src/hotspot/share/classfile/javaClasses.cpp

rev 49800 : 8199852: Print more information about class loaders in LinkageErrors.
Reviewed-by: dholmes

*** 4132,4141 ****
--- 4132,4183 ----
  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>";
+   }
+ 
+   bool well_known_loader = SystemDictionary::is_system_class_loader(loader) ||
+                            SystemDictionary::is_platform_class_loader(loader);
+ 
+   const char* name = NULL;
+   oop nameOop = java_lang_ClassLoader::name(loader);
+   if (nameOop != NULL) {
+     name = java_lang_String::as_utf8_string(nameOop);
+   }
+   if (name == NULL) {
+     // Use placeholder for missing name to have fixed message format.
+     name = "<unnamed>";
+   }
+ 
+   stringStream ss;
+   ss.print("\"%s\" (instance of %s", name, loader->klass()->external_name());
+   if (!well_known_loader) {
+     const char* parentName = NULL;
+     oop pl = java_lang_ClassLoader::parent(loader);
+     if (pl != NULL) {
+       oop parentNameOop = java_lang_ClassLoader::name(pl);
+       if (parentNameOop != NULL) {
+         parentName = java_lang_String::as_utf8_string(parentNameOop);
+         if (parentName == NULL) {
+           parentName = "<unnamed>";
+         }
+       }
+       ss.print(", child of \"%s\" %s", parentName, pl->klass()->external_name());
+     } else {
+       ss.print(", child of <bootstrap>");
+     }
+   }
+   ss.print(")");
+ 
+   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); \