[Caml-list] Problem with using oo in dynamically loaded bytecode ocaml runtime

[Tomasz Zielonka <zielony@cs.net.pl>]

Hi

Situation: 

I'm doing some integration of OCaml and PostgreSQL. PostgreSQL loads a
DSO which implements so called "procedural language call handler". 

I've built this DSO by ld-shared'ing libcamlrun.a with some additional C
.o files, .o with wrappers for callback'ed ocaml funs, .o with new
primitives and .o with ocaml bytecode. I also removed main.o from
libcamlrun.

I linked bytecode files into .o with following command:

  ocamlc -g -custom -output-obj -o plocamlb_bytecode.o plocamlb_spi.cmo \
  plocamlb_mlfuns.cmo

Problem: Everything worked fine until I wanted to define a class.

When I define a class with _no methods_, it works, but there is little
use of such class.

When I define any method in this class (but still don't use a single
instance of the class) it stops working. After loading the DSO, ocaml
raises Not_found exception and quits.

I wanted to use CAMLRUNPARAM b (stack backtrace) option, but apparently
it doesn't work with such a library/DSO (Program not linked with -g,
cannot print stack backtrace).

I couldn't force ocamlc to keep DBUG section. I'm not sure it would
help, because read_debug_info tries to open executable file, not the
loaded DSO. I tried several caml_main_param[0] (different files), no
luck.

When I make native/opt library _and_ define a method, I get corrupted
memory in the postgresql backend.

So:
1) There is a bug, but where? In my program, in OCaml?
2) How to get stack backtrace in this situation?

thank you in advance
tom

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   .-.   Tomasz Zielonka                           CYBER SERVICE
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