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|
{- A pool of "git-annex transferkeys" processes
-
- Copyright 2013 Joey Hess <joey@kitenet.net>
-
- Licensed under the GNU GPL version 3 or higher.
-}
module Assistant.TransferrerPool where
import Assistant.Common
import Assistant.Types.TransferrerPool
import Logs.Transfer
import Utility.Batch
import qualified Command.TransferKeys as T
import Control.Concurrent.STM
import System.Process (create_group, std_in, std_out)
import Control.Exception (throw)
import Control.Concurrent
{- Runs an action with a Transferrer from the pool. -}
withTransferrer :: FilePath -> BatchCommandMaker -> TransferrerPool -> (Transferrer -> IO a) -> IO a
withTransferrer program batchmaker pool a = do
t <- maybe (mkTransferrer program batchmaker) (checkTransferrer program batchmaker)
=<< atomically (tryReadTChan pool)
v <- tryNonAsync $ a t
unlessM (putback t) $
void $ forkIO $ stopTransferrer t
either throw return v
where
putback t = atomically $ ifM (isEmptyTChan pool)
( do
writeTChan pool t
return True
, return False
)
{- Requests that a Transferrer perform a Transfer, and waits for it to
- finish. -}
performTransfer :: Transferrer -> Transfer -> AssociatedFile -> IO Bool
performTransfer transferrer t f = catchBoolIO $ do
T.sendRequest t f (transferrerWrite transferrer)
T.readResponse (transferrerRead transferrer)
{- Starts a new git-annex transferkeys process, setting up handles
- that will be used to communicate with it. -}
mkTransferrer :: FilePath -> BatchCommandMaker -> IO Transferrer
mkTransferrer program batchmaker = do
{- It runs as a batch job. -}
let (program', params') = batchmaker (program, [Param "transferkeys"])
{- It's put into its own group so that the whole group can be
- killed to stop a transfer. -}
(Just writeh, Just readh, _, pid) <- createProcess
(proc program' $ toCommand params')
{ create_group = True
, std_in = CreatePipe
, std_out = CreatePipe
}
fileEncoding readh
fileEncoding writeh
return $ Transferrer
{ transferrerRead = readh
, transferrerWrite = writeh
, transferrerHandle = pid
}
{- Checks if a Transferrer is still running. If not, makes a new one. -}
checkTransferrer :: FilePath -> BatchCommandMaker -> Transferrer -> IO Transferrer
checkTransferrer program batchmaker t =
maybe (return t) (const $ mkTransferrer program batchmaker)
=<< getProcessExitCode (transferrerHandle t)
{- Closing the fds will stop the transferrer. -}
stopTransferrer :: Transferrer -> IO ()
stopTransferrer t = do
hClose $ transferrerRead t
hClose $ transferrerWrite t
void $ waitForProcess $ transferrerHandle t
|
