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|
{- git-annex lock files.
-
- Copyright 2012, 2014 Joey Hess <joey@kitenet.net>
-
- Licensed under the GNU GPL version 3 or higher.
-}
{-# LANGUAGE CPP #-}
module Annex.LockFile (
lockFileShared,
unlockFile,
getLockPool,
withExclusiveLock,
) where
import Common.Annex
import Annex
import Types.LockPool
import qualified Git
import Annex.Perms
import Utility.LockFile
import qualified Data.Map as M
{- Create a specified lock file, and takes a shared lock, which is retained
- in the pool. -}
lockFileShared :: FilePath -> Annex ()
lockFileShared file = go =<< fromLockPool file
where
go (Just _) = noop -- already locked
go Nothing = do
#ifndef mingw32_HOST_OS
mode <- annexFileMode
lockhandle <- liftIO $ noUmask mode $ lockShared (Just mode) file
#else
lockhandle <- liftIO $ waitToLock $ lockShared file
#endif
changeLockPool $ M.insert file lockhandle
unlockFile :: FilePath -> Annex ()
unlockFile file = maybe noop go =<< fromLockPool file
where
go lockhandle = do
liftIO $ dropLock lockhandle
changeLockPool $ M.delete file
getLockPool :: Annex LockPool
getLockPool = getState lockpool
fromLockPool :: FilePath -> Annex (Maybe LockHandle)
fromLockPool file = M.lookup file <$> getLockPool
changeLockPool :: (LockPool -> LockPool) -> Annex ()
changeLockPool a = do
m <- getLockPool
changeState $ \s -> s { lockpool = a m }
{- Runs an action with an exclusive lock held. If the lock is already
- held, blocks until it becomes free. -}
withExclusiveLock :: (Git.Repo -> FilePath) -> Annex a -> Annex a
withExclusiveLock getlockfile a = do
lockfile <- fromRepo getlockfile
createAnnexDirectory $ takeDirectory lockfile
mode <- annexFileMode
bracketIO (lock mode lockfile) dropLock (const a)
where
#ifndef mingw32_HOST_OS
lock mode = noUmask mode . lockExclusive (Just mode)
#else
lock _mode = waitToLock . lockExclusive
#endif
|
