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