_ak_object_pool_8h

Wwise SDK 2022.1.18

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 #ifndef _AKPOOLALLOCATOR_H
 #define _AKPOOLALLOCATOR_H
  
 #include <AK/Tools/Common/AkObject.h>
 #include <AK/Tools/Common/AkAssert.h>
 #include <AK/Tools/Common/AkArray.h>
  
 /// Extra debug option when calling ObjectPool::Deallocate.
 /// Going through the free list can be slow when the object count is high.
 #define AK_OBJECT_POOL_EXTRA_SAFETY
  
 namespace UnitTest { struct ObjectPoolHelper; }
  
 namespace AK
 {
     template<AkMemID T_MEMID = AkMemID_Object>
     using ObjectPoolDefaultAllocator = AkArrayAllocatorNoAlign<T_MEMID>;
  
     struct ObjectPoolNoLock
     {
         inline static constexpr void Lock() {}
         inline static constexpr void Unlock() {}
     };
  
     using ObjectPoolDefaultLockType = ObjectPoolNoLock;
  
     /// An object pool of N reusable objects with one allocation.
     template<
         typename T,
         typename AllocatorType = ObjectPoolDefaultAllocator<>,
         typename LockType = ObjectPoolDefaultLockType>
         class ObjectPool : AllocatorType, LockType
     {
     public:
         using ValueType = T;
         using SizeType = AkUInt32;
         static constexpr SizeType kInvalidIndex = (SizeType)-1;
  
         union DataType
         {
             inline ValueType& Data() { return *(ValueType*)data; }
             inline const ValueType& Data() const { return *(const ValueType*)data; }
             alignas(ValueType) uint8_t data[sizeof(ValueType)];
             SizeType next;
         };
  
         using AllocatorType::AllocatorType;
  
         ObjectPool() = default;
         ObjectPool(const ObjectPool&) = delete;
         ObjectPool(ObjectPool&&) = delete;
  
         inline ~ObjectPool() { AKASSERT(!m_data); }
  
         ObjectPool& operator=(const ObjectPool&) = delete;
         ObjectPool& operator=(ObjectPool&&) = delete;
  
         inline AKRESULT Init(SizeType count)
         {
             AKASSERT(!m_data && "ObjectPool is already initialized, call 'Term' before calling 'Init' again");
             AKASSERT(count && "ObjectPool count must be greater than zero");
             AKASSERT(count < kInvalidIndex && "ObjectPool count is above SizeType's maximum capacity");
  
             if (m_data || !count)
                 return AK_InvalidParameter;
  
             m_data = reinterpret_cast<DataType*>(AllocatorType::Alloc(count * sizeof(DataType)));
             m_capacity = 0;
             m_size = 0;
             m_freeList = 0;
  
             if (!m_data)
                 return AK_InsufficientMemory;
  
             m_capacity = count;
  
             for (SizeType i = 0; i < m_capacity - 1; i++)
                 m_data[i].next = i + 1;
  
             m_data[m_capacity - 1].next = kInvalidIndex;
  
             return AK_Success;
         }
  
         inline void Term()
         {
             // Only assert when some object are still allocated and ValueType is not trivially destructible.
             AKASSERT(m_size == 0 && "Can't call Term() when some objects are still allocated");
  
             if (!m_data)
                 return;
  
             AllocatorType::Free(m_data);
             m_data = nullptr;
             m_capacity = 0;
             m_size = 0;
             m_freeList = 0;
         }
  
         AK_NODISCARD inline SizeType Size() const { return m_size; }
         AK_NODISCARD inline SizeType Capacity() const { return m_capacity; }
  
         AK_NODISCARD inline bool IsFull() const { return m_size >= m_capacity; }
         AK_NODISCARD inline bool IsEmpty() const { return m_size == 0; }
  
         /// Allocates a new object.
         /// @returns the object on success or nullptr if it fails (already full).
         /// @{
         AK_NODISCARD inline ValueType* Allocate()
         {
             if (IsFull())
                 return nullptr;
  
             LockType::Lock();
             DataType& data = m_data[m_freeList];
             m_freeList = data.next;
             m_size++;
             LockType::Unlock();
             return &data.Data();
         }
  
         /// Initialize memory before returning.
         AK_NODISCARD inline ValueType* AllocateZeroFilled()
         {
             ValueType* value = Allocate();
             if (value)
                 AKPLATFORM::AkMemSet((void*)value, 0, (AkUInt32)sizeof(ValueType));
  
             return value;
         }
         /// @}
  
         /// Deallocates given pointer.
         /// Calling Deallocate when IsEmpty() returns true is undefined behaviour.
         /// Calling Deallocate with a pointer that wasn't allocated by this pool is undefined behaviour.
         ///
         /// You can define AK_OBJECT_POOL_EXTRA_SAFETY for extra debugging check.
         inline AKRESULT Deallocate(ValueType* data)
         {
             AKASSERT(data && "Deallocating null data");
             DataType* tdata = reinterpret_cast<DataType*>(data);
  
             // Check if data is in memory range.
             AKASSERT((tdata >= m_data && tdata < m_data + m_capacity) && "Pointer address out of range");
             if (tdata < m_data || tdata >= m_data + m_capacity)
                 return AK_InvalidParameter;
  
             LockType::Lock();
             AKASSERT(m_size && "Trying to deallocate when empty");
  
 #ifdef AK_OBJECT_POOL_EXTRA_SAFETY
             AKASSERT(IsAllocated((SizeType)(tdata - m_data)));
 #endif
             m_size--;
             tdata->next = m_freeList;
             m_freeList = (SizeType)(tdata - m_data);
             LockType::Unlock();
  
             return AK_Success;
         }
  
         /// Deallocates all objects.
         /// This function should only be called if ValueType is trivially destructible.
         inline void Clear()
         {
             for (SizeType i = 0; i < m_capacity - 1; i++)
                 m_data[i].next = i + 1;
  
             m_data[m_capacity - 1].next = kInvalidIndex;
             m_size = 0;
             m_freeList = 0;
         }
  
     private:
         DataType* m_data = nullptr;
         SizeType m_capacity = 0;
         SizeType m_size = 0;
         SizeType m_freeList = 0;
  
         friend struct UnitTest::ObjectPoolHelper;
  
         inline bool IsAllocated(SizeType index) const
         {
             for (SizeType k = m_freeList; k != kInvalidIndex; k = m_data[k].next)
                 if (index == k)
                     return false;
  
             return true;
         }
     };
 } // namespace AK
 #endif