A Java library for generating Time-Sorted Unique Identifiers (TSID).

It brings together ideas from Twitter's Snowflake and ULID Spec.

In summary:

• Sorted by generation time;
• Can be stored as an integer of 64 bits;
• Can be stored as a string of 13 chars;
• String format is encoded to Crockford's base32;
• String format is URL safe, is case insensitive, and has no hyphens;
• Shorter than UUID, ULID and KSUID.

This project contains a micro benchmark and a good amount of unit tests.

The jar file can be downloaded directly from maven.org.

Recommended readings:

• Javadocs
• FAQ wiki page
• How to not use TSID factories
• The best UUID type for a database Primary Key
• The primary key dilemma: ID vs UUID and some practical solutions
• The best way to generate a TSID entity identifier with JPA and Hibernate
• Primary keys in the DB - what to use? ID vs UUID or is there something else?

Create a TSID:

Tsid tsid = TsidCreator.getTsid();

Create a TSID as long:

long number = TsidCreator.getTsid().toLong(); // 38352658567418872

Create a TSID as String:

String string = TsidCreator.getTsid().toString(); // 01226N0640J7Q

The TSID generator is thread-safe.

Add these lines to your pom.xml:

<!-- https://search.maven.org/artifact/com.github.f4b6a3/tsid-creator -->
<dependency>
  <groupId>com.github.f4b6a3</groupId>
  <artifactId>tsid-creator</artifactId>
  <version>5.2.4</version>
</dependency>

See more options in maven.org.

Module and bundle names are the same as the root package name.

• JPMS module name: com.github.f4b6a3.tsid
• OSGi symbolic name: com.github.f4b6a3.tsid

The Tsid.toLong() method simply unwraps the internal long value of a TSID.

long tsid = TsidCreator.getTsid().toLong();

Sequence of TSIDs:

38352658567418867
38352658567418868
38352658567418869
38352658567418870
38352658567418871
38352658567418872
38352658567418873
38352658567418874
38352658573940759 < millisecond changed
38352658573940760
38352658573940761
38352658573940762
38352658573940763
38352658573940764
38352658573940765
38352658573940766
         ^      ^ look
                                   
|--------|------|
   time   random

The Tsid.toString() method encodes a TSID to Crockford's base 32 encoding. The returned string is 13 characters long.

String tsid = TsidCreator.getTsid().toString();

Sequence of TSID strings:

01226N0640J7K
01226N0640J7M
01226N0640J7N
01226N0640J7P
01226N0640J7Q
01226N0640J7R
01226N0640J7S
01226N0640J7T
01226N0693HDA < millisecond changed
01226N0693HDB
01226N0693HDC
01226N0693HDD
01226N0693HDE
01226N0693HDF
01226N0693HDG
01226N0693HDH
        ^   ^ look
                                   
|-------|---|
   time random

The string format can be useful for languages that store numbers in double-precision 64-bit binary format IEEE 754, such as Javascript.

The term TSID stands for (roughly) Time-Sorted ID. A TSID is a number that is formed by the creation time along with random bits.

The TSID has 2 components:

• Time component (42 bits)
• Random component (22 bits)

The time component is the count of milliseconds since 2020-01-01 00:00:00 UTC.

The Random component has 2 sub-parts:

• Node ID (0 to 20 bits)
• Counter (2 to 22 bits)

The counter bits depend on the node bits. If the node bits are 10, the counter bits are limited to 12. In this example, the maximum node value is 2^10-1 = 1023 and the maximum counter value is 2^12-1 = 4095. So the maximum TSIDs that can be generated per millisecond is 4096.

The node identifier uses 10 bits of the random component by default in the TsidFactory. It's possible to adjust the node bits to a value between 0 and 20. The counter bits are affected by the node bits.

This is the default TSID structure:

                                            adjustable
                                           <---------->
|------------------------------------------|----------|------------|
       time (msecs since 2020-01-01)           node       counter
                42 bits                       10 bits     12 bits

- time:    2^42 = ~69 years or ~139 years (with adjustable epoch)
- node:    2^10 = 1,024 (with adjustable bits)
- counter: 2^12 = 4,096 (initially random)

Notes:
The node is adjustable from 0 to 20 bits.
The node bits affect the counter bits.
The time component can be used for ~69 years if stored in a SIGNED 64 bits integer field.
The time component can be used for ~139 years if stored in a UNSIGNED 64 bits integer field.

The time component can be 1 ms or more ahead of the system time when necessary to maintain monotonicity and generation speed.

The simplest way to avoid collisions is to make sure that each generator has its exclusive node ID.

The node ID can be given to TsidFactory by defining the tsidcreator.node system property or the TSIDCREATOR_NODE environment variable. Otherwise, the node identifier will be chosen randomly.

The total number of nodes can be given to TsidFactory by defining the tsidcreator.node.count system property or the TSIDCREATOR_NODE_COUNT environment variable. If this property or variable is set, TsidFactory will adjust the amount of bits needed to fit the given node count. For example, if the value 100 is given, the number of bits reserved for the node ID is set to 7, which is the minimum number of bits needed to fit 100 nodes. Otherwise, the default number of bits is set to 10, which can accommodate 1024 nodes.

System properties:

• tsidcreator.node: the node identifier.
• tsidcreator.node.count: the total number of nodes.

Environment variables:

• TSIDCREATOR_NODE: the node identifier.
• TSIDCREATOR_NODE_COUNT: the total number of nodes.

Using system properties:

// append to VM arguments
-Dtsidcreator.node="755"

// append to VM arguments
-Dtsidcreator.node="42" \
-Dtsidcreator.node.count="100"

Using environment variables:

# append to ~/.profile
export TSIDCREATOR_NODE="492"

# append to ~/.profile
export TSIDCREATOR_NODE="123"
export TSIDCREATOR_NODE_COUNT="200"

Create a quick TSID:

Tsid tsid = Tsid.fast();

Create a TSID from a canonical string (13 chars):

Tsid tsid = Tsid.from("0123456789ABC");

Convert a TSID into a canonical string in lower case:

String string = tsid.toLowerCase(); // 0123456789abc

Get the creation instant of a TSID:

Instant instant = tsid.getInstant(); // 2020-04-15T22:31:02.458Z

Encode a TSID to base-62:

String string = tsid.encode(62); // 0T5jFDIkmmy

Format a TSID to a string starting with a letter, where "K" is the letter and "%S" is a placeholder:

String string = tsid.format("K%S"); // K0AWE5HZP3SKTK

A key generator that makes substitution easy if necessary:

package com.example;

import com.github.f4b6a3.tsid.TsidCreator;

public class KeyGenerator {
    public static String next() {
        return TsidCreator.getTsid().toString();
    }
}

String key = KeyGenerator.next();

A TsidFactory with a FIXED node identifier:

int node = 256; // max: 2^10
TsidFactory factory = new TsidFactory(node);

// use the factory
Tsid tsid = factory.create();

A TsidFactory with a FIXED node identifier and CUSTOM node bits:

// setup a factory for up to 64 nodes and 65536 ID/ms.
TsidFactory factory = TsidFactory.builder()
    .withNodeBits(6)      // max: 20
    .withNode(63)         // max: 2^nodeBits
    .build();

// use the factory
Tsid tsid = factory.create();

A TsidFactory with a CUSTOM epoch:

// use a CUSTOM epoch that starts from the fall of the Berlin Wall
Instant customEpoch = Instant.parse("1989-11-09T00:00:00Z");
TsidFactory factory = TsidFactory.builder().withCustomEpoch(customEpoch).build();

// use the factory
Tsid tsid = factory.create();

A TsidFactory with java.util.Random:

// use a `java.util.Random` instance for fast generation
TsidFactory factory = TsidFactory.builder().withRandom(new Random()).build();

// use the factory
Tsid tsid = factory.create();

A TsidFactory with RandomGenerator (JDK 17+):

// use a random function that returns an int value
RandomGenerator random = RandomGenerator.getDefault();
TsidFactory factory = TsidFactory.builder()
    .withRandomFunction(() -> random.nextInt())
    .build();

// use the factory
Tsid tsid = factory.create();

A TsidFactory with ThreadLocalRandom:

// use a random function that returns an int value
TsidFactory factory = TsidFactory.builder()
    .withRandomFunction(() -> ThreadLocalRandom.current().nextInt())
    .build();

// use the factory
Tsid tsid = factory.create();

A TsidFactory that creates TSIDs similar to Twitter Snowflakes:

// Twitter Snowflakes have 5 bits for datacenter ID and 5 bits for worker ID
int datacenter = 1; // max: 2^5-1 = 31
int worker = 1;     // max: 2^5-1 = 31
int node = (datacenter << 5 | worker); // max: 2^10-1 = 1023

// Twitter Epoch is fixed in 1288834974657 (2010-11-04T01:42:54.657Z)
Instant customEpoch = Instant.ofEpochMilli(1288834974657L);

// a function that returns an array with ZEROS, making the factory
// to RESET the counter to ZERO when the millisecond changes
IntFunction<byte[]> randomFunction = (x) -> new byte[x];

// a factory that returns TSIDs similar to Twitter Snowflakes
TsidFactory factory = TsidFactory.builder()
		.withRandomFunction(randomFunction)
		.withCustomEpoch(customEpoch)
		.withNode(node)
		.build();

// use the factory
Tsid tsid = factory.create();

A TsidFactory that creates TSIDs similar to Discord Snowflakes:

// Discord Snowflakes have 5 bits for worker ID and 5 bits for process ID
int worker = 1;  // max: 2^5-1 = 31
int process = 1; // max: 2^5-1 = 31
int node = (worker << 5 | process); // max: 2^10-1 = 1023

// Discord Epoch starts in the first millisecond of 2015
Instant customEpoch = Instant.parse("2015-01-01T00:00:00.000Z");

// a factory that returns TSIDs similar to Discord Snowflakes
TsidFactory factory = TsidFactory.builder()
		.withCustomEpoch(customEpoch)
		.withNode(node)
		.build();

// use the factory
Tsid tsid = factory.create();

This section shows benchmarks comparing TsidCreator to java.util.UUID.

---------------------------------------------------------------------------
THROUGHPUT (operations/msec)       Mode  Cnt      Score      Error   Units
---------------------------------------------------------------------------
UUID_randomUUID                   thrpt    5   1630,938 ±  183,581  ops/ms
UUID_randomUUID_toString          thrpt    5   1604,916 ±  189,711  ops/ms
-  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  - 
Tsid_fast                         thrpt    5  37397,739 ± 1128,756  ops/ms
Tsid_fast_toString                thrpt    5  21144,662 ±  673,939  ops/ms
-  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  - 
TsidCreator_getTsid256            thrpt    5  10727,236 ±  761,920  ops/ms
TsidCreator_getTsid256_toString   thrpt    5   6813,193 ±  867,041  ops/ms
-  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  - 
TsidCreator_getTsid1024           thrpt    5  12146,561 ± 1533,959  ops/ms
TsidCreator_getTsid1024_toString  thrpt    5   6507,373 ±  729,444  ops/ms
-  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  -  - 
TsidCreator_getTsid4096           thrpt    5  11589,976 ± 1757,076  ops/ms
TsidCreator_getTsid4096_toString  thrpt    5   6497,042 ± 1339,480  ops/ms
---------------------------------------------------------------------------
Total time: 00:03:22
---------------------------------------------------------------------------

Number of threads used in this the benchmark: 4.

System: CPU i7-8565U, 16G RAM, Ubuntu 22.04, JVM 11, rng-tools installed.

To execute the benchmark, run ./benchmark/run.sh.

Ports and forks:

Other OSS:

This library is Open Source software released under the MIT license.