GraalVM native shared library for scala

[burakakca]

Feature request

Please include the following information:

I'm looking for a Native Shared Library and I want to achieve with scala

Is your feature request related to a problem? Please describe.

Error: Entry point method MyMath$.incrementFunctionScala is not static. Add a static modifier to the method.

import com.google.common.math.IntMath
import org.graalvm.nativeimage.IsolateThread
import org.graalvm.nativeimage.c.function.CEntryPoint


class MyMath {
  override def toString = "Hello"
}

object MyMath {
  var count = 0

  @CEntryPoint(name = "ceilingPowerOfTwoScala")
  def ceilingPowerOfTwoScala(thread: IsolateThread, x: Int): Int = {
    count = IntMath.ceilingPowerOfTwo(x)
    count
  }

  @CEntryPoint(name = "incrementFunctionScala")
  def incrementFunctionScala(thread: IsolateThread): Int = IntMath.checkedAdd(count, 1)
}

Task :app:nativeCompile
[native-image-plugin] GraalVM Toolchain detection is enabled
[native-image-plugin] GraalVM uses toolchain detection. Selected:
[native-image-plugin]    - language version: 17
[native-image-plugin]    - vendor: GraalVM Community
[native-image-plugin]    - runtime version: 17.0.5+8-jvmci-22.3-b08
[native-image-plugin] Native Image executable path: /home/burak/graalvm-ce-java17-22.3.0/lib/svm/bin/native-image
========================================================================================================================
GraalVM Native Image: Generating 'libmymath' (shared library)...
========================================================================================================================

[1/7] Initializing...                                                                                    (0.0s @ 0.14GB)
Error: Entry point method MyMath$.incrementFunctionScala is not static. Add a static modifier to the method.
Error: Use -H:+ReportExceptionStackTraces to print stacktrace of underlying exception
------------------------------------------------------------------------------------------------------------------------
                        0.2s (8.7% of total time) in 10 GCs | Peak RSS: 0.63GB | CPU load: 4.03
========================================================================================================================
Failed generating 'libmymath' after 1.8s.

On another hand, without that example, I get the below section of output and there is no .h header file for my object

class MyMath {
  override def toString = "Hello"
}

object MyMath {
  def getFoo = "Foo"
}

Describe who do you think will benefit the most.
to reach scala environment

[oubidar-Abderrahim]

Thank you for your report, tracked internally on GR 42873

[tarsa]

Error: Entry point method MyMath$.incrementFunctionScala is not static. Add a static modifier to the method.

import com.google.common.math.IntMath
import org.graalvm.nativeimage.IsolateThread
import org.graalvm.nativeimage.c.function.CEntryPoint


class MyMath {
  override def toString = "Hello"
}

object MyMath {
  var count = 0

  @CEntryPoint(name = "ceilingPowerOfTwoScala")
  def ceilingPowerOfTwoScala(thread: IsolateThread, x: Int): Int = {
    count = IntMath.ceilingPowerOfTwo(x)
    count
  }

  @CEntryPoint(name = "incrementFunctionScala")
  def incrementFunctionScala(thread: IsolateThread): Int = IntMath.checkedAdd(count, 1)
}

if you're using scala 3 then probably adding @static annotation could help. the final code would be something like:

import com.google.common.math.IntMath
import org.graalvm.nativeimage.IsolateThread
import org.graalvm.nativeimage.c.function.CEntryPoint

import scala.annotation.static

class MyMath {
  override def toString = "Hello"
}

object MyMath {
  @static // i'm not sure if it's needed here
  var count = 0

  @CEntryPoint(name = "ceilingPowerOfTwoScala")
  @static
  def ceilingPowerOfTwoScala(thread: IsolateThread, x: Int): Int = {
    count = IntMath.ceilingPowerOfTwo(x)
    count
  }

  @CEntryPoint(name = "incrementFunctionScala")
  @static
  def incrementFunctionScala(thread: IsolateThread): Int = IntMath.checkedAdd(count, 1)
}

simpler example: https://scastie.scala-lang.org/Wj7SuiilQRuXsKgmxXQlAA

[burakakca]

Yes, It works in scala 3 but my codebase in scala 2

[tarsa]

Yes, It works in scala 3 but my codebase in scala 2

it seems that the problem is more with scala 2 than with native-image.

as a workaround, you can mix java and scala code, e.g. define an entrypoint in java that calls methods on scala singleton objects. theoretically, graalvm native-image could do that workaround automatically, but then it would need to be able to recognize singletons and treat their methods somewhat like static ones.