NAME
ost::MemPager -
The memory pager is used to allocate cumulative memory pages for
storing object specific ’persistant’ data that is presumed to persist
during the life of a given derived object.
SYNOPSIS
#include <misc.h>
Inherited by ost::Keydata [protected], ost::SharedMemPager, and
ost::StackPager [protected].
Classes
struct _page
Public Member Functions
int getPages (void)
Return the total number of pages that have been allocated for this
memory pool.
Protected Member Functions
virtual void * first (size_t size)
Allocate first workspace from paged memory.
virtual void * alloc (size_t size)
Allocate memory from either the currently active page, or allocate
a new page for the object.
char * first (char *str)
Allocate a string from the memory pager pool and copy the string
into its new memory area.
char * alloc (const char *str)
Allocate a string from the memory pager pool and copy the string
inti its new memory area.
MemPager (size_t pagesize=4096)
Create a paged memory pool for cumulative storage.
void purge (void)
purge the current memory pool.
void clean (void)
Clean for memory cleanup before exiting.
virtual ~MemPager ()
Delete the memory pool and all allocated memory.
Friends
class String
class MemPagerObject
Detailed Description
The memory pager is used to allocate cumulative memory pages for
storing object specific ’persistant’ data that is presumed to persist
during the life of a given derived object.
When the object is destroyed, all accumulated data is automatically
purged.
There are a number of odd and specialized utility classes found in
Common C++. The most common of these is the ’MemPager’ class. This is
basically a class to enable page-grouped ’cumulative’ memory
allocation; all accumulated allocations are dropped during the
destructor. This class has found it’s way in a lot of other utility
classes in Common C++.
Author:
David Sugar <dyfet@ostel.com> Accumulative object memory allocator.
Constructor & Destructor Documentation
ost::MemPager::MemPager (size_t pagesize = 4096) [protected]
Create a paged memory pool for cumulative storage. This pool allocates
memory in fixed ’pagesize’ chunks. Ideal performance is achived when
the pool size matches the system page size. This pool can only exist in
derived objects.
Parameters:
pagesize page size to allocate chunks.
virtual ost::MemPager::~MemPager () [protected, virtual]
Delete the memory pool and all allocated memory.
Member Function Documentation
char* ost::MemPager::alloc (const char * str) [protected]
Allocate a string from the memory pager pool and copy the string inti
it’s new memory area. This checks only the last active page for
available space before allocating a new page.
Parameters:
str string to allocate and copy into paged memory pool.
Returns:
copy of string from allocated memory.
virtual void* ost::MemPager::alloc (size_t size) [protected, virtual]
Allocate memory from either the currently active page, or allocate a
new page for the object. Parameters:
size size of memory to allocate.
Returns:
pointer to allocated memory.
Reimplemented in ost::SharedMemPager.
Referenced by ost::MemPagerObject::operator new(), and
ost::MemPagerObject::operator new[]().
void ost::MemPager::clean (void) [protected]
Clean for memory cleanup before exiting.
char* ost::MemPager::first (char * str) [protected]
Allocate a string from the memory pager pool and copy the string into
it’s new memory area. This method allocates memory by first searching
for an available page, and then allocating a new page if no space is
found.
Parameters:
str string to allocate and copy into paged memory pool.
Returns:
copy of string from allocated memory.
virtual void* ost::MemPager::first (size_t size) [protected, virtual]
Allocate first workspace from paged memory. This method scans all
currently allocated blocks for available space before adding new pages
and hence is both slower and more efficient.
Parameters:
size size of memory to allocate.
Returns:
pointer to allocated memory.
Reimplemented in ost::SharedMemPager.
int ost::MemPager::getPages (void) [inline]
Return the total number of pages that have been allocated for this
memory pool. Returns:
number of pages allocated.
void ost::MemPager::purge (void) [protected]
purge the current memory pool.
Reimplemented in ost::StackPager, and ost::SharedMemPager.
Friends And Related Function Documentation
friend class MemPagerObject [friend]
friend class String [friend]
Author
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