Hi Coleen, thanks for looking at my change..
> For the record, I think the C++ implementation is more straightforward > than trying to use the Stackwalker and ASM because there's other code > just like it right here. You have all the information you need directly > in the Throwable.backtrace field. Walking it makes sense to me. Also > the StackWalker has a cost because it creates ResolvedMethodNames that > must be interned in the native code in case of redefinition. Yes, I also think that a Java implementation has more costs at runtime. But as this is only encountered if the message is actually accessed, it's not that much of a concern. > I didn't make it through the code for bytecodeUtils but I think it > should be in the interpreter directory where all the other bytecode > iterating methods are. I moved it to the interpreter directory. http://cr.openjdk.java.net/~goetz/wr19/8218628-exMsg-NPE/05-otherMessages/ > It does seem expensive when printing an NPE > message. I wonder if there's some easily helpful variable names that > you could pick out and not have to do all this work for every sort of > bytecode. I'll describe the algorithm in some detail in the paper requested. This might answer this point. > Also the file uses non hotspot names also like > 'createInvalidSource' that should be fixed. I still need to fix these. I’ll leave this to a final review. The code still might be discarded in favour of another implementation. > http://cr.openjdk.java.net/~goetz/wr19/8218628-exMsg- > NPE/02/src/hotspot/share/classfile/javaClasses.cpp.udiff.html > > There's a 'version' in the backtrace. If the method->version() doesn't > match the one in the backtrace, this should return false, because the > method was redefined and the bci probably won't match. There's a bunch > of code in javaClasses that does the similar thing. Starting with the back trace, I will always get the right bytecodes. The backtrace keeps the method alive as I understand. The problem I mentioned in other mails is to get that accessible in Java code ... for the C-implementation I have all the proper information just per design of the metaspace/backtrace etc. at hand. Best regards, Goetz. > > This isn't a full review. > > Thanks, > Coleen > > > > > Thanks! > > Goetz > > > >> Also, it was not strictly correct when I said all that is retained is > >> the method bytecodes. Exception tables, line number tables and local var > >> name & type tables are also retained. > >> > >> regards, > >> > >> > >> Andrew Dinn > >> ----------- > >> Senior Principal Software Engineer > >> Red Hat UK Ltd > >> Registered in England and Wales under Company Registration No. > 03798903 > >> Directors: Michael Cunningham, Michael ("Mike") O'Neill, Eric Shander
