Overview

This class simply dispatches between a primary and secondary allocator. Any attempt to allocate memory will first be handled by the primary allocator. If it cannot allocate memory, e.g. because it is out of memory, the secondary alloator will try to allocate memory instead.

Inheritance diagram for pw::allocator::FallbackAllocator:

Public Member Functions
	FallbackAllocator (pw::Allocator &primary, pw::Allocator &secondary)

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)

Protected Member Functions
void *	DoAllocate (Layout layout) override

void	DoDeallocate (void *ptr) override

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 info_type, const void *ptr) 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)

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

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

◆ FallbackAllocator()

pw::allocator::FallbackAllocator::FallbackAllocator	(	pw::Allocator &	primary,
		pw::Allocator &	secondary
	)

Constructor.

Parameters

[in]	primary	Allocator tried first. Must implement `Query`.
[in]	secondary	Allocator tried if `primary` fails a request.

Member Function Documentation

◆ DoAllocate()

void * pw::allocator::FallbackAllocator::DoAllocate ( Layout layout )

overrideprotectedvirtual

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::FallbackAllocator::DoDeallocate ( void * ptr )

overrideprotected

Releases a previously-allocated block of memory.

The given pointer must have been previously provided by this memory resource; otherwise the behavior is undefined.

Parameters

[in] ptr Pointer to previously-allocated memory.

◆ DoGetAllocated()

size_t pw::allocator::FallbackAllocator::DoGetAllocated ( ) const

overrideprotectedvirtual

Returns the total bytes that have been allocated by this allocator, or size_t(-1) if this allocator does not track its total allocated bytes.

Reimplemented from pw::Allocator.

◆ DoGetInfo()

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

overrideprotected

◆ DoMeasureFragmentation()

std::optional< Fragmentation > pw::allocator::FallbackAllocator::DoMeasureFragmentation ( ) const

overrideprotectedvirtual

Returns fragmentation information for the allocator's memory region.

The default implementation simply returns std::nullopt, indicating that tracking memory fragmentation is not supported.

Reimplemented from pw::Allocator.

◆ DoResize()

bool pw::allocator::FallbackAllocator::DoResize	(	void *	ptr,
		size_t	new_size
	)

overrideprotectedvirtual

Modifies the size of an previously-allocated block of memory without copying any data.

Returns true if its size was changed without copying data to a new allocation; otherwise returns false.

In particular, it always returns true if the old_layout.size() equals new_size, and always returns false if the given pointer is null, the old_layout.size() is 0, or the new_size is 0.

Parameters

[in]	ptr	Pointer to previously-allocated memory.
[in]	new_size	Requested new size for the memory allocation.

Reimplemented from pw::Allocator.

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

pw_allocator/public/pw_allocator/fallback_allocator.h

Overview

Public Member Functions

Protected Member Functions

Additional Inherited Members

Constructor & Destructor Documentation

◆ FallbackAllocator()

Member Function Documentation

◆ DoAllocate()

◆ DoDeallocate()

◆ DoGetAllocated()

◆ DoGetInfo()

◆ DoMeasureFragmentation()

◆ DoResize()