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/*
* Copyright (C) 2014 The Android Open Source Project
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
#ifndef ART_RUNTIME_REFLECTIVE_HANDLE_H_
#define ART_RUNTIME_REFLECTIVE_HANDLE_H_
#include "base/value_object.h"
#include "reflective_reference.h"
namespace art {
// This is a holder similar to Handle<T> that is used to hold reflective references to ArtField and
// ArtMethod structures. A reflective reference is one that must be updated if the underlying class
// or instances are replaced due to structural redefinition or some other process. In general these
// don't need to be used. It's only when it's important that a reference to a field not become
// obsolete and it needs to be held over a suspend point that this should be used.
template <typename T>
class ReflectiveHandle : public ValueObject {
public:
static_assert(std::is_same_v<T, ArtField> || std::is_same_v<T, ArtMethod>,
"Expected ArtField or ArtMethod");
ReflectiveHandle() : reference_(nullptr) {}
ALWAYS_INLINE ReflectiveHandle(const ReflectiveHandle<T>& handle) = default;
ALWAYS_INLINE ReflectiveHandle<T>& operator=(const ReflectiveHandle<T>& handle) = default;
ALWAYS_INLINE explicit ReflectiveHandle(ReflectiveReference<T>* reference)
: reference_(reference) {}
ALWAYS_INLINE T& operator*() const REQUIRES_SHARED(Locks::mutator_lock_) {
return *Get();
}
ALWAYS_INLINE T* operator->() const REQUIRES_SHARED(Locks::mutator_lock_) {
return Get();
}
ALWAYS_INLINE T* Get() const REQUIRES_SHARED(Locks::mutator_lock_) {
return reference_->Ptr();
}
ALWAYS_INLINE bool IsNull() const {
// It's safe to null-check it without a read barrier.
return reference_->IsNull();
}
ALWAYS_INLINE bool operator!=(std::nullptr_t) const REQUIRES_SHARED(Locks::mutator_lock_) {
return !IsNull();
}
ALWAYS_INLINE bool operator==(std::nullptr_t) const REQUIRES_SHARED(Locks::mutator_lock_) {
return IsNull();
}
protected:
ReflectiveReference<T>* reference_;
private:
friend class BaseReflectiveHandleScope;
template <size_t kNumFieldReferences, size_t kNumMethodReferences>
friend class StackReflectiveHandleScope;
};
// Handles that support assignment.
template <typename T>
class MutableReflectiveHandle : public ReflectiveHandle<T> {
public:
MutableReflectiveHandle() {}
ALWAYS_INLINE MutableReflectiveHandle(const MutableReflectiveHandle<T>& handle)
REQUIRES_SHARED(Locks::mutator_lock_) = default;
ALWAYS_INLINE MutableReflectiveHandle<T>& operator=(const MutableReflectiveHandle<T>& handle)
REQUIRES_SHARED(Locks::mutator_lock_) = default;
ALWAYS_INLINE explicit MutableReflectiveHandle(ReflectiveReference<T>* reference)
REQUIRES_SHARED(Locks::mutator_lock_)
: ReflectiveHandle<T>(reference) {}
ALWAYS_INLINE T* Assign(T* reference) REQUIRES_SHARED(Locks::mutator_lock_) {
ReflectiveReference<T>* ref = ReflectiveHandle<T>::reference_;
T* old = ref->Ptr();
ref->Assign(reference);
return old;
}
private:
friend class BaseReflectiveHandleScope;
template <size_t kNumFieldReferences, size_t kNumMethodReferences>
friend class StackReflectiveHandleScope;
};
template<typename T>
class ReflectiveHandleWrapper : public MutableReflectiveHandle<T> {
public:
ReflectiveHandleWrapper(T** obj, const MutableReflectiveHandle<T>& handle)
: MutableReflectiveHandle<T>(handle), obj_(obj) {
}
ReflectiveHandleWrapper(const ReflectiveHandleWrapper&) = default;
~ReflectiveHandleWrapper() {
*obj_ = MutableReflectiveHandle<T>::Get();
}
private:
T** const obj_;
};
} // namespace art
#endif // ART_RUNTIME_REFLECTIVE_HANDLE_H_
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