This function returns the size, in bytes, of a memory block allocated from a heap by the HeapAlloc or HeapReAlloc function.
At a Glance
| Header file: | Winbase.h |
| Windows CE versions: | 1.0 and later |
Syntax
DWORD HeapSize( HANDLE hHeap, DWORD dwFlags, LPCVOID lpMem);
Parameters
hHeap
[in] Handle to the heap in which the memory block resides. This handle is returned by the HeapCreate or GetProcessHeap function.
dwFlags
[in] Specifies several controllable aspects of accessing the memory block. Only one flag is currently defined; however, all other flag values are reserved for future use. Specifying this flag will override the corresponding flag specified in the flOptions parameter when the heap was created by using the HeapCreate function:
| Value | Description |
| HEAP_NO_SERIALIZE | Specifies that mutual exclusion will not be used while HeapSize is accessing the heap. |
| This flag should not be specified when accessing the process heap. The system may create additional threads within the application’s process that simultaneously access the process heap. |
lpmem
[in] Pointer to the memory block whose size the function will obtain. This is a pointer returned by the HeapAlloc or HeapReAlloc function.
Return Values
The size, in bytes, of the allocated memory block indicates success. 0xFFFFFFFF indicates failure. The function does not call SetLastError. An application cannot call GetLastError for extended error information.
Remarks
Serialization ensures mutual exclusion when two or more threads attempt to simultaneously allocate or free blocks from the same heap. There is a small performance cost to serialization, but it must be used whenever multiple threads allocate and free memory from the same heap. Setting the HEAP_NO_SERIALIZE flag eliminates mutual exclusion on the heap. Without serialization, two or more threads that use the same heap handle might attempt to allocate or free memory simultaneously, likely causing corruption in the heap. The HEAP_NO_SERIALIZE flag can, therefore, be safely used only in the following situations:
See Also