git-annex/Annex/LockPool/PosixOrPid.hs

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{- Wraps Utility.LockPool, making pid locks be used when git-annex is so
- configured.
-
- Copyright 2015-2021 Joey Hess <id@joeyh.name>
-
- Licensed under the GNU AGPL version 3 or higher.
-}
module Annex.LockPool.PosixOrPid (
LockFile,
LockHandle,
lockShared,
lockExclusive,
tryLockShared,
tryLockExclusive,
dropLock,
checkLocked,
LockStatus(..),
getLockStatus,
checkSaneLock,
) where
import Common
import Types
import qualified Annex
import qualified Utility.LockPool.Posix as Posix
import qualified Utility.LockPool.PidLock as Pid
import qualified Utility.LockPool.LockHandle as H
import Utility.FileMode
import Utility.LockPool.LockHandle (LockHandle, dropLock)
import Utility.LockFile.Posix (openLockFile)
import Utility.LockPool.STM (LockFile, LockMode(..))
import Utility.LockFile.LockStatus
import Config (pidLockFile)
import Messages (warning)
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import Git.Quote
import System.Posix
lockShared :: Maybe ModeSetter -> LockFile -> Annex LockHandle
lockShared m f = pidLock m f LockShared $ Posix.lockShared m f
lockExclusive :: Maybe ModeSetter -> LockFile -> Annex LockHandle
lockExclusive m f = pidLock m f LockExclusive $ Posix.lockExclusive m f
tryLockShared :: Maybe ModeSetter -> LockFile -> Annex (Maybe LockHandle)
tryLockShared m f = tryPidLock m f LockShared $ Posix.tryLockShared m f
tryLockExclusive :: Maybe ModeSetter -> LockFile -> Annex (Maybe LockHandle)
tryLockExclusive m f = tryPidLock m f LockExclusive $ Posix.tryLockExclusive m f
checkLocked :: LockFile -> Annex (Maybe Bool)
checkLocked f = Posix.checkLocked f `pidLockCheck` checkpid
where
checkpid pidlock = Pid.checkLocked pidlock >>= \case
-- Only return true when the posix lock file exists.
Just _ -> Posix.checkLocked f
Nothing -> return Nothing
getLockStatus :: LockFile -> Annex LockStatus
getLockStatus f = Posix.getLockStatus f
`pidLockCheck` Pid.getLockStatus
checkSaneLock :: LockFile -> LockHandle -> Annex Bool
checkSaneLock f h = H.checkSaneLock f h
`pidLockCheck` flip Pid.checkSaneLock h
pidLockCheck :: IO a -> (LockFile -> IO a) -> Annex a
pidLockCheck posixcheck pidcheck = debugLocks $
liftIO . maybe posixcheck pidcheck =<< pidLockFile
pidLock :: Maybe ModeSetter -> LockFile -> LockMode -> IO LockHandle -> Annex LockHandle
pidLock m f lockmode posixlock = debugLocks $ go =<< pidLockFile
where
go Nothing = liftIO posixlock
go (Just pidlock) = do
timeout <- annexPidLockTimeout <$> Annex.getGitConfig
liftIO $ dummyPosixLock m f
Pid.waitLock f lockmode timeout pidlock (warning . UnquotedString)
tryPidLock :: Maybe ModeSetter -> LockFile -> LockMode -> IO (Maybe LockHandle) -> Annex (Maybe LockHandle)
tryPidLock m f lockmode posixlock = debugLocks $ liftIO . go =<< pidLockFile
where
go Nothing = posixlock
go (Just pidlock) = do
dummyPosixLock m f
Pid.tryLock f lockmode pidlock
-- The posix lock file is created even when using pid locks, in order to
-- avoid complicating any code that might expect to be able to see that
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-- lock file. But, it's not locked.
dummyPosixLock :: Maybe ModeSetter -> LockFile -> IO ()
dummyPosixLock m f = bracket (openLockFile ReadLock m f) closeFd (const noop)