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..

1 files changed, 29 insertions, 19 deletions

diff --git a/Annex/Drop.hs b/Annex/Drop.hs
index 09ca822a3..61b0cf9e1 100644
--- a/Annex/Drop.hs
+++ b/Annex/Drop.hs
@@ -11,6 +11,7 @@ import Common.Annex
 import Logs.Trust
 import Config.NumCopies
 import Types.Remote (uuid)
+import Types.Key (key2file)
 import qualified Remote
 import qualified Command.Drop
 import Command
@@ -43,15 +44,14 @@ type Reason = String
  - or commandAction.
  -}
 handleDropsFrom :: [UUID] -> [Remote] -> Reason -> Bool -> Key -> AssociatedFile -> Maybe Remote -> CommandActionRunner -> Annex ()
-handleDropsFrom _ _ _ _ _ Nothing _ _ = noop
-handleDropsFrom locs rs reason fromhere key (Just afile) knownpresentremote runner = do
+handleDropsFrom locs rs reason fromhere key afile knownpresentremote runner = do
 	fs <- ifM isDirect
 		( do
 			l <- associatedFilesRelative key
 			if null l
-				then return [afile]
+				then return $ maybe [] (:[]) afile
 				else return l
-		, return [afile]
+		, return $ maybe [] (:[]) afile
 		)
 	n <- getcopies fs
 	if fromhere && checkcopies n Nothing
@@ -60,7 +60,9 @@ handleDropsFrom locs rs reason fromhere key (Just afile) knownpresentremote runn
   where
 	getcopies fs = do
 		(untrusted, have) <- trustPartition UnTrusted locs
-		numcopies <- maximum <$> mapM getFileNumCopies fs
+		numcopies <- if null fs
+			then getNumCopies
+			else maximum <$> mapM getFileNumCopies fs
 		return (NumCopies (length have), numcopies, S.fromList untrusted)
 
 	{- Check that we have enough copies still to drop the content.
@@ -85,28 +87,36 @@ handleDropsFrom locs rs reason fromhere key (Just afile) knownpresentremote runn
 			dropr fs r n >>= go fs rest
 		| otherwise = noop
 
-	checkdrop fs n@(have, numcopies, _untrusted) u a =
-		ifM (allM (wantDrop True u . Just) fs)
-			( ifM (safely $ runner $ a numcopies)
-				( do
-					liftIO $ debugM "drop" $ unwords
-						[ "dropped"
-						, afile
-						, "(from " ++ maybe "here" show u ++ ")"
-						, "(copies now " ++ show (fromNumCopies have - 1) ++ ")"
-						, ": " ++ reason
-						]
-					return $ decrcopies n u
+	checkdrop fs n u a
+		| null fs = check $ -- no associated files; unused content
+			wantDrop True u (Just key) Nothing
+		| otherwise = check $
+			allM (wantDrop True u (Just key) . Just) fs
+		where
+			check c = ifM c
+				( dodrop n u a
 				, return n
 				)
+
+	dodrop n@(have, numcopies, _untrusted) u a = 
+		ifM (safely $ runner $ a numcopies)
+			( do
+				liftIO $ debugM "drop" $ unwords
+					[ "dropped"
+					, fromMaybe (key2file key) afile
+					, "(from " ++ maybe "here" show u ++ ")"
+					, "(copies now " ++ show (fromNumCopies have - 1) ++ ")"
+					, ": " ++ reason
+					]
+				return $ decrcopies n u
 			, return n
 			)
 
 	dropl fs n = checkdrop fs n Nothing $ \numcopies ->
-		Command.Drop.startLocal (Just afile) numcopies key knownpresentremote
+		Command.Drop.startLocal afile numcopies key knownpresentremote
 
 	dropr fs r n  = checkdrop fs n (Just $ Remote.uuid r) $ \numcopies ->
-		Command.Drop.startRemote (Just afile) numcopies key r
+		Command.Drop.startRemote afile numcopies key r
 
 	slocs = S.fromList locs