Proposed API for JEP 259: Stack-Walking API

[Daniel Fuchs]

Hi Peter,

You also get Thread.currentThread().getClass() if you call
StackWalker.getCallerClass() from main().

Because who is the caller of main()?

cheers,

-- daniel

On 03/11/15 13:45, Peter Levart wrote:
> Hi Mandy,
>
> Great API.
>
> One thing I noticed is method StackWalker.getCallerClass() which is
> described as equivalent to the following:
>
>   walk((s) -> s.map(StackFrame::getDeclaringClass)
>                    .skip(2)
> .findFirst()).orElse(Thread.currentThread().getClass());
>
> ... the .orElse is presumably meant for the case when getCallerClass()
> is called directly from within Thread.run() method right? In that case
> Thread's implementation class is presented as the one doing the
> invocation of Thread.run(), which seems logical.
>
> But what about if getCallerClass() is called from a method that has been
> invoked from native code via JNI in a newly attached thread that was not
> started in Java (like the main method)? We will also get the Thread's
> implementation class as the caller. Is this still logical?
>
> What would it be if getCallerClass() returned just Optional<Class<?>>
> and was left to the user to decide what to do in corner cases when there
> is no Java caller?
>
> So returning java.lang.Class objects is safe now there is jigsaw to
> enforce isolation when doing reflection on them. It's great to see how
> things fall together nicely.
>
> Regards, Peter
>
> On 10/30/2015 08:04 PM, Mandy Chung wrote:
>> JEP 259:http://openjdk.java.net/jeps/259
>>
>> Javadoc for the proposed StackWalker API:
>>
>> http://cr.openjdk.java.net/~mchung/jdk9/jep259/api/java/lang/StackWalker.html
>>
>>
>> A simple way to walk the stack:
>>
>>     StackWalker walker = new
>> StackWalker(StackWalker.Option.CLASS_REFERENCE);
>>     walker.walk((s) ->  s.filter(f ->
>> interestingClasses.contains(f.getDeclaringClass())).findFirst());
>>
>> The current usage of sun.reflect.Reflection.getCallerClass(int depth)
>> can be replaced with this StackWalker API.
>>
>> Any feedback on the proposed API is appreciated.
>>
>> Mandy
>>
>> P.S. webrev of the current implementation:
>>     http://cr.openjdk.java.net/~mchung/jdk9/jep259/webrev.00/
>>
>>
>>
>>
>>
>>
>>
>