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

[mandy chung]

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