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|
{- Adds hooks to remotes.
-
- Copyright 2012 Joey Hess <id@joeyh.name>
-
- Licensed under the GNU GPL version 3 or higher.
-}
{-# LANGUAGE CPP #-}
module Remote.Helper.Hooks (addHooks) where
import qualified Data.Map as M
import Annex.Common
import Types.Remote
import Types.CleanupActions
import qualified Annex
import Annex.LockFile
import Annex.LockPool
#ifndef mingw32_HOST_OS
import Annex.Perms
#endif
{- Modifies a remote's access functions to first run the
- annex-start-command hook, and trigger annex-stop-command on shutdown.
- This way, the hooks are only run when a remote is actively being used.
-}
addHooks :: Remote -> Remote
addHooks r = addHooks' r
(remoteAnnexStartCommand $ gitconfig r)
(remoteAnnexStopCommand $ gitconfig r)
addHooks' :: Remote -> Maybe String -> Maybe String -> Remote
addHooks' r Nothing Nothing = r
addHooks' r starthook stophook = r'
where
r' = r
{ storeKey = \k f p -> wrapper $ storeKey r k f p
, retrieveKeyFile = \k f d p -> wrapper $ retrieveKeyFile r k f d p
, retrieveKeyFileCheap = \k af f -> wrapper $ retrieveKeyFileCheap r k af f
, removeKey = wrapper . removeKey r
, checkPresent = wrapper . checkPresent r
}
where
wrapper = runHooks r' starthook stophook
runHooks :: Remote -> Maybe String -> Maybe String -> Annex a -> Annex a
runHooks r starthook stophook a = do
dir <- fromRepo gitAnnexRemotesDir
let lck = dir </> remoteid ++ ".lck"
whenM (notElem lck . M.keys <$> getLockCache) $ do
liftIO $ createDirectoryIfMissing True dir
firstrun lck
a
where
remoteid = show (uuid r)
run Nothing = noop
run (Just command) = void $ liftIO $
boolSystem "sh" [Param "-c", Param command]
firstrun lck = do
-- Take a shared lock; This indicates that git-annex
-- is using the remote, and prevents other instances
-- of it from running the stophook. If another
-- instance is shutting down right now, this
-- will block waiting for its exclusive lock to clear.
lockFileCached lck
-- The starthook is run even if some other git-annex
-- is already running, and ran it before.
-- It would be difficult to use locking to ensure
-- it's only run once, and it's also possible for
-- git-annex to be interrupted before it can run the
-- stophook, in which case the starthook
-- would be run again by the next git-annex.
-- So, requiring idempotency is the right approach.
run starthook
Annex.addCleanup (StopHook $ uuid r) $ runstop lck
runstop lck = do
-- Drop any shared lock we have, and take an
-- exclusive lock, without blocking. If the lock
-- succeeds, we're the only process using this remote,
-- so can stop it.
unlockFile lck
#ifndef mingw32_HOST_OS
mode <- annexFileMode
v <- noUmask mode $ tryLockExclusive (Just mode) lck
#else
v <- liftIO $ lockExclusive lck
#endif
case v of
Nothing -> noop
Just lockhandle -> do
run stophook
liftIO $ dropLock lockhandle
|
