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{-# LANGUAGE CPP #-}
#if !MIN_VERSION_directory(1,3,8)
{-# LANGUAGE Safe #-}
#endif
module System.Log.FastLogger.File
( FileLogSpec(..)
, TimedFileLogSpec (..)
, check
, rotate
, prefixTime
) where
import Data.ByteString.Char8 (unpack)
import System.Directory (doesFileExist, doesDirectoryExist, getPermissions, writable, renameFile)
import System.FilePath (takeDirectory, dropFileName, takeFileName, (</>))
import System.Log.FastLogger.Imports
import System.Log.FastLogger.Types (TimeFormat, FormattedTime)
-- | The spec for logging files
data FileLogSpec = FileLogSpec {
log_file :: FilePath
, log_file_size :: Integer -- ^ Max log file size (in bytes) before requiring rotation.
, log_backup_number :: Int -- ^ Max number of rotated log files to keep around before overwriting the oldest one.
}
-- | The spec for time based rotation. It supports post processing of log files. Does
-- not delete any logs. Example:
--
-- @
-- timeRotate fname = LogFileTimedRotate
-- (TimedFileLogSpec fname timeFormat sametime compressFile)
-- defaultBufSize
-- where
-- timeFormat = "%FT%H%M%S"
-- sametime = (==) `on` C8.takeWhile (/='T')
-- compressFile fp = void . forkIO $
-- callProcess "tar" [ "--remove-files", "-caf", fp <> ".gz", fp ]
-- @
data TimedFileLogSpec = TimedFileLogSpec {
timed_log_file :: FilePath -- ^ base file path
, timed_timefmt :: TimeFormat -- ^ time format to prepend
, timed_same_timeframe :: FormattedTime -> FormattedTime -> Bool
-- ^ function that compares two
-- formatted times as specified by
-- timed_timefmt and decides if a
-- new rotation is supposed to
-- begin
, timed_post_process :: FilePath -> IO () -- ^ processing function called asynchronously after a file is added to the rotation
}
-- | Checking if a log file can be written.
check :: FilePath -> IO ()
check file = do
dirExist <- doesDirectoryExist dir
unless dirExist $ fail $ dir ++ " does not exist or is not a directory."
dirPerm <- getPermissions dir
unless (writable dirPerm) $ fail $ dir ++ " is not writable."
exist <- doesFileExist file
when exist $ do
perm <- getPermissions file
unless (writable perm) $ fail $ file ++ " is not writable."
where
dir = takeDirectory file
-- | Rotating log files.
rotate :: FileLogSpec -> IO ()
rotate spec = mapM_ move srcdsts
where
path = log_file spec
n = log_backup_number spec
dsts' = reverse . ("":) . map (('.':). show) $ [0..n-1]
dsts = map (path++) dsts'
srcs = tail dsts
srcdsts = zip srcs dsts
move (src,dst) = do
exist <- doesFileExist src
when exist $ renameFile src dst
-- | Prefix file name with formatted time
prefixTime :: FormattedTime -> FilePath -> FilePath
prefixTime time path = dropFileName path </> unpack time ++ "-" ++ takeFileName path
|
