missionary.core/!

Usage

• (!)

The interruption checking synchronizer. Throws an instance of Cancelled if current evaluation context is interrupted, otherwise returns nil.

Example : explicit interruption check when an asynchronous operation doesn't support it.

(require '[missionary.core :as m])

;; slurp is not interruptible
(def fetch-page (m/via m/blk (slurp "https://clojure.org")))

;; this is a long-lived task, it must terminate on cancellation
;; the interruption status is polled inside the loop
(def repeat-fetch
  (m/sp
    (loop []
      (m/? fetch-page)
      (m/!) (recur))))

;; without interruption check, the call would never return
;; because timeout waits for repeat-fetch termination
(m/? (m/timeout repeat-fetch 500 :timeout))
:= :timeout

Synchronicity

• interruption checking return is synchronous with the call.

See also

• synchronizers
• sp
• cp
• ap