S3: finish converting to aws library

Implemented the Retriever.

Unfortunately, it is a fileRetriever and not a byteRetriever.
It should be possible to convert this to a byteRetiever, but I got stuck:
The conduit sink needs to process individual chunks, but a byteRetriever
needs to pass a single L.ByteString to its callback for processing. I
looked into using unsafeInerlaveIO to build up the bytestring lazily,
but the sink is already operating under conduit's inversion of control,
and does not run directly in IO anyway.

On the plus side, no more memory leak..

Remote/S3.hs

@@ -15,6 +15,7 @@ import qualified Aws.S3 as S3
 import qualified Data.Text as T
 import qualified Data.Text.Encoding as T
 import qualified Data.ByteString.Lazy as L
+import qualified Data.ByteString as S
 import qualified Data.Map as M
 import Data.Char
 import Network.Socket (HostName)
@@ -23,6 +24,7 @@ import Network.HTTP.Client (defaultManagerSettings, managerResponseTimeout, resp
 import Network.HTTP.Types
 import Control.Monad.Trans.Resource
 import Control.Monad.Catch
+import Data.Conduit
 
 import Common.Annex
 import Types.Remote
@@ -36,6 +38,7 @@ import qualified Remote.Helper.AWS as AWS
 import Creds
 import Annex.UUID
 import Logs.Web
+import Utility.Metered
 
 type BucketName = String
 
@@ -145,14 +148,27 @@ store r h = fileStorer $ \k f p -> do
 	
 	return True
 
+{- Implemented as a fileRetriever, that uses conduit to stream the chunks
+ - out to the file. Would be better to implement a byteRetriever, but
+ - that is difficult. -}
 retrieve :: S3Handle -> Retriever
-retrieve _h = error "TODO"
-	{- 
-	resourcePrepare (const $ s3Action r False) $ \(conn, bucket) ->
-	byteRetriever $ \k sink ->
-		liftIO (getObject conn $ bucketKey r bucket k)
-			>>= either s3Error (sink . obj_data)
-	-}
+retrieve h = fileRetriever $ \f k p -> liftIO $ runResourceT $ do
+	(fr, fh) <- allocate (openFile f WriteMode) hClose
+	let req = S3.getObject (hBucket h) (hBucketObject h k)
+	S3.GetObjectResponse { S3.gorResponse = rsp } <- sendS3Handle' h req
+	responseBody rsp $$+- sinkprogressfile fh p zeroBytesProcessed
+	release fr
+  where
+	sinkprogressfile fh meterupdate sofar = do
+		mbs <- await
+		case mbs of
+			Nothing -> return ()
+			Just bs -> do
+				let sofar' = sofar -- addBytesProcessed $ S.length bs
+				liftIO $ do
+					void $ meterupdate sofar'
+					S.hPut fh bs
+				sinkprogressfile fh meterupdate sofar'
 
 retrieveCheap :: Key -> FilePath -> Annex Bool
 retrieveCheap _ _ = return False
@@ -289,9 +305,14 @@ sendS3Handle
 	=> S3Handle 
 	-> req
 	-> Annex res
-sendS3Handle h = liftIO . runResourceT . call
-  where
-	call = AWS.pureAws (hawscfg h) (hs3cfg h) (hmanager h)
+sendS3Handle h r = liftIO $ runResourceT $ sendS3Handle' h r
+
+sendS3Handle'
+	:: (AWS.Transaction r a, AWS.ServiceConfiguration r ~ S3.S3Configuration)
+	=> S3Handle
+	-> r
+	-> ResourceT IO a
+sendS3Handle' h = AWS.pureAws (hawscfg h) (hs3cfg h) (hmanager h)
 
 withS3Handle :: RemoteConfig -> UUID -> (S3Handle -> Annex a) -> Annex a
 withS3Handle c u a = do