. You can also
find this and other articles at his web site at http://www.wizsoft.com/~poul/srs/
I wrote this class for very common situation: when you have to allocate
many of small objects of the same size; the obvious case is some class widely used in a
program. The assumption that all objects on the heap are of the same size allows to
minimize allocation overhead to zero. Indeed, every allocation block in the regular
heap is preceded by block size. But when the size is known in advance, you could save this
place. The technique is simple: the heap manager requests big blocks of the memory
from some common heap. Every block of memory is either occupied by allocated
object, or points to the next free block. Therefore it manages "in place" linked
list of free items without any overhead. The sources are here.
NB: Feel free to remove inlines if you’re more concerned about size
then about speed.
local heap machinery.
Helper class CWizLocalHeapLock useful for locking the heap in the
multithreading environment.
Files LOCALHEP.H and LOCALHEP.CPP
.
avoid mess with local heap parameters.
Class CWizDefaultTypedLocalHeap
derived from CWizTypedLocalHeap and supplies reasonable default parameters.
Define DECLARE_LOCAL_HEAP forces objects of any class to be
allocated from it’s own private local heap. Very useful in new-intensive
algorithms.
Files TypedLocalHeap.CPP and TypedLocalHeap.H
.
– wrapper for Win32 API virtual memory machinery.
Derived template class CWizTypedVMem to be used as virtual array.
Files VIRT_MEM.H and VIRT_MEM.CPP
.
- CWizFileMapping – kind of file mapping wrapper.
- CWizFileMapView – view of this mapping (actual memory
address). - template <class TYPE> class CWizFileView – kind of "virtual array"
mirroring a file. - template <class TYPE> class CWizROFileView – read-only view (virtual array) of an
existing file. - CWizFullFileView – read/write file mapping. Uses CWizTempFileStrategy for managing
temporary files. - template <class TYPE> class CWizTypedFullFileView – typed derivative of
CWizFullFileView.
Files FILE_MAP.H and FILE_MAP.CPP
.
- CWizFileROFileMapping – implements
"windowed" view to memory mapping.Useful when address space is low or when
access to the file is rare.
Nested class Window acts like actual window to the mapping and moves itself by demand.
This class has template parameter LOCKER which implements multithreading synchronization
for Window objects. Two classes supplied for this: - CWizFileMapNoLocker – no locking and synchronization. Useful when:
a) only
single thread accesses the view or
b) another synchronization implemented in your application or
c) you are absolutely sure it’s no need for synchronization. - CWizFileMapCritSectLocker – uses critical section for synchronization between
threads.Please note that synchronization is managed only when retrieving
the view from memory mapping. Every view supposed to be thread-specific or at protected by
another way. - template<class LOCKER, class DATA> class CWizTypedFileROFileMapping –
typed derivative of CWizFileROFileMapping (like virtual array of structs).
Because of strange compilation errors -:) the nested class is called Wnd instead of
Window.
Files FileMapWindow.H and FileMapWindow.CPP .