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fine-grained locking when annex.pidlock is enabled

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This locking has been missing from the beginning of annex.pidlock.
It used to be possble, when two threads are doing conflicting things,
for both to run at the same time despite using locking. Seems likely
that nothing actually had a problem, but it was possible, and this
eliminates that possible source of failure.

Sponsored-by: Dartmouth College's Datalad project
This commit is contained in:
Joey Hess 2021-12-03 17:20:21 -04:00
parent a5fcc03595
commit e5ca67ea1c
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GPG key ID: DB12DB0FF05F8F38
6 changed files with 121 additions and 61 deletions
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24
Annex/LockPool/PosixOrPid.hs
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@ -1,7 +1,7 @@
{- Wraps Utility.LockPool, making pid locks be used when git-annex is so
- configured.
-
- Copyright 2015-2020 Joey Hess <id@joeyh.name>
- Copyright 2015-2021 Joey Hess <id@joeyh.name>
-
- Licensed under the GNU AGPL version 3 or higher.
-}
@ -28,7 +28,7 @@ import qualified Utility.LockPool.PidLock as Pid
import qualified Utility.LockPool.LockHandle as H
import Utility.LockPool.LockHandle (LockHandle, dropLock)
import Utility.LockFile.Posix (openLockFile)
import Utility.LockPool.STM (LockFile)
import Utility.LockPool.STM (LockFile, LockMode(..))
import Utility.LockFile.LockStatus
import Config (pidLockFile)
import Messages (warning)
@ -36,16 +36,16 @@ import Messages (warning)
import System.Posix
lockShared :: Maybe FileMode -> LockFile -> Annex LockHandle
lockShared m f = pidLock m f $ Posix.lockShared m f
lockShared m f = pidLock m f LockShared $ Posix.lockShared m f
lockExclusive :: Maybe FileMode -> LockFile -> Annex LockHandle
lockExclusive m f = pidLock m f $ Posix.lockExclusive m f
lockExclusive m f = pidLock m f LockExclusive $ Posix.lockExclusive m f
tryLockShared :: Maybe FileMode -> LockFile -> Annex (Maybe LockHandle)
tryLockShared m f = tryPidLock m f $ Posix.tryLockShared m f
tryLockShared m f = tryPidLock m f LockShared $ Posix.tryLockShared m f
tryLockExclusive :: Maybe FileMode -> LockFile -> Annex (Maybe LockHandle)
tryLockExclusive m f = tryPidLock m f $ Posix.tryLockExclusive m f
tryLockExclusive m f = tryPidLock m f LockExclusive $ Posix.tryLockExclusive m f
checkLocked :: LockFile -> Annex (Maybe Bool)
checkLocked f = Posix.checkLocked f `pidLockCheck` checkpid
@ -67,22 +67,22 @@ pidLockCheck :: IO a -> (LockFile -> IO a) -> Annex a
pidLockCheck posixcheck pidcheck = debugLocks $
liftIO . maybe posixcheck pidcheck =<< pidLockFile
pidLock :: Maybe FileMode -> LockFile -> IO LockHandle -> Annex LockHandle
pidLock m f posixlock = debugLocks $ go =<< pidLockFile
pidLock :: Maybe FileMode -> 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 timeout pidlock warning
Pid.waitLock f lockmode timeout pidlock warning
tryPidLock :: Maybe FileMode -> LockFile -> IO (Maybe LockHandle) -> Annex (Maybe LockHandle)
tryPidLock m f posixlock = debugLocks $ liftIO . go =<< pidLockFile
tryPidLock :: Maybe FileMode -> 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 pidlock
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