用rust写lisp解释器2 （实现一个简单的异步模型（channel + thread => go））

背景

前段时间实现了一个 call-with-tcp-listener 过程（函数）

 (call-with-tcp-listener "127.0.0.1:8088" ( lambda (in) (
      (display  (req-read-string in))
      "HTTP/1.1 200 OK\r\n\r\n hello word"
 )))

如果是简单的返回数据还不存在问题，但是当涉及到io的时候就会出现阻塞的情况，最简单的解决方案就是一个请求一个线程，但是这种模型开销比较大，所以想到了线程池，然后就实现了一个及其简单的版本

实现

使用到了 thread + channel + lambda-lep + apply 这几个过程
首先定义一个线程池
async.lisp

(
    (define thread-qty (* (get-os-cpu-num) 2))
    (define thread-count 1)
    (define barrier (make-barrier thread-qty))
    (define channel (make-channel))
    (while (<  thread-count thread-qty)
        (  
            (thread-run (lambda () (
                (channel-for-each (lambda (task) (
                    ( task)
                )) channel)
                (barrier-wait barrier)
                ;; (loop ((<- channel)))
            )))
            (set! thread-count (+ thread-count 1))))
    (define go (lambda-lep (task) (
       (apply (`(-> ,channel ,task)))
    )))
    (export go)
)

如何使用

(
    (import (go) from "./async.lisp")
    (go 
        (lambda () 
            (println (current-thread-name) " hello rust-lisp!"))))

控制台会输出

thread-1 hello rust-lisp!

重构

让我们在结合 call-with-tcp-listener 过程完善一下吧
首先重构一下 call-with-tcp-listener 过程使其接受out port
main.lisp

(
    (def handler (in out) (
        ;; 模拟io读取等待
        (sleep 1)
        (println (current-thread-name))
        (display  (req-read-string in))
        (write-string "HTTP/1.1 200 OK\r\n\r\n hello word" out )
    ))
    (call-with-tcp-listener "127.0.0.1:8088" ( lambda (in out) (
         ( handler in out)
    ))))

然后使用go 过程实现任务提交
main.lisp

(
    (load "./lib.lisp")
    (import (go) from "./async.lisp")
    (def handler (in out) (
        ;; 模拟io读取等待
        (sleep 1)
        (println (current-thread-name))
        (display  (req-read-string in))
        (write-string "HTTP/1.1 200 OK\r\n\r\n hello word" out )
    ))
    (call-with-tcp-listener "127.0.0.1:8088" ( lambda (in out) (
         (go (lambda () (handler in out)))
    ))))

任务提交之后,下面这段代码会从channel中读取到最新提交的 task (过程) 然后执行。

(channel-for-each (lambda (task) (
                    (task)
                )) channel)

运行后访问 控制台打印如下

thread1
GET / HTTP/1.0
Host: 127.0.0.1:8088
User-Agent: ApacheBench/2.3
Accept: */*

async.lisp 源码