Block allocators

Overview

Classes
class	pw::allocator::BestFitAllocator< BlockType >
class	pw::allocator::BlockAllocator< BlockType_ >
class	pw::allocator::BasicBucketAllocator< BlockType >
class	pw::allocator::BucketAllocator< BlockType, kMinInnerSize, kNumBuckets >
class	pw::allocator::DlAllocator< BlockType >
class	pw::allocator::FirstFitAllocator< BlockType >
struct	pw::allocator::TlsfDefaults
struct	pw::allocator::TlsfIndices
	Pair used to index a bucket in a two dimensional array. More...
class	pw::allocator::TlsfAllocator< BlockType, kMinSize, kNumShelves >
class	pw::allocator::WorstFitAllocator< BlockType >

Typedefs
template<typename OffsetType >
using	pw::allocator::BestFitBlock = DetailedBlock< OffsetType, GenericFastSortedItem >
	Alias for a default block type that is compatible with FirstFitAllocator.
template<typename OffsetType = uintptr_t>
using	pw::allocator::BucketBlock = DetailedBlock< OffsetType, UnorderedItem >
template<typename OffsetType >
using	pw::allocator::DlBlock = DetailedBlock< OffsetType, GenericFastSortedItem >
	Alias for a default block type that is compatible with DlAllocator.
template<typename OffsetType >
using	pw::allocator::FirstFitBlock = DetailedBlock< OffsetType, SequencedItem >
	Alias for a default block type that is compatible with FirstFitAllocator.
template<typename OffsetType >
using	pw::allocator::TlsfBlock = DetailedBlock< OffsetType, GenericFastSortedItem >
	Alias for a default block type that is compatible with TlsfAllocator.
template<typename OffsetType >
using	pw::allocator::WorstFitBlock = DetailedBlock< OffsetType, GenericFastSortedItem >
	Alias for a default block type that is compatible with FirstFitAllocator.

Functions
size_t	pw::allocator::BestFitAllocator< BlockType >::DoGetMaxAllocatable () override
BlockResult< BlockType >	pw::allocator::BestFitAllocator< BlockType >::ChooseBlock (Layout layout) override
void	pw::allocator::BestFitAllocator< BlockType >::ReserveBlock (BlockType &block) override
void	pw::allocator::BestFitAllocator< BlockType >::RecycleBlock (BlockType &block) override

Typedef Documentation

BucketBlock

template<typename OffsetType = uintptr_t>

using pw::allocator::BucketBlock = typedef DetailedBlock<OffsetType, UnorderedItem>

Alias for a default block type that is compatible with BucketAllocator.

Function Documentation

ChooseBlock()

template<typename BlockType >

BlockResult< BlockType > pw::allocator::BestFitAllocator< BlockType >::ChooseBlock ( Layout  layout )

overrideprivatevirtual

Selects a free block to allocate from.

This method represents the allocator-specific strategy of choosing which block should be used to satisfy allocation requests. If the returned result indicates success, block will be replaced by the chosen block.

Parameters

block	Used to return the chosen block.
layout	Same as Allocator::Allocate.

Implements pw::allocator::BlockAllocator< BlockType_ >.

DoGetMaxAllocatable()

template<typename BlockType >

size_t pw::allocator::BestFitAllocator< BlockType >::DoGetMaxAllocatable

overrideprivatevirtual

Returns the largest single allocation that can succeed, given the current state of the allocator.

The largest allocation possible at any given time is the inner size of the largest free block. This method may be expensive to call if the block allocator implementation does not track its largest block. As a result, it should primarily be used for diagnostic purposes after an allocation failure, e.g.

auto my_object = block_allocator.MakeUnique<MyObject>(my_args);
if (my_object == nullptr) {
  PW_LOG("failed to allocate: needed %zu bytes, but only have %zu",
    sizeof(MyObject), block_allocator.GetMaxAllocatable());
}

Note that this method does not consider alignment. An allocation with a large alignment requirement may fail even when a large enough block is available if that block cannot satisfy the alignment requirement.

Implements pw::allocator::BlockAllocator< BlockType_ >.

RecycleBlock()

template<typename BlockType >

void pw::allocator::BestFitAllocator< BlockType >::RecycleBlock ( BlockType &  block )

overrideprivatevirtual

Indicates that a block is now free.

Does nothing by default. Derived class may overload to do additional bookkeeeping.

Parameters

block

The block being freed.

Reimplemented from pw::allocator::BlockAllocator< BlockType_ >.

ReserveBlock()

template<typename BlockType >

void pw::allocator::BestFitAllocator< BlockType >::ReserveBlock ( BlockType &  block )

overrideprivatevirtual

Indicates that a block will no longer be free.

Does nothing by default. Derived class may overload to do additional bookkeeeping.

Parameters

block

The block being freed.

Reimplemented from pw::allocator::BlockAllocator< BlockType_ >.