我正在尝试用 common lisp 编写一个简单的异步服务器。强调简单。这是Take 2 （感谢 Rainer 的建议和格式化）：
(ql:quickload (list :cl-ppcre :usocket))
(defpackage :test-server (:use :cl :cl-ppcre :usocket))
(in-package :test-server)
(defvar *socket-handle* nil)
(defparameter *channel* nil)
(defclass buffer ()
((contents :accessor contents :initform nil)
(started :reader started :initform (get-universal-time))
(state :accessor state :initform :empty)))
(defun listen-on (port &optional (stream *standard-output*))
(setf *socket-handle* (socket-listen "127.0.0.1" port :reuse-address t))
(let ((conns (list *socket-handle*))
(buffers (make-hash-table)))
(loop (loop for ready in (wait-for-input conns :ready-only t)
do (if (typep ready 'stream-server-usocket)
(push (socket-accept ready) conns)
(let ((buf (gethash ready buffers (make-instance 'buffer))))
(buffered-read! (socket-stream ready) buf)
(when (starts-with? (list #\newline #\return #\newline #\return)
(contents buf))
(format stream "COMPLETE ~s~%"
(coerce (reverse (contents buf)) 'string))
(setf conns (remove ready conns))
(remhash ready buffers)
(let ((parsed (parse buf)))
(format stream "PARSED: ~s~%" parsed)
(handle-request ready (parse buf))))))))))
(defmethod parse ((buf buffer))
(let ((lines (split "\\r?\\n" (coerce (reverse (contents buf)) 'string))))
(second (split " " (first lines)))))
HTTP 写入：
(defmethod http-write (stream (line-end (eql :crlf)))
(declare (ignore line-end))
(write-char #\return stream)
(write-char #\linefeed stream)
(values))
(defmethod http-write (stream (line string))
(write-string line stream)
(http-write stream :crlf)
(values))
(defmethod http-write (stream (lst list))
(mapc (lambda (thing) (http-write stream thing)) lst)
(values))
如何处理请求：
(defmethod handle-request (socket request)
(let ((s (socket-stream socket)))
(cond ((string= "/sub" request)
(subscribe! socket))
((string= "/pub" request)
(publish! "Got a message!")
(http-write s (list "HTTP/1.1 200 OK"
"Content-Type: text/plain; charset=UTF-8"
"Cache-Control: no-cache, no-store, must-revalidate"
"Content-Length: 10" :crlf
"Published!" :crlf))
(socket-close socket))
(t (http-write s (list "HTTP/1.1 200 OK"
"Content-Type: text/plain; charset=UTF-9"
"Content-Length: 2" :crlf
"Ok" :crlf))
(socket-close socket)))))
发布！
(defun publish! (msg)
(loop for sock in *channel*
do (handler-case
(let ((s (socket-stream sock)))
(format s "data: ~a" msg)
(http-write s (list :crlf :crlf))
(force-output s))
(error (e)
(declare (ignore e))
(setf *channel* (remove sock *channel*))))))
订阅！
(defun subscribe! (sock)
(let ((s (socket-stream sock)))
(http-write s (list "HTTP/1.1 200 OK"
"Content-Type: text/event-stream; charset=utf-8"
"Transfer-Encoding: chunked"
"Connection: keep-alive"
"Expires: Thu, 01 Jan 1970 00:00:01 GMT"
"Cache-Control: no-cache, no-store, must-revalidate" :crlf))
(force-output s)
(push sock *channel*)))
基本实用程序：
(defmethod starts-with? ((prefix list) (list list) &optional (test #'eql))
(loop for (p . rest-p) on prefix for (l . rest-l) on list
when (or (and rest-p (not rest-l)) (not (funcall test p l)))
do (return nil)
finally (return t)))
(defun stop ()
(when *socket-handle*
(loop while (socket-close *socket-handle*))
(setf *socket-handle* nil
*channel* nil)))
(defmethod buffered-read! (stream (buffer buffer))
(loop for char = (read-char-no-hang stream nil :eof)
until (or (null char) (eql :eof char))
do (push char (contents buffer))))
总结是：
- 它侦听指定端口并将请求数据转储到指定流
- 如果它收到对 的请求
"/sub"，它应该保留该套接字以供进一步写入。 - 如果它收到对 的请求
"/pub"，它应该向所有现有订阅者发送一条短消息 plain-text"Ok"它会根据任何其他请求发回 a 。
像往常一样，欢迎所有反馈。从第 2 版开始（添加了 HTTP 友好的行尾和几个战略性的force-output调用），浏览器似乎对我更满意，但是当消息实际发送到现有通道时，Chrome 仍然会窒息。知道剩下的错误publish!是什么吗？
要清楚，做
var src = new EventSource("/sub");
src.onerror = function (e) { console.log("ERROR", e); };
src.onopen = function (e) { console.log("OPEN", e); };
src.onmessage = function (e) { console.log("MESSAGE", e) };
现在让我在 FireFox 中获得一个工作事件流（它触发onopen，并触发onmessage每次发送的更新）。但在 Chrome 中失败（触发器onopen，每次更新触发onerror而不是onmessage）。
任何帮助表示赞赏。