Added GraalVM native support to Apache FreeMarker

[fugerit79]

Native support

In this pull request :

GraalVM native support

1. Added native-image.properties to initialize at runtime relevant classes
2. Added resource-config.json to track resources to include in the native executable
3. Added boolean IS_GRAALVM_NATIVE = System.getProperty( "org.graalvm.nativeimage.imagecode" ) != null in logger to avoid runtime initialization error
4. Added dependency to GraalVM SDK

Test module

Added a test module to build as a GraalVM native image.

1. Build the main Apache FreeMarker proejct :

./gradlew build -Pfreemarker.allowUnsignedReleaseBuild=true

2. Build the test module native image with GraalVM :

./gradlew :freemarker-test-graalvm-native:nativeCompile 

3. Run the project :

./freemarker-test-graalvm-native/build/native/nativeCompile/freemarker-test-graalvm-native 

CI

Updated CI to test the GraalVM native support by building and running the test module as a native executable.

[fugerit79]

@ddekany

I misunderstood at the beginning.

I’ve pushed some modifications, and hopefully, it should be fine now.

I’ve also done some additional testing and made the following changes:

• Improved the native test by adding relevant reflection configurations.
• Added some comments.
• Fixed a couple of typos.
• Substitution (Log4jOverSLF4JTesterSubstitute) is no more needed after graalvm native check in logger

Additionally I tested the pull request on my fork : 

https://github.com/fugerit-org/freemarker/actions/workflows/ci.yml

I really hope now everything is ok.

See you

[ddekany]

But that still prefers Log4J API instead of SLF4J API when we have log4j-over-slf4j, under GrallVM Native only, and it should prefer SLF4J in that case. I know, this Logger class is a mess. Anyway, I looked into more, and the easiest way to achieve what I said is just changing isAutoDetected so that if IS_GRAALVM_NATIVE is true, then we return true for LIBRARY_SLF4J. Actually, even better long term, let's return true for LIBRARY_COMMONS too, and that way for GraalVM Native we just brought ahead what's planned for 2.4 anyway.

[fugerit79]

I'm having a deeper look at it.

[fugerit79]

@ddekany let's see if this is ok for you.

I preferred to create separate methods so maybe it's easier to understand than complex conditional statements, do you agree?

    // legacy auto-detection (until FreeMarker 2.3.X)
    private static boolean isAutoDetectedLegacy( int libraryEnum ) {
        return !(libraryEnum == LIBRARY_AUTO || libraryEnum == LIBRARY_NONE
                || libraryEnum == LIBRARY_SLF4J || libraryEnum == LIBRARY_COMMONS);
    }

    // next generation auto-detection (FreeMarker 2.4.X and on)
    private static boolean isAutoDetectedNG( int libraryEnum ) {
        return !(libraryEnum == LIBRARY_AUTO || libraryEnum == LIBRARY_NONE);
    }

    private static boolean isAutoDetected(int libraryEnum) {
        // 2.4: Remove libraryEnum == LIBRARY_SLF4J || libraryEnum == LIBRARY_COMMONS (use only isAutoDetectedNG()=
        return IS_GRAALVM_NATIVE ? isAutoDetectedNG(libraryEnum) : isAutoDetectedLegacy(libraryEnum);
    }

At beginning didn't fully grasped the meaning of all logger detection logic. I hope that now it is ok.

[ddekany]

Don't we also need to add freemarker/ext/beans/unsafeMethods.properties accessed from freemarker.ext.beans.LegacyDefaultMemberAccessPolicy here?

[fugerit79]

Maybe 'freemarker/ext/beans/unsafeMethods.properties' when freemarker.ext.beans.LegacyDefaultMemberAccessPolicy is reachable? (just commited it this way)

do you think is it better to squash commits?

[ddekany]

new Version(Configuration.getVersion().toString()), because, recycling the current version like that is in principle not allowed (current only logs a WARN, eventually will throw exception). (Because, people almost always do this by mistake, not understanding what that setting does. So in the rare cases where you really mean to do it, there's some gymnastic involved.)

[fugerit79]

Ok, updated this one too. (in production projects I never resuse it).

[ddekany]

Please add the licence header to the template instead (inside <#-- ... -->)

[fugerit79]

I think this is done too. Sorry If i missed it

[fugerit79]

@ddekanyI have squashed everything into two commits :

• GraalVM native support implementation
• Tests and CI

I hope all your requests have been fulfilled.

Regards