Overview

Size-independent buddy allocator.

This allocator allocates blocks of memory whose sizes are powers of two. See also https://en.wikipedia.org/wiki/Buddy_memory_allocation.

Compared to BuddyAllocator, this implementation is size-agnostic with respect to the number of buckets.

Inheritance diagram for pw::allocator::internal::GenericBuddyAllocator:

Public Member Functions
void	InitBuckets (span< UnorderedBucket< BuddyBlock > > buckets, size_t min_outer_size)

void	Init (ByteSpan region)
	Sets the memory used to allocate blocks.

Public Member Functions inherited from pw::Allocator
void *	Allocate (Layout layout)

template<typename T , int &... kExplicitGuard, typename... Args>
std::enable_if_t<!std::is_array_v< T >, T * >	New (Args &&... args)

template<typename T , int &... kExplicitGuard, typename ElementType = std::remove_extent_t<T>, std::enable_if_t< is_bounded_array_v< T >, int > = 0>
ElementType *	New ()

template<typename T , int &... kExplicitGuard, typename ElementType = std::remove_extent_t<T>, std::enable_if_t< is_unbounded_array_v< T >, int > = 0>
ElementType *	New (size_t count)

template<typename T , int &... kExplicitGuard, typename ElementType = std::remove_extent_t<T>, std::enable_if_t< is_unbounded_array_v< T >, int > = 0>
ElementType *	New (size_t count, size_t alignment)
	Constructs an `alignment`-byte aligned array of `count` objects.

template<typename T , int &... kExplicitGuard, std::enable_if_t<!std::is_array_v< T >, int > = 0, typename... Args>
UniquePtr< T >	MakeUnique (Args &&... args)

template<typename T , int &... kExplicitGuard, std::enable_if_t< is_unbounded_array_v< T >, int > = 0>
UniquePtr< T >	MakeUnique (size_t size)

template<typename T , int &... kExplicitGuard, std::enable_if_t< is_unbounded_array_v< T >, int > = 0>
UniquePtr< T >	MakeUnique (size_t size, size_t alignment)

template<typename T , int &... kExplicitGuard, std::enable_if_t< is_bounded_array_v< T >, int > = 0>
UniquePtr< T >	MakeUnique ()

template<typename T , int &... kExplicitGuard, std::enable_if_t<!std::is_array_v< T >, int > = 0, typename... Args>
SharedPtr< T >	MakeShared (Args &&... args)

template<typename T , int &... kExplicitGuard, std::enable_if_t< is_unbounded_array_v< T >, int > = 0>
SharedPtr< T >	MakeShared (size_t size)

template<typename T , int &... kExplicitGuard, std::enable_if_t< is_unbounded_array_v< T >, int > = 0>
SharedPtr< T >	MakeShared (size_t size, size_t alignment)

template<typename T , int &... kExplicitGuard, std::enable_if_t< is_bounded_array_v< T >, int > = 0>
SharedPtr< T >	MakeShared ()

bool	Resize (void *ptr, size_t new_size)

void *	Reallocate (void *ptr, Layout new_layout)

size_t	GetAllocated () const

std::optional< allocator::Fragmentation >	MeasureFragmentation () const
	Returns fragmentation information for the allocator's memory region.

Public Member Functions inherited from pw::Deallocator
constexpr const Capabilities &	capabilities () const

constexpr bool	HasCapability (Capability capability) const
	Returns whether a given capability is enabled for this object.

void	Deallocate (void *ptr)

template<typename ElementType >
void	DeleteArray (ElementType *ptr, size_t count)

StatusWithSize	GetCapacity () const

bool	IsEqual (const Deallocator &other) const

template<typename T , int &... kExplicitGuard, std::enable_if_t<!std::is_array_v< T >, int > = 0>
void	Delete (T *ptr)

template<typename T , int &... kExplicitGuard, typename ElementType = std::remove_extent_t<T>, std::enable_if_t< is_bounded_array_v< T >, int > = 0>
void	Delete (ElementType *ptr)

template<typename T , int &... kExplicitGuard, typename ElementType = std::remove_extent_t<T>, std::enable_if_t< is_unbounded_array_v< T >, int > = 0>
void	Delete (ElementType *ptr, size_t count)

Static Public Attributes
static constexpr Capabilities	kCapabilities

static constexpr size_t	kDefaultMinOuterSize = 16

static constexpr size_t	kDefaultNumBuckets = 16

Protected Member Functions
void	CrashIfAllocated ()

Protected Member Functions inherited from pw::Allocator
constexpr	Allocator ()=default
	TODO(b/326509341): Remove when downstream consumers migrate.

constexpr	Allocator (const Capabilities &capabilities)

virtual std::optional< allocator::Fragmentation >	DoMeasureFragmentation () const

Protected Member Functions inherited from pw::Deallocator
constexpr	Deallocator ()=default
	TODO(b/326509341): Remove when downstream consumers migrate.

constexpr	Deallocator (const Capabilities &capabilities)

Private Member Functions
void *	DoAllocate (Layout layout) override

void	DoDeallocate (void *ptr) override

Result< Layout >	DoGetInfo (InfoType info_type, const void *ptr) const override

Additional Inherited Members
Public Types inherited from pw::Deallocator
using	Capabilities = allocator::Capabilities

using	Capability = allocator::Capability

using	Layout = allocator::Layout

Static Protected Attributes inherited from pw::Deallocator
template<typename T >
static constexpr bool	is_bounded_array_v

template<typename T >
static constexpr bool	is_unbounded_array_v

Member Function Documentation

◆ CrashIfAllocated()

void pw::allocator::internal::GenericBuddyAllocator::CrashIfAllocated ( )

protected

Ensures all allocations have been freed. Crashes with a diagnostic message If any allocations remain outstanding.

◆ DoAllocate()

void * pw::allocator::internal::GenericBuddyAllocator::DoAllocate ( Layout layout )

overrideprivatevirtual

Allocates a block of memory with the specified size and alignment.

Returns nullptr if the allocation cannot be made, or the layout has a size of 0.

Parameters

[in] layout Describes the memory to be allocated.

Implements pw::Allocator.

◆ DoDeallocate()

void pw::allocator::internal::GenericBuddyAllocator::DoDeallocate ( void * ptr )

overrideprivate

◆ DoGetInfo()

Result< Layout > pw::allocator::internal::GenericBuddyAllocator::DoGetInfo	(	InfoType	info_type,
		const void *	ptr
	)		const

overrideprivate

◆ InitBuckets()

void pw::allocator::internal::GenericBuddyAllocator::InitBuckets	(	span< UnorderedBucket< BuddyBlock > >	buckets,
		size_t	min_outer_size
	)

Sets up buckets for a buddy allocator.

Parameters

[in]	buckets	Storage for buckets of free blocks.
[in]	min_outer_size	Outer size of the blocks in the first bucket.

Member Data Documentation

◆ kCapabilities

constexpr Capabilities pw::allocator::internal::GenericBuddyAllocator::kCapabilities

staticconstexpr

Initial value:

=
      kImplementsGetUsableLayout | kImplementsGetAllocatedLayout |
      kImplementsGetCapacity | kImplementsRecognizes

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

pw_allocator/public/pw_allocator/buddy_allocator.h

Overview

Public Member Functions

Static Public Attributes

Protected Member Functions

Private Member Functions

Additional Inherited Members