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author | 2011-07-01 15:24:07 -0400 | |
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committer | 2011-07-01 15:30:42 -0400 | |
commit | cdbcd6f495580ee927a85af0581661b486c8ef77 (patch) | |
tree | 87f3f882bb543bbed05147ce416805387a45082d /PresenceLog.hs | |
parent | ceb887d82669b3ec694f31a899b59eefe0f5f352 (diff) |
add web special remote
Generalized LocationLog to PresenceLog, and use a presence log to record
urls for the web special remote.
Diffstat (limited to 'PresenceLog.hs')
-rw-r--r-- | PresenceLog.hs | 123 |
1 files changed, 123 insertions, 0 deletions
diff --git a/PresenceLog.hs b/PresenceLog.hs new file mode 100644 index 000000000..71d78f1ed --- /dev/null +++ b/PresenceLog.hs @@ -0,0 +1,123 @@ +{- git-annex presence log + - + - This is used to store presence information in the git-annex branch in + - a way that can be union merged. + - + - A line of the log will look like: "date N INFO" + - Where N=1 when the INFO is present, and 0 otherwise. + - + - Copyright 2010-2011 Joey Hess <joey@kitenet.net> + - + - Licensed under the GNU GPL version 3 or higher. + -} + +module PresenceLog ( + LogStatus(..), + readLog, + writeLog, + logNow, + compactLog, + currentLog +) where + +import Data.Time.Clock.POSIX +import Data.Time +import System.Locale +import qualified Data.Map as Map +import Control.Monad.State (liftIO) + +import qualified Branch +import Types + +data LogLine = LogLine { + date :: POSIXTime, + status :: LogStatus, + info :: String +} deriving (Eq) + +data LogStatus = InfoPresent | InfoMissing | Undefined + deriving (Eq) + +instance Show LogStatus where + show InfoPresent = "1" + show InfoMissing = "0" + show Undefined = "undefined" + +instance Read LogStatus where + readsPrec _ "1" = [(InfoPresent, "")] + readsPrec _ "0" = [(InfoMissing, "")] + readsPrec _ _ = [(Undefined, "")] + +instance Show LogLine where + show (LogLine d s i) = unwords [show d, show s, i] + +instance Read LogLine where + -- This parser is robust in that even unparsable log lines are + -- read without an exception being thrown. + -- Such lines have a status of Undefined. + readsPrec _ string = + if length w >= 3 + then maybe bad good pdate + else bad + where + w = words string + s = read $ w !! 1 + i = w !! 2 + pdate :: Maybe UTCTime + pdate = parseTime defaultTimeLocale "%s%Qs" $ head w + + good v = ret $ LogLine (utcTimeToPOSIXSeconds v) s i + bad = ret $ LogLine 0 Undefined "" + ret v = [(v, "")] + +{- Reads a log file. + - Note that the LogLines returned may be in any order. -} +readLog :: FilePath -> Annex [LogLine] +readLog file = return . parseLog =<< Branch.get file + +parseLog :: String -> [LogLine] +parseLog s = filter parsable $ map read $ lines s + where + -- some lines may be unparseable, avoid them + parsable l = status l /= Undefined + +{- Stores a set of lines in a log file -} +writeLog :: FilePath -> [LogLine] -> Annex () +writeLog file ls = Branch.change file (unlines $ map show ls) + +{- Generates a new LogLine with the current date. -} +logNow :: LogStatus -> String -> Annex LogLine +logNow s i = do + now <- liftIO $ getPOSIXTime + return $ LogLine now s i + +{- Reads a log and returns only the info that is still in effect. -} +currentLog :: FilePath -> Annex [String] +currentLog file = do + ls <- readLog file + return $ map info $ filterPresent ls + +{- Returns the info from LogLines that are in effect. -} +filterPresent :: [LogLine] -> [LogLine] +filterPresent ls = filter (\l -> InfoPresent == status l) $ compactLog ls + +type LogMap = Map.Map String LogLine + +{- Compacts a set of logs, returning a subset that contains the current + - status. -} +compactLog :: [LogLine] -> [LogLine] +compactLog ls = compactLog' Map.empty ls +compactLog' :: LogMap -> [LogLine] -> [LogLine] +compactLog' m [] = Map.elems m +compactLog' m (l:ls) = compactLog' (mapLog m l) ls + +{- Inserts a log into a map of logs, if the log has better (ie, newer) + - information than the other logs in the map -} +mapLog :: LogMap -> LogLine -> LogMap +mapLog m l = + if better + then Map.insert i l m + else m + where + better = maybe True (\l' -> date l' <= date l) $ Map.lookup i m + i = info l |