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      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_READ_BARRIER_H_
     18 #define ART_RUNTIME_READ_BARRIER_H_
     19 
     20 #include "base/mutex.h"
     21 #include "base/macros.h"
     22 #include "offsets.h"
     23 #include "read_barrier_c.h"
     24 
     25 // This is a C++ (not C) header file, separate from read_barrier_c.h
     26 // which needs to be a C header file for asm_support.h.
     27 
     28 namespace art {
     29 namespace mirror {
     30   class Object;
     31   template<typename MirrorType> class HeapReference;
     32 }  // namespace mirror
     33 
     34 class ReadBarrier {
     35  public:
     36   // It's up to the implementation whether the given field gets
     37   // updated whereas the return value must be an updated reference.
     38   template <typename MirrorType, ReadBarrierOption kReadBarrierOption = kWithReadBarrier>
     39   ALWAYS_INLINE static MirrorType* Barrier(
     40       mirror::Object* obj, MemberOffset offset, mirror::HeapReference<MirrorType>* ref_addr)
     41       SHARED_LOCKS_REQUIRED(Locks::mutator_lock_);
     42 
     43   // It's up to the implementation whether the given root gets updated
     44   // whereas the return value must be an updated reference.
     45   template <typename MirrorType, ReadBarrierOption kReadBarrierOption = kWithReadBarrier>
     46   ALWAYS_INLINE static MirrorType* BarrierForRoot(MirrorType** root)
     47       SHARED_LOCKS_REQUIRED(Locks::mutator_lock_);
     48 };
     49 
     50 }  // namespace art
     51 
     52 #endif  // ART_RUNTIME_READ_BARRIER_H_
     53