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|
{-# LANGUAGE CPP #-}
module Network.Wai.Logger.Date (
ZonedDate
, DateRef
, dateInit
, getDate
) where
import Control.Applicative
import Data.ByteString (ByteString)
import qualified Data.ByteString.Char8 as BS
import Data.IORef
import Data.Time
import System.Locale
#if WINDOWS
#define TIME UTCTime
#define GETTIME getCurrentTime
#else
import System.Posix (EpochTime, epochTime)
import Data.Time.Clock.POSIX
#define TIME EpochTime
#define GETTIME epochTime
#endif
-- | A type for zoned date.
type ZonedDate = ByteString
data DateCache = DateCache {
unixTime :: !TIME
, zonedDate :: !ZonedDate
}
-- | Reference to the 'ZonedDate' cache.
newtype DateRef = DateRef (IORef DateCache)
-- | Getting 'ZonedDate' from the 'ZonedDate' cache.
getDate :: DateRef -> IO ZonedDate
getDate (DateRef ref) = do
newEt <- GETTIME
cache <- readIORef ref
let oldEt = unixTime cache
if oldEt == newEt then
return $ zonedDate cache
else do
newCache <- newDate newEt
writeIORef ref newCache
return $ zonedDate newCache
newDate :: TIME -> IO DateCache
newDate et = DateCache et . format <$> toZonedTime et
where
toZonedTime = utcToLocalZonedTime . toUTC
#if WINDOWS
toUTC = id
#else
toUTC = posixSecondsToUTCTime . realToFrac
#endif
format = BS.pack . formatTime defaultTimeLocale "%d/%b/%Y:%T %z"
-- | Initializing the 'ZonedDate' cache.
dateInit :: IO DateRef
dateInit = DateRef <$> (GETTIME >>= newDate >>= newIORef)
|
