103 lines
3.3 KiB
Haskell
103 lines
3.3 KiB
Haskell
{- git-annex assistant daemon status
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-
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- Copyright 2012 Joey Hess <joey@kitenet.net>
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-}
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module Assistant.DaemonStatus where
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import Common.Annex
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import Utility.TempFile
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import Assistant.ThreadedMonad
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import Control.Concurrent
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import System.Posix.Types
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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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data DaemonStatus = DaemonStatus
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-- False when the daemon is performing its startup scan
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{ scanComplete :: Bool
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-- Time when a previous process of the daemon was running ok
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, lastRunning :: Maybe POSIXTime
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}
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deriving (Show)
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type DaemonStatusHandle = MVar DaemonStatus
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newDaemonStatus :: DaemonStatus
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newDaemonStatus = DaemonStatus
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{ scanComplete = False
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, lastRunning = Nothing
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}
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getDaemonStatus :: DaemonStatusHandle -> Annex DaemonStatus
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getDaemonStatus = liftIO . readMVar
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modifyDaemonStatus :: DaemonStatusHandle -> (DaemonStatus -> DaemonStatus) -> Annex ()
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modifyDaemonStatus handle a = liftIO $ modifyMVar_ handle (return . a)
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{- Load any previous daemon status file, and store it in the MVar for this
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- process to use as its DaemonStatus. -}
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startDaemonStatus :: Annex DaemonStatusHandle
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startDaemonStatus = do
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file <- fromRepo gitAnnexDaemonStatusFile
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status <- liftIO $
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catchDefaultIO (readDaemonStatusFile file) newDaemonStatus
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liftIO $ newMVar status { scanComplete = False }
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{- This thread wakes up periodically and writes the daemon status to disk. -}
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daemonStatusThread :: ThreadState -> DaemonStatusHandle -> IO ()
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daemonStatusThread st handle = do
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checkpoint
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forever $ do
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threadDelay tenMinutes
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checkpoint
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where
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checkpoint = runThreadState st $ do
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file <- fromRepo gitAnnexDaemonStatusFile
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status <- getDaemonStatus handle
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liftIO $ writeDaemonStatusFile file status
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tenMinutes = 10 * 60 * 1000000 -- microseconds
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{- Don't just dump out the structure, because it will change over time,
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- and parts of it are not relevant. -}
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writeDaemonStatusFile :: FilePath -> DaemonStatus -> IO ()
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writeDaemonStatusFile file status =
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viaTmp writeFile file =<< serialized <$> getPOSIXTime
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where
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serialized now = unlines
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[ "lastRunning:" ++ show now
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, "scanComplete:" ++ show (scanComplete status)
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]
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readDaemonStatusFile :: FilePath -> IO DaemonStatus
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readDaemonStatusFile file = parse <$> readFile file
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where
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parse = foldr parseline newDaemonStatus . lines
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parseline line status
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| key == "lastRunning" = parseval readtime $ \v ->
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status { lastRunning = Just v }
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| key == "scanComplete" = parseval readish $ \v ->
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status { scanComplete = v }
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| otherwise = status -- unparsable line
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where
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(key, value) = separate (== ':') line
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parseval parser a = maybe status a (parser value)
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readtime s = do
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d <- parseTime defaultTimeLocale "%s%Qs" s
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Just $ utcTimeToPOSIXSeconds d
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{- Checks if a time stamp was made after the daemon was lastRunning.
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-
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- Some slop is built in; this really checks if the time stamp was made
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- at least ten minutes after the daemon was lastRunning. This is to
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- ensure the daemon shut down cleanly, and deal with minor clock skew.
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-
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- If the daemon has never ran before, this always returns False.
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-}
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afterLastDaemonRun :: EpochTime -> DaemonStatus -> Bool
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afterLastDaemonRun timestamp status = maybe False (< t) (lastRunning status)
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where
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t = realToFrac (timestamp + slop) :: POSIXTime
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slop = 10 * 60
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