126 lines
3.3 KiB
Haskell
126 lines
3.3 KiB
Haskell
{- git-annex lock files.
|
|
-
|
|
- Copyright 2012-2024 Joey Hess <id@joeyh.name>
|
|
-
|
|
- Licensed under the GNU AGPL version 3 or higher.
|
|
-}
|
|
|
|
{-# LANGUAGE CPP #-}
|
|
|
|
module Annex.LockFile (
|
|
lockFileCached,
|
|
unlockFile,
|
|
getLockCache,
|
|
fromLockCache,
|
|
withSharedLock,
|
|
withExclusiveLock,
|
|
takeExclusiveLock,
|
|
tryExclusiveLock,
|
|
trySharedLock,
|
|
) where
|
|
|
|
import Annex.Common
|
|
import Annex
|
|
import Types.LockCache
|
|
import Annex.Perms
|
|
import Annex.LockPool
|
|
|
|
import qualified Data.Map as M
|
|
|
|
{- Create a specified lock file, and takes a shared lock, which is retained
|
|
- in the cache. -}
|
|
lockFileCached :: OsPath -> Annex ()
|
|
lockFileCached file = go =<< fromLockCache file
|
|
where
|
|
go (Just _) = noop -- already locked
|
|
go Nothing = do
|
|
#ifndef mingw32_HOST_OS
|
|
mode <- annexFileMode
|
|
lockhandle <- lockShared (Just mode) file
|
|
#else
|
|
lockhandle <- liftIO $ waitToLock $ lockShared file
|
|
#endif
|
|
changeLockCache $ M.insert file lockhandle
|
|
|
|
unlockFile :: OsPath -> Annex ()
|
|
unlockFile file = maybe noop go =<< fromLockCache file
|
|
where
|
|
go lockhandle = do
|
|
liftIO $ dropLock lockhandle
|
|
changeLockCache $ M.delete file
|
|
|
|
getLockCache :: Annex LockCache
|
|
getLockCache = getState lockcache
|
|
|
|
fromLockCache :: OsPath -> Annex (Maybe LockHandle)
|
|
fromLockCache file = M.lookup file <$> getLockCache
|
|
|
|
changeLockCache :: (LockCache -> LockCache) -> Annex ()
|
|
changeLockCache a = do
|
|
m <- getLockCache
|
|
changeState $ \s -> s { lockcache = a m }
|
|
|
|
{- Runs an action with a shared lock held. If an exclusive lock is held,
|
|
- blocks until it becomes free. -}
|
|
withSharedLock :: OsPath -> Annex a -> Annex a
|
|
withSharedLock lockfile a = debugLocks $ do
|
|
createAnnexDirectory $ takeDirectory lockfile
|
|
mode <- annexFileMode
|
|
bracket (lock mode lockfile) (liftIO . dropLock) (const a)
|
|
where
|
|
#ifndef mingw32_HOST_OS
|
|
lock mode = lockShared (Just mode)
|
|
#else
|
|
lock _mode = liftIO . waitToLock . lockShared
|
|
#endif
|
|
|
|
{- Runs an action with an exclusive lock held. If the lock is already
|
|
- held, blocks until it becomes free. -}
|
|
withExclusiveLock :: OsPath -> Annex a -> Annex a
|
|
withExclusiveLock lockfile a = bracket
|
|
(takeExclusiveLock lockfile)
|
|
(liftIO . dropLock)
|
|
(const a)
|
|
|
|
{- Takes an exclusive lock, blocking until it's free. -}
|
|
takeExclusiveLock :: OsPath -> Annex LockHandle
|
|
takeExclusiveLock lockfile = debugLocks $ do
|
|
createAnnexDirectory $ takeDirectory lockfile
|
|
mode <- annexFileMode
|
|
lock mode lockfile
|
|
where
|
|
#ifndef mingw32_HOST_OS
|
|
lock mode = lockExclusive (Just mode)
|
|
#else
|
|
lock _mode = liftIO . waitToLock . lockExclusive
|
|
#endif
|
|
|
|
{- Tries to take an exclusive lock and run an action. If the lock is
|
|
- already held, returns Nothing. -}
|
|
tryExclusiveLock :: OsPath -> Annex a -> Annex (Maybe a)
|
|
tryExclusiveLock lockfile a = debugLocks $ do
|
|
createAnnexDirectory $ takeDirectory lockfile
|
|
mode <- annexFileMode
|
|
bracket (lock mode lockfile) (liftIO . unlock) go
|
|
where
|
|
#ifndef mingw32_HOST_OS
|
|
lock mode = tryLockExclusive (Just mode)
|
|
#else
|
|
lock _mode = liftIO . lockExclusive
|
|
#endif
|
|
unlock = maybe noop dropLock
|
|
go Nothing = return Nothing
|
|
go (Just _) = Just <$> a
|
|
|
|
{- Tries to take a shared lock, without blocking.
|
|
-
|
|
- Does not create the lock directory or lock file if it does not exist,
|
|
- taking an exclusive lock will create them.
|
|
-}
|
|
trySharedLock :: OsPath -> Annex (Maybe LockHandle)
|
|
trySharedLock lockfile = debugLocks $
|
|
#ifndef mingw32_HOST_OS
|
|
tryLockShared Nothing lockfile
|
|
#else
|
|
liftIO $ lockShared lockfile
|
|
#endif
|