IAtlMemMgr Class

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This class represents the interface to a memory manager.

__interface __declspec( uuid( "654F7EF5-CFDF-4df9-A450-6C6A13C622C0" )) IAtlMemMgr

Members

Methods

Allocate

Call this method to allocate a block of memory.

Free

Call this method to free a block of memory.

GetSize

Call this method to retrieve the size of an allocated memory block.

Reallocate

Call this method to reallocate a block of memory.

Remarks

This interface is implemented by CComHeap, CCRTHeap, CLocalHeap, CGlobalHeap, or CWin32Heap.

Note

The local and global heap functions are slower than other memory management functions, and do not provide as many features. Therefore, new applications should use the heap functions. These are available in the CWin32Heap class.

Example

// Demonstrate IAtlMemMgr using the five possible 
// memory function implementation classes. 

HRESULT MemoryManagerDemonstration(IAtlMemMgr& MemoryManager) throw()
{
   // The IAtlMemMgr interface guarantees not to throw exceptions 
   // so we can make the same guarantee for this function 
   // without adding exception handling code. 

   // A variable which will point to some allocated memory. 
   void* pMemory = NULL;

   const size_t BytesInChunk = 1024;

   // Allocate a chunk of memory
   pMemory = MemoryManager.Allocate(BytesInChunk);

   // Confirm the validity of the allocated memory 
   if (pMemory == NULL)
      return E_OUTOFMEMORY;

   // Confirm the size of the allocated memory
   ATLASSERT(MemoryManager.GetSize(pMemory) == BytesInChunk);

   // Increase the size of the allocated memory
   pMemory = MemoryManager.Reallocate(pMemory, BytesInChunk * 2);

   // Confirm the validity of the allocated memory 
   if (pMemory == NULL)
      return E_OUTOFMEMORY;

   // Confirm the size of the reallocated  memory
   ATLASSERT(MemoryManager.GetSize(pMemory) == BytesInChunk * 2);

   // Free the allocated memory
   MemoryManager.Free(pMemory);

   return S_OK;
}

int DoMemoryManagerDemonstration()
{
   CComHeap heapCom;
   CCRTHeap heapCrt;
   CLocalHeap heapLocal;
   CGlobalHeap heapGlobal;
   // It is necessary to provide extra information  
   // to the constructor when using CWin32Heap
   CWin32Heap heapWin32(NULL, 4096); 

   ATLASSERT(S_OK==MemoryManagerDemonstration(heapCom));
   ATLASSERT(S_OK==MemoryManagerDemonstration(heapCrt));
   ATLASSERT(S_OK==MemoryManagerDemonstration(heapLocal));
   ATLASSERT(S_OK==MemoryManagerDemonstration(heapGlobal));
   ATLASSERT(S_OK==MemoryManagerDemonstration(heapWin32));

   return 0;
}

Requirements

Header: atlmem.h

See Also

Other Resources

ATL Class Overview