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