git-annex/Remote/Helper/Http.hs
2014-08-08 17:17:36 -04:00

55 lines
1.7 KiB
Haskell

{- helpers for remotes using http
-
- Copyright 2014 Joey Hess <joey@kitenet.net>
-
- Licensed under the GNU GPL version 3 or higher.
-}
module Remote.Helper.Http where
import Common.Annex
import Types.StoreRetrieve
import Utility.Metered
import Remote.Helper.Special
import Network.HTTP.Client (RequestBody(..), Response, responseStatus, responseBody, BodyReader)
import Network.HTTP.Types
import qualified Data.ByteString.Lazy as L
import qualified Data.ByteString as S
import Control.Concurrent
-- A storer that expects to be provided with a http RequestBody containing
-- the content to store.
--
-- Implemented as a fileStorer, so that the content can be streamed
-- from the file in constant space.
httpStorer :: (Key -> RequestBody -> Annex Bool) -> Storer
httpStorer a = fileStorer $ \k f m -> do
size <- liftIO $ (fromIntegral . fileSize <$> getFileStatus f :: IO Integer)
let streamer sink = withMeteredFile f m $ \b -> do
mvar <- newMVar $ L.toChunks b
let getnextchunk = modifyMVar mvar $ pure . pop
sink getnextchunk
let body = RequestBodyStream (fromInteger size) streamer
a k body
where
pop [] = ([], S.empty)
pop (c:cs) = (cs, c)
-- Reads the http body and stores it to the specified file, updating the
-- meter as it goes.
httpBodyRetriever :: FilePath -> MeterUpdate -> Response BodyReader -> IO ()
httpBodyRetriever dest meterupdate resp
| responseStatus resp /= ok200 = error $ show $ responseStatus resp
| otherwise = bracket (openBinaryFile dest WriteMode) hClose (go zeroBytesProcessed)
where
reader = responseBody resp
go sofar h = do
b <- reader
if S.null b
then return ()
else do
let sofar' = addBytesProcessed sofar $ S.length b
S.hPut h b
meterupdate sofar'
go sofar' h