ucommon::memalloc Class Reference

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

#include <memory.h>

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Public Member Functions

virtual void * _alloc (size_t size)
 Allocate memory from the pager heap.
unsigned max (void)
 Get the maximum number of pages that are permitted.
 memalloc (size_t page=0)
 Construct a memory pager.
unsigned pages (void)
 Get the number of pages that have been allocated from the real heap.
void purge (void)
 Purge all allocated memory and heap pages immediately.
unsigned size (void)
 Get the size of a memory page.
unsigned utilization (void)
 Determine fragmentation level of acquired heap pages.
virtual ~memalloc ()
 Destroy a memory pager.

Protected Member Functions

virtual void fault (void)
 Report runtime memory exhaustion.
page_t * pager (void)
 Acquire a new page from the heap.

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@gnutelephony.org>

Definition at line 60 of file memory.h.


Constructor & Destructor Documentation

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

Construct a memory pager.

Parameters:
page size to use or 0 for OS allocation size.

virtual ucommon::memalloc::~memalloc (  )  [virtual]

Destroy a memory pager.

Release all pages back to the heap at once.


Member Function Documentation

virtual void* ucommon::memalloc::_alloc ( size_t  size  )  [virtual]

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:
size of memory request.
Returns:
allocated memory or NULL if not possible.

Implements ucommon::MemoryProtocol.

Reimplemented in ucommon::mempager, and ucommon::bufpager.

unsigned ucommon::memalloc::max ( void   )  [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 118 of file memory.h.

References ucommon::limit().

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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.

unsigned ucommon::memalloc::pages ( void   )  [inline]

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

Returns:
pages allocated from heap.

Reimplemented in ucommon::ObjectPager, ucommon::StringPager, ucommon::DirPager, ucommon::mapof< T, I, M, P >, and ucommon::assoc_pointer< T, I, M, P >.

Definition at line 108 of file memory.h.

unsigned ucommon::memalloc::size ( void   )  [inline]

Get the size of a memory page.

Returns:
size of each pager heap allocation.

Reimplemented in ucommon::ObjectPager, ucommon::StringPager, and ucommon::DirPager.

Definition at line 125 of file memory.h.

unsigned ucommon::memalloc::utilization ( void   ) 

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.

Reimplemented in ucommon::mempager, ucommon::mapof< T, I, M, P >, and ucommon::assoc_pointer< T, I, M, P >.


The documentation for this class was generated from the following file:
Generated on 14 Aug 2013 for UCommon by  doxygen 1.4.7