Re: buffered inter-process communication

[asebian]

> > I am new to chicken and got stuck trying to do buffered inter-process
> > communication.
> > Could someone give me a hint why in the sample code below `copy_b`
> > freezes whereas `copy_c` works as expected?
> > Thanks!
> >
>
> As read-buffered only returns the data buffered by the last read operation,
> your code will not work. You should read block-wise by using "read-string"
> or read byte-wise (as does copy_c in your code).

Have mercy with me!

Re: buffered inter-process communication

[felix . winkelmann]

> Hi,
> I am new to chicken and got stuck trying to do buffered inter-process
> communication.
> Could someone give me a hint why in the sample code below `copy_b`
> freezes whereas `copy_c` works as expected?
> Thanks!
>

As read-buffered only returns the data buffered by the last read operation,
your code will not work. You should read block-wise by using "read-string"
or read byte-wise (as does copy_c in your code).


felix

buffered inter-process communication

[asebian]

Hi,
I am new to chicken and got stuck trying to do buffered inter-process
communication.
Could someone give me a hint why in the sample code below `copy_b`
freezes whereas `copy_c` works as expected?
Thanks!

#!/usr/bin/env -S csi -s

(import (chicken process)
(chicken io)
srfi-1)

(define cmd "/usr/bin/env")

;; copy process out/error to current out/error ports
(call-with-values (lambda () (process* cmd))
  (lambda (in out pid err)
(close-output-port out)
(letrec (;; copy string
 (copy_b (lambda (pair)
   (let ((i (car pair))
 (o (cdr pair)))
 (let ((s (read-buffered i)))
   (if (eof-object? s)
   (close-input-port i)
   (write-string s (string-length s) o))
 ;; copy char
 (copy_c (lambda (pair)
   (let ((i (car pair))
 (o (cdr pair)))
 (when (char-ready? i)
   (let ((c (read-char i)))
 (if (eof-object? c)
 (close-input-port i)
 (write-char c o)))
 ;; recurse over list of port pairs
 (iter (lambda (alist)
 (unless (null? alist)
   (for-each copy_b alist) ; <-- copy_? gets called here
   (iter (filter (lambda (pair)
   (input-port-open? (car pair)))
 alist))
  (iter (list (cons in (current-output-port))
  (cons err (current-error-port)))