src/hotspot/share/classfile/javaClasses.cpp

rev 49271 : 8199852: Print more information about class loaders in LinkageErrors.

@@ -4105,10 +4105,51 @@
 oop java_lang_ClassLoader::unnamedModule(oop loader) {
   assert(is_instance(loader), "loader must be oop");
   return loader->obj_field(unnamedModule_offset);
 }
 
+// Caller needs ResourceMark.
+const char* java_lang_ClassLoader::describe_external(const oop loader) {
+  if (loader == NULL) {
+    return "<bootstrap>";
+  }
+
+  const char* name = NULL;
+  oop nameOop = java_lang_ClassLoader::name(loader);
+  if (nameOop != NULL) {
+    name = java_lang_String::as_utf8_string(nameOop);
+  }
+
+  stringStream ss;
+  const char *seperator;
+  // If we have a name set for this loader, display it. Otherwise use
+  // the class of the loader.
+  if (name != NULL) {
+    ss.print("\"%s\" (instance of %s", name, loader->klass()->external_name());
+    seperator = ", ";
+  } else {
+    ss.print("%s", loader->klass()->external_name());
+    seperator = " (";
+  }
+
+  oop pl = java_lang_ClassLoader::parent(loader);
+  if (pl != NULL) {
+    ss.print("%sparent: ", seperator);
+    oop parentNameOop = java_lang_ClassLoader::name(pl);
+    if (parentNameOop != NULL) {
+      const char* parentName = java_lang_String::as_utf8_string(parentNameOop);
+      if (parentName != NULL) {
+        ss.print("\"%s\" ", parentName);
+      }
+    }
+    ss.print("%s)", pl->klass()->external_name());
+  } else {
+    ss.print("%sparent: <bootstrap>)", seperator);
+  }
+  return ss.as_string();
+}
+
 // Support for java_lang_System
 //
 #define SYSTEM_FIELDS_DO(macro) \
   macro(static_in_offset,  k, "in",  input_stream_signature, true); \
   macro(static_out_offset, k, "out", print_stream_signature, true); \