newlisp读取数据超时功能

newlisp没有提供读取socket数据超时返回的功能。

自己实现了一个：

;; socket.lsp(context 'socket);; return the number of bytes which are ready to read;; throw error if connection is closed(define (net-peek-ex s)  (unless (net-peek s)  (throw-error "connection is closed")));; read specified size of data from connection in specified milliseconds;; s means socket;; timeout means waiting for milliseconds;; return the receivied data;; return () if timeout(define (read-data s timeout number)  (let ((t (time-of-day)) (r 0))    (catch     (while true    (begin       (sleep 1)      (set 'r (net-peek-ex s))      (if (> r 0) (throw r))      (if (> (- (time-of-day) t) timeout) (throw -1))      )) 'q)    (if (!= -1 q)(begin (net-receive s buffer (min q number)) buffer)'())))(define (test)  ;;(set 's (net-connect "localhost" 7777))  (set 's (net-connect "www.baidu.com" 80))  (let (x (read-data s 50 10 buff))    (if x (println x) (println "nil:" x))  ))