GH-537 improve lookup of contextImpl, fallback to defult when GraalVMLocator is not present

Author: thurka

visualvm/sampler.truffle/libsrc/org/graalvm/visualvm/sampler/truffle/stagent/Truffle.java

@@ -151,6 +151,7 @@ private Method getFindActiveEngines() {
         try {
             Method m = Engine.class.getDeclaredMethod("findActiveEngines");
             m.setAccessible(true);
+            if (TruffleJMX.DEBUG) System.out.println("Engine "+m.getDeclaringClass()+" cl "+m.getDeclaringClass().getClassLoader());
             return m;
         } catch (SecurityException ex) {
             Logger.getLogger(Truffle.class.getName()).log(Level.SEVERE, null, ex);

visualvm/sampler.truffle/libsrc/org/graalvm/visualvm/sampler/truffle/stagent/TruffleClassLoader.java

@@ -43,7 +43,7 @@ class TruffleClassLoader extends ClassLoader {
 
     private Collection<ClassLoader> loaders;
 
-    TruffleClassLoader(ClassLoader parent, Unsafe unsafe) throws ClassNotFoundException, NoSuchMethodException, IllegalAccessException, IllegalArgumentException, InvocationTargetException {
+    TruffleClassLoader(ClassLoader parent, Unsafe unsafe) throws NoSuchMethodException, IllegalAccessException, IllegalArgumentException, InvocationTargetException {
         super(parent);
         loaders = getTruffleLocatorLoaders(parent);
         if (loaders == null) {
@@ -54,6 +54,9 @@ class TruffleClassLoader extends ClassLoader {
 
     @Override
     public Class<?> findClass(String name) throws ClassNotFoundException {
+        if (loaders == null) {
+            return super.findClass(name);
+        }
         for (ClassLoader loader : loaders) {
             if (loader == null) {
                 continue;
@@ -75,9 +78,9 @@ private static Class getClass(ClassLoader cl, String className) throws ClassNotF
         }
     }
 
-    private static Collection<ClassLoader> getTruffleLocatorLoaders(ClassLoader cl) throws ClassNotFoundException {
-        Class LocatorClass = getClass(cl, TRUFFLE_LOCATOR_CLASS_NAME);
+    private static Collection<ClassLoader> getTruffleLocatorLoaders(ClassLoader cl) {
         try {
+            Class LocatorClass = getClass(cl, TRUFFLE_LOCATOR_CLASS_NAME);
             return (Collection<ClassLoader>) LocatorClass.getMethod("loaders", (Class[])null).invoke(null, (Object[])null);
         } catch (Exception ex) {
             if (TruffleJMX.DEBUG) {
@@ -87,9 +90,9 @@ private static Collection<ClassLoader> getTruffleLocatorLoaders(ClassLoader cl)
         return null;
     }
 
-    private static Collection<ClassLoader> getGraalVMLocatorLoaders(ClassLoader cl, Unsafe unsafe) throws ClassNotFoundException {
-        Class LocatorClass = getClass(cl, GRAALVM_LOCATOR_CLASS_NAME);
+    private static Collection<ClassLoader> getGraalVMLocatorLoaders(ClassLoader cl, Unsafe unsafe) {
         try {
+            Class LocatorClass = getClass(cl, GRAALVM_LOCATOR_CLASS_NAME);
             Field f = LocatorClass.getDeclaredField("loader");
             Object base = unsafe.staticFieldBase(f);
             ClassLoader loader = (ClassLoader) unsafe.getObject(base, unsafe.staticFieldOffset(f));

visualvm/sampler.truffle/libsrc/org/graalvm/visualvm/sampler/truffle/stagent/TruffleJMX.java

@@ -36,6 +36,8 @@
 import java.net.URL;
 import java.net.URLClassLoader;
 import java.util.Arrays;
+import java.util.HashMap;
+import java.util.Map;
 import java.util.logging.Level;
 import java.util.logging.Logger;
 import javax.management.InstanceAlreadyExistsException;
@@ -104,8 +106,8 @@ private static Object getContext() throws ClassNotFoundException, NoSuchMethodEx
     }
 
     private static Object getContextImpl(Object context) throws IllegalArgumentException, SecurityException, NoSuchFieldException, IllegalAccessException {
-        // return context.impl or context.dispatch
-        Field implField = getDeclaredField(context, "impl", "dispatch");
+        // return context.impl or context.receiver or context.dispatch
+        Field implField = getDeclaredField(context, "impl", "receiver", "dispatch");
         try {
             implField.setAccessible(true);
             Object impl = implField.get(context);
@@ -121,12 +123,11 @@ private static Object getContextImpl(Object context) throws IllegalArgumentExcep
     }
 
     static Field getDeclaredField(Object obj, String... names) throws NoSuchFieldException {
-        for (Field f : obj.getClass().getDeclaredFields()) {
-            for (String name : names) {
-                if (name.equals(f.getName())) {
-                    return f;
-                }
-            }
+        Map<String,Field> fields = new HashMap<>();
+        for (Field f : obj.getClass().getDeclaredFields()) fields.put(f.getName(), f);
+        for (String name : names) {
+            Field f = fields.get(name);
+            if (f!=null) return f;
         }
         throw new NoSuchFieldException(Arrays.toString(names));
     }