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1 /*
2  * Copyright (C) 2013 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_JDWP_OBJECT_REGISTRY_H_
18 #define ART_RUNTIME_JDWP_OBJECT_REGISTRY_H_
19 
20 #include <jni.h>
21 #include <stdint.h>
22 
23 #include <map>
24 
25 #include "base/casts.h"
26 #include "base/safe_map.h"
27 #include "handle.h"
28 #include "jdwp/jdwp.h"
29 #include "obj_ptr.h"
30 
31 namespace art {
32 
33 namespace mirror {
34 class Object;
35 class Class;
36 }  // namespace mirror
37 
38 struct ObjectRegistryEntry {
39   // Is jni_reference a weak global or a regular global reference?
40   jobjectRefType jni_reference_type;
41 
42   // The reference itself.
43   jobject jni_reference;
44 
45   // A reference count, so we can implement DisposeObject.
46   int32_t reference_count;
47 
48   // The corresponding id, so we only need one map lookup in Add.
49   JDWP::ObjectId id;
50 
51   // The identity hash code of the object. This is the same as the key
52   // for object_to_entry_. Store this for DisposeObject().
53   int32_t identity_hash_code;
54 };
55 std::ostream& operator<<(std::ostream& os, const ObjectRegistryEntry& rhs);
56 
57 // Tracks those objects currently known to the debugger, so we can use consistent ids when
58 // referring to them. Normally we keep JNI weak global references to objects, so they can
59 // still be garbage collected. The debugger can ask us to retain objects, though, so we can
60 // also promote references to regular JNI global references (and demote them back again if
61 // the debugger tells us that's okay).
62 class ObjectRegistry {
63  public:
64   ObjectRegistry();
65   ~ObjectRegistry();
66 
67   JDWP::ObjectId Add(ObjPtr<mirror::Object> o)
68       REQUIRES_SHARED(Locks::mutator_lock_)
69       REQUIRES(!Locks::thread_list_lock_, !Locks::thread_suspend_count_lock_, !lock_);
70 
71   JDWP::RefTypeId AddRefType(ObjPtr<mirror::Class> c)
72       REQUIRES_SHARED(Locks::mutator_lock_)
73       REQUIRES(!Locks::thread_list_lock_, !Locks::thread_suspend_count_lock_, !lock_);
74 
75   template<class T>
76   JDWP::ObjectId Add(Handle<T> obj_h)
77       REQUIRES_SHARED(Locks::mutator_lock_)
78       REQUIRES(!Locks::thread_list_lock_, !Locks::thread_suspend_count_lock_, !lock_);
79 
80   JDWP::RefTypeId AddRefType(Handle<mirror::Class> c_h)
81       REQUIRES_SHARED(Locks::mutator_lock_)
82       REQUIRES(!Locks::thread_list_lock_, !Locks::thread_suspend_count_lock_, !lock_);
83 
Get(JDWP::ObjectId id,JDWP::JdwpError * error)84   template<typename T> T Get(JDWP::ObjectId id, JDWP::JdwpError* error)
85       REQUIRES_SHARED(Locks::mutator_lock_) REQUIRES(!lock_) {
86     if (id == 0) {
87       *error = JDWP::ERR_NONE;
88       return nullptr;
89     }
90     return down_cast<T>(InternalGet(id, error));
91   }
92 
93   void Clear() REQUIRES_SHARED(Locks::mutator_lock_) REQUIRES(!lock_);
94 
95   void DisableCollection(JDWP::ObjectId id)
96       REQUIRES_SHARED(Locks::mutator_lock_) REQUIRES(!lock_);
97 
98   void EnableCollection(JDWP::ObjectId id)
99       REQUIRES_SHARED(Locks::mutator_lock_) REQUIRES(!lock_);
100 
101   bool IsCollected(JDWP::ObjectId id)
102       REQUIRES_SHARED(Locks::mutator_lock_) REQUIRES(!lock_);
103 
104   void DisposeObject(JDWP::ObjectId id, uint32_t reference_count)
105       REQUIRES_SHARED(Locks::mutator_lock_) REQUIRES(!lock_);
106 
107   // This is needed to get the jobject instead of the Object*.
108   // Avoid using this and use standard Get when possible.
109   jobject GetJObject(JDWP::ObjectId id) REQUIRES_SHARED(Locks::mutator_lock_) REQUIRES(!lock_);
110 
111  private:
112   template<class T>
113   JDWP::ObjectId InternalAdd(Handle<T> obj_h)
114       REQUIRES_SHARED(Locks::mutator_lock_)
115       REQUIRES(!lock_, !Locks::thread_list_lock_, !Locks::thread_suspend_count_lock_);
116 
117   mirror::Object* InternalGet(JDWP::ObjectId id, JDWP::JdwpError* error)
118       REQUIRES_SHARED(Locks::mutator_lock_) REQUIRES(!lock_);
119 
120   void Demote(ObjectRegistryEntry& entry)
121       REQUIRES_SHARED(Locks::mutator_lock_) REQUIRES(lock_);
122 
123   void Promote(ObjectRegistryEntry& entry)
124       REQUIRES_SHARED(Locks::mutator_lock_) REQUIRES(lock_);
125 
126   bool ContainsLocked(Thread* self,
127                       ObjPtr<mirror::Object> o,
128                       int32_t identity_hash_code,
129                       ObjectRegistryEntry** out_entry)
130       REQUIRES(lock_) REQUIRES_SHARED(Locks::mutator_lock_);
131 
132   Mutex lock_ DEFAULT_MUTEX_ACQUIRED_AFTER;
133   std::multimap<int32_t, ObjectRegistryEntry*> object_to_entry_ GUARDED_BY(lock_);
134   SafeMap<JDWP::ObjectId, ObjectRegistryEntry*> id_to_entry_ GUARDED_BY(lock_);
135 
136   size_t next_id_ GUARDED_BY(lock_);
137 };
138 
139 }  // namespace art
140 
141 #endif  // ART_RUNTIME_JDWP_OBJECT_REGISTRY_H_
142