For providing something informational, option #3 is a good choice.
It's simple (no need for new StackWalker access options), yet sufficient.
The changes look good to me.
Thanks,
-Brent
On 08/28/2017 07:37 PM, mandy chung wrote:
On 8/28/17 4:23 PM, Paul Sandoz wrote:
Hi Mandy,
MethodType::fromMethodDescriptorString​ (and the three arg
Class.forName) requires that a class loader be supplied. Perhaps for
the thing consuming StackWalker it’s not possible to reproduce a
MethodType (or components of) from the descriptor string
The class loader can be obtained from
StackFrame::getDeclaringClass().getClassLoader().
much like it may not possible to reproduce the declaring class from
the class name string, hence the need for RETAIN_CLASS_REFERENCE?
Right and also security permission check can be performed once when
getting StackWalker instance. No security permission check is performed
for each StackFrame::getDeclaringClass for better performance.
If i understand you correctly i think you are saying the method
descriptor is more useful for informational (logging say) purposes?
Yes for completeness since the method signature is currently unavailable.
Mandy
Paul.
On 28 Aug 2017, at 15:57, mandy chung <[email protected]> wrote:
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
