3334130368
This fixes behavior in this situation: l1 <- lockShared Nothing "lck" l2 <- lockShared Nothing "lck" dropLock l1 dropLock l2 Before, the lock was dropped upon the second dropLock call, but the fd remained open, and would never be closed while the program was running. Fixed by a rather round-about method, but it should work well enough. It would have been simpler to open open the shared lock once, and not open it again in the second call to lockShared. But, that's difficult to do atomically. This also affects Windows and PID locks, not just posix locks. In the case of pid locks, multiple calls to waitLock within the same process are allowed because the side lock is locked using a posix lock, and so multiple exclusive locks can be taken in the same process. So, this change fixes a similar problem with pid locks. l1 <- waitLock (Seconds 1) "lck" l2 <- waitLock (Seconds 1) "lck" dropLock l1 dropLock l2 Here the l2 side lock fd remained open but not locked, although the pid lock file was removed. After this change, the second dropLock will close both fds to the side lock, and delete the pidlock.
74 lines
2.2 KiB
Haskell
74 lines
2.2 KiB
Haskell
{- Posix lock files, using lock pools.
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-
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- Copyright 2015 Joey Hess <id@joeyh.name>
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-
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- License: BSD-2-clause
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-}
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module Utility.LockPool.Posix (
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P.LockFile,
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LockHandle,
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lockShared,
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lockExclusive,
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tryLockShared,
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tryLockExclusive,
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checkLocked,
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getLockStatus,
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LockStatus(..),
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dropLock,
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checkSaneLock,
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) where
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import qualified Utility.LockFile.Posix as F
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import Utility.LockFile.LockStatus
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import qualified Utility.LockPool.STM as P
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import Utility.LockPool.STM (LockFile, LockMode(..))
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import Utility.LockPool.LockHandle
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import System.IO
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import System.Posix
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import Data.Maybe
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import Control.Applicative
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import Prelude
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-- Takes a shared lock, blocking until the lock is available.
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lockShared :: Maybe FileMode -> LockFile -> IO LockHandle
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lockShared mode file = makeLockHandle P.lockPool file
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(\p f -> P.waitTakeLock p f LockShared)
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(\f -> mk <$> F.lockShared mode f)
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-- Takes an exclusive lock, blocking until the lock is available.
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lockExclusive :: Maybe FileMode -> LockFile -> IO LockHandle
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lockExclusive mode file = makeLockHandle P.lockPool file
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(\p f -> P.waitTakeLock p f LockExclusive)
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(\f -> mk <$> F.lockExclusive mode f)
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-- Tries to take a shared lock, but does not block.
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tryLockShared :: Maybe FileMode -> LockFile -> IO (Maybe LockHandle)
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tryLockShared mode file = tryMakeLockHandle P.lockPool file
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(\p f -> P.tryTakeLock p f LockShared)
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(\f -> fmap mk <$> F.tryLockShared mode f)
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-- Tries to take an exclusive lock, but does not block.
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tryLockExclusive :: Maybe FileMode -> LockFile -> IO (Maybe LockHandle)
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tryLockExclusive mode file = tryMakeLockHandle P.lockPool file
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(\p f -> P.tryTakeLock p f LockExclusive)
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(\f -> fmap mk <$> F.tryLockExclusive mode f)
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-- Returns Nothing when the file doesn't exist, for cases where
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-- that is different from it not being locked.
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checkLocked :: LockFile -> IO (Maybe Bool)
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checkLocked file = P.getLockStatus P.lockPool file
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(pure (Just True))
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(F.checkLocked file)
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getLockStatus :: LockFile -> IO LockStatus
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getLockStatus file = P.getLockStatus P.lockPool file
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(StatusLockedBy <$> getProcessID)
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(F.getLockStatus file)
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mk :: F.LockHandle -> FileLockOps
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mk h = FileLockOps
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{ fDropLock = F.dropLock h
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, fCheckSaneLock = \f -> F.checkSaneLock f h
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}
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