UCommon
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ucommon::memalloc Class Reference

A memory protocol pager for private heap manager. More...

#include <memory.h>

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Public Member Functions

void assign (memalloc &source)
 Assign foreign pager to us. More...
 
unsigned max (void) const
 Get the maximum number of pages that are permitted. More...
 
 memalloc (size_t page=0)
 Construct a memory pager. More...
 
 memalloc (const memalloc &copy)
 
unsigned pages (void) const
 Get the number of pages that have been allocated from the real heap. More...
 
void purge (void)
 Purge all allocated memory and heap pages immediately.
 
size_t size (void) const
 Get the size of a memory page. More...
 
unsigned utilization (void) const
 Determine fragmentation level of acquired heap pages. More...
 
virtual ~memalloc ()
 Destroy a memory pager. More...
 

Protected Member Functions

virtual void * _alloc (size_t size)
 Allocate memory from the pager heap. More...
 
page_t * pager (void)
 Acquire a new page from the heap. More...
 

Protected Attributes

unsigned limit
 

Friends

class bufpager
 

Detailed Description

A memory protocol pager for private heap manager.

This is used to allocate in an optimized manner, as it assumes no mutex locks are held or used as part of it's own internal processing. It also is designed for optimized performance.

Author
David Sugar dyfet.nosp@m.@gnu.nosp@m.telep.nosp@m.hony.nosp@m..org

Definition at line 61 of file memory.h.

Constructor & Destructor Documentation

◆ memalloc()

ucommon::memalloc::memalloc ( size_t  page = 0)

Construct a memory pager.

Parameters
pagesize to use or 0 for OS allocation size.

◆ ~memalloc()

virtual ucommon::memalloc::~memalloc ( )
virtual

Destroy a memory pager.

Release all pages back to the heap at once.

Member Function Documentation

◆ _alloc()

virtual void* ucommon::memalloc::_alloc ( size_t  size)
protectedvirtual

Allocate memory from the pager heap.

The size of the request must be less than the size of the memory page used. This implements the memory protocol allocation method.

Parameters
sizeof memory request.
Returns
allocated memory or NULL if not possible.

Reimplemented in ucommon::mempager.

◆ assign()

void ucommon::memalloc::assign ( memalloc source)

Assign foreign pager to us.

This relocates the heap references to our object, clears the other object.

◆ max()

unsigned ucommon::memalloc::max ( void  ) const
inline

Get the maximum number of pages that are permitted.

One can use a derived class to set and enforce a maximum limit to the number of pages that will be allocated from the real heap. This is often used to detect and bring down apps that are leaking.

Returns
page allocation limit.

Definition at line 117 of file memory.h.

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◆ pager()

page_t* ucommon::memalloc::pager ( void  )
protected

Acquire a new page from the heap.

This is mostly used internally.

Returns
page structure of the newly acquired memory page.

◆ pages()

unsigned ucommon::memalloc::pages ( void  ) const
inline

Get the number of pages that have been allocated from the real heap.

Returns
pages allocated from heap.

Definition at line 106 of file memory.h.

◆ size()

size_t ucommon::memalloc::size ( void  ) const
inline

Get the size of a memory page.

Returns
size of each pager heap allocation.

Definition at line 125 of file memory.h.

◆ utilization()

unsigned ucommon::memalloc::utilization ( void  ) const

Determine fragmentation level of acquired heap pages.

This is represented as an average % utilization (0-100) and represents the used portion of each allocated heap page verse the page size. Since requests that cannot fit on an already allocated page are moved into a new page, there is some unusable space left over at the end of the page. When utilization approaches 100, this is good. A low utilization may suggest a larger page size should be used.

Returns
pager utilization.

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