Invoke Main.main via JVM and its JNI

Author: JaroslavTulach

engine/runner/src/main/java/org/enso/runner/Main.java

@@ -38,6 +38,7 @@
 import org.enso.editions.DefaultEdition;
 import org.enso.libraryupload.LibraryUploader.UploadFailedError;
 import org.enso.os.environment.chdir.WorkingDirectory;
+import org.enso.os.environment.jni.JVM;
 import org.enso.pkg.Contact;
 import org.enso.pkg.PackageManager;
 import org.enso.pkg.PackageManager$;
@@ -1404,10 +1405,9 @@ private boolean isJvmModeEnabled(CommandLine line) {
   }
 
   private void launchJvm(
-      CommandLine line, Map<String, String> props, File component, String javaPath)
+      CommandLine line, Map<String, String> props, File component, String javaHome)
       throws IOException, InterruptedException {
     var commandAndArgs = new ArrayList<String>();
-    commandAndArgs.add(javaPath);
     var jvmOptions = System.getenv("JAVA_OPTS");
     if (jvmOptions != null) {
       for (var op : jvmOptions.split(" ")) {
@@ -1435,6 +1435,9 @@ private void launchJvm(
     commandAndArgs.add(component.getPath());
     commandAndArgs.add("-m");
     commandAndArgs.add("org.enso.runner/org.enso.runner.Main");
+
+    var jvm = JVM.create(javaHome, commandAndArgs.toArray(new String[0]));
+    commandAndArgs.clear();
     var it = line.iterator();
     while (it.hasNext()) {
       var op = it.next();
@@ -1456,16 +1459,11 @@ private void launchJvm(
       }
     }
     commandAndArgs.addAll(line.getArgList());
-    var pb = new ProcessBuilder();
-    pb.inheritIO();
-    pb.command(commandAndArgs);
-    var p = pb.start();
-    var exitCode = p.waitFor();
-    if (exitCode == 0) {
-      throw exitSuccess();
-    } else {
-      throw doExit(exitCode);
-    }
+
+    jvm.executeMain("org/enso/runner/Main", commandAndArgs.toArray(new String[0]));
+
+    // the above call should never return
+    throw doExit(1);
   }
 
   private void launch(String[] args) throws IOException, InterruptedException, URISyntaxException {

lib/java/os-environment/src/main/java/org/enso/os/environment/jni/JVM.java

@@ -34,12 +34,45 @@ public static JVM create(String javaHome, String... options) {
     return new JVM(createJvmFn, options);
   }
 
+  /**
+   * Executes main method of provided class
+   *
+   * @param classNameWithSlashes class (with `/` as separators) to search main method in
+   * @param args arguments to pass to the main method
+   */
+  public void executeMain(String classNameWithSlashes, String[] args) {
+    var e = env();
+    try (var className = CTypeConversion.toCString(classNameWithSlashes);
+        var mainName = CTypeConversion.toCString("main");
+        var stringName = CTypeConversion.toCString("java/lang/String");
+        var mainSig = CTypeConversion.toCString("([Ljava/lang/String;)V"); ) {
+      var fn = e.getFunctions();
+      var mainClazz = fn.getFindClass().call(e, className.get());
+      assert mainClazz.isNonNull() : "Class not found " + classNameWithSlashes;
+      var mainMethod = fn.getGetStaticMethodID().call(e, mainClazz, mainName.get(), mainSig.get());
+      assert mainMethod.isNonNull() : "main method found in " + classNameWithSlashes;
+      var stringClazz = fn.getFindClass().call(e, stringName.get());
+      var argsCopy =
+          fn.getNewObjectArray().call(e, args.length, stringClazz, WordFactory.nullPointer());
+
+      for (var i = 0; i < args.length; i++) {
+        try (var ithArg = CTypeConversion.toCString(args[i]); ) {
+          var str = fn.getNewStringUTF().call(e, ithArg.get());
+          fn.getSetObjectArrayElement().call(e, argsCopy, i, str);
+        }
+      }
+      var arg = StackValue.get(JNI.JValue.class);
+      arg.setJObject(argsCopy);
+      fn.getCallStaticVoidMethodA().call(e, mainClazz, mainMethod, arg);
+    }
+  }
+
   /**
    * Initialize or just obtain environment associated with this JVM.
    *
    * @return JNI environment to make calls into the JVM
    */
-  public final JNI.JNIEnv env() {
+  final JNI.JNIEnv env() {
     if (env.isNull()) {
       env = initializeEnv();
     }