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|
{- git-annex presence log, pure operations
-
- Copyright 2010-2013 Joey Hess <id@joeyh.name>
-
- Licensed under the GNU GPL version 3 or higher.
-}
module Logs.Presence.Pure where
import Data.Time.Clock.POSIX
import qualified Data.Map as M
import Common.Annex
import Logs.TimeStamp
import Utility.QuickCheck
data LogLine = LogLine {
date :: POSIXTime,
status :: LogStatus,
info :: String
} deriving (Eq, Show)
data LogStatus = InfoPresent | InfoMissing | InfoDead
deriving (Eq, Show, Bounded, Enum)
{- Parses a log file. Unparseable lines are ignored. -}
parseLog :: String -> [LogLine]
parseLog = mapMaybe parseline . lines
where
parseline l = LogLine
<$> parsePOSIXTime d
<*> parseStatus s
<*> pure rest
where
(d, pastd) = separate (== ' ') l
(s, rest) = separate (== ' ') pastd
parseStatus :: String -> Maybe LogStatus
parseStatus "1" = Just InfoPresent
parseStatus "0" = Just InfoMissing
parseStatus "X" = Just InfoDead
parseStatus _ = Nothing
{- Generates a log file. -}
showLog :: [LogLine] -> String
showLog = unlines . map genline
where
genline (LogLine d s i) = unwords [show d, genstatus s, i]
genstatus InfoPresent = "1"
genstatus InfoMissing = "0"
genstatus InfoDead = "X"
{- Given a log, returns only the info that is are still in effect. -}
getLog :: String -> [String]
getLog = map info . filterPresent . parseLog
{- Returns the info from LogLines that are in effect. -}
filterPresent :: [LogLine] -> [LogLine]
filterPresent = filter (\l -> InfoPresent == status l) . compactLog
{- Compacts a set of logs, returning a subset that contains the current
- status. -}
compactLog :: [LogLine] -> [LogLine]
compactLog = mapLog . logMap
type LogMap = M.Map String LogLine
mapLog :: LogMap -> [LogLine]
mapLog = M.elems
logMap :: [LogLine] -> LogMap
logMap = foldr insertNewerLogLine M.empty
insertBetter :: (LogLine -> Bool) -> LogLine -> LogMap -> Maybe LogMap
insertBetter betterthan l m
| better = Just (M.insert i l m)
| otherwise = Nothing
where
better = maybe True betterthan (M.lookup i m)
i = info l
{- Inserts a log into a map of logs, if the log has newer
- information than the other logs in the map for the same info. -}
insertNewerLogLine :: LogLine -> LogMap -> LogMap
insertNewerLogLine l m = fromMaybe m $ insertBetter newer l m
where
newer l' = date l' <= date l
{- Inserts the log unless there's already one in the map with
- the same status for its info, in which case there's no need to
- change anything, to avoid log churn. -}
insertNewStatus :: LogLine -> LogMap -> Maybe LogMap
insertNewStatus l m = insertBetter diffstatus l m
where
diffstatus l' = status l' /= status l
instance Arbitrary LogLine where
arbitrary = LogLine
<$> arbitrary
<*> elements [minBound..maxBound]
<*> arbitrary `suchThat` ('\n' `notElem`)
prop_parse_show_log :: [LogLine] -> Bool
prop_parse_show_log l = parseLog (showLog l) == l
|
