Make Javalin more GraalVM friendly about javalin.github.io HOT 5 OPEN

        Javalin javalin = Javalin.create(config -> {
            // Using a custom thread pool for virtual threads instead of the default Javalin LoomUtil.LoomThreadPool.
            // This is because it uses reflection to create new threads which causes an error in GraalVM.
            config.jetty.threadPool = new ThreadPool() {
                @Override
                public void join() { /*no-op*/ }

                @Override
                public int getThreads() {
                    return 1;
                }

                @Override
                public int getIdleThreads() {
                    return 1;
                }

                @Override
                public boolean isLowOnThreads() {
                    return false;
                }

                @Override
                public void execute(@NonNull Runnable command) {
                    AppConfig.virtualThreadFactory.newThread(command).start();
                }
            };
        });

import com.oracle.svm.core.annotate.Alias;
import com.oracle.svm.core.annotate.Substitute;
import com.oracle.svm.core.annotate.TargetClass;
import io.javalin.util.NamedVirtualThreadFactory;

import java.util.concurrent.atomic.AtomicInteger;

@TargetClass(NamedVirtualThreadFactory.class)
public final class Target_io_javalin_util_NamedVirtualThreadFactory {
    @Alias
    AtomicInteger threadCount;

    @Alias
    String prefix;

    @Substitute
    public Thread newThread(Runnable runnable) {
        return Thread.ofVirtual()
                .name(prefix + "-Virtual-" + threadCount.getAndIncrement())
                .unstarted(runnable);
    }
}