parse logs

Parser.hs

{-# LANGUAGE NoMonomorphismRestriction #-}

import Text.Parsec
import Data.List.Split (splitOn)

--field = lexeme $ noneOf " "
field = manyTill anyChar space

logline = do
  try (do
          Text.Parsec.count 3 field
          string "usage INFO "
          manyTill anyChar (char ':')
          string "presentations_delete "
          return True) 
    <|> return False

parseLogline = parse logline ""

parseLoglines = map parseLogline

isRight (Right x) = x
isRight _ = False

-- I guess there is a built in function to get Xth element of a list
-- at fields x = head (drop x fields)
at = (!!)

-- this is a simple pattern matching
match_usage_and_function pattern fields  = if at fields 3 == "usage" then (at (splitOn ":" (at fields 5 )) 1) == pattern else False

-- this is the reduce of map reduce
countTrue True acc = acc + 1
countTrue _ acc = acc

count :: (a -> Bool) -> [a] -> Int
count p = length . filter p

-- would it be nicer to write
-- count x ys = length (filter (== x) ys)
-- count True
reducer = Main.count (== True) 

-- split every line to list of words
tokenized = map words

-- and the actual map / reduce to count frequence of events
m = map (match_usage_and_function "presentations_delete") . tokenized
r = reducer . m

s = "2012-06-01 01:23:03,657 app6 usage INFO 264:presentations_delete User 10179708 deleted presentation 30334553 (owner: 10179708, title: Frank Macfarlane Burnet, public: 0, version: 14, created: 2012-05-"
inp n = take n $ repeat s

a = inp 100000

main = do
  print $ length $ filter isRight (parseLoglines a)
  print $ r a