Source code of Windows XP (NT5)
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/*****************************************************************************
*
* (C) COPYRIGHT MICROSOFT CORPORATION, 2000
*
* TITLE: cntutils.inl
*
* VERSION: 1.0
*
* AUTHOR: LazarI
*
* DATE: 23-Dec-2000
*
* DESCRIPTION: Containers and algorithms utility templates (Impl.)
*
*****************************************************************************/
////////////////////////////////////////////////
//
// class CFastHeap<T>
//
// fast cached heap for fixed chunks
// of memory (MT safe)
//
template <class T>
CFastHeap<T>::CFastHeap<T>(int iCacheSize):
#if DBG
m_iPhysicalAllocs(0),
m_iLogicalAllocs(0),
#endif
m_pFreeList(NULL),
m_iCacheSize(iCacheSize),
m_iCached(0)
{
// nothing
}
template <class T>
CFastHeap<T>::~CFastHeap<T>()
{
// delete the cache
while( m_pFreeList )
{
HeapItem *pItem = m_pFreeList;
m_pFreeList = m_pFreeList->pNext;
delete pItem;
#if DBG
m_iPhysicalAllocs--;
#endif
}
#if DBG
ASSERT(0 == m_iPhysicalAllocs);
ASSERT(0 == m_iLogicalAllocs);
#endif
}
template <class T>
HRESULT CFastHeap<T>::Alloc(const T &data, HANDLE *ph)
{
CCSLock::Locker lock(m_csLock);
HRESULT hr = E_INVALIDARG;
if( ph )
{
*ph = NULL;
HeapItem *pi = NULL;
if( m_pFreeList )
{
// we have an item in the cache, just use it
pi = m_pFreeList;
m_pFreeList = m_pFreeList->pNext;
m_iCached--;
ASSERT(m_iCached >= 0);
}
else
{
// no items in the cache, allocate new one
pi = new HeapItem;
#if DBG
m_iPhysicalAllocs++;
#endif
}
if( pi )
{
pi->data = data;
*ph = reinterpret_cast<HANDLE>(pi);
#if DBG
m_iLogicalAllocs++;
#endif
}
hr = (*ph) ? S_OK : E_OUTOFMEMORY;
}
return hr;
}
template <class T>
HRESULT CFastHeap<T>::Free(HANDLE h)
{
CCSLock::Locker lock(m_csLock);
HRESULT hr = E_INVALIDARG;
if( h )
{
#if DBG
m_iLogicalAllocs--;
#endif
ASSERT(m_iCached >= 0);
HeapItem *pi = reinterpret_cast<HeapItem*>(h);
if( m_iCached < m_iCacheSize )
{
// the number of cached items is less than the
// cache size, so we put this item in the cache
pi->pNext = m_pFreeList;
m_pFreeList = pi;
m_iCached++;
}
else
{
// enough items cached, delete this one
delete pi;
#if DBG
m_iPhysicalAllocs--;
#endif
}
hr = S_OK;
}
return hr;
}
template <class T>
HRESULT CFastHeap<T>::GetItem(HANDLE h, T **ppData)
{
// just return the item ptr. no need to aquire the CS as this is
// readonly function and Alloc/Free cannot invalidate the item.
*ppData = &(reinterpret_cast<HeapItem*>(h)->data);
return S_OK;
}