1 /* 2 * Copyright (C) 2017 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 #pragma once 18 19 /* 20 * See documentation in RefBase.h 21 */ 22 23 #include <atomic> 24 25 #include <sys/types.h> 26 27 namespace android { 28 29 class ReferenceRenamer; 30 31 template <class T> 32 class LightRefBase 33 { 34 public: 35 inline LightRefBase() : mCount(0) { } 36 inline void incStrong(__attribute__((unused)) const void* id) const { 37 mCount.fetch_add(1, std::memory_order_relaxed); 38 } 39 inline void decStrong(__attribute__((unused)) const void* id) const { 40 if (mCount.fetch_sub(1, std::memory_order_release) == 1) { 41 std::atomic_thread_fence(std::memory_order_acquire); 42 delete static_cast<const T*>(this); 43 } 44 } 45 //! DEBUGGING ONLY: Get current strong ref count. 46 inline int32_t getStrongCount() const { 47 return mCount.load(std::memory_order_relaxed); 48 } 49 50 typedef LightRefBase<T> basetype; 51 52 protected: 53 inline ~LightRefBase() { } 54 55 private: 56 friend class ReferenceMover; 57 inline static void renameRefs(size_t /*n*/, const ReferenceRenamer& /*renamer*/) { } 58 inline static void renameRefId(T* /*ref*/, const void* /*old_id*/ , const void* /*new_id*/) { } 59 60 private: 61 mutable std::atomic<int32_t> mCount; 62 }; 63 64 65 // This is a wrapper around LightRefBase that simply enforces a virtual 66 // destructor to eliminate the template requirement of LightRefBase 67 class VirtualLightRefBase : public LightRefBase<VirtualLightRefBase> { 68 public: 69 virtual ~VirtualLightRefBase() = default; 70 }; 71 72 }; // namespace android 73
