rlm@0: (ns rlm.iterate
rlm@0:   "from the clojure mailing list"
rlm@0:   {:author "tsuraan"}
rlm@0:   (:gen-class
rlm@0:    :name "iterate"
rlm@0:    :main true
rlm@0:    ))
rlm@0: 
rlm@0: 
rlm@0: (set! *warn-on-reflection* true)
rlm@0: (import java.io.FileInputStream)
rlm@0: 
rlm@0: (def *numbytes* (* 16 1024 1024))
rlm@0: 
rlm@0: 
rlm@0: (defmacro better-areduce [a idx ret init expr]
rlm@0:   `(let [a# ~a
rlm@0: 	 alength# (alength a#)]
rlm@0:      (loop [~idx (int 0) ~ret ~init]
rlm@0:        (if (< ~idx alength#)
rlm@0: 	 (recur (unchecked-inc ~idx) ~expr)
rlm@0: 	 ~ret))))
rlm@0: 
rlm@0: (defn translated-countnl
rlm@0:   [#^bytes buf]
rlm@0:   (let [total-length (alength buf)]
rlm@0:     (loop [count (int 0) current-index (int 0)]
rlm@0:       (if (>= current-index total-length)
rlm@0: 	count
rlm@0: 	(let [new-count
rlm@0: 	      (if (= (aget #^bytes buf current-index) (byte 10))
rlm@0: 		(unchecked-inc count)
rlm@0: 		count)]
rlm@0: 	  
rlm@0: 	  (recur new-count (unchecked-inc current-index))))))) 
rlm@0: 	 
rlm@0: (defn countnl-classic
rlm@0:   [#^bytes buf]
rlm@0:   (let [nl (byte 10)]
rlm@0:     (areduce buf idx count 0
rlm@0: 	     (if (= (aget buf idx) nl)
rlm@0: 	       (inc count)
rlm@0: 	       count))))
rlm@0: 
rlm@0: 
rlm@0: (defn countnl-lite
rlm@0:   "this is the absolute fastest function I could come up with.
rlm@0:    still 2.25 times slower that the java version."
rlm@0:   [#^bytes buf]
rlm@0:   (areduce buf idx count (int 0)
rlm@0: 	   (if (= (clojure.lang.RT/aget buf idx) 10)
rlm@0: 	     (unchecked-add count 1)
rlm@0: 	     count)))
rlm@0: 
rlm@0: 
rlm@0: (defn #^Boolean is-ten? [#^Integer A]
rlm@0:      (= A 10))
rlm@0: 
rlm@0: (defn countnl-max-power
rlm@0:   [#^bytes buf]
rlm@0:   (areduce buf idx count (int 0)
rlm@0: 	   (if (is-ten? (clojure.lang.RT/aget buf idx))
rlm@0: 	     (unchecked-inc count)
rlm@0: 	     count)))
rlm@0: 
rlm@0: 
rlm@0: 
rlm@0: 
rlm@0: 			 
rlm@0: 			    
rlm@0: 
rlm@0: 			  
rlm@0: 	     
rlm@0: 
rlm@0: 
rlm@0: "(times are averages with 10 rounds)
rlm@0: no-modifications 
rlm@0:    classic:  198.151
rlm@0:    lite:     186.668
rlm@0: 
rlm@0: unchecked-inc
rlm@0:    classic:  177.938
rlm@0:    lite:     129.604
rlm@0: 
rlm@0: inlined-let
rlm@0:    classic:  202.604
rlm@0:    lite:     195.357
rlm@0: 
rlm@0: make nl a constant
rlm@0:    classic:
rlm@0:    lite:     361.734
rlm@0: 
rlm@0: make nl a constant with type hint
rlm@0:    lite:     394.45
rlm@0: 
rlm@0: literal 10, no let
rlm@0:    lite:     102.876
rlm@0: 
rlm@0:  (int 10) instead of literal 10
rlm@0:    lite:     194.904
rlm@0: 
rlm@0:  (unchecked-add count 0) instead of count
rlm@0:    lite:     209.186
rlm@0: 
rlm@0:  direct reference to RT/aget, bypassing int cast
rlm@0:    lite:      99.767
rlm@0: 
rlm@0:  (int 0) instead of 0 initialization of count
rlm@0:    lite:      66.446
rlm@0: 
rlm@0:  make nl an (int 10) instead of (byte 10)
rlm@0:    lite:     180.003 
rlm@0: "
rlm@0: 
rlm@0: 
rlm@0: 
rlm@0: 
rlm@0: 
rlm@0: (defmacro time-multi
rlm@0:   "Evaluates expr and prints the time it took.  Returns the value of
rlm@0:  expr."
rlm@0:   {:added "1.0"}
rlm@0:   [expr]
rlm@0:   `(let [start# (. System (nanoTime))
rlm@0:          ret# ~expr
rlm@0: 	 end# (/ (double (- (. System (nanoTime)) start#)) 1000000.0)]
rlm@0:      (prn (str "Elapsed time: " end# " msecs"))
rlm@0:      [ret# end#]))
rlm@0: 
rlm@0: 
rlm@0: 
rlm@0: (defn run [countnl-impl]
rlm@0:   (let [ifs (FileInputStream. "/dev/urandom")
rlm@0: 	buf (make-array Byte/TYPE *numbytes*)
rlm@0: 	runs 10]
rlm@0:     (loop [n 0 total-time 0]
rlm@0:       (if (= n runs) (/ total-time runs)
rlm@0: 	  (let [sz (.read #^FileInputStream ifs buf)]
rlm@0: 	    (println "Wanted" *numbytes* "got" sz "bytes")
rlm@0: 	    (let [[count time] (time-multi (countnl-impl buf))]
rlm@0: 	      (println "Got" count "nls")
rlm@0: 	      (recur (inc n) (+ total-time time))))))))
rlm@0: 
rlm@0: (defn -main [& ignore]
rlm@0:   (run countnl-lite)
rlm@0:   (run countnl-classic)
rlm@0:   )
rlm@0: 
rlm@0: 
rlm@0: