Try to find class resource to avoid exception

The exception thrown here when we cannot find a class can be very
expensive at boot time. For most third-party extensions, this
exception will be raised twice for every bound method, due to
double-checking the classloader under lock a second time. By first
looking for a .class resource, we can avoid the expensive
exception if it is unlikely to succeed.

core/src/main/java/org/jruby/internal/runtime/methods/InvocationMethodFactory.java

@@ -56,6 +56,7 @@
 
 import java.io.PrintWriter;
 import java.lang.reflect.Modifier;
+import java.net.URL;
 import java.util.Collections;
 import java.util.List;
 
@@ -263,11 +264,11 @@ public Class getAnnotatedMethodClass(List<JavaMethodDescriptor> descs) {
 
         Class superclass = determineSuperclass(info);
 
-        Class c = tryClass(generatedClassName, desc1.declaringClass, superclass);
+        Class c = tryClass(generatedClassName, generatedClassPath, desc1.declaringClass, superclass);
         if (c == null) {
             synchronized (syncObject) {
                 // try again
-                c = tryClass(generatedClassName, desc1.declaringClass, superclass);
+                c = tryClass(generatedClassName, generatedClassPath, desc1.declaringClass, superclass);
                 if (c == null) {
                     if (DEBUG) LOG.debug("Generating " + generatedClassName + ", min: " + info.getMin() + ", max: " + info.getMax() + ", hasBlock: " + info.isBlock() + ", rest: " + info.isRest());
 
@@ -631,14 +632,16 @@ private static void loadReceiver(String typePath, JavaMethodDescriptor desc, Ski
         }
     }
 
-    private Class tryClass(String name, Class targetClass, Class expectedSuperclass) {
+    private Class tryClass(String name, String path, Class targetClass, Class expectedSuperclass) {
         final Class c;
         try {
-            if (classLoader == null) {
-                c = Class.forName(name, true, classLoader);
-            } else {
-                c = classLoader.loadClass(name);
+            URL resource = classLoader.findResource(path + ".class");
+            if (resource == null) {
+                if (DEBUG) LOG.debug("could not find class file for " + name);
+                seenUndefinedClasses = true;
+                return null;
             }
+            c = classLoader.loadClass(name);
         } catch (ClassNotFoundException e) {
             if (DEBUG) LOG.debug(e);
             seenUndefinedClasses = true;