1bee3ba042
It's not needed to parse the whole ULID timestamp. All is needed is to check the first two bits. They are extra bits added by the base-32 encoding. Both bits must be ZERO. |
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| LICENSE | ||
| README.md | ||
| pom.xml | ||
README.md
ULID Creator
A Java library for generating ULIDs.
- Generated in lexicographical order;
- Can be stored as a UUID/GUID;
- Can be stored as a string of 26 chars;
- String format is encoded to Crockford's base32;
- String format is URL safe, case insensitive and accepts hyphens.
How to Use
Create a ULID:
UUID ulid = UlidCreator.getUlid(); // 01706d6c-6aad-c795-370c-98d0be881bba
Create a ULID string:
String ulid = UlidCreator.getUlidString(); // 01E1PPRTMSQ34W7JR5YSND6B8Z
Maven dependency
Add these lines to your pom.xml.
<!-- https://search.maven.org/artifact/com.github.f4b6a3/ulid-creator -->
<dependency>
<groupId>com.github.f4b6a3</groupId>
<artifactId>ulid-creator</artifactId>
<version>2.3.2</version>
</dependency>
See more options in maven.org.
Implementation
ULID
The GUIDs in this library are based on the ULID specification. The first 48 bits represent the count of milliseconds since Unix Epoch, 1 January 1970. The remaining 60 bits are generated by a secure random number generator.
Every time the timestamp changes the random part is reset to a new random value. If the current timestamp is equal to the previous one, the random bits are incremented by 1.
The default random number generator is java.security.SecureRandom.
// GUID based on ULID spec
UUID ulid = UlidCreator.getUlid();
// GUID based on ULID spec
// Compatible with RFC-4122 UUID v4
UUID ulid = UlidCreator.getUlid4();
Sequence of GUIDs based on ULID spec:
01706d6c-6aac-80bd-7ff5-f660c2dd58ea
01706d6c-6aac-80bd-7ff5-f660c2dd58eb
01706d6c-6aac-80bd-7ff5-f660c2dd58ec
01706d6c-6aac-80bd-7ff5-f660c2dd58ed
01706d6c-6aac-80bd-7ff5-f660c2dd58ee
01706d6c-6aac-80bd-7ff5-f660c2dd58ef
01706d6c-6aac-80bd-7ff5-f660c2dd58f0
01706d6c-6aac-80bd-7ff5-f660c2dd58f1
01706d6c-6aad-c795-370c-98d0be881bb8 < millisecond changed
01706d6c-6aad-c795-370c-98d0be881bb9
01706d6c-6aad-c795-370c-98d0be881bba
01706d6c-6aad-c795-370c-98d0be881bbb
01706d6c-6aad-c795-370c-98d0be881bbc
01706d6c-6aad-c795-370c-98d0be881bbd
01706d6c-6aad-c795-370c-98d0be881bbe
01706d6c-6aad-c795-370c-98d0be881bbf
^ look ^ look
|------------|---------------------|
millisecs randomness
ULID string
The ULID string is a sequence of 26 chars. See the ULID specification for more information.
See the section on GUIDs to know how the 128 bits are generated in this library.
// String based on ULID spec
String ulid = UlidCreator.getUlidString();
// String based on ULID spec
// Compatible with RFC-4122 UUID v4
String ulid = UlidCreator.getUlidString4();
Sequence of Strings based on ULID spec:
01E1PPRTMSQ34W7JR5YSND6B8T
01E1PPRTMSQ34W7JR5YSND6B8V
01E1PPRTMSQ34W7JR5YSND6B8W
01E1PPRTMSQ34W7JR5YSND6B8X
01E1PPRTMSQ34W7JR5YSND6B8Y
01E1PPRTMSQ34W7JR5YSND6B8Z
01E1PPRTMSQ34W7JR5YSND6B90
01E1PPRTMSQ34W7JR5YSND6B91
01E1PPRTMTYMX8G17TWSJJZMEE < millisecond changed
01E1PPRTMTYMX8G17TWSJJZMEF
01E1PPRTMTYMX8G17TWSJJZMEG
01E1PPRTMTYMX8G17TWSJJZMEH
01E1PPRTMTYMX8G17TWSJJZMEJ
01E1PPRTMTYMX8G17TWSJJZMEK
01E1PPRTMTYMX8G17TWSJJZMEM
01E1PPRTMTYMX8G17TWSJJZMEN
^ look ^ look
|---------|--------------|
millisecs randomness
How use the UlidSpecCreator directly
These are some examples of using the UlidSpecCreator to create ULID strings:
// with your custom timestamp strategy
TimestampStrategy customStrategy = new CustomTimestampStrategy();
UlidSpecCreator creator = UlidCreator.getUlidSpecCreator()
.withTimestampStrategy(customStrategy);
String ulid = creator.createString();
// with your custom random strategy that wraps any random generator
RandomStrategy customStrategy = new CustomRandomStrategy();
UlidSpecCreator creator = UlidCreator.getUlidSpecCreator()
.withRandomStrategy(customStrategy);
String ulid = creator.createString();
// with `java.util.Random` number generator
Random random = new Random();
UlidSpecCreator creator = UlidCreator.getUlidSpecCreator()
.withRandomGenerator(random);
String ulid = creator.createString();
Benchmark
This section shows benchmarks comparing UlidCreator to java.util.UUID.
- ulid-creator v2.1.0:
---------------------------------------------------------------------------
THROUGHPUT Mode Cnt Score Error Units
---------------------------------------------------------------------------
Throughput.JDK_RandomBased thrpt 5 2196,215 ± 13,668 ops/ms
Throughput.UlidCreator_Ulid thrpt 5 19224,340 ± 106,231 ops/ms
Throughput.UlidCreator_UlidString thrpt 5 5006,424 ± 26,946 ops/ms
---------------------------------------------------------------------------
Total time: 00:04:01
---------------------------------------------------------------------------
- ulid-creator v2.2.0:
---------------------------------------------------------------------------
THROUGHPUT Mode Cnt Score Error Units
---------------------------------------------------------------------------
Throughput.JDK_RandomBased thrpt 5 2191,690 ± 8,947 ops/ms
Throughput.UlidCreator_Ulid thrpt 5 19236,123 ± 156,123 ops/ms
Throughput.UlidCreator_UlidString thrpt 5 12893,016 ± 179,618 ops/ms <- 2.5x faster
---------------------------------------------------------------------------
Total time: 00:04:01
---------------------------------------------------------------------------
The ULID string generation is 2.5x faster in version 2.2.0 than before.
System: CPU i5-3330, 8G RAM, Ubuntu 20.04.