Overview

template<size_t kMinOuterSize_ = internal::GenericBuddyAllocator::kDefaultMinOuterSize, size_t kNumBuckets = internal::GenericBuddyAllocator::kDefaultNumBuckets>
class pw::allocator::BuddyAllocator< kMinOuterSize_, kNumBuckets >

Allocator that uses the buddy memory allocation algorithm.

This allocator allocates blocks of memory whose sizes are powers of two. This allows the allocator to satisfy requests to acquire and release memory very quickly, at the possible cost of higher internal fragmentation. In particular:

The maximum alignment for this allocator is kMinInnerSize.
The minimum size of an allocation is kMinInnerSize. Less may be requested, but it will be satisfied by a block of that inner size.
The maximum size of an allocation is kMinInnerSize << (kNumBuckets - 1).

Use this allocator if you know the needed sizes are close to but less than the block inner sizes and you need high allocator performance.

Template Parameters

kMinOuterSize	Outer size of the smallest allocatable block. Must be a power of two. All allocations will use at least this much memory.
kNumBuckets	Number of buckets. Must be at least 1. Each additional bucket allows combining blocks into larger blocks.

Inheritance diagram for pw::allocator::BuddyAllocator< kMinOuterSize_, kNumBuckets >:

Public Member Functions
constexpr	BuddyAllocator ()
	Constructs an allocator. Callers must call `Init`.

	BuddyAllocator (ByteSpan region)

Public Member Functions inherited from pw::allocator::internal::GenericBuddyAllocator
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, std::enable_if_t<!std::is_array_v< T >, int > = 0, typename... Args>
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 , std::enable_if_t< is_unbounded_array_v< T >, int > = 0>
UniquePtr< T >	MakeUnique (size_t size)

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

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

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

template<typename T , 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< 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 size_t	kMinOuterSize = kMinOuterSize_

Static Public Attributes inherited from pw::allocator::internal::GenericBuddyAllocator
static constexpr Capabilities	kCapabilities

static constexpr size_t	kDefaultMinOuterSize = 16

static constexpr size_t	kDefaultNumBuckets = 16

Additional Inherited Members
Public Types inherited from pw::Allocator
using	Fragmentation = allocator::Fragmentation

Public Types inherited from pw::Deallocator
using	Capabilities = allocator::Capabilities

using	Capability = allocator::Capability

using	Layout = allocator::Layout

Protected Types inherited from pw::Deallocator
enum class	InfoType { kRequestedLayoutOf , kUsableLayoutOf , kAllocatedLayoutOf , kCapacity , kRecognizes }

Protected Member Functions inherited from pw::allocator::internal::GenericBuddyAllocator
void *	DoAllocate (Layout layout) override

void	DoDeallocate (void *ptr) override

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

void	CrashIfAllocated ()

Protected Member Functions inherited from pw::allocator::AbstractAllocator
constexpr	AbstractAllocator (Capabilities capabilities)

bool	DoResize (void *ptr, size_t new_size) override

size_t	DoGetAllocated () const override

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

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

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

constexpr	Allocator (const Capabilities &capabilities)

virtual void *	DoAllocate (Layout layout)=0

virtual bool	DoResize (void *ptr, size_t new_size)

virtual void *	DoReallocate (void *ptr, Layout new_layout)

virtual size_t	DoGetAllocated () const

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

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

constexpr	Deallocator (const Capabilities &capabilities)

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

Result< Layout >	GetRequestedLayout (const void *ptr) const

Result< Layout >	GetUsableLayout (const void *ptr) const

Result< Layout >	GetAllocatedLayout (const void *ptr) const

bool	Recognizes (const void *ptr) const

virtual void	DoDeallocate (void *ptr)=0

virtual Result< Layout >	DoGetInfo (InfoType, const void *) const

Static Protected Member Functions inherited from pw::Deallocator
static Result< Layout >	GetInfo (const Deallocator &deallocator, InfoType info_type, const void *ptr)

static Result< Layout >	GetRequestedLayout (const Deallocator &deallocator, const void *ptr)

static Result< Layout >	GetUsableLayout (const Deallocator &deallocator, const void *ptr)

static Result< Layout >	GetAllocatedLayout (const Deallocator &deallocator, const void *ptr)

static bool	Recognizes (const Deallocator &deallocator, const void *ptr)

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

template<typename T >
static constexpr bool	is_unbounded_array_v = ::pw::is_unbounded_array_v<T>

Constructor & Destructor Documentation

◆ BuddyAllocator()

template<size_t kMinOuterSize_ = internal::GenericBuddyAllocator::kDefaultMinOuterSize, size_t kNumBuckets = internal::GenericBuddyAllocator::kDefaultNumBuckets>

pw::allocator::BuddyAllocator< kMinOuterSize_, kNumBuckets >::BuddyAllocator ( ByteSpan region )

inline

Constructs an allocator, and initializes it with the given memory region.

Parameters

[in] region Region of memory to use when satisfying allocation requests. The region MUST be large enough to fit a least one minimally-size BuddyBlock.

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

Additional Inherited Members

Constructor & Destructor Documentation

◆ BuddyAllocator()