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authorGravatar Joey Hess <joey@kitenet.net>2011-11-12 15:15:57 -0400
committerGravatar Joey Hess <joey@kitenet.net>2011-11-12 15:15:57 -0400
commite9bfa8eaed3ff59a4c0bc8d4d677bc493177807c (patch)
treea15071e2cf3c25e35247940dcb33ca2dbdcd1fe1 /Annex/Branch.hs
parent897bf938f687c1bd9fcfa0097b65708cf0891041 (diff)
avoid unnecessary auto-merge when only changing a file in the branch.
Avoids doing auto-merging in commands that don't need fully current information from the git-annex branch. In particular, git annex add no longer needs to auto-merge. Affected commands: Anything that doesn't look up data from the branch, but does write a change to it. It might seem counterintuitive that we can change a value without first making sure we have the current value. This optimisation works because these two sequences are equivilant: 1. pull from remote 2. union merge 3. read file from branch 4. modify file and write to branch vs. 1. read file from branch 2. modify file and write to branch 3. pull from remote 4. union merge After either sequence, the git-annex branch contains the same logical content for the modified file. (Possibly with lines in a different order or additional old lines of course).
Diffstat (limited to 'Annex/Branch.hs')
-rw-r--r--Annex/Branch.hs25
1 files changed, 20 insertions, 5 deletions
diff --git a/Annex/Branch.hs b/Annex/Branch.hs
index e86a3d7d1..fad818fb0 100644
--- a/Annex/Branch.hs
+++ b/Annex/Branch.hs
@@ -244,9 +244,13 @@ siblingBranches = do
pair l = (head l, last l)
uref (a, _) (b, _) = a == b
-{- Applies a function to modifiy the content of a file. -}
+{- Applies a function to modifiy the content of a file.
+ -
+ - Note that this does not cause the branch to be merged, it only
+ - modifes the current content of the file on the branch.
+ -}
change :: FilePath -> (String -> String) -> Annex ()
-change file a = lockJournal $ get file >>= return . a >>= set file
+change file a = lockJournal $ getStale file >>= return . a >>= set file
{- Records new content of a file into the journal. -}
set :: FilePath -> String -> Annex ()
@@ -259,13 +263,24 @@ set file content = do
-
- Returns an empty string if the file doesn't exist yet. -}
get :: FilePath -> Annex String
-get file = fromcache =<< getCache file
+get = get' False
+
+{- Like get, but does not merge the branch, so the info returned may not
+ - reflect changes in remotes. (Changing the value this returns, and then
+ - merging is always the same as using get, and then changing its value.) -}
+getStale :: FilePath -> Annex String
+getStale = get' True
+
+get' :: Bool -> FilePath -> Annex String
+get' staleok file = fromcache =<< getCache file
where
fromcache (Just content) = return content
fromcache Nothing = fromjournal =<< getJournalFile file
fromjournal (Just content) = cache content
- fromjournal Nothing = withIndexUpdate $
- cache =<< catFile fullname file
+ fromjournal Nothing
+ | staleok = withIndex frombranch
+ | otherwise = withIndexUpdate $ frombranch >>= cache
+ frombranch = catFile fullname file
cache content = do
setCache file content
return content