传感器如何在core.async通道中执行?

时间:2016-01-18 05:32:46

标签: clojure clojurescript core.async

在制作频道时,如下所示:

(chan 10 tx)

如果我创建了10个这样的通道,然后同时向所有人发送消息,那么传感器将如何执行。它们会同时运行还是在一个线程上运行?

1 个答案:

答案 0 :(得分:1)

我认为现在没有定义传感器运行时的行为,但是查看ManyToManyChannel的实现,传感器(add!字段)可以同时被调用从频道写作和阅读。

运行一个简单的测试似乎如果通道未满,写入线程将执行传感器,但如果通道已满,有时读取线程会运行它。

缓冲区小的样本:

(defn thread-name []
  (.getName (Thread/currentThread)))

(require '[clojure.core.async :as async :refer [chan <! >! >!! go]])

(defn p [& args]
  (locking *out*
          (apply println (thread-name) ":" args)))

(defn log [v]
  (p "Transforming" v)
  v)

(def tx (map log))

(def c (chan 1 tx))
(def c2 (chan 1 tx))

(go
  (loop []
    (when-let [v (<! c)]
      (p "Getting from c1" v)
      (<! (async/timeout 100))
      (recur))))

(go
  (loop []
    (when-let [v (<! c2)]
      (p "Getting from c2" v)
      (<! (async/timeout 100))
      (recur))))

(dotimes [_ 5]
  (p "Putting in c1" 1)
  (>!! c 1)
  (p "Putting in c2" 100)
  (>!! c2 100))

产生输出:

nREPL-worker-20 : Transforming 1
nREPL-worker-20 : Putting in c2 100
async-dispatch-33 : Getting from c1 1
nREPL-worker-20 : Transforming 100
nREPL-worker-20 : Putting in c1 1
async-dispatch-31 : Getting from c2 100
nREPL-worker-20 : Transforming 1
nREPL-worker-20 : Putting in c2 100
nREPL-worker-20 : Transforming 100
nREPL-worker-20 : Putting in c1 1
async-dispatch-35 : Getting from c2 100
async-dispatch-34 : Transforming 1 <---- In this case is run in the reading side
async-dispatch-34 : Getting from c1 1
nREPL-worker-20 : Putting in c2 100
nREPL-worker-20 : Transforming 100
async-dispatch-37 : Getting from c2 100
async-dispatch-36 : Getting from c1 1
nREPL-worker-20 : Putting in c1 1