On 10/16/2017 03:31 PM, Alan Bateman wrote:
On 16/10/2017 14:21, Robbin Ehn wrote:
Hi, if you use class file load hook you can add/remove public methods.
Since this is before the class have been published we don't know how it should
look.
Whether this is according to spec or not, I have no clue.
Is it on CFLH ?
No issue adding or removing methods or making any other changes to the class file in the CFLH but only for the initial load. The CFLH will be re-run when the class is
transformed (RetransformClasses) but that cannot add/remove methods or do other schema changes.
There is actually an issue, we start all transformation with 'on' disk version.
If the agent that did the addition of a public method e.g.
exits(removeTransformer) we can never re-transform it, instead we get:
"error method delete"
It have been suggested that we should use 'first published' class version as a
baseline (the version after CFLH), but would break current agents (I assume).
This is my old patch for it:
diff -r 46a21d1c5f1c src/share/vm/prims/jvmtiExport.cpp
--- a/src/share/vm/prims/jvmtiExport.cpp Fri Aug 12 14:12:55 2016 -0700
+++ b/src/share/vm/prims/jvmtiExport.cpp Tue Aug 16 16:22:29 2016 +0200
@@ -661,7 +661,8 @@
if (env->is_retransformable() &&
env->is_enabled(JVMTI_EVENT_CLASS_FILE_LOAD_HOOK)) {
// retransformable agents need to cache the original class file
// bytes if changes are made via the ClassFileLoadHook
- post_to_env(env, true);
+ // cache the last version after load is completed, hence the published
version
+ post_to_env(env, _load_kind != jvmti_class_load_kind_load);
}
}
}
Is it a bug or work as intended? (or a bug we can't fix)
/Robbin
-Alan
