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{- 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 Common.Annex
import Assistant.ThreadedMonad
import Assistant.DaemonStatus
import Assistant.TransferQueue
import Assistant.TransferSlots
import Logs.Transfer
import Annex.Content
import Utility.ThreadScheduler
import Command
import qualified Command.Move
import Data.Time.Clock
import qualified Data.Map as M
{- 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 = runEvery (Seconds 1) $ do
(t, info) <- getNextTransfer transferqueue
whenM (runThreadState st $ shouldTransfer dstatus t) $
void $ inTransferSlot slots $
runTransfer st dstatus t info
{- Checks if the requested transfer is already running, or
- the file to download is already present. -}
shouldTransfer :: DaemonStatusHandle -> Transfer -> Annex Bool
shouldTransfer dstatus t = go =<< currentTransfers <$> getDaemonStatus dstatus
where
go m
| M.member t m = return False
| transferDirection t == Download =
not <$> inAnnex (transferKey t)
| otherwise = return True
{- A transfer is run in a separate process, 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.
-
- However, it 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.
-
- Currently a minimal shutdown is done; the transfer processes are
- effectively running in oneshot mode, without committing changes to the
- git-annex branch, and transfers should never queue git commands to run.
-}
runTransfer :: ThreadState -> DaemonStatusHandle -> Transfer -> TransferInfo -> IO ()
runTransfer st dstatus t info
| transferDirection t == Download = go Command.Move.fromStart
| otherwise = go Command.Move.toStart
where
go cmd = case (transferRemote info, associatedFile info) of
(Nothing, _) -> noop
(_, Nothing) -> noop
(Just remote, Just file) -> do
now <- getCurrentTime
pid <- forkProcess $ unsafeRunThreadState st $ void $
doCommand $ cmd remote False file (transferKey t)
runThreadState st $
adjustTransfers dstatus $
M.insertWith' const t info
{ startedTime = Just now
, transferPid = Just pid
, shouldWait = True
}
|
