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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_MIRROR_REFERENCE_H_
#define ART_RUNTIME_MIRROR_REFERENCE_H_
#include "base/enums.h"
#include "base/locks.h"
#include "base/macros.h"
#include "obj_ptr.h"
#include "object.h"
#include "read_barrier_option.h"
namespace art {
namespace gc {
class ReferenceProcessor;
class ReferenceQueue;
} // namespace gc
struct ReferenceOffsets;
struct FinalizerReferenceOffsets;
namespace mirror {
// C++ mirror of java.lang.ref.Reference
class MANAGED Reference : public Object {
public:
// Size of java.lang.ref.Reference.class.
static uint32_t ClassSize(PointerSize pointer_size);
// Size of an instance of java.lang.ref.Reference.
static constexpr uint32_t InstanceSize() {
return sizeof(Reference);
}
static MemberOffset PendingNextOffset() {
return OFFSET_OF_OBJECT_MEMBER(Reference, pending_next_);
}
static MemberOffset QueueOffset() {
return OFFSET_OF_OBJECT_MEMBER(Reference, queue_);
}
static MemberOffset QueueNextOffset() {
return OFFSET_OF_OBJECT_MEMBER(Reference, queue_next_);
}
static MemberOffset ReferentOffset() {
return OFFSET_OF_OBJECT_MEMBER(Reference, referent_);
}
template<ReadBarrierOption kReadBarrierOption = kWithReadBarrier>
Object* GetReferent() REQUIRES_SHARED(Locks::mutator_lock_) {
return GetFieldObjectVolatile<Object, kDefaultVerifyFlags, kReadBarrierOption>(
ReferentOffset());
}
template<bool kTransactionActive>
void SetReferent(ObjPtr<Object> referent) REQUIRES_SHARED(Locks::mutator_lock_);
template<bool kTransactionActive>
void ClearReferent() REQUIRES_SHARED(Locks::mutator_lock_) {
SetFieldObjectVolatile<kTransactionActive>(ReferentOffset(), nullptr);
}
template <ReadBarrierOption kReadBarrierOption = kWithReadBarrier>
Reference* GetPendingNext() REQUIRES_SHARED(Locks::mutator_lock_) {
return GetFieldObject<Reference, kDefaultVerifyFlags, kReadBarrierOption>(PendingNextOffset());
}
void SetPendingNext(ObjPtr<Reference> pending_next) REQUIRES_SHARED(Locks::mutator_lock_);
// Returns true if the reference's pendingNext is null, indicating it is
// okay to process this reference.
//
// If pendingNext is not null, then one of the following cases holds:
// 1. The reference has already been enqueued to a java ReferenceQueue. In
// this case the referent should not be considered for reference processing
// ever again.
// 2. The reference is currently part of a list of references that may
// shortly be enqueued on a java ReferenceQueue. In this case the reference
// should not be processed again until and unless the reference has been
// removed from the list after having determined the reference is not ready
// to be enqueued on a java ReferenceQueue.
bool IsUnprocessed() REQUIRES_SHARED(Locks::mutator_lock_) {
return GetPendingNext<kWithoutReadBarrier>() == nullptr;
}
private:
// Note: This avoids a read barrier, it should only be used by the GC.
HeapReference<Object>* GetReferentReferenceAddr() REQUIRES_SHARED(Locks::mutator_lock_) {
return GetFieldObjectReferenceAddr<kDefaultVerifyFlags>(ReferentOffset());
}
// Field order required by test "ValidateFieldOrderOfJavaCppUnionClasses".
HeapReference<Reference> pending_next_;
HeapReference<Object> queue_;
HeapReference<Reference> queue_next_;
HeapReference<Object> referent_; // Note this is Java volatile:
friend struct art::ReferenceOffsets; // for verifying offset information
friend class gc::ReferenceProcessor;
friend class gc::ReferenceQueue;
DISALLOW_IMPLICIT_CONSTRUCTORS(Reference);
};
// C++ mirror of java.lang.ref.FinalizerReference
class MANAGED FinalizerReference : public Reference {
public:
static MemberOffset ZombieOffset() {
return OFFSET_OF_OBJECT_MEMBER(FinalizerReference, zombie_);
}
template<bool kTransactionActive>
void SetZombie(ObjPtr<Object> zombie) REQUIRES_SHARED(Locks::mutator_lock_);
Object* GetZombie() REQUIRES_SHARED(Locks::mutator_lock_) {
return GetFieldObjectVolatile<Object>(ZombieOffset());
}
private:
HeapReference<FinalizerReference> next_;
HeapReference<FinalizerReference> prev_;
HeapReference<Object> zombie_;
friend struct art::FinalizerReferenceOffsets; // for verifying offset information
DISALLOW_IMPLICIT_CONSTRUCTORS(FinalizerReference);
};
} // namespace mirror
} // namespace art
#endif // ART_RUNTIME_MIRROR_REFERENCE_H_