEqualTo(const v8::Local<v8::Object>& other) const
{
return m_wrapper == other;
}
// Provides a way to convert Node* to ScriptWrappable* without including
// "core/dom/Node.h".
//
// Example:
// void foo(const void*) { ... } // [1]
// void foo(ScriptWrappable*) { ... } // [2]
// class Node;
// Node* node;
// foo(node); // This calls [1] because there is no definition of Node
// // and compilers do not know that Node is a subclass of
// // ScriptWrappable.
// foo(ScriptWrappable::fromNode(node)); // This calls [2] as expected.
//
// The definition of fromNode is placed in Node.h because we'd like to
// inline calls to fromNode as much as possible.
static ScriptWrappable* fromNode(Node*);
bool setReturnValue(v8::ReturnValue<v8::Value> returnValue)
{
returnValue.Set(m_wrapper);
return containsWrapper();
}
void markAsDependentGroup(ScriptWrappable* groupRoot, v8::Isolate* isolate)
{
ASSERT(containsWrapper());
ASSERT(groupRoot && groupRoot->containsWrapper());
// FIXME: There has to be a better way.
v8::UniqueId groupId(*reinterpret_cast<intptr_t*>(&groupRoot->m_wrapper));
m_wrapper.MarkPartiallyDependent();
isolate->SetObjectGroupId(v8::Persistent<v8::Value>::Cast(m_wrapper), groupId);
}
void setReference(const v8::Persistent<v8::Object>& parent, v8::Isolate* isolate)
{
isolate->SetReference(parent, m_wrapper);
}
bool containsWrapper() const { return !m_wrapper.IsEmpty(); }
#if !ENABLE(OILPAN)
protected:
virtual ~ScriptWrappable()
{
// We must not get deleted as long as we contain a wrapper. If this happens, we screwed up ref
// counting somewhere. Crash here instead of crashing during a later gc cycle.
RELEASE_ASSERT_WITH_SECURITY_IMPLICATION(!containsWrapper());
}
#endif
// With Oilpan we don't need a ScriptWrappable destructor.
//
// - 'RELEASE_ASSERT_WITH_SECURITY_IMPLICATION(!containsWrapper())' is not needed
// because Oilpan is not using reference counting at all. If containsWrapper() is true,
// it means that ScriptWrappable still has a wrapper. In this case, the destructor
// must not be called since the wrapper has a persistent handle back to this ScriptWrappable object.
// Assuming that Oilpan's GC is correct (If we cannot assume this, a lot of more things are
// already broken), we must not hit the RELEASE_ASSERT.
private:
void disposeWrapper(v8::Local<v8::Object> wrapper)
{
ASSERT(containsWrapper());
ASSERT(wrapper == m_wrapper);
m_wrapper.Reset();
}
static void setWeakCallback(const v8::WeakCallbackData<v8::Object, ScriptWrappable>& data)
{
data.GetParameter()->disposeWrapper(data.GetValue());
// FIXME: I noticed that 50%~ of minor GC cycle times can be consumed
// inside data.GetParameter()->deref(), which causes Node destructions. We should
// make Node destructions incremental.
releaseObject(data.GetValue());
}
v8::Persistent<v8::Object> m_wrapper;
};
// Defines 'wrapperTypeInfo' virtual method which returns the WrapperTypeInfo of
// the instance. Also declares a static member of type WrapperTypeInfo, of which
// the definition is given by the IDL code generator.
//
// All the derived classes of ScriptWrappable, regardless of directly or
// indirectly, must write this macro in the class definition as long as the
// class has a corresponding .idl file.
#define DEFINE_WRAPPERTYPEINFO() \
public: \
virtual const WrapperTypeInfo* wrapperTypeInfo() const override \
{ \
return &s_wrapperTypeInfo; \
} \
private: \
static const WrapperTypeInfo& s_wrapperTypeInfo
// Defines 'wrapperTypeInfo' virtual method, which should never be called.
//
// This macro is used when there exists a class hierarchy with a root class
// and most of the subclasses are script-wrappable but not all of them.
// In that case, the root class can inherit from ScriptWrappable and use
// this macro, and let subclasses have a choice whether or not use
// DEFINE_WRAPPERTYPEINFO macro. The script-wrappable subclasses which have
// corresponding IDL file must call DEFINE_WRAPPERTYPEINFO, and the others
// must not.
#define DEFINE_WRAPPERTYPEINFO_NOT_REACHED() \
public: \
virtual const WrapperTypeInfo* wrapperTypeInfo() const override \
{ \
ASSERT_NOT_REACHED(); \
return 0; \
} \
private: \
typedef void end_of_define_wrappertypeinfo_not_reached_t
} // namespace blink
#endif // ScriptWrappable_h
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