Guile 1.8 Garbage Collection Question

[Whitlock, Bradley D]

I have built Guile 1.8.8.2 on MinGW.

 

I have wrapped some gtkwave code with Guile and have a memory issue. The following code apparently never frees ‘s’, but I am not sure why.

 

SCM_DEFINE (libguile_fst_writer_emit_value, "libguile-fst-writer-emit-value",

                    3,0,0,

                    (SCM scm_ctx, SCM scm_fsthandle, SCM scm_val),

                    "Write a change on fstHandle")

{

  // Storage for temporary string

  char* s = NULL;

  scm_dynwind_begin (0);

  scm_dynwind_unwind_handler (free, s, SCM_F_WIND_EXPLICITLY);

 

  s = scm_to_locale_string (scm_val);

 

  fstWriterEmitValueChange(SCM_TO_CTX (scm_ctx),

                                                   SCM_TO_FSTHANDLE (scm_fsthandle),

                                                   s_buf);

 

  scm_dynwind_end();

 

  return SCM_UNSPECIFIED;

}

 

The code is called from Scheme land in the following loop:

 

(let loop ((n 0))

  (if (eq? n 10000000) #t

      (begin

 

                ;; Emit some changes on the signal

                (fst-emit-value ctx s (number->string (modulo n 2)))

                (fst-emit-value ctx s1 (number->string (modulo (1+ n) 2)))

                (fst-emit-time-change ctx n)

 

                (loop (1+ n))

                )))

 

It seems to me that the garbage collector never gets a chance to run, so how do I make sure that the gc gets a turn?

 

If I define my function like the following, the leak disappears, but it’s a less desirable solution:

 

SCM_DEFINE (libguile_fst_writer_emit_value, "libguile-fst-writer-emit-value",

                    3,0,0,

                    (SCM scm_ctx, SCM scm_fsthandle, SCM scm_val),

                    "Write a change on fstHandle")

{

  // Storage for temporary string

  char s_buf [1024];

  scm_to_locale_stringbuf (scm_val, s_buf, 1024);

  s = scm_to_locale_string (scm_val);

 

  fstWriterEmitValueChange(SCM_TO_CTX (scm_ctx),

                                                   SCM_TO_FSTHANDLE (scm_fsthandle),

                                                   s_buf);

 

  return SCM_UNSPECIFIED;

}

 

Any suggestion?

 

Thanks,

Brad