中断clojure.core.async呼叫

Question

I am trying to figure out how to write a clojure wrapper using asynchronous channels for a UDP socket.

Considering just the reading part, my goal is to read packets from the socket and put them into a clojure.core.async channel. Independent of whether I use a DatagramChannel or DatagramSocket , reading would require some blocking calls like Selector.select() or DatagramSocket.receive() , which should be put in a loop in a separate thread.

How should I properly stop the receiving thread in this case? In pure Java, I would send an interrupt to the thread, which would stop the blocking read with an InterruptedException , but I am unfamiliar with clojure.core.async , and I don't know how >!! reacts to interrupt.

Answer 1

All you have to do is close the channel . Then, the receiver will read nil on the next read. async uses nil as a sentinel value to indicate "channel closed" to readers. Note this means you cannot send nil over the channel as a normal piece of data, as readers will misinterpret it as meaning "channel closed" (you would have to replace nil data with :my.proj/nil or something).

Then the receiving thread can simply exit whatever loop it is in, and the Thread object will be cleaned up as normal.

See also the infamous Hot Dog Machine example (yum!).