TSparseListSet | Unreal Engine 5.6 Documentation

API > API/Runtime > API/Runtime/GeometryCore

TSparseListSet stores a sparse set of indexed variable-size lists. This is useful in cases where many relatively small lists that have a 1-1 correspondence with a bounded index space are needed, eg for per-vertex lists for a mesh, per-cell lists for an octree, etc.

The interface is compatible with FSmallListSet, which may be more effective for very small lists (optimized for ~8 elements), but does not scale very well to larger lists (10s-to-100s).

Internally, TSparseListSet uses a strategy where the small lists are stored in sequences of fixed-size blocks, similar to FDynamicVector, but the block size is configurable. The blocks are allocated from larger "chunks" of blocks (also of configurable size). These parameters can be set on construction to values appropriate for particular use cases.

TSparseListSet can support parallel insertion into the lists. Note however that lists cannot be added (via AllocateAt) while parallel insertion occurs via Insert(Index). To allow for this type of usage, AllocateAt() returns a FListHandle which can then be used with Insert() or SetValues() even while other AllocateAt() calls occur (within a lock).


Name	TSparseListSet
Type	struct
Header File	/Engine/Source/Runtime/GeometryCore/Public/Util/SparseListSet.h
Include Path	#include "Util/SparseListSet.h"

Syntax

template<typename ElementType>  
struct TSparseListSet

Constructors

Name	Remarks	Include Path	Unreal Specifiers
TSparseListSet ()		Util/SparseListSet.h
TSparseListSet ( int BlockSizeIn, int BlocksPerChunkIn )		Util/SparseListSet.h

Structs

Name	Remarks
FChunk	Large block of memory from which smaller blocks are allocated
FList
FListHandle	Handle to an allocated list returned by AllocateAt()

Variables

Protected

Name	Type	Remarks	Include Path
AllocationLock	FCriticalSection		Util/SparseListSet.h
BlockSize	int	Size of a list memory block, ie lists are allocated in blocks of this size, so also the minimum size (in memory) of a list even if it has 0 elements	Util/SparseListSet.h
BlocksPerChunk	int	Number of memory blocks in a "chunk", chunks are allocated as needed, so minimum size of a TSparseListSet is (BlocksPerChunk * BlockSize * sizeof(ElementType))	Util/SparseListSet.h
ChunkList	TArray< TUniquePtr< FChunk > >		Util/SparseListSet.h
FreeList	TArray< ElementType * >		Util/SparseListSet.h
Lists	TDynamicVector< FList >		Util/SparseListSet.h

Functions

Public

Name	Remarks	Include Path
FListHandle AllocateAt ( int32 ListIndex )	Create a list at the given ListIndex	Util/SparseListSet.h
void Clear ( int32 ListIndex )	Remove all elements from the list at ListIndex	Util/SparseListSet.h
bool Contains ( int32 ListIndex, ElementType Value ) const	Search for the given Value in list at ListIndex	Util/SparseListSet.h
void Enumerate ( int32 ListIndex, FuncType Func ) const	Call ApplyFunc on each element of the list at ListIndex	Util/SparseListSet.h
bool EnumerateEarlyOut ( int32 ListIndex, FuncType ApplyFunc ) const	Call ApplyFunc on each element of the list at ListIndex, until ApplyFunc returns false	Util/SparseListSet.h
int32 GetCount ( int32 ListIndex ) const		Util/SparseListSet.h
void Insert ( FListHandle ListHandle, ElementType Value )	Insert Value into List identified by ListHandle	Util/SparseListSet.h
void Insert ( int32 ListIndex, ElementType Value )	Insert Value into List at ListIndex	Util/SparseListSet.h
bool IsAllocated ( int32 ListIndex ) const		Util/SparseListSet.h
bool Remove ( int32 ListIndex, ElementType Value )	Remove first occurrence of Value from the list at ListIndex	Util/SparseListSet.h
void SetValues ( int32 ListIndex, const TArray< ElementType >& Values )	Set the values of the List at ListIndex	Util/SparseListSet.h
void SetValues ( FListHandle ListHandle, const TArray< ElementType >& Values )	Set the values of the List identified by ListHandle	Util/SparseListSet.h

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