GH-310 handle renamed fields 'impl' and 'creatorApi'

Author: thurka

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

@@ -186,7 +186,7 @@ private Collection<Engine> getAllEngineInstances() {
             if (Engine_findActiveEngines == null) {
                 Collection<Engine> en = new ArrayList();
                 for (Object o : engines.keySet()) {
-                    Field cf = o.getClass().getDeclaredField("creatorApi");
+                    Field cf = TruffleJMX.getDeclaredField(o, "creatorApi", "api");
                     Engine e = (Engine) unsafe.getObject(o, unsafe.objectFieldOffset(cf));
                     en.add(e);
                 }

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

@@ -35,6 +35,7 @@
 import java.net.JarURLConnection;
 import java.net.URL;
 import java.net.URLClassLoader;
+import java.util.Arrays;
 import java.util.logging.Level;
 import java.util.logging.Logger;
 import javax.management.InstanceAlreadyExistsException;
@@ -103,8 +104,8 @@ private static Object getContext() throws ClassNotFoundException, NoSuchMethodEx
     }
 
     private static Object getContextImpl(Object context) throws IllegalArgumentException, SecurityException, NoSuchFieldException, IllegalAccessException {
-        // return context.impl
-        Field implField = context.getClass().getDeclaredField("impl");
+        // return context.impl or context.dispatch
+        Field implField = getDeclaredField(context, "impl", "dispatch");
         try {
             implField.setAccessible(true);
             Object impl = implField.get(context);
@@ -119,6 +120,17 @@ 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;
+                }
+            }
+        }
+        throw new NoSuchFieldException(Arrays.toString(names));
+    }
+
     private static URL getJarURL() throws IOException {
         URL classUrl = ClassLoader.getSystemResource("org/graalvm/visualvm/sampler/truffle/stagent/Truffle.class");
         JarURLConnection connection = (JarURLConnection) classUrl.openConnection();