network.clj

(require '[clojure.java.shell :as shell]
         '[clojure.java.io :as io])

(import '(java.util.concurrent SynchronousQueue))

(defn pings [host output]
  (future
    (let [proc (.start
                (ProcessBuilder.
                 ["ping" "-Dni" "120" host]))]
      (try
        (let [i (.getInputStream proc)
              r (io/reader i)]
          (doseq [l (line-seq r)
                  :when (.contains l "time=")
                  :let [split-line (.split l " ")
                        at (Double/parseDouble
                            (subs (first split-line) 1 (dec (count (first split-line)))))
                        time (Double/parseDouble
                              (last (.split (last (butlast split-line)) "=")))]]
            (.put output {:host host
                          :at at
                          :time time})))
        (finally
          (.destroy proc))))))

(defmacro with-resources [& body]
  `(binding [*resources* (atom ())]
     (try
       ~@body
       (finally
         (doseq [r# @*resources*]
           (.close r#))))))


(let [sql (.start
           (ProcessBuilder.
            ["psql" "-nq"]))
      q (SynchronousQueue.)]
  (pings "192.168.1.1" q)
  (pings "comcast.net" q)
  (pings "8.8.8.8" q)
  (pings "4.2.2.1" q)
  (pings "127.0.0.1" q)
  (pings "oz.local" q)
  (with-open [sql-stream (.getOutputStream sql)
              sql-writer (io/writer sql-stream)]
    (while true
      (let [{:keys [host at time]} (.take q)
            _ (println "inserting" host at time)
            cmd (format "INSERT INTO ping VALUES ('%s', to_timestamp(%s) AT TIME ZONE 'PST',INTERVAL '%s ms');\n"
                        host
                        at
                        time)]
        (.write sql-writer cmd)
        (.flush sql-writer)))))