dropdead per-remote metadata

Had to refactor pure code into separate modules so it is accessible
inside Annex.Branch.Transitions.

This commit was sponsored by Peter on Patreon.

Logs/MetaData.hs

@@ -20,13 +20,9 @@
  - and so foo currently has no value.
  -
  -
- - Copyright 2014-2018 Joey Hess <id@joeyh.name>
- -
  - Licensed under the GNU GPL version 3 or higher.
  -}
 
-{-# OPTIONS_GHC -fno-warn-orphans #-}
-
 module Logs.MetaData (
 	getCurrentMetaData,
 	getCurrentRemoteMetaData,
@@ -44,19 +40,12 @@ import Annex.VectorClock
 import qualified Annex.Branch
 import qualified Annex
 import Logs
-import Logs.SingleValue
 import Logs.TimeStamp
+import Logs.MetaData.Pure
 
 import qualified Data.Set as S
 import qualified Data.Map as M
 
-instance SingleValueSerializable MetaData where
-	serialize = Types.MetaData.serialize
-	deserialize = Types.MetaData.deserialize
-
-logToCurrentMetaData :: [LogEntry MetaData] -> MetaData
-logToCurrentMetaData = currentMetaData . combineMetaData . map value
-
 {- Go through the log from oldest to newest, and combine it all
  - into a single MetaData representing the current state.
  -
@@ -131,66 +120,6 @@ addRemoteMetaData :: Key -> RemoteMetaData -> Annex ()
 addRemoteMetaData k m = do
 	addMetaData' remoteMetaDataLogFile k (fromRemoteMetaData m)
 
-{- Simplify a log, removing historical values that are no longer
- - needed. 
- -
- - This is not as simple as just making a single log line with the newest
- - state of all metadata. Consider this case:
- -
- - We have:
- -
- - 100 foo +x bar +y
- - 200 foo -x
- -
- - An unmerged remote has:
- -
- - 150 bar -y baz +w
- -
- - If what we have were simplified to "200 foo -x bar +y" then when the line
- - from the remote became available, it would be older than the simplified
- - line, and its change to bar would not take effect. That is wrong.
- -
- - Instead, simplify it to:
- -
- - 100 bar +y
- - 200 foo -x
- -
- - (Note that this ends up with the same number of lines as the
- - unsimplified version, so there's really no point in updating
- - the log to this version. Doing so would only add data to git,
- - with little benefit.)
- -
- - Now merging with the remote yields:
- -
- - 100 bar +y
- - 150 bar -y baz +w
- - 200 foo -x
- -
- - Simplifying again:
- -
- - 150 bar +z baz +w
- - 200 foo -x
- -}
-simplifyLog :: Log MetaData -> Log MetaData
-simplifyLog s = case sl of
-	(newest:rest) -> 
-		let sl' = go [newest] (value newest) rest
-		in if length sl' < length sl
-			then S.fromList sl'
-			else s
-	_ -> s
-  where
-	sl = S.toDescList s
-
-	go c _ [] = c
-	go c newer (l:ls)
-		| unique == emptyMetaData = go c newer ls
-		| otherwise = go (l { value = unique } : c)
-			(unionMetaData unique newer) ls
-	  where
-		older = value l
-		unique = older `differenceMetaData` newer
-
 getMetaDataLog :: Key -> Annex (Log MetaData)
 getMetaDataLog key = do
 	config <- Annex.getGitConfig
@@ -218,3 +147,6 @@ copyMetaData oldkey newkey
 				Annex.Branch.change (metaDataLogFile config newkey) $
 					const $ showLog l
 				return True
+
+readLog :: FilePath -> Annex (Log MetaData)
+readLog = parseLog <$$> Annex.Branch.get