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 "class.h" 21 #include "gc_root.h" 22 #include "object.h" 23 #include "object_callbacks.h" 24 #include "read_barrier_option.h" 25 #include "runtime.h" 26 #include "thread.h" 27 28 namespace art { 29 30 namespace gc { 31 32 class ReferenceProcessor; 33 class ReferenceQueue; 34 35 } // namespace gc 36 37 struct ReferenceOffsets; 38 struct FinalizerReferenceOffsets; 39 40 namespace mirror { 41 42 // C++ mirror of java.lang.ref.Reference 43 class MANAGED Reference : public Object { 44 public: 45 // Size of java.lang.ref.Reference.class. 46 static uint32_t ClassSize(size_t pointer_size); 47 48 // Size of an instance of java.lang.ref.Reference. 49 static constexpr uint32_t InstanceSize() { 50 return sizeof(Reference); 51 } 52 53 static MemberOffset PendingNextOffset() { 54 return OFFSET_OF_OBJECT_MEMBER(Reference, pending_next_); 55 } 56 static MemberOffset QueueOffset() { 57 return OFFSET_OF_OBJECT_MEMBER(Reference, queue_); 58 } 59 static MemberOffset QueueNextOffset() { 60 return OFFSET_OF_OBJECT_MEMBER(Reference, queue_next_); 61 } 62 static MemberOffset ReferentOffset() { 63 return OFFSET_OF_OBJECT_MEMBER(Reference, referent_); 64 } 65 template<ReadBarrierOption kReadBarrierOption = kWithReadBarrier> 66 Object* GetReferent() SHARED_REQUIRES(Locks::mutator_lock_) { 67 return GetFieldObjectVolatile<Object, kDefaultVerifyFlags, kReadBarrierOption>( 68 ReferentOffset()); 69 } 70 template<bool kTransactionActive> 71 void SetReferent(Object* referent) SHARED_REQUIRES(Locks::mutator_lock_) { 72 SetFieldObjectVolatile<kTransactionActive>(ReferentOffset(), referent); 73 } 74 template<bool kTransactionActive> 75 void ClearReferent() SHARED_REQUIRES(Locks::mutator_lock_) { 76 SetFieldObjectVolatile<kTransactionActive>(ReferentOffset(), nullptr); 77 } 78 79 Reference* GetPendingNext() SHARED_REQUIRES(Locks::mutator_lock_) { 80 return GetFieldObject<Reference>(PendingNextOffset()); 81 } 82 83 void SetPendingNext(Reference* pending_next) 84 SHARED_REQUIRES(Locks::mutator_lock_) { 85 if (Runtime::Current()->IsActiveTransaction()) { 86 SetFieldObject<true>(PendingNextOffset(), pending_next); 87 } else { 88 SetFieldObject<false>(PendingNextOffset(), pending_next); 89 } 90 } 91 92 // Returns true if the reference's pendingNext is null, indicating it is 93 // okay to process this reference. 94 // 95 // If pendingNext is not null, then one of the following cases holds: 96 // 1. The reference has already been enqueued to a java ReferenceQueue. In 97 // this case the referent should not be considered for reference processing 98 // ever again. 99 // 2. The reference is currently part of a list of references that may 100 // shortly be enqueued on a java ReferenceQueue. In this case the reference 101 // should not be processed again until and unless the reference has been 102 // removed from the list after having determined the reference is not ready 103 // to be enqueued on a java ReferenceQueue. 104 bool IsUnprocessed() SHARED_REQUIRES(Locks::mutator_lock_) { 105 return GetPendingNext() == nullptr; 106 } 107 108 template<ReadBarrierOption kReadBarrierOption = kWithReadBarrier> 109 static Class* GetJavaLangRefReference() SHARED_REQUIRES(Locks::mutator_lock_) { 110 DCHECK(!java_lang_ref_Reference_.IsNull()); 111 return java_lang_ref_Reference_.Read<kReadBarrierOption>(); 112 } 113 static void SetClass(Class* klass); 114 static void ResetClass(); 115 static void VisitRoots(RootVisitor* visitor) SHARED_REQUIRES(Locks::mutator_lock_); 116 117 private: 118 // Note: This avoids a read barrier, it should only be used by the GC. 119 HeapReference<Object>* GetReferentReferenceAddr() SHARED_REQUIRES(Locks::mutator_lock_) { 120 return GetFieldObjectReferenceAddr<kDefaultVerifyFlags>(ReferentOffset()); 121 } 122 123 // Field order required by test "ValidateFieldOrderOfJavaCppUnionClasses". 124 HeapReference<Reference> pending_next_; 125 HeapReference<Object> queue_; 126 HeapReference<Reference> queue_next_; 127 HeapReference<Object> referent_; // Note this is Java volatile: 128 129 static GcRoot<Class> java_lang_ref_Reference_; 130 131 friend struct art::ReferenceOffsets; // for verifying offset information 132 friend class gc::ReferenceProcessor; 133 friend class gc::ReferenceQueue; 134 DISALLOW_IMPLICIT_CONSTRUCTORS(Reference); 135 }; 136 137 // C++ mirror of java.lang.ref.FinalizerReference 138 class MANAGED FinalizerReference : public Reference { 139 public: 140 static MemberOffset ZombieOffset() { 141 return OFFSET_OF_OBJECT_MEMBER(FinalizerReference, zombie_); 142 } 143 144 template<bool kTransactionActive> 145 void SetZombie(Object* zombie) SHARED_REQUIRES(Locks::mutator_lock_) { 146 return SetFieldObjectVolatile<kTransactionActive>(ZombieOffset(), zombie); 147 } 148 Object* GetZombie() SHARED_REQUIRES(Locks::mutator_lock_) { 149 return GetFieldObjectVolatile<Object>(ZombieOffset()); 150 } 151 152 private: 153 HeapReference<FinalizerReference> next_; 154 HeapReference<FinalizerReference> prev_; 155 HeapReference<Object> zombie_; 156 157 friend struct art::FinalizerReferenceOffsets; // for verifying offset information 158 DISALLOW_IMPLICIT_CONSTRUCTORS(FinalizerReference); 159 }; 160 161 } // namespace mirror 162 } // namespace art 163 164 #endif // ART_RUNTIME_MIRROR_REFERENCE_H_ 165
