409 lines
13 KiB
Haskell
409 lines
13 KiB
Haskell
{- git-annex chunked remotes
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-
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- Copyright 2014 Joey Hess <id@joeyh.name>
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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 Remote.Helper.Chunked (
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ChunkSize,
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ChunkConfig(..),
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describeChunkConfig,
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getChunkConfig,
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storeChunks,
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removeChunks,
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retrieveChunks,
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checkPresentChunks,
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) where
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import Common.Annex
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import Utility.DataUnits
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import Types.StoreRetrieve
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import Types.Remote
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import Types.Key
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import Logs.Chunk
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import Utility.Metered
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import Crypto (EncKey)
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import Backend (isStableKey)
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import qualified Data.ByteString.Lazy as L
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import qualified Data.Map as M
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data ChunkConfig
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= NoChunks
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| UnpaddedChunks ChunkSize
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| LegacyChunks ChunkSize
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deriving (Show)
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describeChunkConfig :: ChunkConfig -> String
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describeChunkConfig NoChunks = "none"
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describeChunkConfig (UnpaddedChunks sz) = describeChunkSize sz ++ "chunks"
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describeChunkConfig (LegacyChunks sz) = describeChunkSize sz ++ " chunks (old style)"
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describeChunkSize :: ChunkSize -> String
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describeChunkSize sz = roughSize storageUnits False (fromIntegral sz)
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noChunks :: ChunkConfig -> Bool
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noChunks NoChunks = True
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noChunks _ = False
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getChunkConfig :: RemoteConfig -> ChunkConfig
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getChunkConfig m =
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case M.lookup "chunksize" m of
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Nothing -> case M.lookup "chunk" m of
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Nothing -> NoChunks
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Just v -> readsz UnpaddedChunks v "chunk"
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Just v -> readsz LegacyChunks v "chunksize"
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where
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readsz c v f = case readSize dataUnits v of
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Just size
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| size == 0 -> NoChunks
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| size > 0 -> c (fromInteger size)
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_ -> error $ "bad configuration " ++ f ++ "=" ++ v
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-- An infinite stream of chunk keys, starting from chunk 1.
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newtype ChunkKeyStream = ChunkKeyStream [Key]
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chunkKeyStream :: Key -> ChunkSize -> ChunkKeyStream
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chunkKeyStream basek chunksize = ChunkKeyStream $ map mk [1..]
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where
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mk chunknum = sizedk { keyChunkNum = Just chunknum }
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sizedk = basek { keyChunkSize = Just (toInteger chunksize) }
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nextChunkKeyStream :: ChunkKeyStream -> (Key, ChunkKeyStream)
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nextChunkKeyStream (ChunkKeyStream (k:l)) = (k, ChunkKeyStream l)
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nextChunkKeyStream (ChunkKeyStream []) = error "expected infinite ChunkKeyStream"
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takeChunkKeyStream :: ChunkCount -> ChunkKeyStream -> [Key]
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takeChunkKeyStream n (ChunkKeyStream l) = genericTake n l
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-- Number of chunks already consumed from the stream.
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numChunks :: ChunkKeyStream -> Integer
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numChunks = pred . fromJust . keyChunkNum . fst . nextChunkKeyStream
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{- Splits up the key's content into chunks, passing each chunk to
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- the storer action, along with a corresponding chunk key and a
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- progress meter update callback.
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-
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- To support resuming, the checker is used to find the first missing
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- chunk key. Storing starts from that chunk.
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-
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- This buffers each chunk in memory, so can use a lot of memory
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- with a large ChunkSize.
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- More optimal versions of this can be written, that rely
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- on L.toChunks to split the lazy bytestring into chunks (typically
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- smaller than the ChunkSize), and eg, write those chunks to a Handle.
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- But this is the best that can be done with the storer interface that
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- writes a whole L.ByteString at a time.
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-}
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storeChunks
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:: UUID
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-> ChunkConfig
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-> Key
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-> FilePath
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-> MeterUpdate
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-> Storer
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-> CheckPresent
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-> Annex Bool
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storeChunks u chunkconfig k f p storer checker =
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case chunkconfig of
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(UnpaddedChunks chunksize) | isStableKey k ->
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bracketIO open close (go chunksize)
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_ -> storer k (FileContent f) p
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where
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open = tryIO $ openBinaryFile f ReadMode
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close (Right h) = hClose h
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close (Left _) = noop
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go _ (Left e) = do
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warning (show e)
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return False
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go chunksize (Right h) = do
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let chunkkeys = chunkKeyStream k chunksize
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(chunkkeys', startpos) <- seekResume h chunkkeys checker
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b <- liftIO $ L.hGetContents h
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gochunks p startpos chunksize b chunkkeys'
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gochunks :: MeterUpdate -> BytesProcessed -> ChunkSize -> L.ByteString -> ChunkKeyStream -> Annex Bool
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gochunks meterupdate startpos chunksize = loop startpos . splitchunk
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where
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splitchunk = L.splitAt chunksize
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loop bytesprocessed (chunk, bs) chunkkeys
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| L.null chunk && numchunks > 0 = do
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-- Once all chunks are successfully
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-- stored, update the chunk log.
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chunksStored u k (FixedSizeChunks chunksize) numchunks
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return True
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| otherwise = do
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liftIO $ meterupdate' zeroBytesProcessed
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let (chunkkey, chunkkeys') = nextChunkKeyStream chunkkeys
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ifM (storer chunkkey (ByteContent chunk) meterupdate')
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( do
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let bytesprocessed' = addBytesProcessed bytesprocessed (L.length chunk)
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loop bytesprocessed' (splitchunk bs) chunkkeys'
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, return False
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)
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where
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numchunks = numChunks chunkkeys
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{- The MeterUpdate that is passed to the action
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- storing a chunk is offset, so that it reflects
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- the total bytes that have already been stored
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- in previous chunks. -}
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meterupdate' = offsetMeterUpdate meterupdate bytesprocessed
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{- Check if any of the chunk keys are present. If found, seek forward
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- in the Handle, so it will be read starting at the first missing chunk.
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- Returns the ChunkKeyStream truncated to start at the first missing
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- chunk, and the number of bytes skipped due to resuming.
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-
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- As an optimisation, if the file fits into a single chunk, there's no need
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- to check if that chunk is present -- we know it's not, because otherwise
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- the whole file would be present and there would be no reason to try to
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- store it.
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-}
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seekResume
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:: Handle
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-> ChunkKeyStream
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-> CheckPresent
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-> Annex (ChunkKeyStream, BytesProcessed)
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seekResume h chunkkeys checker = do
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sz <- liftIO (hFileSize h)
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if sz <= fromMaybe 0 (keyChunkSize $ fst $ nextChunkKeyStream chunkkeys)
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then return (chunkkeys, zeroBytesProcessed)
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else check 0 chunkkeys sz
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where
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check pos cks sz
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| pos >= sz = do
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-- All chunks are already stored!
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liftIO $ hSeek h AbsoluteSeek sz
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return (cks, toBytesProcessed sz)
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| otherwise = do
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v <- tryNonAsync (checker k)
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case v of
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Right True ->
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check pos' cks' sz
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_ -> do
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when (pos > 0) $
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liftIO $ hSeek h AbsoluteSeek pos
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return (cks, toBytesProcessed pos)
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where
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(k, cks') = nextChunkKeyStream cks
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pos' = pos + fromMaybe 0 (keyChunkSize k)
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{- Removes all chunks of a key from a remote, by calling a remover
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- action on each.
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-
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- The remover action should succeed even if asked to
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- remove a key that is not present on the remote.
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-
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- This action may be called on a chunked key. It will simply remove it.
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-}
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removeChunks :: (Key -> Annex Bool) -> UUID -> ChunkConfig -> EncKey -> Key -> Annex Bool
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removeChunks remover u chunkconfig encryptor k = do
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ls <- chunkKeys u chunkconfig k
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ok <- allM (remover . encryptor) (concat ls)
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when ok $ do
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let chunksizes = catMaybes $ map (keyChunkSize <=< headMaybe) ls
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forM_ chunksizes $ chunksRemoved u k . FixedSizeChunks . fromIntegral
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return ok
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{- Retrieves a key from a remote, using a retriever action.
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-
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- When the remote is chunked, tries each of the options returned by
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- chunkKeys until it finds one where the retriever successfully
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- gets the first chunked key. The content of that key, and any
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- other chunks in the list is fed to the sink.
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-
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- If retrival of one of the subsequent chunks throws an exception,
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- gives up and returns False. Note that partial data may have been
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- written to the sink in this case.
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-
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- Resuming is supported when using chunks. When the destination file
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- already exists, it skips to the next chunked key that would be needed
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- to resume.
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-}
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retrieveChunks
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:: Retriever
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-> UUID
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-> ChunkConfig
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-> EncKey
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-> Key
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-> FilePath
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-> MeterUpdate
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-> (Maybe Handle -> Maybe MeterUpdate -> ContentSource -> Annex Bool)
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-> Annex Bool
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retrieveChunks retriever u chunkconfig encryptor basek dest basep sink
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| noChunks chunkconfig =
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-- Optimisation: Try the unchunked key first, to avoid
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-- looking in the git-annex branch for chunk counts
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-- that are likely not there.
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getunchunked `catchNonAsync`
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const (go =<< chunkKeysOnly u basek)
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| otherwise = go =<< chunkKeys u chunkconfig basek
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where
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go ls = do
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currsize <- liftIO $ catchMaybeIO $ getFileSize dest
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let ls' = maybe ls (setupResume ls) currsize
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if any null ls'
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then return True -- dest is already complete
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else firstavail currsize ls' `catchNonAsync` giveup
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giveup e = do
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warning (show e)
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return False
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firstavail _ [] = return False
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firstavail currsize ([]:ls) = firstavail currsize ls
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firstavail currsize ((k:ks):ls)
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| k == basek = getunchunked
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`catchNonAsync` (const $ firstavail currsize ls)
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| otherwise = do
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let offset = resumeOffset currsize k
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let p = maybe basep
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(offsetMeterUpdate basep . toBytesProcessed)
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offset
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v <- tryNonAsync $
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retriever (encryptor k) p $ \content ->
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bracketIO (maybe opennew openresume offset) hClose $ \h -> do
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void $ tosink (Just h) p content
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let sz = toBytesProcessed $
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fromMaybe 0 $ keyChunkSize k
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getrest p h sz sz ks
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`catchNonAsync` giveup
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case v of
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Left e
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| null ls -> giveup e
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| otherwise -> firstavail currsize ls
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Right r -> return r
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getrest _ _ _ _ [] = return True
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getrest p h sz bytesprocessed (k:ks) = do
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let p' = offsetMeterUpdate p bytesprocessed
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liftIO $ p' zeroBytesProcessed
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ifM (retriever (encryptor k) p' $ tosink (Just h) p')
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( getrest p h sz (addBytesProcessed bytesprocessed sz) ks
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, giveup "chunk retrieval failed"
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)
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getunchunked = retriever (encryptor basek) basep $ tosink Nothing basep
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opennew = openBinaryFile dest WriteMode
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-- Open the file and seek to the start point in order to resume.
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openresume startpoint = do
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-- ReadWriteMode allows seeking; AppendMode does not.
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h <- openBinaryFile dest ReadWriteMode
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hSeek h AbsoluteSeek startpoint
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return h
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{- Progress meter updating is a bit tricky: If the Retriever
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- populates a file, it is responsible for updating progress
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- as the file is being retrieved.
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-
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- However, if the Retriever generates a lazy ByteString,
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- it is not responsible for updating progress (often it cannot).
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- Instead, the sink is passed a meter to update as it consumes
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- the ByteString.
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-}
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tosink h p content = sink h p' content
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where
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p'
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| isByteContent content = Just p
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| otherwise = Nothing
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{- Can resume when the chunk's offset is at or before the end of
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- the dest file. -}
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resumeOffset :: Maybe Integer -> Key -> Maybe Integer
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resumeOffset Nothing _ = Nothing
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resumeOffset currsize k
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| offset <= currsize = offset
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| otherwise = Nothing
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where
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offset = chunkKeyOffset k
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{- Drops chunks that are already present in a file, based on its size.
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- Keeps any non-chunk keys.
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-}
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setupResume :: [[Key]] -> Integer -> [[Key]]
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setupResume ls currsize = map dropunneeded ls
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where
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dropunneeded [] = []
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dropunneeded l@(k:_) = case keyChunkSize k of
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Just chunksize | chunksize > 0 ->
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genericDrop (currsize `div` chunksize) l
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_ -> l
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{- Checks if a key is present in a remote. This requires any one
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- of the lists of options returned by chunkKeys to all check out
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- as being present using the checker action.
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-
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- Throws an exception if the remote is not accessible.
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-}
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checkPresentChunks
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:: CheckPresent
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-> UUID
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-> ChunkConfig
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-> EncKey
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-> Key
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-> Annex Bool
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checkPresentChunks checker u chunkconfig encryptor basek
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| noChunks chunkconfig = do
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-- Optimisation: Try the unchunked key first, to avoid
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-- looking in the git-annex branch for chunk counts
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-- that are likely not there.
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v <- check basek
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case v of
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Right True -> return True
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Left e -> checklists (Just e) =<< chunkKeysOnly u basek
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_ -> checklists Nothing =<< chunkKeysOnly u basek
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| otherwise = checklists Nothing =<< chunkKeys u chunkconfig basek
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where
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checklists Nothing [] = return False
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checklists (Just deferrederror) [] = throwM deferrederror
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checklists d (l:ls)
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| not (null l) = do
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v <- checkchunks l
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case v of
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Left e -> checklists (Just e) ls
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Right True -> return True
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Right False -> checklists Nothing ls
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| otherwise = checklists d ls
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checkchunks :: [Key] -> Annex (Either SomeException Bool)
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checkchunks [] = return (Right True)
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checkchunks (k:ks) = do
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v <- check k
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case v of
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Right True -> checkchunks ks
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Right False -> return $ Right False
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Left e -> return $ Left e
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check = tryNonAsync . checker . encryptor
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{- A key can be stored in a remote unchunked, or as a list of chunked keys.
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- This can be the case whether or not the remote is currently configured
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- to use chunking.
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-
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- It's even possible for a remote to have the same key stored multiple
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- times with different chunk sizes!
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-
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- This finds all possible lists of keys that might be on the remote that
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- can be combined to get back the requested key, in order from most to
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- least likely to exist.
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-}
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chunkKeys :: UUID -> ChunkConfig -> Key -> Annex [[Key]]
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chunkKeys u chunkconfig k = do
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l <- chunkKeysOnly u k
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return $ if noChunks chunkconfig
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then [k] : l
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else l ++ [[k]]
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chunkKeysOnly :: UUID -> Key -> Annex [[Key]]
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chunkKeysOnly u k = map (toChunkList k) <$> getCurrentChunks u k
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toChunkList :: Key -> (ChunkMethod, ChunkCount) -> [Key]
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toChunkList k (FixedSizeChunks chunksize, chunkcount) =
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takeChunkKeyStream chunkcount $ chunkKeyStream k chunksize
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toChunkList _ (UnknownChunks _, _) = []
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