使用带有core.async通道的http-kit长轮询

Question

我有一些长时间运行的进程，当进程完成时，返回一个带有结果的core.async通道。

现在，我想使用HTTP使用长轮询来返回结果。不幸的是，我有点搞不懂这样做的正确方式是什么。

目前，我有一个处理程序(连接到一个路由)，它启动处理调用并在完成时发送结果：

(defn handler
  [request]
  (let [c (process request)] ;; long running process that returns a channel
    (http/with-channel request channel
      (http/send! channel {:status 200
                           :body (<!! (go (<! c)))))
      (http/on-close channel (fn [_] (async/close! c))))))

有效，但我不确定这是不是正确的方法。

编辑，因为<!!是阻塞的，我现在正在尝试一个非阻塞变体的围棋循环。

(defn handler
  [request]
  (let [c (process request)]
    (http/with-channel request channel
      (async/go-loop [v (<! c)]
        (http/send! channel {:status 200
                             :body v}))
      (http/on-close channel (fn [_] (async/close! c))))))

Answer 1

为什么不在围棋区发送频道呢？

(http/with-channel request channel
  (go (http/send! channel (<! c))))

<!!阻塞了-因此，仅仅在处理程序中直接调用<!! c并没有真正的优势：

(defn handler [request] (let [c (process request)] ;; long running process that returns a channel {:status 200 :body (<!! c)}))

针对问题更新进行编辑:更新后的代码可以工作--这是一个功能齐全的命名空间，适合我：

(ns async-resp.core
  (:require [org.httpkit.server :as http]
            [clojure.core.async :as async :refer (<! >! go chan go-loop close! timeout)]))

(defn process
  [_]
  (let [ch (chan)]
    (go
      (<! (timeout 5000))
      (>! ch "TEST"))
    ch))

(defn test-handler
  [request]
  (let [c (process request)]
    (http/with-channel request channel
      (go-loop [v (<! c)]
        (http/send! channel {:status 200
                             :body v}))
      (http/on-close channel (fn [_] (close! c))))))

(defn run
  []
  (http/run-server test-handler {}))

然而，到目前为止，我不得不手动将tools.analyzer.jvm依赖项添加到project.clj中--因为我按原样使用core.async获得编译失败。

检查你在运行最新的core.async和分析器吗？