Struct EntityRecordHeader

Namespace

Typhon.Engine

Assembly

Typhon.Engine.dll

Header of an entity record stored in the per-archetype LinearHash. 14 bytes: BornTSN (6B) + DiedTSN (6B) + EnabledBits (2B). Component locations (4B × N) follow immediately after in raw byte storage.

public struct EntityRecordHeader

Inherited Members

ValueType.Equals(object)

ValueType.GetHashCode()

ValueType.ToString()

object.GetType()

object.Equals(object, object)

object.ReferenceEquals(object, object)

Remarks

TSN packing follows the same pattern as CompRevStorageElement: upper 32 bits + lower 16 bits = 48-bit TSN. Non-aligned 6-byte fields are safe because the per-bucket OLC latch serializes writers and detects torn reads.

Fields

BornTsnHigh

Upper 32 bits of the 48-bit BornTSN; combine with BornTsnLow via BornTSN.

public uint BornTsnHigh

Field Value

uint

BornTsnLow

Lower 16 bits of the 48-bit BornTSN; combine with BornTsnHigh via BornTSN.

public ushort BornTsnLow

Field Value

ushort

DiedTsnHigh

Upper 32 bits of the 48-bit DiedTSN; combine with DiedTsnLow via DiedTSN. 0 = alive.

public uint DiedTsnHigh

Field Value

uint

DiedTsnLow

Lower 16 bits of the 48-bit DiedTSN; combine with DiedTsnHigh via DiedTSN. 0 = alive.

public ushort DiedTsnLow

Field Value

ushort

EnabledBits

Per-component enable mask: bit N set means component slot N is enabled.

public ushort EnabledBits

Field Value

ushort

Properties

BornTSN

48-bit BornTSN packed as upper 32 + lower 16.

public long BornTSN { readonly get; set; }

Property Value

long

DiedTSN

48-bit DiedTSN packed as upper 32 + lower 16.

public long DiedTSN { readonly get; set; }

Property Value

long

IsAlive

True if the entity has not been destroyed (DiedTSN == 0).

public readonly bool IsAlive { get; }

Property Value

bool

Methods

IsVisibleAt(long)

Check whether this entity is visible to a transaction with the given TSN.

public readonly bool IsVisibleAt(long txTsn)

Parameters

txTsn long

Returns

bool

Remarks

Visibility rules (snapshot isolation):

• BornTSN == 0: genesis entity, always visible
• BornTSN != 0 and BornTSN > txTsn: not born yet → invisible
• DiedTSN == 0: alive → visible (if born)
• DiedTSN != 0 and DiedTSN <= txTsn: dead at this snapshot → invisible