improve handling of unmerged git-annex branches in readonly repo

git-annex info was displaying a message that didn't make sense in
context.

In calcRepoSizes, it seems better to return the information from the
git-annex branch, rather than giving up. Especially since balanced
preferred content uses it, and we can't just give up evaluating a
preferred content expression if git-annex is to be usable in such a
readonly repo.

Commit 6d7ecd9e5d nobly wanted git-annex
to behave the same with such unmerged branches as it does when it can
merge them. But for the purposes of preferred content, it seems to me
there's a sense that such an unmerged branch is the same as a remote we
have not pulled from. The balanced preferred content will either way
operate under outdated information, and so make not the best choices.

Annex/Branch.hs

@@ -1,6 +1,6 @@
 {- management of the git-annex branch
  -
- - Copyright 2011-2023 Joey Hess <id@joeyh.name>
+ - Copyright 2011-2024 Joey Hess <id@joeyh.name>
  -
  - Licensed under the GNU AGPL version 3 or higher.
  -}
@@ -36,6 +36,7 @@ module Annex.Branch (
 	performTransitions,
 	withIndex,
 	precache,
+	UnmergedBranches(..),
 	overBranchFileContents,
 	updatedFromTree,
 ) where
@@ -977,6 +978,15 @@ prepRememberTreeish treeish graftpoint parent = do
 	inRepo $ Git.Branch.commitTree cmode
 		["graft cleanup"] [c] origtree
 
+{- UnmergedBranches is used to indicate when a value was calculated in a
+ - read-only repository that has other git-annex branches that have not
+ - been merged in. The value does not include information from those
+ - branches.
+ -}
+data UnmergedBranches t
+	= UnmergedBranches t 
+	| NoUnmergedBranches t
+
 {- Runs an action on the content of selected files from the branch.
  - This is much faster than reading the content of each file in turn,
  - because it lets git cat-file stream content without blocking.
@@ -989,20 +999,17 @@ prepRememberTreeish treeish graftpoint parent = do
  - with different content. This happens rarely, only when the journal
  - contains additional information, and the last version of the
  - file it returns is the most current one.
- -
- - In a read-only repository that has other git-annex branches that have
- - not been merged in, returns Nothing, because it's not possible to
- - efficiently handle that.
  -}
 overBranchFileContents
 	:: (RawFilePath -> Maybe v)
 	-> (Annex (Maybe (v, RawFilePath, Maybe L.ByteString)) -> Annex a)
-	-> Annex (Maybe a)
+	-> Annex (UnmergedBranches a)
 overBranchFileContents select go = do
 	st <- update
-	if not (null (unmergedRefs st))
-		then return Nothing
-		else Just <$> overBranchFileContents' select go st
+	v <- overBranchFileContents' select go st
+	return $ if not (null (unmergedRefs st))
+		then UnmergedBranches v
+		else NoUnmergedBranches v
 
 overBranchFileContents'
 	:: (RawFilePath -> Maybe v)

Annex/RepoSize.hs

@@ -8,6 +8,7 @@
 module Annex.RepoSize where
 
 import Annex.Common
+import Annex.Branch (UnmergedBranches(..))
 import Types.RepoSize
 import Logs.Location
 import Logs.UUID
@@ -24,10 +25,12 @@ calcRepoSizes :: Annex (M.Map UUID RepoSize)
 calcRepoSizes = do
 	knownuuids <- M.keys <$> uuidDescMap
 	let startmap = M.fromList $ map (\u -> (u, RepoSize 0)) knownuuids
-	overLocationLogs startmap $ \k locs m ->
-		return $ 
-			let sz = fromMaybe 0 $ fromKey keySize k
-			in foldl' (flip $ M.alter $ addksz sz) m locs
+	overLocationLogs startmap accum >>= \case
+		UnmergedBranches m -> return m
+		NoUnmergedBranches m -> return m
   where
 	addksz ksz (Just (RepoSize sz)) = Just $ RepoSize $ sz + ksz
 	addksz ksz Nothing = Just $ RepoSize ksz
+	accum k locs m = return $ 
+		let sz = fromMaybe 0 $ fromKey keySize k
+		in foldl' (flip $ M.alter $ addksz sz) m locs

CmdLine/Seek.hs

@@ -287,6 +287,9 @@ withKeyOptions' ko auto mkkeyaction fallbackaction worktreeitems = do
 		overLocationLogs' () 
 			(\reader cont -> checktimelimit (discard reader) cont) 
 			(\k _ () -> keyaction Nothing (SeekInput [], k, mkActionItem k))
+			>>= \case
+				Annex.Branch.NoUnmergedBranches () -> return ()
+				Annex.Branch.UnmergedBranches () -> giveup "This repository is read-only, and there are unmerged git-annex branches, which prevents operating on all keys. (Set annex.merge-annex-branches to false to ignore the unmerged git-annex branches.)"
 
 	runkeyaction getks = do
 		keyaction <- mkkeyaction

Command/Info.hs

@@ -33,6 +33,7 @@ import Annex.WorkTree
 import Logs.UUID
 import Logs.Trust
 import Logs.Location
+import Annex.Branch (UnmergedBranches(..))
 import Annex.NumCopies
 import Git.Config (boolConfig)
 import qualified Git.LsTree as LsTree
@@ -640,7 +641,7 @@ cachedAllRepoData = do
 		Just _ -> return s
 		Nothing -> do
 			matcher <- lift getKeyOnlyMatcher
-			!(d, rd) <- lift $ overLocationLogs (emptyKeyInfo, mempty) $ \k locs (d, rd) -> do
+			r <- lift $ overLocationLogs (emptyKeyInfo, mempty) $ \k locs (d, rd) -> do
 				ifM (matchOnKey matcher k)
 					( do
 						alivelocs <- snd
@@ -650,9 +651,14 @@ cachedAllRepoData = do
 						return (d', rd')
 					, return (d, rd)
 					)
-			let s' = s { allRepoData = Just d, repoData = rd }
-			put s'
-			return s'
+			case r of
+				NoUnmergedBranches (!(d, rd)) -> do
+					let s' = s { allRepoData = Just d, repoData = rd }
+					put s'
+					return s'
+				UnmergedBranches _ -> do
+					lift $ warning "This repository is read-only, and there are unmerged git-annex branches. Information from those branches is not included here."
+					return s
   where
 	accumrepodata k = M.alter (Just . addKey k . fromMaybe emptyKeyInfo)
 

Database/ImportFeed.hs

@@ -188,8 +188,8 @@ updateFromLog db@(ImportFeedDbHandle h) (oldtree, currtree)
 	-- is faster than diffing from the empty tree
 	-- and looking up every log file.
 	scanbranch = Annex.Branch.overBranchFileContents toscan goscan >>= \case
-		Just () -> return ()
-		Nothing -> scandiff
+		Annex.Branch.NoUnmergedBranches () -> return ()
+		Annex.Branch.UnmergedBranches () -> scandiff
 	
 	toscan f
 		| isUrlLog f = Just ()

Limit.hs

@@ -600,10 +600,12 @@ limitFullyBalanced mu getgroupmap groupname = Right $ MatchFiles
 		maxsizes <- getMaxSizes
 		-- XXX do not calc this every time!
 		sizemap <- calcRepoSizes
+		let keysize = fromMaybe 0 (fromKey keySize key)
 		let hasspace u = case (M.lookup u maxsizes, M.lookup u sizemap) of
 			(Just (MaxSize maxsize), Just (RepoSize reposize)) ->
-				reposize + fromMaybe 0 (fromKey keySize key) 
-					<= maxsize
+				if maybe False (`S.member` notpresent) mu
+					then reposize <= maxsize
+					else reposize + keysize <= maxsize
 			_ -> True
 		let candidates = S.filter hasspace groupmembers
 		return $ if S.null candidates

Logs/Location.hs

@@ -219,14 +219,14 @@ loggedKeysFor' u = loggedKeys' isthere
 		return there
 
 {- This is much faster than loggedKeys. -}
-overLocationLogs :: v -> (Key -> [UUID] -> v -> Annex v) -> Annex v
+overLocationLogs :: v -> (Key -> [UUID] -> v -> Annex v) -> Annex (Annex.Branch.UnmergedBranches v)
 overLocationLogs v = overLocationLogs' v (flip const)
 
 overLocationLogs'
 	 :: v 
 	-> (Annex (Maybe (Key, RawFilePath, Maybe L.ByteString)) -> Annex v -> Annex v)
         -> (Key -> [UUID] -> v -> Annex v)
-        -> Annex v
+        -> Annex (Annex.Branch.UnmergedBranches v)
 overLocationLogs' iv discarder keyaction = do
 	config <- Annex.getGitConfig
 	clusters <- getClusters
@@ -245,9 +245,7 @@ overLocationLogs' iv discarder keyaction = do
 				)
 		Nothing -> return v
 
-	Annex.Branch.overBranchFileContents getk (go iv) >>= \case
-		Just r -> return r
-		Nothing -> giveup "This repository is read-only, and there are unmerged git-annex branches, which prevents operating on all keys. (Set annex.merge-annex-branches to false to ignore the unmerged git-annex branches.)"
+	Annex.Branch.overBranchFileContents getk (go iv)
 
 -- Cannot import Logs.Cluster due to a cycle.
 -- Annex.clusters gets populated when starting up git-annex.