git-annex/Remote/Helper/Hooks.hs
Joey Hess 9e11699c76 connect existing meters to the transfer log for downloads
Most remotes have meters in their implementations of retrieveKeyFile
already. Simply hooking these up to the transfer log makes that information
available. Easy peasy.

This is particularly valuable information for encrypted remotes, which
otherwise bypass the assistant's polling of temp files, and so don't have
good progress bars yet.

Still some work to do here (see progressbars.mdwn changes), but this
is entirely an improvement from the lack of progress bars for encrypted
downloads.
2013-04-11 17:32:31 -04:00

86 lines
2.8 KiB
Haskell

{- Adds hooks to remotes.
-
- Copyright 2012 Joey Hess <joey@kitenet.net>
-
- Licensed under the GNU GPL version 3 or higher.
-}
module Remote.Helper.Hooks (addHooks) where
import qualified Data.Map as M
import Common.Annex
import Types.Remote
import qualified Annex
import Annex.LockPool
import Annex.Perms
{- 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 f -> wrapper $ retrieveKeyFileCheap r k f
, removeKey = \k -> wrapper $ removeKey r k
, hasKey = \k -> wrapper $ hasKey r k
}
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 (not . any (== lck) . M.keys <$> getPool) $ 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.
lockFile 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 (remoteid ++ "-stop-command") $ 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
mode <- annexFileMode
fd <- liftIO $ noUmask mode $
openFd lck ReadWrite (Just mode) defaultFileFlags
v <- liftIO $ tryIO $
setLock fd (WriteLock, AbsoluteSeek, 0, 0)
case v of
Left _ -> noop
Right _ -> run stophook
liftIO $ closeFd fd