Vkm::Engine::SlotAllocator Class Reference

Lightweight slot allocator that issues generation-safe handles. More...

#include <slot_allocator.h>

Public Member Functions
StorageIndex	allocate (bool *recycled=nullptr)
	Allocate a new handle with a unique index and current generation.
void	free (StorageIndex id)
	Free a handle, bumping its generation and recycling the slot.
bool	has (StorageIndex id) const
	Test whether a handle is still valid.
StorageIndex	handleAt (uint32_t index) const
	Rebuild the handle naming a sparse slot, generation included.
bool	isAliveAtIndex (uint32_t index) const
	Check whether index currently holds a live slot.
StorageIndex	allocateAt (uint32_t index)
	Allocate a slot at a specific index.
template<typename Fn>
void	forEach (Fn &&fn) const
	Invoke fn(index) for every currently-alive slot.
void	clear ()
	Reset every slot to dead, bumping generations so outstanding handles go stale.
void	swap (SlotAllocator &other) noexcept
	Swap internal state with another allocator.
size_t	size () const
	Number of live slots.
size_t	extent () const
	Number of slots the table spans, live or free, slot 0 included.

Static Public Attributes
static constexpr uint32_t	MAX_CLAIMED_INDEX = 1u << 22
	The highest index allocateAt will claim.

Detailed Description

Lightweight slot allocator that issues generation-safe handles.

Generation counters detect stale handles; a free list recycles in O(1). Stores no per-slot data.

Member Function Documentation

allocate()

StorageIndex Vkm::Engine::SlotAllocator::allocate ( bool * recycled = nullptr )

inline

Allocate a new handle with a unique index and current generation.

Parameters

[out]

recycled

True when the slot came off the free list (used before, or an allocateAt gap); false when freshly grown, so nothing keyed by its index can be under it.

Returns

A handle with index > 0.

free()

void Vkm::Engine::SlotAllocator::free ( StorageIndex id )

inline

Free a handle, bumping its generation and recycling the slot.

A dead handle asserts and is refused: freeing twice underflows m_liveCount.

Parameters

id	Live handle to free.

has()

bool Vkm::Engine::SlotAllocator::has ( StorageIndex id ) const

inline

Test whether a handle is still valid.

Parameters

id	Handle to validate.

Returns

True if alive and generation matches.

handleAt()

StorageIndex Vkm::Engine::SlotAllocator::handleAt ( uint32_t index ) const

inline

Rebuild the handle naming a sparse slot, generation included.

A dead slot yields its real generation, so the handle fails has().

Parameters

index

Sparse slot index.

Returns

The handle for that slot, null when the index is out of reach.

isAliveAtIndex()

bool Vkm::Engine::SlotAllocator::isAliveAtIndex ( uint32_t index ) const

inline

Check whether index currently holds a live slot.

Parameters

index

Sparse slot index; out of reach is fine.

Returns

True when that slot is live; never for slot 0.

allocateAt()

StorageIndex Vkm::Engine::SlotAllocator::allocateAt ( uint32_t index )

inline

Allocate a slot at a specific index.

For a loader whose entities keep their saved slot indices. Gaps grown across go onto the free list. A claimed slot still in the free list is skipped when popped, not erased (a linear find per call).

Parameters

index

Slot to claim; must be free.

Returns

The new handle, or null for slot 0, an index past MAX_CLAIMED_INDEX (test for these: the index often comes from outside the process), or a live slot (also asserts).

forEach()

template<typename Fn>

void Vkm::Engine::SlotAllocator::forEach ( Fn && fn ) const

inline

Invoke fn(index) for every currently-alive slot.

Template Parameters

Fn	Callable taking a uint32_t slot index.

Parameters

fn	Called once per live slot, ascending by index; never slot 0.

swap()

void Vkm::Engine::SlotAllocator::swap ( SlotAllocator & other )

inlinenoexcept

Swap internal state with another allocator.

For Scene's staging-then-swap load, without copying or moving.

Parameters

other

Allocator to trade state with.

size()

size_t Vkm::Engine::SlotAllocator::size ( ) const

inline

Number of live slots.

Returns

The live slot count.

extent()

size_t Vkm::Engine::SlotAllocator::extent ( ) const

inline

Number of slots the table spans, live or free, slot 0 included.

Returns

One past the highest slot ever handed out.

Member Data Documentation

MAX_CLAIMED_INDEX

uint32_t Vkm::Engine::SlotAllocator::MAX_CLAIMED_INDEX = 1u << 22

staticconstexpr

The highest index allocateAt will claim.

allocateAt grows the table to an index often read from a file or a datagram, so this bounds what a file or a peer can make it allocate.

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

• core/memory/slot_allocator.h