git-annex/Command/TransferInfo.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

64 lines
1.8 KiB
Haskell

{- git-annex command
-
- Copyright 2012 Joey Hess <joey@kitenet.net>
-
- Licensed under the GNU GPL version 3 or higher.
-}
module Command.TransferInfo where
import Common.Annex
import Command
import Annex.Content
import Logs.Transfer
import Types.Key
import qualified Fields
import Utility.Metered
def :: [Command]
def = [noCommit $ command "transferinfo" paramKey seek SectionPlumbing
"updates sender on number of bytes of content received"]
seek :: CommandSeek
seek = withWords start
{- Security:
-
- The transfer info file contains the user-supplied key, but
- the built-in guards prevent slashes in it from showing up in the filename.
- It also contains the UUID of the remote. But slashes are also filtered
- out of that when generating the filename.
-
- Checks that the key being transferred is inAnnex, to prevent
- malicious spamming of bogus keys. Does not check that a transfer
- of the key is actually in progress, because this could be started
- concurrently with sendkey, and win the race.
-}
start :: [String] -> CommandStart
start (k:[]) = do
case file2key k of
Nothing -> error "bad key"
(Just key) -> whenM (inAnnex key) $ do
file <- Fields.getField Fields.associatedFile
u <- maybe (error "missing remoteuuid") toUUID
<$> Fields.getField Fields.remoteUUID
let t = Transfer
{ transferDirection = Upload
, transferUUID = u
, transferKey = key
}
info <- liftIO $ startTransferInfo file
(update, tfile, _) <- mkProgressUpdater t info
liftIO $ mapM_ void
[ tryIO $ forever $ do
bytes <- readUpdate
maybe (error "transferinfo protocol error")
(update . toBytesProcessed) bytes
, tryIO $ removeFile tfile
, exitSuccess
]
stop
start _ = error "wrong number of parameters"
readUpdate :: IO (Maybe Integer)
readUpdate = readish <$> getLine