sync --content: New option that makes the content of annexed files be transferred.

Similar to the assistant, this honors any configured preferred content
expressions.

I am not entirely happpy with the implementation. It would be nicer if
the seek function returned a list of actions which included the individual
file gets and copies and drops, rather than the current list of calls to
syncContent. This would allow getting rid of the somewhat reundant display
of "sync file [ok|failed]" after the get/put display.

But, do that, withFilesInGit would need to somehow be able to construct
such a mixed action list. And it would be less efficient than the current
implementation, which is able to reuse several values between eg get and
drop.

Note that currently this does not try to satisfy numcopies when
getting/putting files (numcopies are of course checked when dropping
files!) This makes it like the assistant, and unlike get --auto
and copy --auto, which do duplicate files when numcopies is not yet
satisfied. I don't know if this is the right decision; it only seemed to
make sense to have this parallel the assistant as far as possible to start
with, since I know the assistant works.

This commit was sponsored by Øyvind Andersen Holm.

Assistant/Drop.hs

@@ -5,24 +5,15 @@
  - Licensed under the GNU GPL version 3 or higher.
  -}
 
-module Assistant.Drop where
+module Assistant.Drop (
+	handleDrops,
+	handleDropsFrom,
+) where
 
 import Assistant.Common
 import Assistant.DaemonStatus
+import Annex.Drop (handleDropsFrom, Reason)
 import Logs.Location
-import Logs.Trust
-import Types.Remote (uuid)
-import qualified Remote
-import qualified Command.Drop
-import Command
-import Annex.Wanted
-import Annex.Exception
-import Config
-import Annex.Content.Direct
-
-import qualified Data.Set as S
-
-type Reason = String
 
 {- Drop from local and/or remote when allowed by the preferred content and
  - numcopies settings. -}
@@ -31,82 +22,4 @@ handleDrops _ _ _ Nothing _ = noop
 handleDrops reason fromhere key f knownpresentremote = do
 	syncrs <- syncDataRemotes <$> getDaemonStatus
 	locs <- liftAnnex $ loggedLocations key
-	handleDropsFrom locs syncrs reason fromhere key f knownpresentremote
-
-{- The UUIDs are ones where the content is believed to be present.
- - The Remote list can include other remotes that do not have the content;
- - only ones that match the UUIDs will be dropped from.
- - If allowed to drop fromhere, that drop will be tried first.
- -
- - In direct mode, all associated files are checked, and only if all
- - of them are unwanted are they dropped.
- -}
-handleDropsFrom :: [UUID] -> [Remote] -> Reason -> Bool -> Key -> AssociatedFile -> Maybe Remote -> Assistant ()
-handleDropsFrom _ _ _ _ _ Nothing _ = noop
-handleDropsFrom locs rs reason fromhere key (Just afile) knownpresentremote = do
-	fs <- liftAnnex $ ifM isDirect
-		( do
-			l <- associatedFilesRelative key
-			if null l
-				then return [afile]
-				else return l
-		, return [afile]
-		)
-	n <- getcopies fs
-	if fromhere && checkcopies n Nothing
-		then go fs rs =<< dropl fs n
-		else go fs rs n
-  where
-	getcopies fs = liftAnnex $ do
-		(untrusted, have) <- trustPartition UnTrusted locs
-		numcopies <- maximum <$> mapM (getNumCopies <=< numCopies) fs
-		return (length have, numcopies, S.fromList untrusted)
-
-	{- Check that we have enough copies still to drop the content.
-	 - When the remote being dropped from is untrusted, it was not
-	 - counted as a copy, so having only numcopies suffices. Otherwise,
-	 - we need more than numcopies to safely drop. -}
-	checkcopies (have, numcopies, _untrusted) Nothing = have > numcopies
-	checkcopies (have, numcopies, untrusted) (Just u)
-		| S.member u untrusted = have >= numcopies
-		| otherwise = have > numcopies
-	
-	decrcopies (have, numcopies, untrusted) Nothing =
-		(have - 1, numcopies, untrusted)
-	decrcopies v@(_have, _numcopies, untrusted) (Just u)
-		| S.member u untrusted = v
-		| otherwise = decrcopies v Nothing
-
-	go _ [] _ = noop
-	go fs (r:rest) n
-		| uuid r `S.notMember` slocs = go fs rest n
-		| checkcopies n (Just $ Remote.uuid r) =
-			dropr fs r n >>= go fs rest
-		| otherwise = noop
-
-	checkdrop fs n@(have, numcopies, _untrusted) u a =
-		ifM (liftAnnex $ allM (wantDrop True u . Just) fs)
-			( ifM (liftAnnex $ safely $ doCommand $ a (Just numcopies))
-				( do
-					debug
-						[ "dropped"
-						, afile
-						, "(from " ++ maybe "here" show u ++ ")"
-						, "(copies now " ++ show (have - 1) ++ ")"
-						, ": " ++ reason
-						]
-					return $ decrcopies n u
-				, return n
-				)
-			, return n
-			)
-
-	dropl fs n = checkdrop fs n Nothing $ \numcopies ->
-		Command.Drop.startLocal (Just afile) numcopies key knownpresentremote
-
-	dropr fs r n  = checkdrop fs n (Just $ Remote.uuid r) $ \numcopies ->
-		Command.Drop.startRemote (Just afile) numcopies key r
-
-	safely a = either (const False) id <$> tryAnnex a
-
-	slocs = S.fromList locs
+	liftAnnex $ handleDropsFrom locs syncrs reason fromhere key f knownpresentremote