Review Request JDK-8186050: StackFrame should provide the method signature

[mandy chung]

On 9/2/17 2:57 AM, Peter Levart wrote:
> Hi Mandy,
>
> The API looks fine to me.
>
> Note that there is an opportunity for a follow-up optimization of the 
> StackFrameInfo::getDescriptor() case. When MemberName's 'type' field 
> is filled by native expandFromVM() it is usually filled with the 
> descriptor string. MemberName::getMethodType() then parses this string 
> into a MemberType, resolving all the types. So when 
> StackFrameInfo::getDescriptor() is called, the descriptor string is 
> 1st parsed into MethodType and then formatted back to the descriptor. 
> By introducing new method into package-private MemberName - say 
> getMethodDescriptorString(), this intermediate conversion could often 
> be avoided (for example, if getMethodDescriptorString() was called 
> before getMethodType() on an instance of MethodName).
>
Good suggestion.

Updated webrev:
http://cr.openjdk.java.net/~mchung/jdk10/webrevs/8186050/webrev.02/

Thanks
Mandy
> Regards, Peter
>
> On 09/01/2017 07:39 AM, mandy chung wrote:
>> Updated webrev:
>> http://cr.openjdk.java.net/~mchung/jdk10/webrevs/8186050/webrev.01/index.html 
>>
>>
>> This introduces two new methods, StackFrame::getMethodType and 
>> StackFrame::getDescriptor.
>>
>> Mandy
>>
>> On 8/30/17 12:25 AM, Remi Forax wrote:
>>> Hi Mandy,
>>> thanks for taking care of this.
>>>
>>> In my opinion, we should provide both getMethodType() and 
>>> getDescriptor(),
>>> getDescriptor() is handy for logging (finding the right overload 
>>> when line numbers are not present) and getMethodType() is the one 
>>> you whant if you want to inspect the runtime view of the stack 
>>> frames (and by example interact with java.lang.invoke). For me, it's 
>>> the same reason that give us getDeclaringClass() and getClassName() 
>>> in the current API.
>>>
>>> So getDescriptor() can be called with no restriction but 
>>> getMethodType() requires RETAIN_CLASS_REFERENCE.
>>>
>>> regards,
>>> Rémi
>>>
>>> ----- Mail original -----
>>>> De: "mandy chung" <mandy.chung at oracle.com>
>>>> À: "core-libs-dev" <core-libs-dev at openjdk.java.net>
>>>> Envoyé: Mardi 29 Août 2017 00:57:28
>>>> Objet: Review Request JDK-8186050: StackFrame should provide the 
>>>> method signature
>>>> Method signature is missing in the StackFrame API. This proposes to 
>>>> add
>>>> StackFrame::getMethodDescriptor method to return the method descriptor
>>>> in a stack frame.
>>>>
>>>> Webrev at:
>>>> http://cr.openjdk.java.net/~mchung/jdk10/webrevs/8186050/webrev.00/index.html 
>>>>
>>>>
>>>> There are a couple options how to present the method signature in the
>>>> API level:
>>>> 1. Class<?>[] getParameterTypes() and Class<?> getReturnTypes() 
>>>> similiar
>>>> to what java.lang.reflect.Method has.
>>>> 2. java.lang.invoke.MethodType
>>>> 3. a String representation (i) comma-separated list of the method's
>>>> formal parameter types (ii) bytecode method descriptor as specified 
>>>> in JVMS
>>>>
>>>> Returning Class<?> instance should require to add a new StackWalker
>>>> option to access to the parameter types and return type for option #1
>>>> and #2. StackFrame::getDeclaringClass requires the stack walker to 
>>>> have
>>>> the RETAIN_CLASS_REFERENCE capability.
>>>>
>>>> Option #2 returning MethodType is handy while java.lang would 
>>>> reference
>>>> a type in java.lang.invoke.
>>>>
>>>> Option #3 requires the caller to parse the return string and call
>>>> Class.forName to get the Class<?> instance. OTOH
>>>> MethodType::fromMethodDescriptorString method that returns MethodType
>>>> from a bytecode method descriptor string.
>>>>
>>>> Method signature is for information for typical cases. Getting 
>>>> Class<?>
>>>> for the parameter types and return type would be a niche case. I think
>>>> returning the method descriptor string is a good option - keep the API
>>>> simple and can use MethodType::fromMethodDescriptorString to get back
>>>> the types if needed.
>>>>
>>>> thanks
>>>> Mandy
>>
>