Forwarding allocators

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Allocator implementations that don’t allocate memory directly and instead rely on other allocators while providing additional behaviors.

Learn more: Forwarding allocator concept

Classes
class	pw::allocator::AllocatorAsPool
	Implementation of Pool that satisfies requests using an Allocator. More...
class	pw::allocator::FallbackAllocator
class	pw::allocator::GuardedAllocator< BlockAllocatorType, LockType >
class	pw::allocator::PmrAllocator
class	pw::allocator::SynchronizedAllocator< LockType >
struct	pw::allocator::AddTrackingAllocatorAsChild
class	pw::allocator::TrackingAllocator< MetricsType >

Typedefs
using	pw::allocator::NoSync = pw::sync::NoLock
template<typename MetricsType >
using	pw::allocator::TrackingAllocatorImpl = TrackingAllocator< MetricsType >

Functions
void *	pw::allocator::TrackingAllocator< MetricsType >::DoAllocate (Layout layout) override
void	pw::allocator::TrackingAllocator< MetricsType >::DoDeallocate (void *ptr) override
bool	pw::allocator::TrackingAllocator< MetricsType >::DoResize (void *ptr, size_t new_size) override
void *	pw::allocator::TrackingAllocator< MetricsType >::DoReallocate (void *ptr, Layout new_layout) override

Variables
static constexpr struct pw::allocator::AddTrackingAllocatorAsChild	pw::allocator::kAddTrackingAllocatorAsChild = {}

Typedef Documentation

NoSync

using pw::allocator::NoSync = typedef pw::sync::NoLock

Tag type used to indicate synchronization is NOT desired.

This can be useful with allocator parameters for module configuration, e.g. PW_MALLOC_LOCK_TYPE.

Function Documentation

DoAllocate()

template<typename MetricsType >

void * pw::allocator::TrackingAllocator< MetricsType >::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()

template<typename MetricsType >

void pw::allocator::TrackingAllocator< MetricsType >::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.

DoReallocate()

template<typename MetricsType >

void * pw::allocator::TrackingAllocator< MetricsType >::DoReallocate ( void *  ptr, Layout  new_layout  )

overrideprivatevirtual

Modifies the size of a previously-allocated block of memory.

Returns pointer to the modified block of memory, or nullptr if the memory could not be modified.

The data stored by the memory being modified must be trivially copyable. If it is not, callers should themselves attempt to Resize, then Allocate, move the data, and Deallocate as needed.

If nullptr is returned, the block of memory is unchanged. In particular, if the new_layout has a size of 0, the given pointer will NOT be deallocated.

TODO(b/331290408): This error condition needs to be better communicated to module users, who may assume the pointer is freed.

Unlike Resize, providing a null pointer will return a new allocation.

If the request can be satisfied using Resize, the alignment parameter may be ignored.

Parameters

[in]	ptr	Pointer to previously-allocated memory.
[in]	new_layout	Describes the memory to be allocated.

Reimplemented from pw::Allocator.

DoResize()

template<typename MetricsType >

bool pw::allocator::TrackingAllocator< MetricsType >::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.