fe::Arena Class Reference

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

#include <fe/arena.h>

Classes
struct	Allocator
struct	Deleter

Public Member Functions
Allocator
An allocator in order to use this Arena for containers. Construct it via Arena::allocator.
template<class T >
Allocator< T >	allocator ()
	Create Allocator from Arena.
Construction/Destruction
	Arena (size_t page_size=Default_Page_Size)
	Arena (const Arena &)=delete
	Arena (Arena &&other) noexcept
Arena &	operator= (Arena)=delete
Allocate
Arena &	align (size_t a)
	Align next allocate(size_t) to a.
void *	allocate (size_t num_bytes)
	Get n bytes of fresh memory.
template<class T >
T *	allocate (size_t num_elems)

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

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

Smart Pointer
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
template<class T >
using	Ptr = std::unique_ptr< T, Deleter< T > >
template<class T , class... Args>
Ptr< T >	mk (Args &&... args)

Deallocate
Deallocate memory again in reverse order.
using	State = std::pair< size_t, size_t >
	Goes back to state in Arena.
void	deallocate (size_t num_bytes)
	Removes num_bytes again.
State	state () const
void	deallocate (State state)

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 just as been acquired.

Definition at line 17 of file arena.h.

Member Typedef Documentation

Ptr

template<class T >

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

Definition at line 67 of file arena.h.

State

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

Goes back to state in Arena.

Use like this:

auto state = arena.state();
auto ptr   = arena.allocate(n);
if (/* I don't want that *‍/) arena.deallocate(state);

Warning

Only use, if you really know what you are doing.

Definition at line 127 of file arena.h.

Constructor & Destructor Documentation

Arena() [1/3]

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

inline

Definition at line 76 of file arena.h.

Arena() [2/3]

fe::Arena::Arena ( const Arena &  )

delete

Arena() [3/3]

fe::Arena::Arena ( Arena &&  other )

inlinenoexcept

Definition at line 81 of file arena.h.

References swap.

Member Function Documentation

align()

Arena & fe::Arena::align ( size_t  a )

inline

Align next allocate(size_t) to a.

Definition at line 92 of file arena.h.

Referenced by allocate(), and fe::SymPool::sym().

allocate() [1/2]

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

inline

Get n bytes of fresh memory.

Definition at line 95 of file arena.h.

Referenced by fe::Arena::Allocator< T >::allocate(), allocate(), mk(), and fe::SymPool::sym().

allocate() [2/2]

template<class T >

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

inline

Definition at line 106 of file arena.h.

References align(), and allocate().

allocator()

template<class T >

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

inline

Create Allocator from Arena.

Definition at line 47 of file arena.h.

deallocate() [1/2]

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

inline

Removes num_bytes again.

Definition at line 117 of file arena.h.

Referenced by fe::SymPool::sym().

deallocate() [2/2]

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

inline

Definition at line 129 of file arena.h.

References state().

mk()

template<class T , class... Args>

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

inline

Definition at line 68 of file arena.h.

References allocate().

operator=()

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

delete

state()

State fe::Arena::state ( ) const

inline

Definition at line 128 of file arena.h.

Referenced by deallocate(), and fe::SymPool::sym().

Friends And Related Symbol Documentation

swap

void swap ( Arena &  a1, Arena &  a2  )

friend

Definition at line 137 of file arena.h.

Referenced by Arena().

Member Data Documentation

Default_Page_Size

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

staticconstexpr

1MB.

Definition at line 19 of file arena.h.

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

• fe/arena.h