pw::allocator::FallbackAllocator Class Reference

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, 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)

Protected Member Functions
std::optional< allocator::Fragmentation >	DoMeasureFragmentation () 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 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
bool	DoResize (void *ptr, size_t new_size) override
size_t	DoGetAllocated () const 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

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 )

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::FallbackAllocator::DoDeallocate ( void *  ptr )

overrideprivate

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

overrideprivatevirtual

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

overrideprivate

DoMeasureFragmentation()

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

inlineoverrideprotectedvirtual

Virtual MeasureFragmentation function that can be overridden by derived classes.

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  )

overrideprivatevirtual

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.

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

• pw_allocator/public/pw_allocator/fallback_allocator.h