1 /* 2 * Copyright (C) 2014 The Android Open Source Project 3 * 4 * Licensed under the Apache License, Version 2.0 (the "License"); 5 * you may not use this file except in compliance with the License. 6 * You may obtain a copy of the License at 7 * 8 * http://www.apache.org/licenses/LICENSE-2.0 9 * 10 * Unless required by applicable law or agreed to in writing, software 11 * distributed under the License is distributed on an "AS IS" BASIS, 12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 13 * See the License for the specific language governing permissions and 14 * limitations under the License. 15 */ 16 17 #ifndef ART_RUNTIME_MIRROR_REFERENCE_H_ 18 #define ART_RUNTIME_MIRROR_REFERENCE_H_ 19 20 #include "base/enums.h" 21 #include "class.h" 22 #include "gc_root.h" 23 #include "obj_ptr.h" 24 #include "object.h" 25 #include "object_callbacks.h" 26 #include "read_barrier_option.h" 27 #include "runtime.h" 28 #include "thread.h" 29 30 namespace art { 31 32 namespace gc { 33 34 class ReferenceProcessor; 35 class ReferenceQueue; 36 37 } // namespace gc 38 39 struct ReferenceOffsets; 40 struct FinalizerReferenceOffsets; 41 42 namespace mirror { 43 44 // C++ mirror of java.lang.ref.Reference 45 class MANAGED Reference : public Object { 46 public: 47 // Size of java.lang.ref.Reference.class. 48 static uint32_t ClassSize(PointerSize pointer_size); 49 50 // Size of an instance of java.lang.ref.Reference. 51 static constexpr uint32_t InstanceSize() { 52 return sizeof(Reference); 53 } 54 55 static MemberOffset PendingNextOffset() { 56 return OFFSET_OF_OBJECT_MEMBER(Reference, pending_next_); 57 } 58 static MemberOffset QueueOffset() { 59 return OFFSET_OF_OBJECT_MEMBER(Reference, queue_); 60 } 61 static MemberOffset QueueNextOffset() { 62 return OFFSET_OF_OBJECT_MEMBER(Reference, queue_next_); 63 } 64 static MemberOffset ReferentOffset() { 65 return OFFSET_OF_OBJECT_MEMBER(Reference, referent_); 66 } 67 template<ReadBarrierOption kReadBarrierOption = kWithReadBarrier> 68 Object* GetReferent() REQUIRES_SHARED(Locks::mutator_lock_) { 69 return GetFieldObjectVolatile<Object, kDefaultVerifyFlags, kReadBarrierOption>( 70 ReferentOffset()); 71 } 72 template<bool kTransactionActive> 73 void SetReferent(ObjPtr<Object> referent) REQUIRES_SHARED(Locks::mutator_lock_); 74 template<bool kTransactionActive> 75 void ClearReferent() REQUIRES_SHARED(Locks::mutator_lock_) { 76 SetFieldObjectVolatile<kTransactionActive>(ReferentOffset(), nullptr); 77 } 78 79 template <ReadBarrierOption kReadBarrierOption = kWithReadBarrier> 80 Reference* GetPendingNext() REQUIRES_SHARED(Locks::mutator_lock_) { 81 return GetFieldObject<Reference, kDefaultVerifyFlags, kReadBarrierOption>(PendingNextOffset()); 82 } 83 84 void SetPendingNext(ObjPtr<Reference> pending_next) REQUIRES_SHARED(Locks::mutator_lock_); 85 86 // Returns true if the reference's pendingNext is null, indicating it is 87 // okay to process this reference. 88 // 89 // If pendingNext is not null, then one of the following cases holds: 90 // 1. The reference has already been enqueued to a java ReferenceQueue. In 91 // this case the referent should not be considered for reference processing 92 // ever again. 93 // 2. The reference is currently part of a list of references that may 94 // shortly be enqueued on a java ReferenceQueue. In this case the reference 95 // should not be processed again until and unless the reference has been 96 // removed from the list after having determined the reference is not ready 97 // to be enqueued on a java ReferenceQueue. 98 bool IsUnprocessed() REQUIRES_SHARED(Locks::mutator_lock_) { 99 return GetPendingNext<kWithoutReadBarrier>() == nullptr; 100 } 101 102 template<ReadBarrierOption kReadBarrierOption = kWithReadBarrier> 103 static Class* GetJavaLangRefReference() REQUIRES_SHARED(Locks::mutator_lock_) { 104 DCHECK(!java_lang_ref_Reference_.IsNull()); 105 return java_lang_ref_Reference_.Read<kReadBarrierOption>(); 106 } 107 static void SetClass(ObjPtr<Class> klass); 108 static void ResetClass(); 109 static void VisitRoots(RootVisitor* visitor) REQUIRES_SHARED(Locks::mutator_lock_); 110 111 private: 112 // Note: This avoids a read barrier, it should only be used by the GC. 113 HeapReference<Object>* GetReferentReferenceAddr() REQUIRES_SHARED(Locks::mutator_lock_) { 114 return GetFieldObjectReferenceAddr<kDefaultVerifyFlags>(ReferentOffset()); 115 } 116 117 // Field order required by test "ValidateFieldOrderOfJavaCppUnionClasses". 118 HeapReference<Reference> pending_next_; 119 HeapReference<Object> queue_; 120 HeapReference<Reference> queue_next_; 121 HeapReference<Object> referent_; // Note this is Java volatile: 122 123 static GcRoot<Class> java_lang_ref_Reference_; 124 125 friend struct art::ReferenceOffsets; // for verifying offset information 126 friend class gc::ReferenceProcessor; 127 friend class gc::ReferenceQueue; 128 DISALLOW_IMPLICIT_CONSTRUCTORS(Reference); 129 }; 130 131 // C++ mirror of java.lang.ref.FinalizerReference 132 class MANAGED FinalizerReference : public Reference { 133 public: 134 static MemberOffset ZombieOffset() { 135 return OFFSET_OF_OBJECT_MEMBER(FinalizerReference, zombie_); 136 } 137 138 template<bool kTransactionActive> 139 void SetZombie(ObjPtr<Object> zombie) REQUIRES_SHARED(Locks::mutator_lock_); 140 141 Object* GetZombie() REQUIRES_SHARED(Locks::mutator_lock_) { 142 return GetFieldObjectVolatile<Object>(ZombieOffset()); 143 } 144 145 private: 146 HeapReference<FinalizerReference> next_; 147 HeapReference<FinalizerReference> prev_; 148 HeapReference<Object> zombie_; 149 150 friend struct art::FinalizerReferenceOffsets; // for verifying offset information 151 DISALLOW_IMPLICIT_CONSTRUCTORS(FinalizerReference); 152 }; 153 154 } // namespace mirror 155 } // namespace art 156 157 #endif // ART_RUNTIME_MIRROR_REFERENCE_H_ 158
