module System.Log.FastLogger.Date (
ZonedDate
, DateRef
, dateInit
, getDate
) where
import Control.Applicative
import Data.ByteString (ByteString)
import Data.IORef
#if WINDOWS
import qualified Data.ByteString.Char8 as BS
import Data.Time
import System.Locale
#define TIME UTCTime
#define GETTIME getCurrentTime
#else
import Data.UnixTime
import System.Posix (EpochTime, epochTime)
#define TIME EpochTime
#define GETTIME epochTime
#endif
type ZonedDate = ByteString
data DateCache = DateCache {
timeKey :: !TIME
, zonedDate :: !ZonedDate
} deriving (Eq, Show)
newtype DateRef = DateRef (IORef DateCache)
getDate :: DateRef -> IO ZonedDate
getDate (DateRef ref) = do
newEt <- GETTIME
cache <- readIORef ref
let oldEt = timeKey cache
if oldEt == newEt then
return $ zonedDate cache
else do
newCache <- newDate newEt
writeIORef ref newCache
return $ zonedDate newCache
newDate :: TIME -> IO DateCache
#if WINDOWS
newDate et = DateCache et . format <$> toZonedTime et
where
format = BS.pack . formatTime defaultTimeLocale "%d/%b/%Y:%T %z"
toZonedTime = utcToLocalZonedTime
#else
newDate et = return $ DateCache et $ toZonedTime et
where
toZonedTime = formatUnixTime "%d/%b/%Y:%T %z" . fromEpochTime
#endif
dateInit :: IO DateRef
dateInit = DateRef <$> (GETTIME >>= newDate >>= newIORef)