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