Repository tuning parameters can now be passed when initializing a repository for the first time.

* init: Repository tuning parameters can now be passed when initializing a
  repository for the first time. For details, see
  http://git-annex.branchable.com/tuning/
* merge: Refuse to merge changes from a git-annex branch of a repo
  that has been tuned in incompatable ways.

7 files changed, 79 insertions, 6 deletions

diff --git a/Annex/AutoMerge.hs b/Annex/AutoMerge.hs
index 92cccc004..f0f183dfb 100644
--- a/Annex/AutoMerge.hs
+++ b/Annex/AutoMerge.hs
@@ -134,7 +134,7 @@ resolveMerge' (Just us) them u = do
 	
 	makelink key = do
 		let dest = variantFile file key
-		l <- inRepo $ gitAnnexLink dest key
+		l <- calcRepo $ gitAnnexLink dest key
 		replacewithlink dest l
 		stageSymlink dest =<< hashSymlink l
 
diff --git a/Annex/Branch.hs b/Annex/Branch.hs
index 2191ec263..c67270312 100644
--- a/Annex/Branch.hs
+++ b/Annex/Branch.hs
@@ -49,9 +49,11 @@ import Annex.Perms
 import Logs
 import Logs.Transitions
 import Logs.Trust.Pure
+import Logs.Difference.Pure
 import Annex.ReplaceFile
 import qualified Annex.Queue
 import Annex.Branch.Transitions
+import qualified Annex
 
 {- Name of the branch that is used to store git-annex's information. -}
 name :: Git.Ref
@@ -160,6 +162,7 @@ updateTo pairs = do
 			<$> getLocal transitionsLog
 		unless (null branches) $ do
 			showSideAction merge_desc
+			mapM_ checkBranchDifferences refs
 			mergeIndex jl refs
 		let commitrefs = nub $ fullname:refs
 		unlessM (handleTransitions jl localtransitions commitrefs) $ do
@@ -537,3 +540,11 @@ performTransitionsLocked jl ts neednewlocalbranch transitionedrefs = do
 				apply rest hasher file content' trustmap
 			PreserveFile ->
 				apply rest hasher file content trustmap
+
+checkBranchDifferences :: Git.Ref -> Annex ()
+checkBranchDifferences ref = do
+	theirdiffs <- allDifferences . parseDifferencesLog . decodeBS
+		<$> catFile ref differenceLog
+	mydiffs <- annexDifferences <$> Annex.getGitConfig
+	when (theirdiffs /= mydiffs) $
+		error "Remote repository is tuned in incompatable way; cannot be merged with local repository."
diff --git a/Annex/Content.hs b/Annex/Content.hs
index 73f27fd28..a78cf674c 100644
--- a/Annex/Content.hs
+++ b/Annex/Content.hs
@@ -446,7 +446,7 @@ removeAnnex (ContentLock key) = withObjectLoc key remove removedirect
 		removeInodeCache key
 		mapM_ (resetfile cache) fs
 	resetfile cache f = whenM (sameInodeCache f cache) $ do
-		l <- inRepo $ gitAnnexLink f key
+		l <- calcRepo $ gitAnnexLink f key
 		secureErase f
 		replaceFile f $ makeAnnexLink l
 
diff --git a/Annex/Difference.hs b/Annex/Difference.hs
new file mode 100644
index 000000000..cb363e80c
--- /dev/null
+++ b/Annex/Difference.hs
@@ -0,0 +1,60 @@
+{- git-annex repository differences
+ -
+ - Copyright 2015 Joey Hess <id@joeyh.name>
+ -
+ - Licensed under the GNU GPL version 3 or higher.
+ -}
+
+module Annex.Difference (
+	module Types.Difference,
+	setDifferences,
+) where
+
+import Common.Annex
+import Types.Difference
+import Logs.Difference
+import Config
+import Annex.UUID
+import Logs.UUID
+import Annex.Version
+import qualified Annex
+
+import qualified Data.Map as M
+
+-- Differences are only allowed to be tweaked when initializing a
+-- repository for the first time, and then only if there is not another
+-- known uuid. If the repository was cloned from elsewhere, it inherits
+-- the existing settings.
+--
+-- Must be called before setVersion, so it can check if this is the first
+-- time the repository is being initialized.
+setDifferences :: Annex ()
+setDifferences = do
+	u <- getUUID
+	otherds <- either error return 
+		=<< sanityCheckDifferences . allDifferences
+			<$> recordedDifferences
+	ds <- mappend otherds . annexDifferences <$> Annex.getGitConfig
+	when (ds /= mempty) $ do
+		ds'@(Differences l) <- ifM (isJust <$> getVersion)
+			( do
+				oldds <- recordedDifferencesFor u
+				when (ds /= oldds) $
+					warning $ "Cannot change tunable parameters in already initialized repository."
+				return oldds
+			, if otherds == mempty
+				then ifM (not . null . filter (/= u) . M.keys <$> uuidMap)
+					( do
+						warning "Cannot change tunable parameters in a clone of an existing repository."
+						return mempty
+					, return ds
+					)
+				else if otherds /= ds
+					then do
+						warning "The specified tunable parameters differ from values being used in other clones of this repository."
+						return otherds
+					else return ds
+			)
+		forM_ l $ \d ->
+			setConfig (ConfigKey $ differenceConfigKey d) (differenceConfigVal d)
+		recordDifferences ds' u
diff --git a/Annex/Direct.hs b/Annex/Direct.hs
index 06d0342c1..1c733cb55 100644
--- a/Annex/Direct.hs
+++ b/Annex/Direct.hs
@@ -86,7 +86,7 @@ stageDirect = do
 		deletegit file
 	
 	stageannexlink file key = do
-		l <- inRepo $ gitAnnexLink file key
+		l <- calcRepo $ gitAnnexLink file key
 		stageSymlink file =<< hashSymlink l
 		void $ addAssociatedFile key file
 
@@ -131,7 +131,7 @@ addDirect file cache = do
 		return False
 	got (Just (key, _)) = ifM (sameInodeCache file [cache])
 		( do
-			l <- inRepo $ gitAnnexLink file key
+			l <- calcRepo $ gitAnnexLink file key
 			stageSymlink file =<< hashSymlink l
 			addInodeCache key cache
 			void $ addAssociatedFile key file
@@ -282,7 +282,7 @@ updateWorkTree d oldref = do
 	 - with the content. -}
 	movein item makeabs k f = unlessM (goodContent k f) $ do
 		preserveUnannexed item makeabs f oldref
-		l <- inRepo $ gitAnnexLink f k
+		l <- calcRepo $ gitAnnexLink f k
 		replaceFile f $ makeAnnexLink l
 		toDirect k f
 	
diff --git a/Annex/Init.hs b/Annex/Init.hs
index 24c5e18b1..3f27a1172 100644
--- a/Annex/Init.hs
+++ b/Annex/Init.hs
@@ -27,6 +27,7 @@ import Logs.UUID
 import Logs.Trust.Basic
 import Types.TrustLevel
 import Annex.Version
+import Annex.Difference
 import Annex.UUID
 import Config
 import Annex.Direct
@@ -73,6 +74,7 @@ initialize' = do
 	checkCrippledFileSystem
 	unlessM isBare $
 		hookWrite preCommitHook
+	setDifferences
 	setVersion supportedVersion
 	ifM (crippledFileSystem <&&> not <$> isBare)
 		( do
diff --git a/Annex/View.hs b/Annex/View.hs
index 3a9168f6c..315cc7df2 100644
--- a/Annex/View.hs
+++ b/Annex/View.hs
@@ -354,7 +354,7 @@ applyView' mkviewedfile getfilemetadata view = do
 		let metadata' = getfilemetadata f `unionMetaData` metadata
 		forM_ (genviewedfiles f metadata') $ \fv -> do
 			f' <- fromRepo $ fromTopFilePath $ asTopFilePath fv
-			stagesymlink uh hasher f' =<< inRepo (gitAnnexLink f' k)
+			stagesymlink uh hasher f' =<< calcRepo (gitAnnexLink f' k)
 	go uh hasher f Nothing
 		| "." `isPrefixOf` f = do
 			s <- liftIO $ getSymbolicLinkStatus f