Re: Problem using generic types?

[Andi Vajda]

 Hi Petrus,
On Mon, 30 Dec 2013, Petrus Hyvönen wrote:

Andi, great to hear that you could reproduce it. I'm very thankful if you
could have a look at it, I've been struggling to understand how the
machinery behind this works, but far from it still..

I think I fixed the problem and added an improvement to generics support 
along the way. Please check out rev 1557423 from jcc's trunk, rebuild 
your module with it and let me know how it's working for you.

The bug had to do with SimpleClass2's wrapper class missing its parameters 
slot which it should get from its superclass, SimpleClass. When calling a
method on SimpleClass from SimpleClass2, the missing parameters in the
wrapper's struct would cause memory to get trashed.

In addition to fixing the bug, I also improved support for fixed class 
parameters. Now, if you change SimpleClass's return_null() method to return 
new Integer(12) instead, when calling it on SimpleClass2, 12 is returned 
instead of <Object: 12>.

Andi..

public class SimpleClass<T> { 
public SimpleClass() { 
System.out.println("Created SimpleClass"); 
}
    public T return_null() {
        return (T) new Integer(12);
    }

}



Best Regards
/Petrus



On Mon, Dec 30, 2013 at 10:36 AM, Andi Vajda <va...@apache.org> wrote:


On Sun, 29 Dec 2013, Petrus Hyvönen wrote:

 I have distilled the library that I have some trouble with and I think I
have an example that is failing due to same problem I think. I am not good
in java, but have tried to follow the logic from the library I'm wrapping.
The function of the example does not make sense in itself.

public class SimpleClass<T> {
public SimpleClass() {
System.out.println("Created SimpleClass");
}
   public T return_null() {
       return  null;
   }

}



public class SimpleClass2 extends SimpleClass<Integer>{

public SimpleClass2(){}
   public void testInJava(){
   System.out.println(this.return_null());
   }
}


It seems to me that there is some problem with methods inherited that
returns a generic type, failing in wrapType when this is to be wrapped.

The python script that fails:

a= SimpleClass()
print a.return_null()

b = SimpleClass2()
b.testInJava()

print b.return_null()  #Fails in wrapType

I don't know if the return null is a bad thing to do in java, but the
error
seems very similar to what I experience in the larger library. I have a
skeleton of that this is slightly larger, but not returning null, but
trying to keep the lenght of example low :)

Any comments highly appriciated :)


I've been able to reproduce the problem.
Thank you for providing an isolated test case !

Andi..



best Regards
/Petrus






On Fri, Dec 27, 2013 at 6:25 PM, Andi Vajda <va...@apache.org> wrote:


 On Dec 27, 2013, at 17:36, Petrus Hyvönen <petrus.hyvo...@gmail.com>

wrote:


Dear Andi,

I am working on debugging the failure and try to understand a bit how
JCC
works internally. I haven't gone very far but in case you have some
pointers from these early debugging sessions I would be very thankful. I
know it's complex, and I should try to make some smaller test cases, but

I

don't really have a grasp yet where the problem might be.

Writing this might help me also to get some structure in my thinking :)



The main crash seems to be in the last line, wrapType(), of
__wrap__.cpp:

     static PyObject

 *t_AbstractReconfigurableDetector_withHandler(t_
AbstractReconfigurableDetector

*self, PyObject *arg)
       {
         ::org::orekit::propagation::events::handlers::EventHandler
a0((jobject) NULL);
         PyTypeObject **p0;
         ::org::orekit::propagation::events::EventDetector
result((jobject) NULL);

         if (!parseArg(arg, "K",

 ::org::orekit::propagation::events::handlers::
EventHandler::initializeClass,

&a0, &p0,

 ::org::orekit::propagation::events::handlers::t_
EventHandler::parameters_))

         {
           OBJ_CALL(result = self->object.withHandler(a0));
           return self->parameters[0] != NULL ?
wrapType(self->parameters[0], result.this$) :
::org::orekit::propagation::events::t_EventDetector::wrap_
Object(result);
         }

The parameters[0] does not seem to be null, but neither is it a valid
object, in my debugger it says 0xbaadf00d {ob_refcnt=??? ob_type=???
ob_size=??? ...}     _typeobject *, wrapType is called and when trying
to
access the wrapfn it crashes.

The main python lines are:
tmp1 = ElevationDetector(sta1Frame)                    #

ElevationDetector

is a java public class ElevationDetector extends
AbstractReconfigurableDetector<ElevationDetector>
hand = ContinueOnEvent().of_(ElevationDetector)   # a
java ContinueOnEvent<ElevationDetector> object
elDetector = tmp1.withHandler(hand)     #Crash. withHandler is a method
that is inherited from AbstractReconfigurableDetector to

ElevationDetector


This crashes when interactively entered on the python prompt (or in
other
interactive consoles), but seems to work if executed directly without
interactivity. This difference makes me think that it might be something
with garbage collection, but don't know.

Any comments appriciated, I know this is likely very difficult to
comment
on as it's not very encapsulated.


Right, so unless you can isolate this into something I can reproduce, I'm
afraid there isn't much I can comment.
It is quite likely that by the time you have that reproducible test case
ready, you also have the solution to the problem. Or I might be able to
help then...

Andi..


Regards
/Petrus






 On Sun, Dec 15, 2013 at 10:36 AM, Andi Vajda <va...@apache.org> wrote:


 On Dec 15, 2013, at 5:43, Petrus Hyvönen <petrus.hyvo...@gmail.com>

wrote:

Hi Andi,

I see your point and have now kept in the pure python domain.

If I run my script from the shell by "python script.py" it does not

crash. However if I execute it line-by-line in python it crashes (or in
other tools such as ipython notebook).

All classes used are non-wrapped java classes, but I get the same

effect

with classes made for python subclassing.

I am getting this on both MacOSX 64-bit python and Windows 7 32-bit

python.



 elDetector =

elDetector.withHandler(ContinueOnEvent().of_(ElevationDetector))

#
# A fatal error has been detected by the Java Runtime Environment:
#
#  SIGSEGV (0xb) at pc=0x000000010005da1a, pid=3318, tid=1287
#
# JRE version: Java(TM) SE Runtime Environment (7.0_45-b18) (build

1.7.0_45-b18)

# Java VM: Java HotSpot(TM) 64-Bit Server VM (24.45-b08 mixed mode

bsd-amd64 compressed oops)

# Problematic frame:
# C  [libpython2.7.dylib+0x5aa1a]  PyObject_GetAttr+0x1a
#


from the stack it seems like there is somthing happening in "wrapType"
Stack: [0x00007fff5fb80000,0x00007fff5fc00000],
 sp=0x00007fff5fbff470,

free space=509k

Native frames: (J=compiled Java code, j=interpreted, Vv=VM code,

C=native code)

C  [libpython2.7.dylib+0x5aa1a]  PyObject_GetAttr+0x1a
C  [_orekit.so+0xa80878]  wrapType(_typeobject*, _jobject*
const&)+0x58
C  [_orekit.so+0x554400]


 org::orekit::propagation::events::t_AbstractReconfigurableDetector
_withHandler(org::orekit::propagation::events::t_
AbstractReconfigurableDetector*,

_object*)+0x1c0


First, is the generic class assignment correct as if to write "new

ContinueOnEvent<ElevationDetector>()" in java? And is it ok to use

regular

java objects/types?


Any other comments to move forward highly appriciated.. Is it somehow

possible to get more log what is going wrong?

You could compile the whole thing for debugging, by adding --debug
after
'build' in the jcc invocation and run it with gdb.

If you can isolate a reproducible crash into a small test case, I can

also

take a look at it.

Andi..


WIth best regards
/Petrus



 On 15 Dec 2013, at 2:40 , Andi Vajda <va...@apache.org> wrote:


 On Dec 14, 2013, at 19:14, Petrus Hyvönen <petrus.hyvo...@gmail.com


wrote:


Hi,

I'm having a problem with I think might be related to generic types,

but not sure at all.


I'm wrapping a orbit calculation library, which has been working
well

but in latest version is using generic types and I'm getting some

problems.

The script works when executed in plain python, but fails in ipython
notebook on this last line when executed as a couple of cells.


What is an 'ipython notebook' ?

Andi.,


The section with problem in my script is:
elDetector =

ElevationDetector(sta1Frame).withConstantElevation(math.
radians(5.0))

elDetector =

elDetector.withHandler(ContinueOnEvent().of_(ElevationDetector))


In Java it would typically look something like:

ElevationDetector detector = new ElevationDetector(topo)
                                        .withConstantElevation(x)
                                        .withHandler(new

ContinueOnEvent<ElevationDetector>());


It produces correct results in plain python, but crashes the kernel

in

ipython if executed as cells, and in exection from spyder I get an error
message:


" elDetector =

elDetector.withHandler(ContinueOnEvent().of_(ElevationDetector))

AttributeError: 'str' object has no attribute 'wrapfn_' "

As I have been using this setup stabely with lots of other functions

it feels like there is something with the generic type line, but I
don't
really know how to get any further? I'm confused by that the pauses in

the

execution could seem to affect the result.


Any comments highly appriciated...

Best Regards
/Petrus




--
_____________________________________________
Petrus Hyvönen, Uppsala, Sweden
Mobile Phone/SMS:+46 73 803 19 00





--
_____________________________________________
Petrus Hyvönen, Uppsala, Sweden
Mobile Phone/SMS:+46 73 803 19 00




--
_____________________________________________
Petrus Hyvönen, Uppsala, Sweden
Mobile Phone/SMS:+46 73 803 19 00