204 lines
7 KiB
Haskell
204 lines
7 KiB
Haskell
{- git-annex assistant pending transfer queue
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-
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- Copyright 2012 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.TransferQueue (
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TransferQueue,
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Schedule(..),
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newTransferQueue,
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getTransferQueue,
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queueTransfers,
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queueTransfersMatching,
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queueDeferredDownloads,
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queueTransfer,
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queueTransferAt,
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queueTransferWhenSmall,
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getNextTransfer,
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getMatchingTransfers,
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dequeueTransfers,
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) where
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import Common.Annex
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import Assistant.DaemonStatus
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import Logs.Transfer
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import Types.Remote
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import qualified Remote
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import qualified Types.Remote as Remote
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import Control.Concurrent.STM
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import qualified Data.Map as M
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data TransferQueue = TransferQueue
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{ queuesize :: TVar Int
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, queuelist :: TVar [(Transfer, TransferInfo)]
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, deferreddownloads :: TVar [(Key, AssociatedFile)]
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}
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data Schedule = Next | Later
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deriving (Eq)
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newTransferQueue :: IO TransferQueue
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newTransferQueue = atomically $ TransferQueue
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<$> newTVar 0
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<*> newTVar []
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<*> newTVar []
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{- Reads the queue's content without blocking or changing it. -}
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getTransferQueue :: TransferQueue -> IO [(Transfer, TransferInfo)]
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getTransferQueue q = atomically $ readTVar $ queuelist q
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stubInfo :: AssociatedFile -> Remote -> TransferInfo
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stubInfo f r = stubTransferInfo
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{ transferRemote = Just r
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, associatedFile = f
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}
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{- Adds transfers to queue for some of the known remotes. -}
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queueTransfers :: Schedule -> TransferQueue -> DaemonStatusHandle -> Key -> AssociatedFile -> Direction -> Annex ()
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queueTransfers = queueTransfersMatching (const True)
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{- Adds transfers to queue for some of the known remotes, that match a
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- condition. -}
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queueTransfersMatching :: (UUID -> Bool) -> Schedule -> TransferQueue -> DaemonStatusHandle -> Key -> AssociatedFile -> Direction -> Annex ()
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queueTransfersMatching matching schedule q dstatus k f direction = do
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rs <- sufficientremotes
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=<< knownRemotes <$> liftIO (getDaemonStatus dstatus)
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let matchingrs = filter (matching . Remote.uuid) rs
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if null matchingrs
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then defer
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else forM_ matchingrs $ \r -> liftIO $
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enqueue schedule q dstatus (gentransfer r) (stubInfo f r)
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where
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sufficientremotes rs
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{- Queue downloads from all remotes that
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- have the key, with the cheapest ones first.
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- More expensive ones will only be tried if
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- downloading from a cheap one fails. -}
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| direction == Download = do
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uuids <- Remote.keyLocations k
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return $ filter (\r -> uuid r `elem` uuids) rs
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{- TODO: Determine a smaller set of remotes that
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- can be uploaded to, in order to ensure all
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- remotes can access the content. Currently,
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- send to every remote we can. -}
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| otherwise = return $ filter (not . Remote.readonly) rs
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gentransfer r = Transfer
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{ transferDirection = direction
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, transferKey = k
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, transferUUID = Remote.uuid r
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}
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defer
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{- Defer this download, as no known remote has the key. -}
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| direction == Download = void $ liftIO $ atomically $
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modifyTVar' (deferreddownloads q) $
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\l -> (k, f):l
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| otherwise = noop
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{- Queues any deferred downloads that can now be accomplished, leaving
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- any others in the list to try again later. -}
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queueDeferredDownloads :: Schedule -> TransferQueue -> DaemonStatusHandle -> Annex ()
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queueDeferredDownloads schedule q dstatus = do
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rs <- knownRemotes <$> liftIO (getDaemonStatus dstatus)
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l <- liftIO $ atomically $ swapTVar (deferreddownloads q) []
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left <- filterM (queue rs) l
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unless (null left) $
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liftIO $ atomically $ modifyTVar' (deferreddownloads q) $
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\new -> new ++ left
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where
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queue rs (k, f) = do
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uuids <- Remote.keyLocations k
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let sources = filter (\r -> uuid r `elem` uuids) rs
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unless (null sources) $
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forM_ sources $ \r -> liftIO $
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enqueue schedule q dstatus
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(gentransfer r) (stubInfo f r)
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return $ null sources
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where
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gentransfer r = Transfer
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{ transferDirection = Download
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, transferKey = k
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, transferUUID = Remote.uuid r
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}
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enqueue :: Schedule -> TransferQueue -> DaemonStatusHandle -> Transfer -> TransferInfo -> IO ()
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enqueue schedule q dstatus t info
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| schedule == Next = go (new:)
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| otherwise = go (\l -> l++[new])
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where
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new = (t, info)
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go modlist = do
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atomically $ do
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void $ modifyTVar' (queuesize q) succ
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void $ modifyTVar' (queuelist q) modlist
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void $ notifyTransfer dstatus
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{- Adds a transfer to the queue. -}
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queueTransfer :: Schedule -> TransferQueue -> DaemonStatusHandle -> AssociatedFile -> Transfer -> Remote -> IO ()
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queueTransfer schedule q dstatus f t remote =
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enqueue schedule q dstatus t (stubInfo f remote)
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{- Blocks until the queue is no larger than a given size, and then adds a
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- transfer to the queue. -}
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queueTransferAt :: Int -> Schedule -> TransferQueue -> DaemonStatusHandle -> AssociatedFile -> Transfer -> Remote -> IO ()
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queueTransferAt wantsz schedule q dstatus f t remote = do
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atomically $ do
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sz <- readTVar (queuesize q)
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unless (sz <= wantsz) $
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retry -- blocks until queuesize changes
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enqueue schedule q dstatus t (stubInfo f remote)
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queueTransferWhenSmall :: TransferQueue -> DaemonStatusHandle -> AssociatedFile -> Transfer -> Remote -> IO ()
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queueTransferWhenSmall = queueTransferAt 10 Later
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{- Blocks until a pending transfer is available in the queue,
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- and removes it.
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-
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- Checks that it's acceptable, before adding it to the
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- the currentTransfers map. If it's not acceptable, it's discarded.
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-
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- This is done in a single STM transaction, so there is no window
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- where an observer sees an inconsistent status. -}
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getNextTransfer :: TransferQueue -> DaemonStatusHandle -> (TransferInfo -> Bool) -> IO (Maybe (Transfer, TransferInfo))
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getNextTransfer q dstatus acceptable = atomically $ do
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sz <- readTVar (queuesize q)
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if sz < 1
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then retry -- blocks until queuesize changes
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else do
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(r@(t,info):rest) <- readTVar (queuelist q)
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writeTVar (queuelist q) rest
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void $ modifyTVar' (queuesize q) pred
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if acceptable info
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then do
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adjustTransfersSTM dstatus $
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M.insertWith' const t info
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return $ Just r
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else return Nothing
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{- Moves transfers matching a condition from the queue, to the
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- currentTransfers map. -}
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getMatchingTransfers :: TransferQueue -> DaemonStatusHandle -> (Transfer -> Bool) -> IO [(Transfer, TransferInfo)]
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getMatchingTransfers q dstatus c = atomically $ do
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ts <- dequeueTransfersSTM q c
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unless (null ts) $
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adjustTransfersSTM dstatus $ \m -> M.union m $ M.fromList ts
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return ts
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{- Removes transfers matching a condition from the queue, and returns the
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- removed transfers. -}
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dequeueTransfers :: TransferQueue -> DaemonStatusHandle -> (Transfer -> Bool) -> IO [(Transfer, TransferInfo)]
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dequeueTransfers q dstatus c = do
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removed <- atomically $ dequeueTransfersSTM q c
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unless (null removed) $
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notifyTransfer dstatus
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return removed
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dequeueTransfersSTM :: TransferQueue -> (Transfer -> Bool) -> STM [(Transfer, TransferInfo)]
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dequeueTransfersSTM q c = do
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(removed, ts) <- partition (c . fst)
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<$> readTVar (queuelist q)
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void $ writeTVar (queuesize q) (length ts)
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void $ writeTVar (queuelist q) ts
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return removed
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