Question

我在普通的lisp中尝试一个简单的echo服务器（我使用clisp）。我在http://rosettacode.org/wiki/Echo_server#Common_Lisp

中尝试了这个例子

CLISP版本（没有usocket）工作正常。

当我尝试usocket版本（使用clisp）时，我收到以下错误：

* - 条件 CDR :: INPUT不是列表发生。

提前感谢您的回复，迪米瑞斯

Answer 1

我不确定答案，但我认为这可以追溯到等待输入和等待输入内部 。功能等待输入具有以下定义（缩写）：

(defun wait-for-input (socket-or-sockets &key timeout ready-only)
  "Waits for one or more streams to become ready for reading from
the socket.  When `timeout' (a non-negative real number) is
specified, wait `timeout' seconds, or wait indefinitely when
it isn't specified.  A `timeout' value of 0 (zero) means polling. …"
  (unless (wait-list-p socket-or-sockets)
    (let ((wl (make-wait-list (if (listp socket-or-sockets)
                                  socket-or-sockets (list socket-or-sockets)))))
      (multiple-value-bind
            (socks to)
          (wait-for-input wl :timeout timeout :ready-only ready-only)
        (return-from wait-for-input
          (values (if ready-only socks socket-or-sockets) to)))))
  (let* ((start (get-internal-real-time))
         (sockets-ready 0))
    (dolist (x (wait-list-waiters socket-or-sockets))
      (when (setf (state x)
                  #+(and win32 (or sbcl ecl)) nil ; they cannot rely on LISTEN
                  #-(and win32 (or sbcl ecl))
                  (if (and (stream-usocket-p x)
                           (listen (socket-stream x)))
                      :read
                      nil))
        (incf sockets-ready)))
    ;; the internal routine is responsibe for
    ;; making sure the wait doesn't block on socket-streams of
    ;; which theready- socket isn't ready, but there's space left in the
    ;; buffer
    (wait-for-input-internal socket-or-sockets
                             :timeout (if (zerop sockets-ready) timeout 0))
    (let ((to-result (when timeout
                       (let ((elapsed (/ (- (get-internal-real-time) start)
                                         internal-time-units-per-second)))
                         (when (< elapsed timeout)
                           (- timeout elapsed))))))
      (values (if ready-only
                  (remove-if #'null (wait-list-waiters socket-or-sockets) :key #'state)
                  socket-or-sockets)
              to-result))))

请注意，最后一部分使用

调用 wait-for-input-internal

(wait-for-input-internal socket-or-sockets
                         :timeout (if (zerop sockets-ready) timeout 0))

现在，名称 socket-or-sockets 意味着它的值可以是单个套接字或套接字列表。但是，让我们来看看CLISP的 wait-for-input-internal 的定义（它在backend/<implementation>.lisp中定义）：

(defmethod wait-for-input-internal (wait-list &key timeout)
  (with-mapped-conditions ()
    (multiple-value-bind
        (secs musecs)
        (split-timeout (or timeout 1))
      (dolist (x (wait-list-%wait wait-list))
        (setf (cdr x) :INPUT))
      (let* ((request-list (wait-list-%wait wait-list))
             (status-list (if timeout
                              (socket:socket-status request-list secs musecs)
                            (socket:socket-status request-list)))
             (sockets (wait-list-waiters wait-list)))
        (do* ((x (pop sockets) (pop sockets))
              (y (cdr (pop status-list)) (cdr (pop status-list))))
             ((null x))
          (when (member y '(T :INPUT))
            (setf (state x) :READ)))
        wait-list))))

：INPUT 有两种用途。似乎等待列表的每个元素都应该是一个缺点，其cdr包含某种状态。也许用单个套接字调用 wait-for-input （毕竟，参数名称是 socket-or-sockets ，当调用 wait-for-input-internal ，它会期待一个列表。这可能导致后者在期待(<something> . :INPUT)时获得((<something . :INPUT))。我＆＃39;但是我不确定。但无论如何，错误来自这里的某个地方。

与cl-usocket共同使用的回声服务器

1 个答案: