108 lines
2.8 KiB
Haskell
108 lines
2.8 KiB
Haskell
{- git-annex presence log
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-
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- This is used to store presence information in the git-annex branch in
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- a way that can be union merged.
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-
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- A line of the log will look like: "date N INFO"
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- Where N=1 when the INFO is present, and 0 otherwise.
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-
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- Copyright 2010-2011 Joey Hess <joey@kitenet.net>
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-
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- Licensed under the GNU GPL version 3 or higher.
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-}
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module Logs.Presence (
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LogStatus(..),
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LogLine,
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addLog,
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readLog,
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getLog,
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parseLog,
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showLog,
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logNow,
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compactLog,
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currentLog,
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) where
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import Data.Time.Clock.POSIX
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import Data.Time
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import System.Locale
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import qualified Data.Map as M
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import Common.Annex
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import qualified Annex.Branch
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data LogLine = LogLine {
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date :: POSIXTime,
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status :: LogStatus,
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info :: String
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} deriving (Eq)
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data LogStatus = InfoPresent | InfoMissing
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deriving (Eq)
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addLog :: FilePath -> LogLine -> Annex ()
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addLog file line = Annex.Branch.change file $ \s ->
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showLog $ compactLog (line : parseLog s)
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{- Reads a log file.
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- Note that the LogLines returned may be in any order. -}
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readLog :: FilePath -> Annex [LogLine]
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readLog file = parseLog <$> Annex.Branch.get file
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{- Parses a log file. Unparseable lines are ignored. -}
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parseLog :: String -> [LogLine]
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parseLog = mapMaybe (parseline . words) . lines
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where
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parseline (a:b:c:_) = do
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d <- parseTime defaultTimeLocale "%s%Qs" a
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s <- parsestatus b
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Just $ LogLine (utcTimeToPOSIXSeconds d) s c
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parseline _ = Nothing
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parsestatus "1" = Just InfoPresent
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parsestatus "0" = Just InfoMissing
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parsestatus _ = Nothing
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{- Generates a log file. -}
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showLog :: [LogLine] -> String
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showLog = unlines . map genline
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where
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genline (LogLine d s i) = unwords [show d, genstatus s, i]
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genstatus InfoPresent = "1"
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genstatus InfoMissing = "0"
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{- Generates a new LogLine with the current date. -}
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logNow :: LogStatus -> String -> Annex LogLine
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logNow s i = do
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now <- liftIO getPOSIXTime
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return $ LogLine now s i
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{- Reads a log and returns only the info that is still in effect. -}
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currentLog :: FilePath -> Annex [String]
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currentLog file = map info . filterPresent <$> readLog file
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{- Given a log, returns only the info that is are still in effect. -}
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getLog :: String -> [String]
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getLog = map info . filterPresent . parseLog
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{- Returns the info from LogLines that are in effect. -}
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filterPresent :: [LogLine] -> [LogLine]
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filterPresent = filter (\l -> InfoPresent == status l) . compactLog
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{- Compacts a set of logs, returning a subset that contains the current
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- status. -}
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compactLog :: [LogLine] -> [LogLine]
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compactLog = M.elems . foldr mapLog M.empty
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type LogMap = M.Map String LogLine
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{- Inserts a log into a map of logs, if the log has better (ie, newer)
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- information than the other logs in the map -}
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mapLog :: LogLine -> LogMap -> LogMap
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mapLog l m
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| better = M.insert i l m
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| otherwise = m
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where
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better = maybe True newer $ M.lookup i m
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newer l' = date l' <= date l
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i = info l
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