finish up basic chunked remote groundwork

Chunk retrieval and reassembly, removal, and checking if all necessary
chunks are present.

This commit was sponsored by Damien Raude-Morvan.

Remote/Helper/Chunked.hs

@@ -5,14 +5,16 @@
  - Licensed under the GNU GPL version 3 or higher.
  -}
 
-module Remote.Helper.Chunked
-	( ChunkSize
-	, ChunkConfig(..)
-	, chunkConfig
-	, storeChunks
-	, chunkKeys
-	, meteredWriteFileChunks
-	) where
+module Remote.Helper.Chunked (
+	ChunkSize,
+	ChunkConfig(..),
+	chunkConfig,
+	storeChunks,
+	chunkKeys,
+	removeChunks,
+	retrieveChunks,
+	hasKeyChunks,
+) where
 
 import Common.Annex
 import Utility.DataUnits
@@ -21,6 +23,7 @@ import Types.Key
 import Logs.Chunk.Pure (ChunkSize, ChunkCount)
 import Logs.Chunk
 import Utility.Metered
+import Crypto (EncKey)
 
 import qualified Data.ByteString.Lazy as L
 import qualified Data.ByteString as S
@@ -69,8 +72,10 @@ numChunks = pred . fromJust . keyChunkNum . fst . nextChunkKeyStream
  -
  - Note that the storer action is responsible for catching any
  - exceptions it may encounter.
+ -
+ - This action may be called on a chunked key. It will simply store it.
  -}
-storeChunks :: UUID -> ChunkConfig -> Key -> FilePath -> MeterUpdate -> (Key -> L.ByteString -> MeterUpdate -> Annex Bool) -> Annex Bool
+storeChunks :: UUID -> ChunkConfig -> Key -> FilePath -> MeterUpdate -> (Key -> L.ByteString -> MeterUpdate -> IO Bool) -> Annex Bool
 storeChunks u chunkconfig k f p storer = metered (Just p) k $ \meterupdate ->
 	either (\e -> liftIO (print e) >> return False) (go meterupdate)
 		=<< (liftIO $ tryIO $ L.readFile f)
@@ -78,7 +83,7 @@ storeChunks u chunkconfig k f p storer = metered (Just p) k $ \meterupdate ->
 	go meterupdate b = case chunkconfig of
 		(UnpaddedChunks chunksize) | not (isChunkKey k) ->
 			gochunks meterupdate chunksize b (chunkKeyStream k chunksize)
-		_ -> storer k b meterupdate
+		_ -> liftIO $ storer k b meterupdate
 
 	gochunks :: MeterUpdate -> ChunkSize -> L.ByteString -> ChunkKeyStream -> Annex Bool
 	gochunks meterupdate chunksize lb =
@@ -107,7 +112,7 @@ storeChunks u chunkconfig k f p storer = metered (Just p) k $ \meterupdate ->
 
 		storechunk bytesprocessed sz bs c chunkkeys = do
 			let (chunkkey, chunkkeys') = nextChunkKeyStream chunkkeys
-			ifM (storer chunkkey (L.fromChunks $ reverse c) meterupdate')
+			ifM (liftIO $ storer chunkkey (L.fromChunks $ reverse c) meterupdate')
 				( do
 					let bytesprocessed' = addBytesProcessed bytesprocessed (chunksize - sz)
 					loop bytesprocessed' chunksize bs [] chunkkeys'
@@ -129,19 +134,109 @@ storeChunks u chunkconfig k f p storer = metered (Just p) k $ \meterupdate ->
  - requested key.
  -}
 chunkKeys :: UUID -> ChunkConfig -> Key -> Annex [[Key]]
-chunkKeys u (UnpaddedChunks _) k = do
+chunkKeys u (UnpaddedChunks _) k | not (isChunkKey k) = do
 	chunklists <- map (toChunkList k) <$> getCurrentChunks u k
-	return ([k]:chunklists)
+	-- Probably using the chunklists, but the unchunked
+	-- key could be present.
+	return (chunklists ++ [[k]])
 chunkKeys _ _ k = pure [[k]]
 
 toChunkList :: Key -> (ChunkSize, ChunkCount) -> [Key]
 toChunkList k (chunksize, chunkcount) = takeChunkKeyStream chunkcount $
 	chunkKeyStream k chunksize
 
-{- Writes a series of chunks to a file. The feeder is called to get
- - each chunk. -}
-meteredWriteFileChunks :: MeterUpdate -> FilePath -> [v] -> (v -> IO L.ByteString) -> IO ()
-meteredWriteFileChunks meterupdate dest chunks feeder =
-	withBinaryFile dest WriteMode $ \h ->
-		forM_ chunks $
-			meteredWrite meterupdate h <=< feeder
+{- Removes all chunks of a key from a remote, by calling a remover
+ - action on each. The remover action should succeed even if asked to
+ - remove a key that is not present on the remote.
+ -
+ - This action may be called on a chunked key. It will simply remove it.
+ -}
+removeChunks :: (Key -> Annex Bool) -> UUID -> ChunkConfig -> EncKey -> Key -> Annex Bool
+removeChunks remover u chunkconfig encryptor k = do
+	ls <- chunkKeys u chunkconfig k
+	ok <- and <$> mapM (remover . encryptor) (concat ls)
+	when ok $
+		case chunkconfig of
+			(UnpaddedChunks _) | not (isChunkKey k) -> do
+				let chunksizes = catMaybes $ map (keyChunkSize <=< headMaybe) ls
+				forM_ chunksizes $ chunksRemoved u k . fromIntegral
+			_ -> noop
+	return ok
+
+{- Retrieves a key from a remote, using a retriever action that
+ - streams it to a ByteString.
+ -
+ - When the remote is chunked, tries each of the options returned by
+ - chunkKeys until it finds one where the retriever successfully
+ - gets the first key in the list. The content of that key, and any
+ - other chunks in the list is fed to the sink.
+ -
+ - If retrival of one of the subsequent chunks throws an exception,
+ - gives up and returns False. Note that partial data may have been
+ - written to the sink in this case.
+ -}
+retrieveChunks 
+	:: (Key -> IO L.ByteString)
+	-> UUID
+	-> ChunkConfig
+	-> EncKey
+	-> Key
+	-> MeterUpdate
+	-> (MeterUpdate -> L.ByteString -> IO ())
+	-> Annex Bool
+retrieveChunks retriever u chunkconfig encryptor basek basep sink = do
+	ls <- chunkKeys u chunkconfig basek
+	liftIO $ flip catchNonAsync giveup (firstavail ls)
+  where
+	giveup e = print e >> return False
+
+	firstavail [] = return False
+	firstavail ([]:ls) = firstavail ls
+	firstavail ((k:ks):ls) = do
+		v <- tryNonAsync $ retriever (encryptor k)
+		case v of
+			Left e
+				| null ls -> giveup e
+				| otherwise -> firstavail ls
+			Right b -> do
+				sink basep b
+				let sz = toBytesProcessed $
+					fromMaybe 0 $ keyChunkSize k
+				getrest sz sz ks
+
+	getrest _ _ [] = return True
+	getrest sz bytesprocessed (k:ks) = do
+		let p = offsetMeterUpdate basep bytesprocessed
+		sink p =<< retriever (encryptor k)
+		getrest sz (addBytesProcessed bytesprocessed sz) ks
+
+{- Checks if a key is present in a remote. This requires any one
+ - of the lists of options returned by chunkKeys to all check out
+ - as being present using the checker action.
+ -}
+hasKeyChunks
+	:: (Key -> Annex (Either String Bool))
+	-> UUID
+	-> ChunkConfig
+	-> EncKey
+	-> Key
+	-> Annex (Either String Bool)
+hasKeyChunks checker u chunkconfig encryptor basek =
+	checklists impossible =<< chunkKeys u chunkconfig basek
+  where
+	checklists lastfailmsg [] = return $ Left lastfailmsg
+	checklists _ (l:ls)
+		| not (null l) =
+			either (`checklists` ls) (return . Right)
+				=<< checkchunks l
+		| otherwise = checklists impossible ls
+	
+	checkchunks :: [Key] -> Annex (Either String Bool)
+	checkchunks [] = return (Right True)
+	checkchunks (k:ks) = do
+		v <- checker (encryptor k)
+		if v == Right True
+			then checkchunks ks
+			else return v
+
+	impossible = "no recorded chunks"

Remote/Helper/Chunked/Legacy.hs

@@ -9,6 +9,7 @@ module Remote.Helper.Chunked.Legacy where
 
 import Common.Annex
 import Remote.Helper.Chunked
+import Utility.Metered
 
 import qualified Data.ByteString.Lazy as L
 import qualified Control.Exception as E
@@ -114,3 +115,12 @@ storeChunked chunksize dests storer content = either onerr return
 			let (chunk, b') = L.splitAt sz b
 			storer d chunk
 			storechunks sz (d:useddests) ds b'
+
+{- Writes a series of chunks to a file. The feeder is called to get
+ - each chunk.
+ -}
+meteredWriteFileChunks :: MeterUpdate -> FilePath -> [v] -> (v -> IO L.ByteString) -> IO ()
+meteredWriteFileChunks meterupdate dest chunks feeder =
+	withBinaryFile dest WriteMode $ \h ->
+		forM_ chunks $
+			meteredWrite meterupdate h <=< feeder