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ost::MemPager Class Reference

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. More...

#include <misc.h>

Inheritance diagram for ost::MemPager:
ost::Keydata ost::SharedMemPager ost::StackPager

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 it's new memory area.
 
char * alloc (const char *str)
 Allocate a string from the memory pager pool and copy the string inti it's 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.nosp@m.@ost.nosp@m.el.co.nosp@m.m

Accumulative object memory allocator.

Constructor & Destructor Documentation

◆ MemPager()

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
pagesizepage size to allocate chunks.

◆ ~MemPager()

virtual ost::MemPager::~MemPager ( )
protectedvirtual

Delete the memory pool and all allocated memory.

Member Function Documentation

◆ alloc() [1/2]

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
strstring to allocate and copy into paged memory pool.
Returns
copy of string from allocated memory.

◆ alloc() [2/2]

virtual void * ost::MemPager::alloc ( size_t  size)
protectedvirtual

Allocate memory from either the currently active page, or allocate a new page for the object.

Parameters
sizesize of memory to allocate.
Returns
pointer to allocated memory.

Reimplemented in ost::SharedMemPager.

◆ clean()

void ost::MemPager::clean ( void  )
protected

Clean for memory cleanup before exiting.

◆ first() [1/2]

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
strstring to allocate and copy into paged memory pool.
Returns
copy of string from allocated memory.

◆ first() [2/2]

virtual void * ost::MemPager::first ( size_t  size)
protectedvirtual

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
sizesize of memory to allocate.
Returns
pointer to allocated memory.

Reimplemented in ost::SharedMemPager.

◆ getPages()

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.

◆ purge()

void ost::MemPager::purge ( void  )
protected

purge the current memory pool.

Friends And Related Symbol Documentation

◆ MemPagerObject

friend class MemPagerObject
friend

◆ String

friend class String
friend

The documentation for this class was generated from the following file: