72e5764a87
This old code will now be useful for git-annex beyond the assistant. git-annex won't use the CheckTransferrer part, and won't run transferkeys as a batch process, and will want withTransferrer to not shut down transferkeys processes. Still, the rest of this is a good fit for what I need now. Also removed some dead code, and simplified a little bit. This commit was sponsored by Mark Reidenbach on Patreon.
56 lines
1.7 KiB
Haskell
56 lines
1.7 KiB
Haskell
{- A pool of "git-annex transferkeys" processes available for use
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-
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- Copyright 2013-2020 Joey Hess <id@joeyh.name>
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-
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- Licensed under the GNU AGPL version 3 or higher.
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-}
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module Types.TransferrerPool where
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import Annex.Common
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import Control.Concurrent.STM hiding (check)
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type TransferrerPool = TVar (MkCheckTransferrer, [TransferrerPoolItem])
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type CheckTransferrer = IO Bool
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type MkCheckTransferrer = IO (IO Bool)
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{- Each item in the pool may have a transferrer running, and has an
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- IO action that can be used to check if it's still ok to use the
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- transferrer. -}
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data TransferrerPoolItem = TransferrerPoolItem (Maybe Transferrer) CheckTransferrer
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data Transferrer = Transferrer
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{ transferrerRead :: Handle
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, transferrerWrite :: Handle
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, transferrerHandle :: ProcessHandle
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}
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newTransferrerPool :: MkCheckTransferrer -> IO TransferrerPool
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newTransferrerPool c = newTVarIO (c, [])
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popTransferrerPool :: TransferrerPool -> STM (Maybe TransferrerPoolItem, Int)
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popTransferrerPool p = do
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(c, l) <- readTVar p
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case l of
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[] -> return (Nothing, 0)
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(i:is) -> do
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writeTVar p (c, is)
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return $ (Just i, length is)
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pushTransferrerPool :: TransferrerPool -> TransferrerPoolItem -> STM ()
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pushTransferrerPool p i = do
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(c, l) <- readTVar p
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let l' = i:l
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writeTVar p (c, l')
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{- Note that making a CheckTransferrer may allocate resources,
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- such as a NotificationHandle, so it's important that the returned
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- TransferrerPoolItem is pushed into the pool, and not left to be
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- garbage collected. -}
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mkTransferrerPoolItem :: TransferrerPool -> Transferrer -> IO TransferrerPoolItem
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mkTransferrerPoolItem p t = do
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mkcheck <- atomically $ fst <$> readTVar p
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check <- mkcheck
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return $ TransferrerPoolItem (Just t) check
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