44 lines
1.1 KiB
Haskell
44 lines
1.1 KiB
Haskell
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{- git-annex lock pool
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-
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- Copyright 2012 Joey Hess <joey@kitenet.net>
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-
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- Licensed under the GNU GPL version 3 or higher.
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-}
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module Annex.LockPool where
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import qualified Data.Map as M
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import System.Posix.Types (Fd)
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import Common.Annex
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import Annex
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{- Create a specified lock file, and takes a shared lock. -}
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lockFile :: FilePath -> Annex ()
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lockFile file = go =<< fromPool file
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where
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go (Just _) = return () -- already locked
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go Nothing = do
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fd <- liftIO $ openFd file ReadOnly (Just stdFileMode) defaultFileFlags
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liftIO $ waitToSetLock fd (ReadLock, AbsoluteSeek, 0, 0)
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changePool $ M.insert file fd
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unlockFile :: FilePath -> Annex ()
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unlockFile file = go =<< fromPool file
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where
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go Nothing = return ()
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go (Just fd) = do
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liftIO $ closeFd fd
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changePool $ M.delete file
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getPool :: Annex (M.Map FilePath Fd)
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getPool = getState lockpool
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fromPool :: FilePath -> Annex (Maybe Fd)
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fromPool file = M.lookup file <$> getPool
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changePool :: (M.Map FilePath Fd -> M.Map FilePath Fd) -> Annex ()
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changePool a = do
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m <- getPool
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changeState $ \s -> s { lockpool = a m }
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