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annotate src/rlm/iterate.clj @ 0:78a630e650d2

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initial import
author Robert McIntyre <rlm@mit.edu>
date Tue, 18 Oct 2011 00:57:08 -0700
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rlm@0 1 (ns rlm.iterate
rlm@0 2 "from the clojure mailing list"
rlm@0 3 {:author "tsuraan"}
rlm@0 4 (:gen-class
rlm@0 5 :name "iterate"
rlm@0 6 :main true
rlm@0 7 ))
rlm@0 8
rlm@0 9
rlm@0 10 (set! *warn-on-reflection* true)
rlm@0 11 (import java.io.FileInputStream)
rlm@0 12
rlm@0 13 (def *numbytes* (* 16 1024 1024))
rlm@0 14
rlm@0 15
rlm@0 16 (defmacro better-areduce [a idx ret init expr]
rlm@0 17 `(let [a# ~a
rlm@0 18 alength# (alength a#)]
rlm@0 19 (loop [~idx (int 0) ~ret ~init]
rlm@0 20 (if (< ~idx alength#)
rlm@0 21 (recur (unchecked-inc ~idx) ~expr)
rlm@0 22 ~ret))))
rlm@0 23
rlm@0 24 (defn translated-countnl
rlm@0 25 [#^bytes buf]
rlm@0 26 (let [total-length (alength buf)]
rlm@0 27 (loop [count (int 0) current-index (int 0)]
rlm@0 28 (if (>= current-index total-length)
rlm@0 29 count
rlm@0 30 (let [new-count
rlm@0 31 (if (= (aget #^bytes buf current-index) (byte 10))
rlm@0 32 (unchecked-inc count)
rlm@0 33 count)]
rlm@0 34
rlm@0 35 (recur new-count (unchecked-inc current-index)))))))
rlm@0 36
rlm@0 37 (defn countnl-classic
rlm@0 38 [#^bytes buf]
rlm@0 39 (let [nl (byte 10)]
rlm@0 40 (areduce buf idx count 0
rlm@0 41 (if (= (aget buf idx) nl)
rlm@0 42 (inc count)
rlm@0 43 count))))
rlm@0 44
rlm@0 45
rlm@0 46 (defn countnl-lite
rlm@0 47 "this is the absolute fastest function I could come up with.
rlm@0 48 still 2.25 times slower that the java version."
rlm@0 49 [#^bytes buf]
rlm@0 50 (areduce buf idx count (int 0)
rlm@0 51 (if (= (clojure.lang.RT/aget buf idx) 10)
rlm@0 52 (unchecked-add count 1)
rlm@0 53 count)))
rlm@0 54
rlm@0 55
rlm@0 56 (defn #^Boolean is-ten? [#^Integer A]
rlm@0 57 (= A 10))
rlm@0 58
rlm@0 59 (defn countnl-max-power
rlm@0 60 [#^bytes buf]
rlm@0 61 (areduce buf idx count (int 0)
rlm@0 62 (if (is-ten? (clojure.lang.RT/aget buf idx))
rlm@0 63 (unchecked-inc count)
rlm@0 64 count)))
rlm@0 65
rlm@0 66
rlm@0 67
rlm@0 68
rlm@0 69
rlm@0 70
rlm@0 71
rlm@0 72
rlm@0 73
rlm@0 74
rlm@0 75
rlm@0 76 "(times are averages with 10 rounds)
rlm@0 77 no-modifications
rlm@0 78 classic: 198.151
rlm@0 79 lite: 186.668
rlm@0 80
rlm@0 81 unchecked-inc
rlm@0 82 classic: 177.938
rlm@0 83 lite: 129.604
rlm@0 84
rlm@0 85 inlined-let
rlm@0 86 classic: 202.604
rlm@0 87 lite: 195.357
rlm@0 88
rlm@0 89 make nl a constant
rlm@0 90 classic:
rlm@0 91 lite: 361.734
rlm@0 92
rlm@0 93 make nl a constant with type hint
rlm@0 94 lite: 394.45
rlm@0 95
rlm@0 96 literal 10, no let
rlm@0 97 lite: 102.876
rlm@0 98
rlm@0 99 (int 10) instead of literal 10
rlm@0 100 lite: 194.904
rlm@0 101
rlm@0 102 (unchecked-add count 0) instead of count
rlm@0 103 lite: 209.186
rlm@0 104
rlm@0 105 direct reference to RT/aget, bypassing int cast
rlm@0 106 lite: 99.767
rlm@0 107
rlm@0 108 (int 0) instead of 0 initialization of count
rlm@0 109 lite: 66.446
rlm@0 110
rlm@0 111 make nl an (int 10) instead of (byte 10)
rlm@0 112 lite: 180.003
rlm@0 113 "
rlm@0 114
rlm@0 115
rlm@0 116
rlm@0 117
rlm@0 118
rlm@0 119 (defmacro time-multi
rlm@0 120 "Evaluates expr and prints the time it took. Returns the value of
rlm@0 121 expr."
rlm@0 122 {:added "1.0"}
rlm@0 123 [expr]
rlm@0 124 `(let [start# (. System (nanoTime))
rlm@0 125 ret# ~expr
rlm@0 126 end# (/ (double (- (. System (nanoTime)) start#)) 1000000.0)]
rlm@0 127 (prn (str "Elapsed time: " end# " msecs"))
rlm@0 128 [ret# end#]))
rlm@0 129
rlm@0 130
rlm@0 131
rlm@0 132 (defn run [countnl-impl]
rlm@0 133 (let [ifs (FileInputStream. "/dev/urandom")
rlm@0 134 buf (make-array Byte/TYPE *numbytes*)
rlm@0 135 runs 10]
rlm@0 136 (loop [n 0 total-time 0]
rlm@0 137 (if (= n runs) (/ total-time runs)
rlm@0 138 (let [sz (.read #^FileInputStream ifs buf)]
rlm@0 139 (println "Wanted" *numbytes* "got" sz "bytes")
rlm@0 140 (let [[count time] (time-multi (countnl-impl buf))]
rlm@0 141 (println "Got" count "nls")
rlm@0 142 (recur (inc n) (+ total-time time))))))))
rlm@0 143
rlm@0 144 (defn -main [& ignore]
rlm@0 145 (run countnl-lite)
rlm@0 146 (run countnl-classic)
rlm@0 147 )
rlm@0 148
rlm@0 149
rlm@0 150