fix transfers of key with no associated file

Several places assumed this would not happen, and when the AssociatedFile
was Nothing, did nothing.

As part of this, preferred content checks pass the Key around.

Note that checkMatcher is sometimes now called with Just Key and Just File.
It currently constructs a FileMatcher, ignoring the Key. However, if it
constructed a FileKeyMatcher, which contained both, then it might be
possible to speed up parts of Limit, which currently call the somewhat
expensive lookupFileKey to get the Key.

I have not made this optimisation yet, because I am not sure if the key is
always the same. Will need some significant checking to satisfy myself
that's the case..

Assistant/Drop.hs

@@ -19,7 +19,6 @@ import RunCommand
 {- Drop from local and/or remote when allowed by the preferred content and
  - numcopies settings. -}
 handleDrops :: Reason -> Bool -> Key -> AssociatedFile -> Maybe Remote -> Assistant ()
-handleDrops _ _ _ Nothing _ = noop
 handleDrops reason fromhere key f knownpresentremote = do
 	syncrs <- syncDataRemotes <$> getDaemonStatus
 	locs <- liftAnnex $ loggedLocations key

Assistant/Threads/TransferScanner.hs

@@ -164,9 +164,9 @@ expensiveScan urlrenderer rs = unless onlyweb $ batch <~> do
 			let slocs = S.fromList locs
 			let use a = return $ mapMaybe (a key slocs) syncrs
 			ts <- if present
-				then filterM (wantSend True (Just f) . Remote.uuid . fst)
+				then filterM (wantSend True (Just key) (Just f) . Remote.uuid . fst)
 					=<< use (genTransfer Upload False)
-				else ifM (wantGet True $ Just f)
+				else ifM (wantGet True (Just key) (Just f))
 					( use (genTransfer Download True) , return [] )
 			let unwanted' = S.difference unwanted slocs
 			return (unwanted', ts)

Assistant/TransferQueue.hs

@@ -58,7 +58,7 @@ queueTransfers = queueTransfersMatching (const True)
  - condition. Honors preferred content settings. -}
 queueTransfersMatching :: (UUID -> Bool) -> Reason -> Schedule -> Key -> AssociatedFile -> Direction -> Assistant ()
 queueTransfersMatching matching reason schedule k f direction
-	| direction == Download = whenM (liftAnnex $ wantGet True f) go
+	| direction == Download = whenM (liftAnnex $ wantGet True (Just k) f) go
 	| otherwise = go
   where
 	go = do
@@ -82,7 +82,7 @@ queueTransfersMatching matching reason schedule k f direction
 		 - already have it. -}
 		| otherwise = do
 			s <- locs
-			filterM (wantSend True f . Remote.uuid) $
+			filterM (wantSend True (Just k) f . Remote.uuid) $
 				filter (\r -> not (inset s r || Remote.readonly r)) rs
 	  where
 	  	locs = S.fromList <$> Remote.keyLocations k

Assistant/TransferSlots.hs

@@ -103,8 +103,8 @@ runTransferThread' program batchmaker d run = go
 {- By the time this is called, the daemonstatus's currentTransfers map should
  - already have been updated to include the transfer. -}
 genTransfer :: Transfer -> TransferInfo -> TransferGenerator
-genTransfer t info = case (transferRemote info, associatedFile info) of
-	(Just remote, Just file) 
+genTransfer t info = case transferRemote info of
+	Just remote 
 		| Git.repoIsLocalUnknown (Remote.repo remote) -> do
 			-- optimisation for removable drives not plugged in
 			liftAnnex $ recordFailedTransfer t info
@@ -114,7 +114,7 @@ genTransfer t info = case (transferRemote info, associatedFile info) of
 			( do
 				debug [ "Transferring:" , describeTransfer t info ]
 				notifyTransfer
-				return $ Just (t, info, go remote file)
+				return $ Just (t, info, go remote)
 			, do
 				debug [ "Skipping unnecessary transfer:",
 					describeTransfer t info ]
@@ -149,10 +149,12 @@ genTransfer t info = case (transferRemote info, associatedFile info) of
 	 - usual cleanup. However, first check if something else is
 	 - running the transfer, to avoid removing active transfers.
 	 -}
-	go remote file transferrer = ifM (liftIO $ performTransfer transferrer t $ associatedFile info)
+	go remote transferrer = ifM (liftIO $ performTransfer transferrer t $ associatedFile info)
 		( do
-			void $ addAlert $ makeAlertFiller True $
-				transferFileAlert direction True file
+			maybe noop
+				(void . addAlert . makeAlertFiller True 
+					. transferFileAlert direction True)
+				(associatedFile info)
 			unless isdownload $
 				handleDrops
 					("object uploaded to " ++ show remote)
@@ -188,11 +190,11 @@ genTransfer t info = case (transferRemote info, associatedFile info) of
 shouldTransfer :: Transfer -> TransferInfo -> Annex Bool
 shouldTransfer t info
 	| transferDirection t == Download =
-		(not <$> inAnnex key) <&&> wantGet True file
+		(not <$> inAnnex key) <&&> wantGet True (Just key) file
 	| transferDirection t == Upload = case transferRemote info of
 		Nothing -> return False
 		Just r -> notinremote r
-			<&&> wantSend True file (Remote.uuid r)
+			<&&> wantSend True (Just key) file (Remote.uuid r)
 	| otherwise = return False
   where
 	key = transferKey t