Re: [Chicken-users] A more detailed plea for help with FFI...

[Ed Watkeys]

On Dec 15, 2004, at 12:44 PM, Ed Watkeys wrote:

> As soon as I get back from lunch, I'll write a couple programs that 
> create and destroy a million native chicken-string and foreign-string 
> instances and compare the run times.

Running the code below with the set-finalizer! call in 1) place and 2) 
commented out resulted in a runtime delta of about eight seconds on my 
1.33 GHz PB G4 12" running OS X 10.3.6. That means that the overhead of 
handling a finalizer call is about 80 microseconds, or about 0.00008 
seconds. That's about 110,000 processor cycles. Wow.

Ed

;;; code below

#>
#include "string.h"
#include "assert.h"
<#

#>!
static void *make_a_string_c(void) {
  const len = 16; char *s = malloc(len); int i = 0;
  assert(s != NULL);
  for(; i < len-1; i++) s[i] = 'a' + i;
  s[i] = '\0';
  return s;
}

static void free_a_string_c(void *s) {
  if(s) free(s);
}
<#

(define make-a-string
  (lambda ()
    (let ((s (make_a_string_c)))
      (set-finalizer! s free_a_string_c)
      s)))

(letrec
    ((loop
      (lambda (n)
        (cond ((= n 0) #t)
              (else (make-a-string)
                    (loop (- n 1)))))))
  (loop 100000))