Although a while loop does work here, it's just a hack to get the
desired behavior. Have you considered using a scheduled thread pool as
your controller?
For example:
(def ^{:private true} pool (atom nil))
(def ^{:private true} num-threads 3)
(defn- thread-pool []
(swap! pool (fn [p] (or p (ScheduledThreadPoolExecutor. num-threads)))))
(defn schedule-periodic
"Schedules function f to run every 'delay' milliseconds after an
initial delay of 'initial-delay'."
[f initial-delay delay]
(.scheduleWithFixedDelay (thread-pool)
(protect-from-exceptions f)
initial-delay delay TimeUnit/MILLISECONDS))
(defn run-always []
(schedule-periodic dosomething 0 60))
This is a simple example that lacks general robustness around error
handling, but provides a clean way to continuously run things. You can
also provide a clean shutdown a la:
(defn shutdown
"Terminates all periodic tasks."
[]
(swap! pool (fn [p] (when p (.shutdown p)))))
Hope this helps,
Aaron Bedra
--
Clojure/core
http://clojure.com
On 02/21/2011 06:35 PM, Brent Millare wrote:
Seems to work for me. Are you putting something valid in (do
something)?
Also if you want to watch files in a directory, there is JNotify,
which might be useful to you.
On Feb 21, 5:19 pm, clj123<ariela2...@gmail.com> wrote:
Hello,
I'm looking for an on-going service that runs and processes files in a
certain location. This function should be contiously running.
The function that I've used, it always running and when files are
place it does something with it.
(defn run-always []
(while true (dosomething)))
However, it throws an exception:
Expression failed: (run-always)
I'm not sure why it's throwing it, and is there a better way to handle
this kind of service?
Thanks.
--
Cheers,
Aaron Bedra
--
Clojure/core
http://clojure.com
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