Snowflake4J

For high availability within and across data centers, machines generating ids should not have to coordinate with each other.

IDs are composed of:

• time - 41 bits (millisecond precision w/ a custom epoch gives us 69 years)
• configured machine id - 10 bits - gives us up to 1024 machines
• sequence number - 12 bits - rolls over every 4096 per machine (with protection to avoid rollover in the same ms)

References:

• https://github.com/twitter/snowflake/tree/snowflake-2010

Module	Javadoc

Library Features

• protects from non-monotonic clocks, i.e. clocks that run backwards
• snowflake parsing (with id + epoch offset)
• id generation with a customizable epoch offset

Import

Gradle - Kotlin DSL

implementation("com.github.philippheuer.snowflake4j:snowflake4j:1.0.1")

Usage

Id Generation

// initialize global generator instance
SnowflakeGenerator.setInstance(SnowflakeGenerator.builder().epochOffset(offset).nodeId(1).build());
// get id
Snowflake snowflake = SnowflakeGenerator.getInstance().nextSnowflake();
System.out.println(snowflake.getId());

Parsing

Snowflake snowflake = Snowflake.fromSnowflake(1420070400000L, 143000477531897856L);

Default Epoch

The epoch used in the default instance is 2020-10-01T00:00:00.000Z (1601510400000L). Snowflake generation will work for ~69 years after the set epoch.

Common Epochs:

• Discord: 1420070400000

License

Released under the MIT License.