Class DistributedUIDGenerator

A Key generator that uses the current time in ms with the machine id to generate a unique value every time. This means it is safe for multiple users to add entries to the same table without suffering from conflicts due to the entries using the same key but having different values.

The implementation is based on this article https://www.callicoder.com/distributed-unique-id-sequence-number-generator/

The Key is made up of the following components:

Sequence Number	12 Bits(0 - 11)	A local counter per machine that starts at 0 and is incremented by 1 for each new id request that is made during the same millisecond. The value is limited to 12 bytes so can contain 4095 items before the ids for this millisecond are exhausted and the id generator must wait until the next millisecond before it can continue.
Machine Id	10 Bits(12-21)	The Id of the machine. By default, in the Editor, this value is generated from the machines network interface physical address however it can also be set to a user provided value. There is enough space for 1024 machines.
Epoch Timestamp.	41 Bits(22-63)	A timestamp using a custom epoch which is the time the class was created. The maximum timestamp that can be represented is 69 years from the custom epoch, at this point the Key generator will have exhausted its possible unique Ids.

Signed Bit 1 Bit(64) The signed bit is unused by the ID generator. If you wish to add custom Id values then using the signed bit and adding negative ids will avoid conflicts.

Inheritance

Object

DistributedUIDGenerator

Namespace: UnityEngine.Localization.Tables

Syntax

[Serializable]
public class DistributedUIDGenerator : IKeyGenerator

Constructors

DistributedUIDGenerator()

Create a default instance which uses the current time as the CustomEpoch the machines physical address as MachineId.

Declaration

public DistributedUIDGenerator()

DistributedUIDGenerator(Int64)

Creates an instance with a defined CustomEpoch.

Declaration

public DistributedUIDGenerator(long customEpoch)

Parameters

Type	Name	Description
Int64	customEpoch	The custom epoch is used to calculate the timestamp by taking the current time and subtracting the CustomEpoch. The value is then stored in 41 bits giving it a maximum time of 69 years.

Fields

MachineIdPrefKey

The name of the EditorPrefs that is used to store the machine id.

Declaration

public const string MachineIdPrefKey = "KeyGenerator-MachineId"

Field Value

Type	Description
String

Properties

CustomEpoch

The custom epoch used to generate the timestamp.

Declaration

public long CustomEpoch { get; }

Property Value

Type	Description
Int64

MachineId

The Id of the current machine. By default, in the Editor, this value is generated from the machines network interface physical address however it can also be set to a user provided value. There is enough space for 1024 unique machines. Set value will be clamped in the range 1-1023. The value is not serialized into the asset but stored into the EditorPrefs(Editor only).

Declaration

public int MachineId { get; set; }

Property Value

Type	Description
Int32

Methods

GetNextKey()

Returns the next Id using the current time, machine id and sequence number.

Declaration

public long GetNextKey()

Returns

Type	Description
Int64

Implements

IKeyGenerator.GetNextKey()