Memory allocator which uses pools that each manage same-sized objects. More...

#include <PoolAllocator.h>

Inheritance diagram for PoolAllocator:

Data Structures
struct	ObjectPostfix
	Appended in memory after each object. More...

struct	ObjectPrefix
	This data structure is prepended in memory before each object. More...

struct	Pool
	Allocates same-sized objects from a contiguous block of memory. More...

Public Member Functions
	PoolAllocator (Allocator *parent)
	Constructor. More...

virtual Size	size () const
	Get memory size. More...

virtual Size	available () const
	Get memory available. More...

virtual Result	allocate (Range &args)
	Allocate memory. More...

virtual Result	release (const Address addr)
	Release memory. More...

Public Member Functions inherited from Allocator
	Allocator ()
	Default class constructor. More...

	Allocator (const Range range)
	Class constructor with Range input. More...

virtual	~Allocator ()
	Class destructor. More...

void	setParent (Allocator *parent)
	Set parent allocator. More...

Allocator *	parent ()
	Get parent Allocator. More...

Address	base () const
	Get memory base address for allocations. More...

Size	alignment () const
	Get memory alignment in bytes for allocations. More...

Private Types
typedef PoolAllocator::Pool	Pool
	Allocates same-sized objects from a contiguous block of memory. More...

typedef struct PoolAllocator::ObjectPrefix	ObjectPrefix
	This data structure is prepended in memory before each object. More...

typedef struct PoolAllocator::ObjectPostfix	ObjectPostfix
	Appended in memory after each object. More...

Private Member Functions
Size	calculateObjectSize (const Size index) const
	Calculate object size given the Pool index number. More...

Size	calculateObjectCount (const Size objectSize) const
	Calculate minimum object count for a Pool. More...

void	calculateUsage (Size &totalSize, Size &totalUsed) const
	Determine total memory usage. More...

Pool *	retrievePool (const Size inputSize)
	Find a Pool of sufficient size. More...

Pool *	allocatePool (const uint index, const Size objectCount)
	Creates a new Pool instance. More...

Result	releasePool (Pool *pool)
	Release Pool instance memory. More...

Private Attributes
Pool *	m_pools [MaximumPoolSize+1]
	Array of memory pools. More...

Static Private Attributes
static const Size	MinimumPoolSize = 2
	Minimum power of two for a pool size. More...

static const Size	MaximumPoolSize = 27
	Maximum power of two size a pool can be (128MiB). More...

static const u32	ObjectSignature = 0xF7312A56
	Signature value is used to detect object corruption/overflows. More...

Additional Inherited Members
Public Types inherited from Allocator
enum	Result { Success = 0, InvalidAddress, InvalidSize, InvalidAlignment, OutOfMemory }
	Allocation results. More...

typedef struct Allocator::Range	Range
	Describes a range of memory. More...

Static Public Member Functions inherited from Allocator
static void	setDefault (Allocator *alloc)
	Makes the given Allocator the default. More...

static Allocator *	getDefault ()
	Retrieve the currently default Allocator. More...

Protected Member Functions inherited from Allocator
Address	aligned (const Address addr, const Size boundary) const
	Align memory address. More...

Detailed Description

Memory allocator which uses pools that each manage same-sized objects.

Allocates memory from pools each having the size of a power of two. Each pool is pre-allocated and has a bitmap representing free blocks.

Todo:: While this Allocator works well, its performance can be improved. The BitAllocator contains a BitArray that scans its internal array for "free bits". If the caller is unfortunate, the whole array needs to be scanned, adding overhead. The Linux kernel uses a buddy allocator, that basically combines a bit array and a linked list for optimal performance.

Definition at line 45 of file PoolAllocator.h.

Member Typedef Documentation

◆ ObjectPostfix

typedef struct PoolAllocator::ObjectPostfix PoolAllocator::ObjectPostfix

private

Appended in memory after each object.

◆ ObjectPrefix

typedef struct PoolAllocator::ObjectPrefix PoolAllocator::ObjectPrefix

private

This data structure is prepended in memory before each object.

◆ Pool

typedef PoolAllocator::Pool PoolAllocator::Pool

private

Allocates same-sized objects from a contiguous block of memory.

Constructor & Destructor Documentation

◆ PoolAllocator()

PoolAllocator::PoolAllocator ( Allocator * parent )

Constructor.

Parameters

parent Allocator for obtaining new memory to manage

Definition at line 23 of file PoolAllocator.cpp.

References assert, m_pools, NULL, Allocator::parent(), MemoryBlock::set(), and Allocator::setParent().

Member Function Documentation

◆ allocate()

Allocator::Result PoolAllocator::allocate ( Allocator::Range & args )

virtual

Allocate memory.

Parameters

args	Contains the requested size and alignment on input. On output, contains the actual allocated address.

Returns: Result value.

Reimplemented from Allocator.

Definition at line 87 of file PoolAllocator.cpp.

References Allocator::Range::address, Allocator::aligned(), Allocator::Range::alignment, Allocator::InvalidAlignment, Allocator::InvalidSize, ObjectSignature, Allocator::OutOfMemory, PoolAllocator::ObjectPrefix::pool, retrievePool(), PoolAllocator::ObjectPrefix::signature, PoolAllocator::ObjectPostfix::signature, Allocator::Range::size, Allocator::Success, and ZERO.

◆ allocatePool()

PoolAllocator::Pool * PoolAllocator::allocatePool	(	const uint	index,
		const Size	objectCount
	)

private

Creates a new Pool instance.

Parameters

index	Index in the Pools array
objectCount	Allocate for this many of blocks from our parent.

Returns: Pointer to a Pool object on success, ZERO on failure.

Definition at line 212 of file PoolAllocator.cpp.

References Allocator::Range::address, Allocator::aligned(), Allocator::Range::alignment, Allocator::allocate(), assert, calculateObjectSize(), PoolAllocator::Pool::index, m_pools, PoolAllocator::Pool::next, NULL, Allocator::parent(), PoolAllocator::Pool::prev, Allocator::Range::size, Allocator::Success, and ZERO.

Referenced by retrievePool().

◆ available()

Size PoolAllocator::available ( ) const

virtual

Get memory available.

Returns: Size of memory available by the PoolAllocator.

Reimplemented from Allocator.

Definition at line 38 of file PoolAllocator.cpp.

References assert, and calculateUsage().

◆ calculateObjectCount()

Size PoolAllocator::calculateObjectCount ( const Size objectSize ) const

private

Calculate minimum object count for a Pool.

Parameters

objectSize Size per-object in bytes

Returns: Minimum number of objects to allocate

Definition at line 56 of file PoolAllocator.cpp.

References assert, isPowerOfTwo(), and KiloByte.

Referenced by retrievePool().

◆ calculateObjectSize()

Size PoolAllocator::calculateObjectSize ( const Size index ) const

private

Calculate object size given the Pool index number.

Parameters

index Index number in m_pools

Returns: Size in bytes

Definition at line 48 of file PoolAllocator.cpp.

References assert, MaximumPoolSize, and MinimumPoolSize.

Referenced by allocatePool(), and retrievePool().

◆ calculateUsage()

void PoolAllocator::calculateUsage	(	Size &	totalSize,
		Size &	totalUsed
	)		const

private

Determine total memory usage.

Parameters

totalSize	Total memory in bytes owned by the PoolAllocator.
totalUsed	Total memory in bytes actually used.

Definition at line 67 of file PoolAllocator.cpp.

References m_pools, MaximumPoolSize, MinimumPoolSize, and NULL.

Referenced by available(), and size().

◆ release()

Allocator::Result PoolAllocator::release ( const Address addr )

virtual

Release memory.

Parameters

addr	Points to memory previously returned by allocate().

Returns: Result value.

See also: allocate

Reimplemented from Allocator.

Definition at line 130 of file PoolAllocator.cpp.

References assert, NULL, ObjectSignature, releasePool(), PoolAllocator::ObjectPostfix::signature, Allocator::Success, and ZERO.

◆ releasePool()

Allocator::Result PoolAllocator::releasePool ( Pool * pool )

private

Release Pool instance memory.

Parameters

pool	Pool object pointer

Returns: Result value.

Definition at line 272 of file PoolAllocator.cpp.

References PoolAllocator::Pool::index, m_pools, PoolAllocator::Pool::next, NULL, Allocator::parent(), PoolAllocator::Pool::prev, Allocator::release(), and Allocator::Success.

Referenced by release().

◆ retrievePool()

PoolAllocator::Pool * PoolAllocator::retrievePool ( const Size inputSize )

private

Find a Pool of sufficient size.

Parameters

inputSize Requested size of object to store

Returns: Pool object pointer on success or NULL on failure.

Definition at line 165 of file PoolAllocator.cpp.

References allocatePool(), BitAllocator::available(), calculateObjectCount(), calculateObjectSize(), m_pools, MaximumPoolSize, MinimumPoolSize, PoolAllocator::Pool::next, and ZERO.

Referenced by allocate().

◆ size()

Size PoolAllocator::size ( ) const

virtual

Get memory size.

Returns: Size of memory owned by the PoolAllocator.

Reimplemented from Allocator.

Definition at line 30 of file PoolAllocator.cpp.

References calculateUsage().

Field Documentation

◆ m_pools

Pool* PoolAllocator::m_pools[MaximumPoolSize+1]

private

Array of memory pools.

Index represents the power of two.

Definition at line 201 of file PoolAllocator.h.

Referenced by allocatePool(), calculateUsage(), PoolAllocator(), releasePool(), and retrievePool().

◆ MaximumPoolSize

const Size PoolAllocator::MaximumPoolSize = 27

staticprivate

Maximum power of two size a pool can be (128MiB).

Definition at line 53 of file PoolAllocator.h.

Referenced by calculateObjectSize(), calculateUsage(), and retrievePool().

◆ MinimumPoolSize

const Size PoolAllocator::MinimumPoolSize = 2

staticprivate

Minimum power of two for a pool size.

Definition at line 50 of file PoolAllocator.h.

Referenced by calculateObjectSize(), calculateUsage(), and retrievePool().

◆ ObjectSignature

const u32 PoolAllocator::ObjectSignature = 0xF7312A56

staticprivate

Signature value is used to detect object corruption/overflows.

Definition at line 56 of file PoolAllocator.h.

Referenced by allocate(), and release().

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

lib/liballoc/PoolAllocator.h
lib/liballoc/PoolAllocator.cpp

Data Structures

Public Member Functions

Private Types

Private Member Functions

Private Attributes

Static Private Attributes

Additional Inherited Members

Detailed Description

Member Typedef Documentation

◆ ObjectPostfix

◆ ObjectPrefix

◆ Pool

Constructor & Destructor Documentation

◆ PoolAllocator()

Member Function Documentation

◆ allocate()

◆ allocatePool()

◆ available()

◆ calculateObjectCount()

◆ calculateObjectSize()

◆ calculateUsage()

◆ release()

◆ releasePool()

◆ retrievePool()

◆ size()

Field Documentation

◆ m_pools

◆ MaximumPoolSize

◆ MinimumPoolSize

◆ ObjectSignature