Anonymous class

[David Holmes]

<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
>