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C-style structs on the JVM!

ZERO garbage, ZERO reflection, ZERO code generation.
EASY to use, and with INCREDIBLE performance.

Maven Central Build Status license

Declaring Strukts to manage your Strukt

First you need to create a Strukts which manages your Strukt (allocates, frees, etc.).

Fixed: uses a single memory allocation and addresses are given with an offset. This is the fastest option available.

object Points : FixedStrukts(Point::class, capacity)

Persisted fixed: same as above, except uses a memory-mapped file rather than system memory and persists to disk. This means you can allocate with as much space as disk space, rather than RAM. There is practically no performance penalty for using this over .fixed(capacity)!

object Points : FixedStrukts(Point::class, capacity, persistedTo: File|String)

Elastic: similar to .fixed(capacity) except will dynamically resize, and has a performance penalty of a few operations for that capability.

object Points : ElasticStrukts(Point::class, initialCapacity = 1024, growthFactor = 2.0)

Pointed: uses a laid-out pointer system, this option supports unlimited allocations without any "resizing" necessary. Note: Since a memory allocation and a memory copy is necessary, this has slow allocations.

object Points : PointedStrukts(Point::class)

Declaring fields of your Strukt

You need to declare your fields within your Struktss using delegates to the default value.

The value you delegate to determines the field's type, and the default value for each allocation -- in this case it's an Int of the default value 0 for both.

object Points : ElasticStrukts(Point::class) {
	val x by 0
	val y by 0

All primitive types are supported, and even enums:

enum class Type { DEFAULT, SPECIAL }

object Points : ElasticStrukts(Point::class) {
        val x by 0
        val y by 0
        val type by Type.DEFAULT  

Declaring your inline Strukt

inline class Point(override val address: Long = Points()) : Strukt {
	var x
		get() = Points.x(address)
		set(x) = Points.x(address, x)
	var y
		get() = Points.y(address)
		set(y) = Points.y(address, y)

Because of the way inlining works, you'll notice that we need to provide virtual fields using our previously defined fields.

You should also notice the use of Strukts.invoke as a default value for allocating our address.

Allocating a Strukt

The syntax for allocation is the same as a regular object!

For the above Point example, this might look like:

val example = Point()

Accessing fields

Accessing fields is exactly like normal objects!

example.y = 123
println("x: ${example.x}, y: ${example.y}") // 0, 123

Freeing a Strukt

To free any Strukt, you can use:

The reason this longer syntax is necessary is because we want to avoid "generic" type use of our inline class, to prevent creating boxed instances.

Thread Safety

It's easy to make your fields thread-safe! Just annotate them with @ThreadSafe and use a ThreadSafeType (NONE, VOLATILE, or SYNCHRONIZED).

import org.jire.strukt.ThreadSafeType.*

object Points : ElasticStrukts(Point::class) {
  @ThreadSafe(VOLATILE) val x by 0
  @ThreadSafe(SYNCHRONIZED) val y by 0

Using in Java

It's not too hard to define and use a Strukt in Java!

public interface Point extends Strukt {
	Strukts points = Strukts.elastic(Point.class);
	IntField x = points.intField(0);
	IntField y = points.intField(0, ThreadSafeType.VOLATILE);
	static long allocate() {
		return points.allocate();


You can then use it like so:

long example = Point.allocate();

Point.y.set(example, 123);
System.out.println("x: " + Point.x.get(example) + ", y: " + Point.y.get(example)); // 0, 123


Benchmark sources:

Test Bench

  • OS: Windows 10 Pro 64-bit (10.0, Build 19042)
  • CPU: Intel(R) Core(TM) i7-6700K CPU @ 4.60GHz (8 CPUs), ~4.6GHz
  • RAM: 2x 16GB DDR4-2100MHz
  • JMH version: 1.25
  • VM version: JDK 1.8.0_271, Java HotSpot(TM) 64-Bit Server VM, 25.271-b09
  • VM options: Tested on an Intel i7 6700K @ 4.6GHz with default Oracle JDK 8 VM parameters on Windows 10:
Benchmark                                  Mode  Cnt          Score   Error  Units                             thrpt       434769304.174          ops/s                          thrpt       372296437.498          ops/s                            thrpt       438208243.968          ops/s                          thrpt       418701531.606          ops/s

HeapWrite.write                           thrpt       561591456.153          ops/s
PointedWrite.write                        thrpt       622915634.215          ops/s
FixedWrite.write                          thrpt       631370517.687          ops/s
ElasticWrite.write                        thrpt       600571289.654          ops/s

HeapAllocate.allocate                        ss              96.597          ms/op
PointedAllocate.allocate                     ss           20556.955          ms/op
FixedAllocate.allocate                       ss            2436.920          ms/op
ElasticAllocate.allocate                     ss            1882.812          ms/op                               ss            4836.308          ms/op                             ss            4876.006          ms/op