49 lines
1.5 KiB
Haskell
49 lines
1.5 KiB
Haskell
{- Windows lock files, using lock pools.
|
|
-
|
|
- Copyright 2015 Joey Hess <id@joeyh.name>
|
|
-
|
|
- License: BSD-2-clause
|
|
-}
|
|
|
|
module Utility.LockPool.Windows (
|
|
LockHandle,
|
|
lockShared,
|
|
lockExclusive,
|
|
dropLock,
|
|
waitToLock,
|
|
) where
|
|
|
|
import qualified Utility.LockFile.Windows as F
|
|
import qualified Utility.LockPool.STM as P
|
|
import Utility.LockPool.LockHandle
|
|
import Utility.LockPool.STM (LockPool, LockFile, LockMode(..))
|
|
import Utility.Monad
|
|
|
|
import Control.Concurrent.STM
|
|
import System.IO
|
|
import Data.Maybe
|
|
import Control.Applicative
|
|
import Prelude
|
|
|
|
{- Tries to lock a file with a shared lock, which allows other processes to
|
|
- also lock it shared. Fails if the file is exclusively locked. -}
|
|
lockShared :: LockFile -> IO (Maybe LockHandle)
|
|
lockShared file = tryMakeLockHandle
|
|
(P.tryTakeLock P.lockPool file LockShared)
|
|
(F.lockShared file)
|
|
|
|
{- Tries to take an exclusive lock on a file. Fails if another process has
|
|
- a shared or exclusive lock.
|
|
-
|
|
- Note that exclusive locking also prevents the file from being opened for
|
|
- read or write by any other process. So for advisory locking of a file's
|
|
- content, a separate LockFile should be used. -}
|
|
lockExclusive :: LockFile -> IO (Maybe LockHandle)
|
|
lockExclusive file = tryMakeLockHandle
|
|
(P.tryTakeLock P.lockPool file LockExclusive)
|
|
(F.lockExclusive file)
|
|
|
|
{- If the initial lock fails, this is a BUSY wait, and does not
|
|
- guarentee FIFO order of waiters. In other news, Windows is a POS. -}
|
|
waitToLock :: IO (Maybe lockhandle) -> IO lockhandle
|
|
waitToLock = F.waitToLock
|