TSSAMHandleTable | Unreal Engine 5.8 Documentation

Chunked handle table with generational ABA protection.

Storage is backed by TLockFreeAllocOnceIndexedAllocator (chunked pages, pointer-stable GetItem). Slot allocation (FreeList pop / NextIndex++) and lazy page materialization share a single mutex. Serializing producers guarantees a newly-allocated slot's memory is fully initialized before any consumer observes the slot index; register/unregister traffic isn't hot enough to justify a lockless design at this layer.

GetIndex / SetIndex / IsValid are lock-free on the slot's own atomics (generation + registration index); these are called outside Allocate/Release and don't need the table-level mutex. GetIndex additionally range-checks the handle against an atomic NextIndex (release-stored after page materialization in Allocate), rejecting forged or corrupted handles before any storage access.

Generation-based ABA protection: every Release bumps the slot's Generation, invalidating every outstanding copy of the previous handle. A stale handle (generation mismatch):

Returns INDEX_NONE from GetIndex.
Silently no-ops in SetIndex (no clobber of a recycled slot).
Silently no-ops in Release (no double-bump, no double-push to the free list). These checks are enforced with real runtime logic, not check() macros, so the protection holds in shipping builds.


Name	TSSAMHandleTable
Type	class
Header File	/Engine/Source/Runtime/Engine/Public/Streaming/SimpleStreamableAssetManagerHandle.h
Include Path	#include "Streaming/SimpleStreamableAssetManagerHandle.h"

Syntax

template<typename HandleT>  
class TSSAMHandleTable

Typedefs

Name	Type	Remarks	Include Path
FStorage	TLockFreeAllocOnceIndexedAllocator< FSSAMSlot, MaxSlots, SlotsPerPage >		Streaming/SimpleStreamableAssetManagerHandle.h

Constants

Name	Type	Remarks	Include Path
MaxSlots	uint32		Streaming/SimpleStreamableAssetManagerHandle.h
SlotsPerPage	uint32		Streaming/SimpleStreamableAssetManagerHandle.h

Variables

Protected

Name	Type	Remarks	Include Path
FreeList	TArray< uint32 >		Streaming/SimpleStreamableAssetManagerHandle.h
Mutex	UE::FMutex		Streaming/SimpleStreamableAssetManagerHandle.h
NextIndex	std::atomic< uint32 >	Monotonic high-water mark of slot indices ever issued.	Streaming/SimpleStreamableAssetManagerHandle.h
NextMaterializedItem	uint32		Streaming/SimpleStreamableAssetManagerHandle.h
SlotStorage	FStorage	SlotStorage is mutable because TLockFreeAllocOnceIndexedAllocator declares GetItem non-const even though it's semantically a read-only atomic load.	Streaming/SimpleStreamableAssetManagerHandle.h

Functions

Public

Name	Remarks	Include Path
HandleT Allocate()		Streaming/SimpleStreamableAssetManagerHandle.h
uint32 GetAllocatedSize()		Streaming/SimpleStreamableAssetManagerHandle.h
int32 GetIndex ( HandleT SSAMHandle ) const		Streaming/SimpleStreamableAssetManagerHandle.h
bool IsValid ( HandleT SSAMHandle ) const		Streaming/SimpleStreamableAssetManagerHandle.h
int32 Release ( HandleT SSAMHandle )	Invalidate the handle and recycle the slot.	Streaming/SimpleStreamableAssetManagerHandle.h
void SetIndex ( HandleT SSAMHandle, int32 NewIndex )	Store a new registration index.	Streaming/SimpleStreamableAssetManagerHandle.h

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