git-annex/Git/Branch.hs
Joey Hess 03932212ec Avoid using git commit in direct mode, since in some situations it will read the full contents of files in the tree.
The assistant's commit code also always avoids git commit, for simplicity.
Indirect mode sync still does a git commit -a to catch unstaged changes.

Note that this means that direct mode sync no longer runs the pre-commit
hook or any other hooks git commit might call. The git annex pre-commit
hook action for direct mode is however explicitly run. (The assistant
already ran git commit with hooks disabled, so no change there.)
2013-12-01 13:59:45 -04:00

153 lines
4.3 KiB
Haskell

{- git branch stuff
-
- Copyright 2011 Joey Hess <joey@kitenet.net>
-
- Licensed under the GNU GPL version 3 or higher.
-}
{-# LANGUAGE BangPatterns #-}
module Git.Branch where
import Common
import Git
import Git.Sha
import Git.Command
import qualified Git.Ref
{- The currently checked out branch.
-
- In a just initialized git repo before the first commit,
- symbolic-ref will show the master branch, even though that
- branch is not created yet. So, this also looks at show-ref HEAD
- to double-check.
-}
current :: Repo -> IO (Maybe Git.Ref)
current r = do
v <- currentUnsafe r
case v of
Nothing -> return Nothing
Just branch ->
ifM (null <$> pipeReadStrict [Param "show-ref", Param $ show branch] r)
( return Nothing
, return v
)
{- The current branch, which may not really exist yet. -}
currentUnsafe :: Repo -> IO (Maybe Git.Ref)
currentUnsafe r = parse . firstLine
<$> pipeReadStrict [Param "symbolic-ref", Param $ show Git.Ref.headRef] r
where
parse l
| null l = Nothing
| otherwise = Just $ Git.Ref l
{- Checks if the second branch has any commits not present on the first
- branch. -}
changed :: Branch -> Branch -> Repo -> IO Bool
changed origbranch newbranch repo
| origbranch == newbranch = return False
| otherwise = not . null <$> diffs
where
diffs = pipeReadStrict
[ Param "log"
, Param (show origbranch ++ ".." ++ show newbranch)
, Params "--oneline -n1"
] repo
{- Given a set of refs that are all known to have commits not
- on the branch, tries to update the branch by a fast-forward.
-
- In order for that to be possible, one of the refs must contain
- every commit present in all the other refs.
-}
fastForward :: Branch -> [Ref] -> Repo -> IO Bool
fastForward _ [] _ = return True
fastForward branch (first:rest) repo =
-- First, check that the branch does not contain any
-- new commits that are not in the first ref. If it does,
-- cannot fast-forward.
ifM (changed first branch repo)
( no_ff
, maybe no_ff do_ff =<< findbest first rest
)
where
no_ff = return False
do_ff to = do
run [Param "update-ref", Param $ show branch, Param $ show to] repo
return True
findbest c [] = return $ Just c
findbest c (r:rs)
| c == r = findbest c rs
| otherwise = do
better <- changed c r repo
worse <- changed r c repo
case (better, worse) of
(True, True) -> return Nothing -- divergent fail
(True, False) -> findbest r rs -- better
(False, True) -> findbest c rs -- worse
(False, False) -> findbest c rs -- same
{- Commits the index into the specified branch (or other ref),
- with the specified parent refs, and returns the committed sha.
-
- Without allowempy set, avoids making a commit if there is exactly
- one parent, and it has the same tree that would be committed.
-
- Unlike git-commit, does not run any hooks, or examine the work tree
- in any way.
-}
commit :: Bool -> String -> Branch -> [Ref] -> Repo -> IO (Maybe Sha)
commit allowempty message branch parentrefs repo = do
tree <- getSha "write-tree" $
pipeReadStrict [Param "write-tree"] repo
ifM (cancommit tree)
( do
sha <- getSha "commit-tree" $ pipeWriteRead
(map Param $ ["commit-tree", show tree] ++ ps)
(Just $ flip hPutStr message) repo
update branch sha repo
return $ Just sha
, return Nothing
)
where
ps = concatMap (\r -> ["-p", show r]) parentrefs
cancommit tree
| allowempty = return True
| otherwise = case parentrefs of
[p] -> maybe False (tree /=) <$> Git.Ref.tree p repo
_ -> return True
commitAlways :: String -> Branch -> [Ref] -> Repo -> IO Sha
commitAlways message branch parentrefs repo = fromJust
<$> commit True message branch parentrefs repo
{- A leading + makes git-push force pushing a branch. -}
forcePush :: String -> String
forcePush b = "+" ++ b
{- Updates a branch (or other ref) to a new Sha. -}
update :: Branch -> Sha -> Repo -> IO ()
update branch sha = run
[ Param "update-ref"
, Param $ show branch
, Param $ show sha
]
{- Checks out a branch, creating it if necessary. -}
checkout :: Branch -> Repo -> IO ()
checkout branch = run
[ Param "checkout"
, Param "-q"
, Param "-B"
, Param $ show $ Git.Ref.base branch
]
{- Removes a branch. -}
delete :: Branch -> Repo -> IO ()
delete branch = run
[ Param "branch"
, Param "-q"
, Param "-D"
, Param $ show $ Git.Ref.base branch
]