HeapSize (Windows CE 5.0)
This function returns the size, in bytes, of a memory block allocated from a heap by the HeapAlloc or HeapReAlloc function.
DWORD HeapSize( HANDLEhHeap, DWORD dwFlags, LPCVOIDlpMem );
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] Controllable aspects of accessing the memory block.Only one flag is currently defined; however, all other flag values are reserved for future use.
The following table shows the flag you can specify. Specifying this flag overrides the corresponding flag specified in the flOptions parameter if the heap was created using the HeapCreate function.
Value Description HEAP_NO_SERIALIZE Specifies that mutual exclusion is not used while HeapSize is accessing the heap. Do not specify this flag when accessing the process heap. The system might create additional threads within the application's process that simultaneously access the process heap.
This flag is ignored.
lpMem
[in] Valid 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, but it must be used when multiple threads allocate and free memory from the same heap.
A critical section is always used to serialize access to an individual heap. There is a critical section per heap to protect access to each heap.
An attempt to grab a critical section that is not owned is a fast path operation that incurs little overhead. This is similar to using the HEAP_NO_SERIALIZE flag if only one thread was ever accessing a particular heap.
If there is contention for the critical section, and therefore the heap, a new thread request to allocate heap space will serialize.
Requirements
OS Versions: Windows CE 1.0 and later.
Header: Winbase.h.
Link Library: Coredll.lib.
See Also
GetProcessHeap | HeapAlloc | HeapCreate | HeapDestroy | HeapFree | HeapReAlloc | SetLastError
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