[plt-scheme] GC surprise collection

On Sun, 5 Sep 2004 07:02:39 -0700, Matthew Flatt <mflatt at cs.utah.edu> wrote:
> At Sun, 5 Sep 2004 01:30:32 +0900, Daniel Silva wrote:
> > moduleobject.c:
> >
> > PyObject* PyModule_New(char *name)
> > {
> >   Scheme_Object* ns = scheme_make_namespace(0, 0);
> >   assert(SCHEME_NAMESPACEP(o));
> >   return PyModule_SpyNew(name, PySchemeNS_New((Scheme_Env*) ns));
> > }
> 
> The `o' above is supposed to be `ns', right?

Whoops.  Yep,  copy&paste rename typo.

> Assuming the usual assert(), and assuming that PyModule_SpyNew() is a
> function (not a macro), then there's no GC between the return of
> scheme_make_namespace() and call to PySchemeNS_New()...
> 
> > schemensobject.c:
> >
> > PyObject* PySchemeNS_New(Scheme_Env* ns)
> > {
> >   assert(SCHEME_NAMESPACEP((Scheme_Object*)ns));
> >   ...
> >   return (PyObject*) ...;
> > }
> 
> ... so I don't see how this assertion can fail.
>
> Maybe you can create a complete (but as small as possible) example to
> demonstrate the problem.

When I isolate it in a small example, the error doesn't come up
anymore.  Sorry, I'll ask again when I can reproduce it...


/* shell:
mzc --cc ext.c
mzc --ld ext.so ext.o

mzscheme:
(load-extension "ext.so")
(ext-test "foo")

*/

#include <escheme.h>
#include <assert.h>

typedef struct {
 void* ob_type;
} PyObject;

#define MALLOC scheme_malloc

PyObject* PyModule_SpyNew(char *name, PyObject* schemens);
PyObject* PySchemeNS_New(Scheme_Env* ns);

PyObject* PyModule_New(char *name)
{
 Scheme_Object* ns = scheme_make_namespace(0, 0);
 assert(SCHEME_NAMESPACEP(ns));
 return PyModule_SpyNew(name, PySchemeNS_New((Scheme_Env*) ns));
}

PyObject* PySchemeNS_New(Scheme_Env* ns)
{
 PyObject* ret;
 assert(SCHEME_NAMESPACEP((Scheme_Object*)ns));
 printf("PySchemeNS_New\n");
 return ret = (PyObject*) MALLOC(sizeof(PyObject));
}

PyObject* PyModule_SpyNew(char *name, PyObject* schemens)
{
 PyObject* ret;
 printf("PyModule_SpyNew\n");
 return ret = (PyObject*) MALLOC(sizeof(PyObject));  
}

Scheme_Object* ext_test(int argc, Scheme_Object* argv[])
{
  PyObject* pymod;
  assert(SCHEME_STRINGP(argv[0]));
  pymod = PyModule_New(SCHEME_STR_VAL(argv[0]));
  return pymod ? scheme_true : scheme_false;
}

Scheme_Object* scheme_module_name() { return scheme_false; }

Scheme_Object* scheme_reload(Scheme_Env* env)
{
  scheme_add_global( "ext-test",
                     scheme_make_prim_w_arity(ext_test, "ext-test", 1, 1),
                     env );
  return scheme_void;
}

Scheme_Object* scheme_initialize(Scheme_Env* env)
{
  return scheme_reload(env);
}