48 lines
1.5 KiB
Haskell
48 lines
1.5 KiB
Haskell
{- Windows 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.Windows (
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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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dropLock,
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waitToLock,
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) where
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import qualified Utility.LockFile.Windows as F
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import qualified Utility.LockPool.STM as P
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import Utility.LockPool.LockHandle
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import Utility.LockPool.STM (LockFile, LockMode(..))
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{- Tries to lock a file with a shared lock, which allows other processes to
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- also lock it shared. Fails if the file is exclusively locked. -}
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lockShared :: LockFile -> IO (Maybe LockHandle)
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lockShared file = tryMakeLockHandle P.lockPool file
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(\p f -> P.tryTakeLock p f LockShared)
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(\f _ -> fmap mk <$> F.lockShared f)
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{- Tries to take an exclusive lock on a file. Fails if another process has
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- a shared or exclusive lock.
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-
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- Note that exclusive locking also prevents the file from being opened for
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- read or write by any other process. So for advisory locking of a file's
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- content, a separate LockFile should be used. -}
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lockExclusive :: LockFile -> IO (Maybe LockHandle)
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lockExclusive file = tryMakeLockHandle P.lockPool file
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(\p f -> P.tryTakeLock p f LockExclusive)
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(\f _ -> fmap mk <$> F.lockExclusive f)
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{- If the initial lock fails, this is a BUSY wait, and does not
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- guarentee FIFO order of waiters. In other news, Windows is a POS. -}
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waitToLock :: IO (Maybe lockhandle) -> IO lockhandle
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waitToLock = F.waitToLock
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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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}
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