git-annex/Assistant/Threads/Transferrer.hs
2012-08-06 17:09:23 -04:00

120 lines
3.7 KiB
Haskell

{- git-annex assistant data transferrer thread
-
- Copyright 2012 Joey Hess <joey@kitenet.net>
-
- Licensed under the GNU GPL version 3 or higher.
-}
module Assistant.Threads.Transferrer where
import Assistant.Common
import Assistant.ThreadedMonad
import Assistant.DaemonStatus
import Assistant.TransferQueue
import Assistant.TransferSlots
import Assistant.Alert
import Logs.Transfer
import Logs.Presence
import Logs.Location
import Annex.Content
import qualified Remote
import Data.Time.Clock.POSIX
import Data.Time.Clock
import qualified Data.Map as M
thisThread :: ThreadName
thisThread = "Transferrer"
{- For now only one transfer is run at a time. -}
maxTransfers :: Int
maxTransfers = 1
{- Dispatches transfers from the queue. -}
transfererThread :: ThreadState -> DaemonStatusHandle -> TransferQueue -> TransferSlots -> IO ()
transfererThread st dstatus transferqueue slots = go
where
go = getNextTransfer transferqueue dstatus notrunning >>= handle
handle Nothing = go
handle (Just (t, info)) = do
ifM (runThreadState st $ shouldTransfer t info)
( do
debug thisThread [ "Transferring:" , show t ]
notifyTransfer dstatus
transferThread st dstatus slots t info
, do
debug thisThread [ "Skipping unnecessary transfer:" , show t ]
-- getNextTransfer added t to the
-- daemonstatus's transfer map.
void $ removeTransfer dstatus t
)
go
{- Skip transfers that are already running. -}
notrunning i = startedTime i == Nothing
{- Checks if the file to download is already present, or the remote
- being uploaded to isn't known to have the file. -}
shouldTransfer :: Transfer -> TransferInfo -> Annex Bool
shouldTransfer t info
| transferDirection t == Download =
not <$> inAnnex key
| transferDirection t == Upload =
{- Trust the location log to check if the
- remote already has the key. This avoids
- a roundtrip to the remote. -}
case transferRemote info of
Nothing -> return False
Just remote ->
notElem (Remote.uuid remote)
<$> loggedLocations key
| otherwise = return False
where
key = transferKey t
{- A transfer is run in a separate thread, with a *copy* of the Annex
- state. This is necessary to avoid blocking the rest of the assistant
- on the transfer completing, and also to allow multiple transfers to run
- at once. This requires GHC's threaded runtime to work!
-
- The copy of state means that the transfer processes are responsible
- for doing any necessary shutdown cleanups, and that the parent
- thread's cache must be invalidated once a transfer completes, as
- changes may have been made to the git-annex branch.
-}
transferThread :: ThreadState -> DaemonStatusHandle -> TransferSlots -> Transfer -> TransferInfo -> IO ()
transferThread st dstatus slots t info = case (transferRemote info, associatedFile info) of
(Nothing, _) -> noop
(_, Nothing) -> noop
(Just remote, Just file) -> do
tid <- inTransferSlot slots st $
transferprocess remote file
now <- getCurrentTime
adjustTransfers dstatus $
M.insertWith' const t info
{ startedTime = Just $ utcTimeToPOSIXSeconds now
, transferTid = Just tid
}
where
direction = transferDirection t
isdownload = direction == Download
tofrom
| isdownload = "from"
| otherwise = "to"
key = transferKey t
transferprocess remote file = do
showStart "copy" file
showAction $ tofrom ++ " " ++ Remote.name remote
ok <- runTransfer t (Just file) $
if isdownload
then getViaTmp key $
Remote.retrieveKeyFile remote key (Just file)
else do
ok <- Remote.storeKey remote key $ Just file
when ok $
Remote.logStatus remote key InfoPresent
return ok
showEndResult ok
liftIO $ addAlert dstatus $
makeAlertFiller ok $
transferFileAlert direction file