Line data    Source code

       1             : /*
       2             :  *
       3             :  *    Copyright (c) 2020 Project CHIP Authors
       4             :  *
       5             :  *    Licensed under the Apache License, Version 2.0 (the "License");
       6             :  *    you may not use this file except in compliance with the License.
       7             :  *    You may obtain a copy of the License at
       8             :  *
       9             :  *        http://www.apache.org/licenses/LICENSE-2.0
      10             :  *
      11             :  *    Unless required by applicable law or agreed to in writing, software
      12             :  *    distributed under the License is distributed on an "AS IS" BASIS,
      13             :  *    WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
      14             :  *    See the License for the specific language governing permissions and
      15             :  *    limitations under the License.
      16             :  */
      17             : 
      18             : /**
      19             :  * @file
      20             :  *   This file defines a C++ referenced counted object that auto deletes when
      21             :  *   all references to it have been removed.
      22             :  */
      23             : 
      24             : #pragma once
      25             : 
      26             : #include <atomic>
      27             : #include <limits>
      28             : #include <stdlib.h>
      29             : 
      30             : #include <lib/support/CHIPMem.h>
      31             : #include <lib/support/CodeUtils.h>
      32             : 
      33             : namespace chip {
      34             : 
      35             : template <class T>
      36             : class DeleteDeletor
      37             : {
      38             : public:
      39           3 :     static void Release(T * obj) { chip::Platform::Delete(obj); }
      40             : };
      41             : 
      42             : template <class T>
      43             : class NoopDeletor
      44             : {
      45             : public:
      46           0 :     static void Release(T * obj) {}
      47             : };
      48             : 
      49             : /**
      50             :  * A reference counted object maintains a count of usages and when the usage
      51             :  * count drops to 0, it deletes itself.
      52             :  */
      53             : template <class Subclass, class Deletor = DeleteDeletor<Subclass>, int kInitRefCount = 1, typename CounterType = uint32_t>
      54             : class ReferenceCounted
      55             : {
      56             : public:
      57             :     /** Adds one to the usage count of this class */
      58      787640 :     Subclass * Retain()
      59             :     {
      60       26996 :         VerifyOrDie(!kInitRefCount || mRefCount > 0);
      61      787640 :         VerifyOrDie(mRefCount < std::numeric_limits<CounterType>::max());
      62      787640 :         ++mRefCount;
      63             : 
      64      787640 :         return static_cast<Subclass *>(this);
      65             :     }
      66             : 
      67             :     /** Release usage of this class */
      68      790877 :     void Release()
      69             :     {
      70      790877 :         VerifyOrDie(mRefCount != 0);
      71             : 
      72      790877 :         if (--mRefCount == 0)
      73             :         {
      74      138328 :             Deletor::Release(static_cast<Subclass *>(this));
      75             :         }
      76      790877 :     }
      77             : 
      78             :     /** Get the current reference counter value */
      79       16078 :     CounterType GetReferenceCount() const { return mRefCount; }
      80             : 
      81             : private:
      82             :     CounterType mRefCount = kInitRefCount;
      83             : };
      84             : 
      85             : } // namespace chip