<shameless plug>
Something like imminent might be useful here. In particular the section
about combinators: https://github.com/leonardoborges/imminent#combinators
</shameless plug>
On Sat, Apr 9, 2016 at 9:33 PM Gary Verhaegen <gary.verhae...@gmail.com>
wrote:
> You could:
>
> * Create all futures *without* deref'ing them, so they all start in
> parallel;
> * Loop through the futures, asking them if they have finished, and print
> those that have (and remove them from the list)
>
> But if you want to get each result as it comes back, it's probably a
> better fit for core.async than plain futures. I would suggest creating a
> channel with multiple producers and a single consumer, where each producer
> gets a site and the consumer prints the result. That way, you get the
> results as they come.
>
> Here is a rough draft:
>
> (ns cjr-http-test.core
> (:require [clj-http.client :as client]
>
>
> [clojure.core.async :as async :refer [<!! >!!]]))
> (defn get-heads
> [sites]
> (mapv (fn [site] (future {:head (client/head site)
> :url site}))
> sites))
> (def sites ["http://www.google.com";
> "http://www.yahoo.com";
> "http://www.bing.com";])
> (defn use-futures
> []
> (let [head-requests (get-heads sites)]
> (loop [to-check head-requests checked []]
> (cond (and (empty? checked) (empty? to-check))
> :finished
>
> (empty? to-check)
> (recur checked [])
>
> (realized? (first to-check))
> (do (-> to-check first deref :url println)
> (recur (rest to-check) checked))
>
> :else (recur (rest to-check) (cons (first to-check) checked))))))
> (defn use-async
> []
> (let [ch (async/chan)
> producers (mapv (fn [site]
> (doto (Thread. #(>!! ch {:head (client/head site)
> :url site}))
> (.start)))
> sites)
> close-chan (doto (Thread. (fn []
> (mapv #(.join %) producers)
> (async/close! ch)))
> (.start))]
> (loop [v (<!! ch)]
> (if (nil? v) :finished
> (do (-> v :url println)
> (recur (<!! ch)))))))
>
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