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|
{- A pool of "git-annex transfer" processes available for use
-
- Copyright 2013-2020 Joey Hess <id@joeyh.name>
-
- Licensed under the GNU AGPL version 3 or higher.
-}
module Types.TransferrerPool where
import Common
import Control.Concurrent.STM hiding (check)
type TransferrerPool = TVar [TransferrerPoolItem]
type CheckTransferrer = IO Bool
type MkCheckTransferrer = IO (IO Bool)
{- Each item in the pool may have a transferrer running, and has an
- IO action that can be used to check if it's still ok to use the
- transferrer. -}
data TransferrerPoolItem = TransferrerPoolItem (Maybe Transferrer) CheckTransferrer
data Transferrer = Transferrer
{ transferrerRead :: Handle
, transferrerWrite :: Handle
, transferrerHandle :: ProcessHandle
, transferrerShutdown :: IO ()
-- ^ Closes the FDs and waits for the process to exit.
-- Should be used when the transferrer is in between transfers,
-- as otherwise it may not shutdown promptly.
}
newTransferrerPool :: IO TransferrerPool
newTransferrerPool = newTVarIO []
popTransferrerPool :: TransferrerPool -> STM (Maybe TransferrerPoolItem, Int)
popTransferrerPool p = do
l <- readTVar p
case l of
[] -> return (Nothing, 0)
(i:is) -> do
writeTVar p is
return $ (Just i, length is)
pushTransferrerPool :: TransferrerPool -> TransferrerPoolItem -> STM ()
pushTransferrerPool p i = do
l <- readTVar p
let l' = i:l
writeTVar p l'
{- Note that making a CheckTransferrer may allocate resources,
- such as a NotificationHandle, so it's important that the returned
- TransferrerPoolItem is pushed into the pool, and not left to be
- garbage collected. -}
mkTransferrerPoolItem :: MkCheckTransferrer -> Transferrer -> IO TransferrerPoolItem
mkTransferrerPoolItem mkcheck t = do
check <- mkcheck
return $ TransferrerPoolItem (Just t) check
|
