Snowflake Id Generator

Generate unique identifiers based on Twitter's Snowflake ID. Parse a Snowflake to get information about it's creation.

• Snowflakes
• Usage
  • Generate
    • Using the SnowflakeIDGenerator class
    • Using the SnowflakeIDGenerator class as static
    • Using a non-standard date as epoch
  • Parsing an Id
  • The Snowflake object
  • Changing Epoch on generated codes

Snowflakes

Snowflakes (or SnoflakeIds) are a form of generating identifiers used in distributed computing that, when used properly, guarantees uniqueness between systems, since one of it's components refers to the system creating the ID.

The other components refer to the current date and time, in order not to keep track of a long running sequencer (for example, a sequence in a database), and a short (in memory) sequence, to allow the generation of several codes in a short amount of time.

Image Source & credit available in wikimedia. "instance" in this image replaces machineId in the library / package

Usage

Generate

There are 2 ways of using the generator:

• Using the SnowflakeIDGenerator class as a static class. Useful when generating a single code to avoid dealing with constructors and the scope of the generator object.
• Instantiating the SnowflakeIDGenerator class. Recommended if you plan to generate more than a few codes at the same time.

  On version 1.4.2024 and up you can use the interface ISnowflakeIDGenerator. If you prefer to use dependency injection, the package SnowflakeIDGenerator.DependencyInjection might be helpful.

Using the SnowflakeIDGenerator class

1. Instantiate class SnowflakeIDGenerator

SnowflakeIDGenerator generator = new SnowflakeIDGenerator(machineId);

where machineId is the number / identifier of the system currently trying to get an id

Starting on version 1.1.2023 you can instruct the generator to use a custom date as epoch from which the timestamps are derived for the current date.

SnowflakeIDGenerator generator = new SnowflakeIDGenerator(machineId, CustomEpoch);

2. Using the generator object, there are 3 ways of obtaining the code:
   1. Call generator.GetSnowflake() to get a Snowflake object
   2. Call generator.GetCode() to get an Id in number (ulong) format
   3. Call generator.GetCodeString() to get an Id in string format

Using the SnowflakeIDGenerator class as static

If you only need to get a single Id, it's easier to just use the generator class as static.

The method names are the same as when using the generator, except they need the machineId as parameter:

1. Call SnowflakeIDGenerator.GetSnowflake(machineId) to get a Snowflake object
2. Call SnowflakeIDGenerator.GetCode(machineId) to get an Id in number (ulong) format
3. Call SnowflakeIDGenerator.GetCodeString(machineId) to get an Id in string format

Using a non-standard date as epoch

version 1.1.2023 and up

The first component of the codes is the amount of milliseconds elapsed since a set point in time, called epoch. By default, the generator uses the unix epoch (jan-1-1970 12:00:00am) as starting point to count.

Adding a DateTime object as an extra parameter when using the generator allows to change the zero value to be used to count milliseconds to.

DateTime customEpoch = new DateTime(year: 2020, month: 1, day: 1, hour: 0, minute: 0, second: 0, DateTimeKind.Utc);

// Creating the generator class
SnowflakeIDGenerator generator = new SnowflakeIDGenerator(machineId, customEpoch);

// This works when using as static too!
SnowflakeIDGenerator.GetSnowflake(machineId, customEpoch)

Parsing an Id

Parse a Snowflake either from a string or a number (ulong) in order to get information regarding the generation, such as the time or the machine that generated the code.

If a custom epoch was used when generating, that DateTime must be passed as second parameter when parsing in order to get the right generation date.

string s = "06975580616378931208";
ulong n = 6975580821430984519ul;
Snowflake fromString = Snowflake.Parse(s);
var utcDateTimeFromString = fromString.UtcDateTime; // 13/9/2022 22:26:58
var timestampFromString = fromString.Timestamp;     // 1663108018965
var machineIdFromString = fromString.MachineId;     // 477
var sequenceFromString = fromString.Sequence;       // 2056

Snowflake fromNumber = Snowflake.Parse(n);
var utcDateTimeFromNumber = fromNumber.UtcDateTime; // 13/9/2022 22:27:47
var timestampFromNumber = fromNumber.Timestamp;     // 1663108067853
var machineIdFromNumber = fromNumber.MachineId;     // 701
var sequenceFromNumber = fromNumber.Sequence;       // 3911

Additionally, starting on version 1.2.2023 you can cast a string or a number (ulong) directly into a Snowflake without using the Parse() method (only when using the default epoch).

string s = "06975580616378931208";
ulong n = 6975580821430984519ul;
Snowflake fromString = (Snowflake)s;
var utcDateTimeFromString = fromString.UtcDateTime; // 13/9/2022 22:26:58
var timestampFromString = fromString.Timestamp;     // 1663108018965
var machineIdFromString = fromString.MachineId;     // 477
var sequenceFromString = fromString.Sequence;       // 2056

Snowflake fromNumber = (Snowflake)n;
var utcDateTimeFromNumber = fromNumber.UtcDateTime; // 13/9/2022 22:27:47
var timestampFromNumber = fromNumber.Timestamp;     // 1663108067853
var machineIdFromNumber = fromNumber.MachineId;     // 701
var sequenceFromNumber = fromNumber.Sequence;       // 3911

The Snowflake object

While the SnowflakeIDGenerator class keeps track of time, machine and sequence, a Snowflake object keeps track of the meaning of the code, and allows to extract information about said code.

For example, as seen on the parsing an Id section, when working with a Snowflake object (either parsed or just generated), you can see some information. The available fields are:

• UtcDateTime: The creation date (UTC format)
• Timestamp and TimestampInt64 The timestamp component of the code. Amount of milliseconds since the configured epoch
• MachineId and MachineIdInt32: the machine / terminal / server that created the id
• Sequence and SequenceInt32: The sequencer. If greater than 0, multiple ids where generated withing the same millisecond
• Id: The Snowflake id in ulong format
• Code: The Snowflake id as String

Changing Epoch on generated codes

If you need to change the epoch on an already generated code, use ChangeEpoch() to change it keeping the same code but changing the represented date, or use RebaseEpoch() to keep the date but changing the final code.