git-annex/Command/TransferKeys.hs
Joey Hess 34c8af74ba fix inversion of control in CommandSeek (no behavior changes)
I've been disliking how the command seek actions were written for some
time, with their inversion of control and ugly workarounds.

The last straw to fix it was sync --content, which didn't fit the
Annex [CommandStart] interface well at all. I have not yet made it take
advantage of the changed interface though.

The crucial change, and probably why I didn't do it this way from the
beginning, is to make each CommandStart action be run with exceptions
caught, and if it fails, increment a failure counter in annex state.
So I finally remove the very first code I wrote for git-annex, which
was before I had exception handling in the Annex monad, and so ran outside
that monad, passing state explicitly as it ran each CommandStart action.

This was a real slog from 1 to 5 am.

Test suite passes.

Memory usage is lower than before, sometimes by a couple of megabytes, and
remains constant, even when running in a large repo, and even when
repeatedly failing and incrementing the error counter. So no accidental
laziness space leaks.

Wall clock speed is identical, even in large repos.

This commit was sponsored by an anonymous bitcoiner.
2014-01-20 04:57:36 -04:00

139 lines
3.7 KiB
Haskell

{- git-annex command, used internally by assistant
-
- Copyright 2012, 2013 Joey Hess <joey@kitenet.net>
-
- Licensed under the GNU GPL version 3 or higher.
-}
{-# LANGUAGE TypeSynonymInstances, FlexibleInstances #-}
module Command.TransferKeys where
import Common.Annex
import Command
import Annex.Content
import Logs.Location
import Logs.Transfer
import qualified Remote
import Types.Key
import GHC.IO.Handle
data TransferRequest = TransferRequest Direction Remote Key AssociatedFile
def :: [Command]
def = [command "transferkeys" paramNothing seek
SectionPlumbing "transfers keys"]
seek :: CommandSeek
seek = withNothing start
start :: CommandStart
start = withHandles $ \(readh, writeh) -> do
runRequests readh writeh runner
stop
where
runner (TransferRequest direction remote key file)
| direction == Upload =
upload (Remote.uuid remote) key file forwardRetry $ \p -> do
ok <- Remote.storeKey remote key file p
when ok $
Remote.logStatus remote key InfoPresent
return ok
| otherwise = download (Remote.uuid remote) key file forwardRetry $ \p ->
getViaTmp key $ \t -> Remote.retrieveKeyFile remote key file t p
{- stdin and stdout are connected with the caller, to be used for
- communication with it. But doing a transfer might involve something
- that tries to read from stdin, or write to stdout. To avoid that, close
- stdin, and duplicate stderr to stdout. Return two new handles
- that are duplicates of the original (stdin, stdout). -}
withHandles :: ((Handle, Handle) -> Annex a) -> Annex a
withHandles a = do
readh <- liftIO $ hDuplicate stdin
writeh <- liftIO $ hDuplicate stdout
liftIO $ do
nullh <- openFile devNull ReadMode
nullh `hDuplicateTo` stdin
stderr `hDuplicateTo` stdout
a (readh, writeh)
runRequests
:: Handle
-> Handle
-> (TransferRequest -> Annex Bool)
-> Annex ()
runRequests readh writeh a = do
liftIO $ do
hSetBuffering readh NoBuffering
fileEncoding readh
fileEncoding writeh
go =<< readrequests
where
go (d:u:k:f:rest) = do
case (deserialize d, deserialize u, deserialize k, deserialize f) of
(Just direction, Just uuid, Just key, Just file) -> do
mremote <- Remote.remoteFromUUID uuid
case mremote of
Nothing -> sendresult False
Just remote -> sendresult =<< a
(TransferRequest direction remote key file)
_ -> sendresult False
go rest
go [] = noop
go [""] = noop
go v = error $ "transferkeys protocol error: " ++ show v
readrequests = liftIO $ split fieldSep <$> hGetContents readh
sendresult b = liftIO $ do
hPutStrLn writeh $ serialize b
hFlush writeh
sendRequest :: Transfer -> AssociatedFile -> Handle -> IO ()
sendRequest t f h = do
hPutStr h $ intercalate fieldSep
[ serialize (transferDirection t)
, serialize (transferUUID t)
, serialize (transferKey t)
, serialize f
, "" -- adds a trailing null
]
hFlush h
readResponse :: Handle -> IO Bool
readResponse h = fromMaybe False . deserialize <$> hGetLine h
fieldSep :: String
fieldSep = "\0"
class Serialized a where
serialize :: a -> String
deserialize :: String -> Maybe a
instance Serialized Bool where
serialize True = "1"
serialize False = "0"
deserialize "1" = Just True
deserialize "0" = Just False
deserialize _ = Nothing
instance Serialized Direction where
serialize Upload = "u"
serialize Download = "d"
deserialize "u" = Just Upload
deserialize "d" = Just Download
deserialize _ = Nothing
instance Serialized AssociatedFile where
serialize (Just f) = f
serialize Nothing = ""
deserialize "" = Just Nothing
deserialize f = Just $ Just f
instance Serialized UUID where
serialize = fromUUID
deserialize = Just . toUUID
instance Serialized Key where
serialize = key2file
deserialize = file2key