git-annex/Assistant/ScanRemotes.hs
Joey Hess 522f568450 add TransferScanner thread
Efficiently finding transfers that need to be done to get two repos back
in sync seems like an interesting problem.
2012-07-22 23:16:56 -04:00

41 lines
1.1 KiB
Haskell

{- git-annex assistant remotes needing scanning
-
- Copyright 2012 Joey Hess <joey@kitenet.net>
-
- Licensed under the GNU GPL version 3 or higher.
-}
module Assistant.ScanRemotes where
import Common.Annex
import Data.Function
import Control.Concurrent.STM
import Data.Time.Clock
import qualified Data.Map as M
type ScanRemoteMap = TMVar (M.Map Remote UTCTime)
{- The TMVar starts empty, and is left empty when there are no remotes
- to scan. -}
newScanRemoteMap :: IO ScanRemoteMap
newScanRemoteMap = atomically newEmptyTMVar
{- Blocks until there is a remote that needs to be scanned.
- Processes remotes added most recently first. -}
getScanRemote :: ScanRemoteMap -> IO Remote
getScanRemote v = atomically $ do
m <- takeTMVar v
let newest = Prelude.head $ reverse $
map fst $ sortBy (compare `on` snd) $ M.toList m
putTMVar v $ M.delete newest m
return newest
{- Adds new remotes that need scanning to the map. -}
addScanRemotes :: ScanRemoteMap -> [Remote] -> IO ()
addScanRemotes _ [] = return ()
addScanRemotes v rs = do
now <- getCurrentTime
atomically $ do
m <- fromMaybe M.empty <$> tryTakeTMVar v
putTMVar v $ foldr (`M.insert` now) m rs