The code below is using way more RAM than it should. It seems to only
take so long when I build the 'programs' list - the actual
reading/parsing is fast. For a 5MB input file, it's using 50MB of RAM!
Any idea how to combat this?
Thanks,
Lyle
{-# OPTIONS_GHC -fglasgow-exts #-}
-- linear_importer.hs
import Control.Monad (unless)
import Data.ByteString.Char8 (ByteString)
import qualified Data.ByteString.Char8 as BS
import Text.Regex as RE
import Data.Time.Calendar
import Data.Time.LocalTime
import System.Environment
-- Consider adding strictness as necessary for performance.
-- STB time channel
data ChannelChange = ChannelChange Int LocalTime Int
deriving Show
-- channel program_no start
end network_no
data ScheduleProgram = ScheduleProgram Int Int LocalTime
LocalTime (Maybe Int)
deriving Show
main = do
fileNames <- getArgs
ensure (length fileNames == 2) usageMessage
let [eventFileName,programFileName] = fileNames
putStrLn ("Reading program schedule file from '" ++ programFileName
++ "'...")
text <- BS.readFile programFileName
programs <- sequence $ map parseScheduleProgram (BS.lines text)
print (take 20 programs)
return ()
usageMessage = "Usage: linear_importer <channel change file> <schedule
file>"
parseScheduleProgram :: ByteString -> IO ScheduleProgram
parseScheduleProgram s = do
let fields = BS.split '|' s
ensure (length fields == 7) ("Wrong number of fields in schedule
program: " ++ BS.unpack s)
let
[_,channelNoText,programNoText,_,startTimeText,endTimeText,networkNoText]
= fields
let channelNo = read $ BS.unpack channelNoText
programNo = read $ BS.unpack programNoText
startTime <- parseProgramTime startTimeText
endTime <- parseProgramTime endTimeText
let networkNo = if BS.null networkNoText then Nothing else Just
(read (BS.unpack networkNoText))
return $ ScheduleProgram channelNo programNo startTime endTime networkNo
parseProgramTime :: ByteString -> IO LocalTime
parseProgramTime s = do
let parts = BS.split 'T' s
ensure (length parts == 2)
("Expected exactly one T in eventChannelChange time: " ++
BS.unpack s)
let [datePart,timePart] = parts
ensure (BS.length datePart == 8)
("Expected 8 digits in date part of eventChannelChange time: "
++ BS.unpack s)
let (yearPart, monthDayPart) = BS.splitAt 4 datePart
(monthPart, dayPart) = BS.splitAt 2 monthDayPart
year = read $ BS.unpack yearPart
month = read $ BS.unpack monthPart
day = read $ BS.unpack dayPart
let date = fromGregorian year month day
ensure (BS.length timePart == 6)
("Expected 6 digits in time part of eventChannelChange time: "
++ BS.unpack s)
let (hoursPart,minutesSecondsPart) = BS.splitAt 2 timePart
(minutesPart,secondsPart) = BS.splitAt 2 minutesSecondsPart
hours = read $ BS.unpack hoursPart
minutes = read $ BS.unpack minutesPart
seconds = read $ BS.unpack secondsPart
let time = TimeOfDay hours minutes (fromInteger seconds)
return (LocalTime date time)
ensure :: Bool -> String -> IO ()
ensure x s = unless x $ ioError (userError s)
_______________________________________________
Haskell-Cafe mailing list
Haskell-Cafe@haskell.org
http://www.haskell.org/mailman/listinfo/haskell-cafe
