An arena pre-allocates so-called pages of size Arena::page_size_. More...

#include <fe/arena.h>

Classes
class	MemoryResource
	A memory resource bridge in order to use this Arena for pmr containers. More...
struct	Allocator
	An allocator in order to use this Arena for containers. More...
struct	Deleter
class	Ref
	A non-owning pointer into an Arena. More...

Public Types
template<class T>
using	Ptr = std::unique_ptr<T, Deleter<T>>
using	State = std::pair<size_t, size_t>

Public Member Functions
Construction
	Arena (const Arena &)=delete
	Arena (size_t page_size=Default_Page_Size)
	Arena (Arena &&other) noexcept
Arena &	operator= (Arena)=delete
template<class T>
Allocator< T >	allocator () noexcept
	Create Allocator from Arena.
std::pmr::memory_resource *	resource () noexcept
const std::pmr::memory_resource *	resource () const noexcept
template<class T, class... Args>
Ptr< T >	mk (Args &&... args)
	This is a std::unique_ptr that uses the Arena under the hood and whose Deleter will only invoke the destructor but not delete anything; memory will be released upon destruction of the Arena.
template<class T, class... Args>
Ref< T >	ref (Args &&... args)
	Like Arena::mk, but yields a Ref: nothing will ever destroy the object.
template<std::ranges::input_range R, class T = std::ranges::range_value_t<R>>
Span< T >	copy (const R &range)
	An Arena-allocated copy of `range`.
Allocate
void *	allocate (size_t num_bytes, size_t align)
	Get `n` bytes of fresh memory.
template<class T>
T *	allocate (size_t num_elems)
Deallocate
Deallocate memory again in reverse order. Use like this: auto state = arena.state(); auto ptr = arena.allocate(n); if (/* I don't want that /) arena.deallocate(state); fe::Arena::state State state() const noexcept Definition* arena.h:223 Warning Only use, if you really know what you are doing.
void	deallocate (size_t num_bytes) noexcept
	Removes `num_bytes` again.
State	state () const noexcept
void	deallocate (State state) noexcept

Static Public Member Functions
static constexpr size_t	align (size_t i, size_t a) noexcept
	Align `i` to `a`.

Static Public Attributes
static constexpr size_t	Default_Page_Size = 1024 * 1024
	1MB.

Friends
void	swap (Arena &a1, Arena &a2) noexcept

Detailed Description

An arena pre-allocates so-called pages of size Arena::page_size_.

You can use Arena::allocate to obtain memory from this. When a page runs out of memory, the next page will be (pre-)allocated. You cannot directly release memory obtained via this method. Instead, all memory acquired via this Arena will be released as soon as this Arena will be destroyed. As an exception, you can Arena::deallocate memory that has just been acquired.

Definition at line 25 of file arena.h.

Member Typedef Documentation

◆ Ptr

template<class T>

using fe::Arena::Ptr = std::unique_ptr<T, Deleter<T>>

Definition at line 115 of file arena.h.

◆ State

using fe::Arena::State = std::pair<size_t, size_t>

Definition at line 116 of file arena.h.

Constructor & Destructor Documentation

◆ Arena() [1/3]

fe::Arena::Arena ( const Arena & )

delete

References Arena().

Referenced by fe::Arena::Allocator< T >::Allocator(), Arena(), Arena(), fe::Arena::MemoryResource::MemoryResource(), operator=(), and swap.

◆ Arena() [2/3]

fe::Arena::Arena ( size_t page_size = Default_Page_Size )

inlineexplicit

Definition at line 121 of file arena.h.

References Default_Page_Size.

◆ Arena() [3/3]

fe::Arena::Arena ( Arena && other )

inlinenoexcept

Definition at line 125 of file arena.h.

References Arena(), and swap.

Member Function Documentation

◆ align()

constexpr size_t fe::Arena::align	(	size_t	i,
		size_t	a )

inlinestaticconstexprnoexcept

Align i to a.

Definition at line 245 of file arena.h.

Referenced by allocate().

◆ allocate() [1/2]

void * fe::Arena::allocate	(	size_t	num_bytes,
		size_t	align )

inlinenodiscard

Get n bytes of fresh memory.

Note: When a fresh page is allocated, its base is only aligned to the align of the allocation that triggered it. A later allocation in the same page that requests a larger alignment has its offset aligned but may still be under-aligned relative to its request. This is a non-issue for the default (max-aligned) page size and for arenas with uniform alignment; only tiny custom arenas mixing alignments can hit it.

Definition at line 186 of file arena.h.

References align().

Referenced by allocate(), fe::Arena::Allocator< T >::allocate(), and copy().

◆ allocate() [2/2]

template<class T>

T * fe::Arena::allocate ( size_t num_elems )

inlinenodiscard

Definition at line 202 of file arena.h.

References allocate().

◆ allocator()

template<class T>

Allocator< T > fe::Arena::allocator ( )

inlinenoexcept

Create Allocator from Arena.

Definition at line 133 of file arena.h.

References fe::Arena::Allocator< T >::Allocator().

Referenced by fe::Arena::Allocator< T >::Allocator().

◆ copy()

template<std::ranges::input_range R, class T = std::ranges::range_value_t<R>>

Span< T > fe::Arena::copy ( const R & range )

inlinenodiscard

An Arena-allocated copy of range.

Definition at line 168 of file arena.h.

References allocate().

◆ deallocate() [1/2]

void fe::Arena::deallocate ( size_t num_bytes )

inlinenoexcept

Removes num_bytes again.

Definition at line 219 of file arena.h.

◆ deallocate() [2/2]

void fe::Arena::deallocate ( State state )

inlinenoexcept

Definition at line 225 of file arena.h.

References state().

◆ mk()

template<class T, class... Args>

Ptr< T > fe::Arena::mk ( Args &&... args )

inline

This is a std::unique_ptr that uses the Arena under the hood and whose Deleter will only invoke the destructor but not delete anything; memory will be released upon destruction of the Arena.

Use like this:

auto ptr = arena.mk<Foo>(a, b, c); // new Foo(a, b, c) placed into arena

Definition at line 150 of file arena.h.

◆ operator=()

Arena & fe::Arena::operator= ( Arena )

delete

References Arena().

◆ ref()

template<class T, class... Args>

Ref< T > fe::Arena::ref ( Args &&... args )

inline

Like Arena::mk, but yields a Ref: nothing will ever destroy the object.

Use like this:

auto ref = arena.ref<Foo>(a, b, c); // new Foo(a, b, c) placed into arena, never destroyed

fe::Arena::ref

Ref< T > ref(Args &&... args)

Like Arena::mk, but yields a Ref: nothing will ever destroy the object.

Definition arena.h:160

Definition at line 160 of file arena.h.

References fe::Arena::Ref< T >::Ref().

Referenced by fe::Arena::Ref< T >::Ref().

◆ resource() [1/2]

const std::pmr::memory_resource * fe::Arena::resource ( ) const

inlinenoexcept

Definition at line 138 of file arena.h.

◆ resource() [2/2]

std::pmr::memory_resource * fe::Arena::resource ( )

inlinenoexcept

Definition at line 137 of file arena.h.

Referenced by fe::Arena::MemoryResource::do_is_equal().

◆ state()

State fe::Arena::state ( ) const

inlinenodiscardnoexcept

Definition at line 223 of file arena.h.

Referenced by deallocate().

◆ swap

void swap	(	Arena &	a1,
		Arena &	a2 )

friend

Definition at line 235 of file arena.h.

References Arena(), and swap.

Referenced by Arena(), and swap.

Member Data Documentation

◆ Default_Page_Size

size_t fe::Arena::Default_Page_Size = 1024 * 1024

staticconstexpr

1MB.

Definition at line 27 of file arena.h.

Referenced by Arena(), and fe::Patricia< D, KT, K, N >::Patricia().

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

fe/arena.h

Classes

Public Types

Public Member Functions

Static Public Member Functions

Static Public Attributes

Friends

Detailed Description

Member Typedef Documentation

◆ Ptr

◆ State

Constructor & Destructor Documentation

◆ Arena() [1/3]

◆ Arena() [2/3]

◆ Arena() [3/3]

Member Function Documentation

◆ align()

◆ allocate() [1/2]

◆ allocate() [2/2]

◆ allocator()

◆ copy()

◆ deallocate() [1/2]

◆ deallocate() [2/2]

◆ mk()

◆ operator=()

◆ ref()

◆ resource() [1/2]

◆ resource() [2/2]

◆ state()

Friends And Related Symbol Documentation

◆ swap

Member Data Documentation

◆ Default_Page_Size