cxx::Base_slab< Obj_size, Slab_size, Max_free, Alloc > Class Template Reference

Basic slab allocator. More...

#include <slab_alloc>

Inheritance diagram for cxx::Base_slab< Obj_size, Slab_size, Max_free, Alloc >:

Collaboration diagram for cxx::Base_slab< Obj_size, Slab_size, Max_free, Alloc >:

Data Structures
struct	Slab_i
	Type of a slab. More...

Public Types
enum	{ object_size = Obj_size , slab_size = Slab_size , objects_per_slab = (Slab_size - sizeof(Slab_head)) / object_size , max_free_slabs = Max_free }
typedef Alloc< Slab_i >	Slab_alloc
	Type of the backend allocator.

Public Member Functions
void *	alloc () noexcept
	Allocate a new object.
void	free (void *_o) noexcept
	Free the given object (_o).
unsigned	total_objects () const noexcept
	Get the total number of objects managed by the slab allocator.
unsigned	free_objects () const noexcept
	Get the number of objects which can be allocated before a new empty slab needs to be added to the slab allocator.

Detailed Description

template<int Obj_size, int Slab_size = L4_PAGESIZE, int Max_free = 2, template< typename A > class Alloc = New_allocator>
class cxx::Base_slab< Obj_size, Slab_size, Max_free, Alloc >

Basic slab allocator.

Template Parameters

Obj_size	The size of the objects managed by the allocator (in bytes).
Slab_size	The size of a slab (in bytes).
Max_free	The maximum number of free slabs. When this limit is reached slabs are freed, provided that the backend allocator supports allocated memory to be freed.
Alloc	The backend allocator used to allocate slabs.

Definition at line 42 of file slab_alloc.

Member Enumeration Documentation

anonymous enum

template<int Obj_size, int Slab_size = L4_PAGESIZE, int Max_free = 2, template< typename A > class Alloc = New_allocator>

anonymous enum

Enumerator
object_size	Size of an object.
slab_size	Size of a slab.
objects_per_slab	Objects per slab.
max_free_slabs	Maximum number of free slabs.

Definition at line 76 of file slab_alloc.

Member Function Documentation

alloc()

template<int Obj_size, int Slab_size = L4_PAGESIZE, int Max_free = 2, template< typename A > class Alloc = New_allocator>

void * cxx::Base_slab< Obj_size, Slab_size, Max_free, Alloc >::alloc ( )

inlinenoexcept

Allocate a new object.

Returns

A pointer to the new object if the allocation succeeds, or 0 on failure to acquire memory from the backend allocator when the slab cache memory is already exhausted.

Note

The user is responsible for initializing the object.

Definition at line 218 of file slab_alloc.

References cxx::Base_slab< Obj_size, Slab_size, Max_free, Alloc >::free(), cxx::H_list< T, POLICY >::push_front(), and cxx::H_list< T, POLICY >::remove().

Referenced by cxx::Base_slab_static< Obj_size, Slab_size, Max_free, Alloc >::alloc().

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free()

template<int Obj_size, int Slab_size = L4_PAGESIZE, int Max_free = 2, template< typename A > class Alloc = New_allocator>

void cxx::Base_slab< Obj_size, Slab_size, Max_free, Alloc >::free ( void *  _o )

inlinenoexcept

Free the given object (_o).

Precondition

The object must have been allocated with this allocator.

Definition at line 257 of file slab_alloc.

References cxx::Base_slab< Obj_size, Slab_size, Max_free, Alloc >::max_free_slabs, cxx::Base_slab< Obj_size, Slab_size, Max_free, Alloc >::objects_per_slab, cxx::H_list< T, POLICY >::push_front(), cxx::H_list< T, POLICY >::remove(), and cxx::Base_slab< Obj_size, Slab_size, Max_free, Alloc >::slab_size.

Referenced by cxx::Base_slab< Obj_size, Slab_size, Max_free, Alloc >::alloc(), and cxx::Base_slab_static< Obj_size, Slab_size, Max_free, Alloc >::free().

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free_objects()

template<int Obj_size, int Slab_size = L4_PAGESIZE, int Max_free = 2, template< typename A > class Alloc = New_allocator>

unsigned cxx::Base_slab< Obj_size, Slab_size, Max_free, Alloc >::free_objects ( ) const

inlinenoexcept

Get the number of objects which can be allocated before a new empty slab needs to be added to the slab allocator.

Returns

The number of free objects in the slab allocator.

Definition at line 319 of file slab_alloc.

References cxx::Bits::Basic_list< POLICY >::begin(), cxx::Bits::Basic_list< POLICY >::end(), and cxx::Base_slab< Obj_size, Slab_size, Max_free, Alloc >::objects_per_slab.

Referenced by cxx::Base_slab_static< Obj_size, Slab_size, Max_free, Alloc >::free_objects().

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total_objects()

template<int Obj_size, int Slab_size = L4_PAGESIZE, int Max_free = 2, template< typename A > class Alloc = New_allocator>

unsigned cxx::Base_slab< Obj_size, Slab_size, Max_free, Alloc >::total_objects ( ) const

inlinenoexcept

Get the total number of objects managed by the slab allocator.

Returns

The number of objects managed by the allocator (including the free objects).

Definition at line 310 of file slab_alloc.

References cxx::Base_slab< Obj_size, Slab_size, Max_free, Alloc >::objects_per_slab.

Referenced by cxx::Base_slab_static< Obj_size, Slab_size, Max_free, Alloc >::total_objects().

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

• l4/cxx/slab_alloc