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{- A pool of "git-annex transferkeys" processes
-
- Copyright 2013 Joey Hess <id@joeyh.name>
-
- Licensed under the GNU GPL version 3 or higher.
-}
module Assistant.TransferrerPool where
import Assistant.Common
import Assistant.Types.TransferrerPool
import Types.Transfer
import Utility.Batch
import qualified Command.TransferKeys as T
import Control.Concurrent.STM hiding (check)
import Control.Exception (throw)
import Control.Concurrent
{- Runs an action with a Transferrer from the pool.
-
- Only one Transferrer is left running in the pool at a time.
- So if this needed to start a new Transferrer, it's stopped when done.
-}
withTransferrer :: FilePath -> BatchCommandMaker -> TransferrerPool -> (Transferrer -> IO a) -> IO a
withTransferrer program batchmaker pool a = do
(mi, leftinpool) <- atomically (popTransferrerPool pool)
i@(TransferrerPoolItem (Just t) check) <- case mi of
Nothing -> mkTransferrerPoolItem pool =<< mkTransferrer program batchmaker
Just i -> checkTransferrerPoolItem program batchmaker i
v <- tryNonAsync $ a t
if leftinpool == 0
then atomically $ pushTransferrerPool pool i
else do
void $ forkIO $ stopTransferrer t
atomically $ pushTransferrerPool pool $ TransferrerPoolItem Nothing check
either throw return v
{- Check if a Transferrer from the pool is still ok to be used.
- If not, stop it and start a new one. -}
checkTransferrerPoolItem :: FilePath -> BatchCommandMaker -> TransferrerPoolItem -> IO TransferrerPoolItem
checkTransferrerPoolItem program batchmaker i = case i of
TransferrerPoolItem (Just t) check -> ifM check
( return i
, do
stopTransferrer t
new check
)
TransferrerPoolItem Nothing check -> new check
where
new check = do
t <- mkTransferrer program batchmaker
return $ TransferrerPoolItem (Just t) check
{- Requests that a Transferrer perform a Transfer, and waits for it to
- finish. -}
performTransfer :: Transferrer -> Transfer -> TransferInfo -> IO Bool
performTransfer transferrer t info = catchBoolIO $ do
T.sendRequest t info (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
}
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
|
