Anonymous class

[yumin qi]

Hi, David

I am confused here.

As you pointed out:
   Java anonymous classes are not VM anonymous classes.
   VM anonymous classes are created by Unsafe_DefineAnonymousClass only.

Is my understanding right? All all lambda classes are vm anonymous?

Thanks
Yumin

On Fri, Jan 25, 2019 at 7:18 PM David Holmes <david.holmes at oracle.com>
wrote:

> <dropped jdk-dev>
>
> On 25/01/2019 6:52 pm, yumin qi wrote:
> > Hi,
> >
> >    I have a question of anonymous class. We know the anonymous class
> with a
> > host_klass, and the flag is set when the InstanceKlass is created after
> the
> > class parsed. In case of a regular java class file, the flag will be set
> > correctly but for the case it is not set:
> >    SystemDictionary::parse_stream or resolve_from_stream, which is called
> > from JVM_DefineClassWithSource or jni_defineClass. The stack trace like:
> >
> > #1  0x00007f1127291ce7 in
> > SystemDictionary::resolve_from_stream(class_name=0x7f0ee40243f0,
> > class_loader=..., protection_domain=...,d__=0x7f0f04001000) at
> >
> /home/ws/openjdk/8/jdk8u/hotspot/src/share/vm/classfile/systemDictionaryShared.cpp:656
> > #1  0x00007f1127291ce7 in SystemDictionary::resolve_from_stream
> > (class_name=0x7f0ee40243f0, class_loader=..., protection_doma
> > in=...,
> >      st=0x7f0f0a5f3850, verify=true, __the_thread__=0x7f0f04001000)
> >      at
> >
> /home/ws/openjdk/8/jdk8u/hotspot/src/share/vm/classfile/systemDictionary.cpp:1234
> > #2  0x00007f1126f3cadb in jvm_define_class_common (env=0x7f0f04001220,
> > name=0x7f0f0a5f3e60 "com/google/common/collect/Iterato
> > rs$3",
> >      loader=0x7f0f0a5f3f20, buf=0x7f0ee401e210 "\312\376\272\276",
> len=943,
> > pd=0x7f0f0a5f3f48,
> >      source=0x7f0f0a5f3a60 "jar:file:/home/<...>/lib/guava-19.0.jar!/",
> > verify=1 '\001', __the_thread__=0x7f0f04001000) at
> > /home/yumin.qi/ws/openjdk/8/jdk8u/hotspot/src/share/vm/prims/jvm.cpp:1082
> > #3  0x00007f1126f3d019 in JVM_DefineClassWithSource (env=0x7f0f04001220,
> > name=0x7f0f0a5f3e60 "com/google/common/collect/Itera
> > tors$3",
> >      loader=0x7f0f0a5f3f20, buf=0x7f0ee401e210 "\312\376\272\276",
> len=943,
> > pd=0x7f0f0a5f3f48,
> >      source=0x7f0f0a5f3a60 "jar:file:/home/<...>/lib/guava-19.0.jar!/")
> at
> > /home/ws/openjdk/8/jdk8u/hotspot/src/share/vm/prim/jvm.cpp:1102
> > #4  0x00007f112581214f in Java_java_lang_ClassLoader_defineClass1 ()
> >     from
> >
> /home/ws/openjdk/8/jdk8u/build/linux-x86_64-normal-server-slowdebug/images/j2sdk-image/jre/lib/amd64/libjava.so
> > #5  0x00007f11118f5402 in ?? ()
> > #6  0x00007f0f0a5f3f48 in ?? ()
> > #7  0x00007f0f0a5f3f70 in ?? ()
> > #8  0x0000000755dbbc28 in ?? ()
> >
> > The class name is com.google.common.collect.Iterators$3, and it is an
> > anonymous class.
>
> I'm confused. Are you talking about Java level anonymous classes or VM
> anonymous classes as created by Unsafe.defineAnonymousClass? Only VM
> anonymous classes have a "host class". Java level "anonymous classes"
> are just regular classes.
>
> David
> -----
>
>
>
> > This is an example using Guava. I also can reproduce with jdk13.
> >
> > The field after parsing:
> >
> >   _nonstatic_oop_map_size = 1,
> >    _is_marked_dependent = false,
> >    _has_unloaded_dependent = false,
> >    _misc_flags = 38,      ////// <------------ not set for anonymous
> >    _minor_version = 0,
> >    _major_version = 50,
> >    _init_thread = 0x0,
> >    _vtable_len = 8,
> >    _itable_len = 8,
> >
> >    This path is from a custom loader defining a anonymous class, does not
> > set anonymous correctly for the flag. Is this a bug? If in java land,
> > supply a host as parameter,  it can be set correctly in VM part. Should I
> > file a bug for it?
> >
> > Thanks
> > Yumin
> >
>