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{- 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 l = reverse $ map fst $ sortBy (compare `on` snd) $ M.toList m
case l of
[] -> retry -- should never happen
(newest:_) -> do
let m' = M.delete newest m
unless (M.null m') $
putTMVar v 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
|
