Small VM change #2: JVM_ entry point to extend the boot class path

[Karen Kinnear]

Thanks Mark.

If we were planning to leave this in, I'd ask you to remove the  
print_bootclasspath
from SystemDictionary:download_and_retry_class_load since right now
that would have duplicate prints, or better yet have the caller of
update_class_path_entry_list do the printing, including the "cause" of  
the
change. But not a big deal since this is temporary.

thanks,
Karen

On May 18, 2009, at 6:34 PM, Mark Reinhold wrote:

>> Date: Mon, 18 May 2009 16:47:53 -0400
>> From: karen.kinnear at sun.com
>
>> Let's consider this a temporary J1 approach please. After J1 let's
>> have some discussions about alternative approaches please.
>
> Sure, absolutely.
>
>> Question: in jvm.cpp and .hpp in the new
>> JVM_ExtendBootClassPath(JNIEnv *env, jclass cls, const char *path)
>> what is jclass cls used for?
>
> Nothing; that's leftover from an initial version where I thought I was
> going to use RegisterNatives for this entry point.  Removed.
>
>> also in that method, I suspect you too would like the
>> ClassLoader::print_bootclasspath() to be conditional on
>> TraceClassLoading - unless for the demo you want this to print  
>> always.
>
> I meant to remove that entirely, but gating it on TraceClassLoading  
> makes
> sense, so I'll do that.
>
>> Other than that - just for the demo - go for it.
>
> Thanks.  New patch attached FYI.
>
> - Mark
>
> diff -r 403a1b93874f make/linux/makefiles/mapfile-vers-debug
> --- a/make/linux/makefiles/mapfile-vers-debug	Thu May 14 14:48:35  
> 2009 -0700
> +++ b/make/linux/makefiles/mapfile-vers-debug	Mon May 18 15:32:49  
> 2009 -0700
> @@ -87,6 +87,7 @@
>                 JVM_DumpThreads;
>                 JVM_EnableCompiler;
>                 JVM_Exit;
> +                JVM_ExtendBootClassPath;
>                 JVM_FillInStackTrace;
>                 JVM_FindClassFromClass;
>                 JVM_FindClassFromClassLoader;
> diff -r 403a1b93874f make/linux/makefiles/mapfile-vers-product
> --- a/make/linux/makefiles/mapfile-vers-product	Thu May 14 14:48:35  
> 2009 -0700
> +++ b/make/linux/makefiles/mapfile-vers-product	Mon May 18 15:32:49  
> 2009 -0700
> @@ -87,6 +87,7 @@
>                 JVM_DumpThreads;
>                 JVM_EnableCompiler;
>                 JVM_Exit;
> +                JVM_ExtendBootClassPath;
>                 JVM_FillInStackTrace;
>                 JVM_FindClassFromClass;
>                 JVM_FindClassFromClassLoader;
> diff -r 403a1b93874f src/share/vm/classfile/classLoader.cpp
> --- a/src/share/vm/classfile/classLoader.cpp	Thu May 14 14:48:35  
> 2009 -0700
> +++ b/src/share/vm/classfile/classLoader.cpp	Mon May 18 15:32:49  
> 2009 -0700
> @@ -512,12 +512,15 @@
>     // File or directory found
>     ClassPathEntry* new_entry = NULL;
>     create_class_path_entry((char *)path, st, &new_entry,  
> LazyBootClassLoader);
> -    // The kernel VM adds dynamically to the end of the classloader  
> path and
> -    // doesn't reorder the bootclasspath which would break  
> java.lang.Package
> -    // (see PackageInfo).
> -    // Add new entry to linked list
> +    // The kernel VM, and Jigsaw, add dynamically to the end of the  
> classloader
> +    // path and don't reorder the bootclasspath, which would break
> +    // java.lang.Package (see PackageInfo).
>     if (!check_for_duplicates || !contains_entry(new_entry)) {
> +      // Add new entry to linked list
>       add_to_list(new_entry);
> +      if (TraceClassLoading) {
> +        print_bootclasspath();
> +      }
>     }
>   }
> }
> diff -r 403a1b93874f src/share/vm/classfile/classLoader.hpp
> --- a/src/share/vm/classfile/classLoader.hpp	Thu May 14 14:48:35  
> 2009 -0700
> +++ b/src/share/vm/classfile/classLoader.hpp	Mon May 18 15:32:49  
> 2009 -0700
> @@ -190,7 +190,7 @@
>   // to avoid confusing the zip library
>   static bool get_canonical_path(char* orig, char* out, int len);
>  public:
> -  // Used by the kernel jvm.
> +  // Used by the kernel jvm, and by Jigsaw via  
> JVM_ExtendBootClassPath
>   static void update_class_path_entry_list(const char *path,
>                                            bool check_for_duplicates);
>   static void print_bootclasspath();
> diff -r 403a1b93874f src/share/vm/prims/jvm.cpp
> --- a/src/share/vm/prims/jvm.cpp	Thu May 14 14:48:35 2009 -0700
> +++ b/src/share/vm/prims/jvm.cpp	Mon May 18 15:32:49 2009 -0700
> @@ -851,6 +851,17 @@
>             (jclass) JNIHandles::make_local(env, Klass::cast(k)- 
> >java_mirror());
> JVM_END
>
> +JVM_ENTRY(void, JVM_ExtendBootClassPath(JNIEnv *env, const char  
> *path))
> +  JVMWrapper2("JVM_ExtendBootClassPath(%s)", path)
> +  {
> +    // cf. SystemDictionary::download_and_retry_class_load
> +    HandleMark hm(THREAD);
> +    ResourceMark rm(THREAD);
> +    Handle loader_lock(THREAD,  
> SystemDictionary::system_loader_lock());
> +    ObjectLocker ol(loader_lock, THREAD);
> +    ClassLoader::update_class_path_entry_list(path, true);
> +  }
> +JVM_END
>
> // Reflection  
> support 
>  //////////////////////////////////////////////////////////////////////////////
>
> diff -r 403a1b93874f src/share/vm/prims/jvm.h
> --- a/src/share/vm/prims/jvm.h	Thu May 14 14:48:35 2009 -0700
> +++ b/src/share/vm/prims/jvm.h	Mon May 18 15:32:49 2009 -0700
> @@ -438,6 +438,12 @@
>                       jobjectArray constants);
>
> /*
> + * Append a path to the boot class path
> + */
> +JNIEXPORT void JNICALL
> +JVM_ExtendBootClassPath(JNIEnv *env, const char *path);
> +
> +/*
>  * Reflection support functions
>  */