package bartMachine;

import java.io.File;

import java.io.IOException;

import java.lang.instrument.Instrumentation;

import java.util.jar.JarFile;

/**

* Minimal Java agent whose sole purpose is to get bart_java.jar and its

* dependencies onto the system classpath before any user classes load.

*

* Problem: TornadoVM's ASMClassVisitor.getParallelAnnotations() calls

* ClassLoader.getSystemClassLoader().getResourceAsStream("bartMachine/GpuForestPredictor.class")

* rJava adds bart_java.jar to a *child* URLClassLoader after JVM startup, so

* the system classloader cannot see it and TornadoVM bails out to CPU fallback.

*

* Fix: per the Java Instrumentation spec, when a jar is listed as a -javaagent:,

* the JVM appends it to the system class path (equivalent to

* Instrumentation.appendToSystemClassLoaderSearch) before premain is called.

*

* To ensure dependencies (fastutil, etc.) are also visible to classes in

* bart_java.jar when it's on the system classpath, we manually append them

* in premain if they are passed in agentArgs.

*

* Usage in R (before library(bartMachine)):

* deps = c(system.file("java", "fastutil-core-8.5.18.jar", package = "bartMachineJARs"), ...)

* agent_args = paste(deps, collapse = ":") # use ";" on Windows

* options(java.parameters = c(...,

* paste0("-javaagent:", system.file("java","bart_java.jar",package="bartMachine"), "=", agent_args)))

*/

public final class BartJarAgent {

public static void premain(String agentArgs, Instrumentation inst) {

System.setProperty("bartMachine.agent.active", "true");

System.err.println("BartJarAgent: premain called with args: " + agentArgs);

// The -javaagent: mechanism already added THIS jar to the system

// classpath before this method was called.

// Now add any requested dependencies to the system classpath search

if (agentArgs != null && !agentArgs.isEmpty()) {

for (String path : agentArgs.split(File.pathSeparator)) {

if (path.isEmpty()) continue;

File file = new File(path);

if (file.exists()) {

try {

System.err.println("BartJarAgent: Adding to system classpath: " + path);

inst.appendToSystemClassLoaderSearch(new JarFile(file));

} catch (IOException e) {

System.err.println("BartJarAgent: Could not add " + path + " to system classpath: " + e.getMessage());

}

} else {

System.err.println("BartJarAgent: Dependency jar not found: " + path);

}

}

} else {

System.err.println("BartJarAgent: No dependency arguments provided.");

}

}

public static void agentmain(String agentArgs, Instrumentation inst) {

premain(agentArgs, inst);

}

}