Hi all,
i wrote a simple echo server/client. To catch SIGCHLD signal, i install
a signal handler before first `connect'. The problem is that when the
client exits, the handler seems not called. Instead, upon a new client
connected to the server, the handler will be called(due to last
client's exit).
To summarize,
,----[ first client ]
| $ guile -e main server.scm
| server started on localhost:10000
| New client(#(2 2130706433 54570)) incomming
|
| $ guile -e main client.scm
| connected to server
| hi
| hi
|
| $
`----
,----[ second client ]
| $ guile -e main server.scm
| server started on localhost:10000
| New client(#(2 2130706433 47200)) incomming
| child 16648 terminated
| New client(#(2 2130706433 47201)) incomming
|
| $ guile -e main client.scm
| connected to server
| hey
| hey
|
| $
`----
Can the signal handler be called as soon as the client exits?
Attchments are testing codes.
--
William
Work continues in this area.
-- DEC's SPR-Answering-Automaton
;; echo client
(use-modules (ice-9 optargs))
(use-modules (ice-9 getopt-long))
(use-modules (ice-9 rdelim))
(define (hostname->ip hostname)
"Convert HOSTNAME to its IP.
e.g.,
(hostname->ip \"www.google.com\") => \"64.233.189.104\""
(inet-ntop AF_INET (car (hostent:addr-list (gethost hostname)))))
(define (main args)
(let* ((option-spec '((help (single-char #\h) (value #f))
(host (single-char #\H) (value #t))
(port (single-char #\p) (value #t))))
(options (getopt-long args option-spec)))
(if (option-ref options 'help #f)
(usage)
(client (option-ref options 'host "localhost")
(option-ref options 'port "10000")))))
(define (usage)
(display "\
Usage: client.scm [OPTIONS]
-h, --help show this help
-H, --host=LOCALHOST remote address
-p, --port=10000 remote port
")
(exit 1))
(define (client host port)
(let ((s (socket PF_INET SOCK_STREAM 0))
(host-ip (hostname->ip host))
(port-value (string->number port)))
(connect s AF_INET (inet-pton AF_INET host-ip) port-value)
(display "connected to server\n")
(echo-loop s)))
(define (echo-loop server-port)
(let ((line (read-line (current-input-port) 'concat)))
(while (not (eof-object? line))
(display line server-port)
(display (read-line server-port 'concat))
(set! line (read-line (current-input-port) 'concat)))
(close server-port)))
;;; client.scm ends here
;; echo server
(use-modules (ice-9 optargs))
(use-modules (ice-9 format))
(use-modules (ice-9 getopt-long))
(use-modules (ice-9 rdelim))
(define (hostname->ip hostname)
"Convert HOSTNAME to its IP.
e.g.,
(hostname->ip \"www.google.com\") => \"64.233.189.104\""
(inet-ntop AF_INET (car (hostent:addr-list (gethost hostname)))))
(define (main args)
(let* ((option-spec '((help (single-char #\h) (value #f))
(host (single-char #\H) (value #t))
(port (single-char #\p) (value #t))))
(options (getopt-long args option-spec)))
(if (option-ref options 'help #f)
(usage)
(server (option-ref options 'host "localhost")
(option-ref options 'port "10000")))))
(define (usage)
(display "\
Usage: server.scm [OPTIONS]
-h, --help show this help
-H, --host=LOCALHOST listening address
-p, --port=10000 listening port
")
(exit 1))
(define (server host port)
(let* ((s (socket PF_INET SOCK_STREAM 0))
(host-ip (hostname->ip host))
(port-value (string->number port)))
(setsockopt s SOL_SOCKET SO_REUSEADDR 1)
(bind s AF_INET (inet-pton AF_INET host-ip) port-value)
(listen s 5)
(format #t "server started on ~a:~a\n" host port)
(sigaction SIGCHLD
(lambda (sig)
;; (let ((pid (car (waitpid -1 WNOHANG))))
;; (while (> pid 0)
;; (format #t "child ~d terminated\n" pid)
;; (set! pid (car (waitpid -1 WNOHANG)))))))
(format #t
"child ~d terminated\n"
(car (waitpid -1 WNOHANG)))))
(while #t
(let* ((client (accept s))
(client-port (car client)))
(format #t "New client(~S) incomming\n" (cdr client))
(and (zero? (primitive-fork)) ; child
(begin (close-port s)
(echo-loop client-port)
(primitive-exit)))
(close-port client-port)))))
(define (echo-loop port)
"Read from PORT and send back."
(let ((line (read-line port 'concat)))
(while (not (eof-object? line))
(display line port)
(set! line (read-line port 'concat)))
(close-port port)))
;;; server.scm ends here
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