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/*
* Copyright (C) 2009, 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 CrossThreadCopier_h
#define CrossThreadCopier_h
#include "platform/PlatformExport.h"
#include "platform/heap/Handle.h"
#include "wtf/Assertions.h"
#include "wtf/Forward.h"
#include "wtf/PassRefPtr.h"
#include "wtf/RefPtr.h"
#include "wtf/ThreadSafeRefCounted.h"
#include "wtf/TypeTraits.h"
#include <memory>
class SkRefCnt;
namespace WTF {
template <typename T>
class PassedWrapper;
}
namespace blink {
class IntRect;
class IntSize;
class KURL;
class ResourceError;
class ResourceRequest;
class ResourceResponse;
struct CrossThreadResourceResponseData;
struct CrossThreadResourceRequestData;
template <typename T>
struct CrossThreadCopierPassThrough {
STATIC_ONLY(CrossThreadCopierPassThrough);
typedef T Type;
static Type copy(const T& parameter)
{
return parameter;
}
};
template <typename T, bool isArithmeticOrEnum, bool isThreadSafeRefCounted>
struct CrossThreadCopierBase;
// Arithmetic values (integers or floats) and enums can be safely copied.
template <typename T, bool isThreadSafeRefCounted>
struct CrossThreadCopierBase<T, true, isThreadSafeRefCounted> : public CrossThreadCopierPassThrough<T> {
STATIC_ONLY(CrossThreadCopierBase);
};
// Custom copy method for ThreadSafeRefCounted.
template <typename T>
struct CrossThreadCopierBase<T, false, true> {
STATIC_ONLY(CrossThreadCopierBase);
typedef typename WTF::RemoveTemplate<T, RefPtr>::Type TypeWithoutRefPtr;
typedef typename WTF::RemoveTemplate<TypeWithoutRefPtr, PassRefPtr>::Type TypeWithoutPassRefPtr;
typedef typename std::remove_pointer<TypeWithoutPassRefPtr>::type RefCountedType;
// Verify that only one of the above did a change.
static_assert((std::is_same<RefPtr<RefCountedType>, T>::value
|| std::is_same<PassRefPtr<RefCountedType>, T>::value
|| std::is_same<RefCountedType*, T>::value),
"only one type modification should be allowed");
typedef PassRefPtr<RefCountedType> Type;
static Type copy(const T& refPtr)
{
return refPtr;
}
};
template <typename T>
struct CrossThreadCopier : public CrossThreadCopierBase<
T,
std::is_arithmetic<T>::value || std::is_enum<T>::value,
WTF::IsSubclassOfTemplate<typename WTF::RemoveTemplate<T, RefPtr>::Type, ThreadSafeRefCounted>::value
|| WTF::IsSubclassOfTemplate<typename std::remove_pointer<T>::type, ThreadSafeRefCounted>::value
|| WTF::IsSubclassOfTemplate<typename WTF::RemoveTemplate<T, PassRefPtr>::Type, ThreadSafeRefCounted>::value
|| std::is_base_of<SkRefCnt, typename WTF::RemoveTemplate<T, RefPtr>::Type>::value
|| std::is_base_of<SkRefCnt, typename std::remove_pointer<T>::type>::value
|| std::is_base_of<SkRefCnt, typename WTF::RemoveTemplate<T, PassRefPtr>::Type>::value> {
STATIC_ONLY(CrossThreadCopier);
};
// CrossThreadCopier specializations follow.
// nullptr_t can be passed through without any changes.
template <>
struct CrossThreadCopier<std::nullptr_t> : public CrossThreadCopierPassThrough<std::nullptr_t> {
STATIC_ONLY(CrossThreadCopier);
};
// To allow a type to be passed across threads using its copy constructor, add a forward declaration of the type and
// provide a specialization of CrossThreadCopier<T> in this file, like IntRect below.
template <>
struct CrossThreadCopier<IntRect> : public CrossThreadCopierPassThrough<IntRect> {
STATIC_ONLY(CrossThreadCopier);
};
template <>
struct CrossThreadCopier<IntSize> : public CrossThreadCopierPassThrough<IntSize> {
STATIC_ONLY(CrossThreadCopier);
};
template <typename T, typename Deleter>
struct CrossThreadCopier<std::unique_ptr<T, Deleter>> {
STATIC_ONLY(CrossThreadCopier);
using Type = std::unique_ptr<T, Deleter>;
static std::unique_ptr<T, Deleter> copy(std::unique_ptr<T, Deleter> pointer)
{
return pointer; // This is in fact a move.
}
};
template<typename T>
struct CrossThreadCopier<CrossThreadPersistent<T>> : public CrossThreadCopierPassThrough<CrossThreadPersistent<T>> {
STATIC_ONLY(CrossThreadCopier);
};
template<typename T>
struct CrossThreadCopier<CrossThreadWeakPersistent<T>> : public CrossThreadCopierPassThrough<CrossThreadWeakPersistent<T>> {
STATIC_ONLY(CrossThreadCopier);
};
template<typename T>
struct CrossThreadCopier<WeakPtr<T>> : public CrossThreadCopierPassThrough<WeakPtr<T>> {
STATIC_ONLY(CrossThreadCopier);
};
template <typename T>
struct CrossThreadCopier<WTF::PassedWrapper<T>> {
STATIC_ONLY(CrossThreadCopier);
using Type = WTF::PassedWrapper<typename CrossThreadCopier<T>::Type>;
static Type copy(WTF::PassedWrapper<T>&& value) { return passed(CrossThreadCopier<T>::copy(value.moveOut())); }
};
template<typename T>
struct CrossThreadCopier<CrossThreadWeakPersistentThisPointer<T>> : public CrossThreadCopierPassThrough<CrossThreadWeakPersistentThisPointer<T>> {
STATIC_ONLY(CrossThreadCopier);
};
template <>
struct CrossThreadCopier<KURL> {
STATIC_ONLY(CrossThreadCopier);
typedef KURL Type;
PLATFORM_EXPORT static Type copy(const KURL&);
};
template <>
struct CrossThreadCopier<String> {
STATIC_ONLY(CrossThreadCopier);
typedef String Type;
PLATFORM_EXPORT static Type copy(const String&);
};
template <>
struct CrossThreadCopier<ResourceError> {
STATIC_ONLY(CrossThreadCopier);
typedef ResourceError Type;
PLATFORM_EXPORT static Type copy(const ResourceError&);
};
template <>
struct CrossThreadCopier<ResourceRequest> {
STATIC_ONLY(CrossThreadCopier);
typedef WTF::PassedWrapper<std::unique_ptr<CrossThreadResourceRequestData>> Type;
PLATFORM_EXPORT static Type copy(const ResourceRequest&);
};
template <>
struct CrossThreadCopier<ResourceResponse> {
STATIC_ONLY(CrossThreadCopier);
typedef WTF::PassedWrapper<std::unique_ptr<CrossThreadResourceResponseData>> Type;
PLATFORM_EXPORT static Type copy(const ResourceResponse&);
};
template <typename T>
struct CrossThreadCopier<Member<T>> {
STATIC_ONLY(CrossThreadCopier);
static_assert(IsGarbageCollectedType<T>::value, "T must be a garbage-collected type.");
typedef T* Type;
static Type copy(const Member<T>& ptr)
{
return ptr;
}
};
// |T| is a pointer type.
template <typename T>
struct AllowCrossThreadAccessWrapper {
STACK_ALLOCATED();
public:
T value() const { return m_value; }
private:
// Only constructible from AllowCrossThreadAccess*().
explicit AllowCrossThreadAccessWrapper(T value) : m_value(value) { }
template <typename U>
friend AllowCrossThreadAccessWrapper<U*> AllowCrossThreadAccess(U*);
// This raw pointer is safe since AllowCrossThreadAccessWrapper is
// always stack-allocated. Ideally this should be Member<T> if T is
// garbage-collected and T* otherwise, but we don't want to introduce
// another template magic just for distinguishing Member<T> from T*.
// From the perspective of GC, T* always works correctly.
GC_PLUGIN_IGNORE("")
T m_value;
};
template <typename T>
struct CrossThreadCopier<AllowCrossThreadAccessWrapper<T>> {
STATIC_ONLY(CrossThreadCopier);
typedef T Type;
static Type copy(const AllowCrossThreadAccessWrapper<T>& wrapper) { return wrapper.value(); }
};
template <typename T>
AllowCrossThreadAccessWrapper<T*> AllowCrossThreadAccess(T* value)
{
static_assert(!IsGarbageCollectedType<T>::value, "Use wrapCrossThreadPersistent() instead for garbage-collected pointers");
static_assert(!WTF::IsSubclassOfTemplate<T, ThreadSafeRefCounted>::value, "Use PassRefPtr<T> instead for ThreadSafeRefCounted");
return AllowCrossThreadAccessWrapper<T*>(value);
}
} // namespace blink
#endif // CrossThreadCopier_h