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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 "class.h"
#include "gc_root.h"
#include "object.h"
#include "object_callbacks.h"
#include "read_barrier_option.h"
#include "thread.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();
// 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() SHARED_LOCKS_REQUIRED(Locks::mutator_lock_) {
return GetFieldObjectVolatile<Object, kDefaultVerifyFlags, kReadBarrierOption>(
ReferentOffset());
}
template<bool kTransactionActive>
void SetReferent(Object* referent) SHARED_LOCKS_REQUIRED(Locks::mutator_lock_) {
SetFieldObjectVolatile<kTransactionActive>(ReferentOffset(), referent);
}
template<bool kTransactionActive>
void ClearReferent() SHARED_LOCKS_REQUIRED(Locks::mutator_lock_) {
SetFieldObjectVolatile<kTransactionActive>(ReferentOffset(), nullptr);
}
// Volatile read/write is not necessary since the java pending next is only accessed from
// the java threads for cleared references. Once these cleared references have a null referent,
// we never end up reading their pending next from the GC again.
Reference* GetPendingNext() SHARED_LOCKS_REQUIRED(Locks::mutator_lock_) {
return GetFieldObject<Reference>(PendingNextOffset());
}
template<bool kTransactionActive>
void SetPendingNext(Reference* pending_next) SHARED_LOCKS_REQUIRED(Locks::mutator_lock_) {
SetFieldObject<kTransactionActive>(PendingNextOffset(), pending_next);
}
bool IsEnqueued() SHARED_LOCKS_REQUIRED(Locks::mutator_lock_) {
// Since the references are stored as cyclic lists it means that once enqueued, the pending
// next is always non-null.
return GetPendingNext() != nullptr;
}
bool IsEnqueuable() SHARED_LOCKS_REQUIRED(Locks::mutator_lock_);
template<ReadBarrierOption kReadBarrierOption = kWithReadBarrier>
static Class* GetJavaLangRefReference() SHARED_LOCKS_REQUIRED(Locks::mutator_lock_) {
DCHECK(!java_lang_ref_Reference_.IsNull());
return java_lang_ref_Reference_.Read<kReadBarrierOption>();
}
static void SetClass(Class* klass);
static void ResetClass(void);
static void VisitRoots(RootCallback* callback, void* arg);
private:
// Note: This avoids a read barrier, it should only be used by the GC.
HeapReference<Object>* GetReferentReferenceAddr() SHARED_LOCKS_REQUIRED(Locks::mutator_lock_) {
return GetFieldObjectReferenceAddr<kDefaultVerifyFlags>(ReferentOffset());
}
// Field order required by test "ValidateFieldOrderOfJavaCppUnionClasses".
HeapReference<Reference> pending_next_; // Note this is Java volatile:
HeapReference<Object> queue_; // Note this is Java volatile:
HeapReference<Reference> queue_next_; // Note this is Java volatile:
HeapReference<Object> referent_; // Note this is Java volatile:
static GcRoot<Class> java_lang_ref_Reference_;
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(Object* zombie) SHARED_LOCKS_REQUIRED(Locks::mutator_lock_) {
return SetFieldObjectVolatile<kTransactionActive>(ZombieOffset(), zombie);
}
Object* GetZombie() SHARED_LOCKS_REQUIRED(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_
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