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new method for merging changes into adjusted branch that avoids unncessary merge conflicts

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Still needs work when there are actual merge conflicts.
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Joey Hess 2016-04-06 15:33:29 -04:00
parent eb9ac8d6d7
commit b9e4e2ba84
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158
Annex/AdjustedBranch.hs
View file

@ -5,6 +5,8 @@
- Licensed under the GNU GPL version 3 or higher.
-}
{-# LANGUAGE BangPatterns #-}
module Annex.AdjustedBranch (
Adjustment(..),
OrigBranch,
@ -40,6 +42,9 @@ import Annex.CatFile
import Annex.Link
import Annex.AutoMerge
import Annex.Content
import Annex.Perms
import Annex.GitOverlay
import Utility.Tmp
import qualified Database.Keys
import qualified Data.Map as M
@ -137,7 +142,7 @@ originalBranch = fmap fromAdjustedBranch <$> inRepo Git.Branch.current
{- Enter an adjusted version of current branch (or, if already in an
- adjusted version of a branch, changes the adjustment of the original
- branch).
t a- branch).
-
- Can fail, if no branch is checked out, or perhaps if staged changes
- conflict with the adjusted branch.
@ -225,80 +230,91 @@ adjustedBranchCommitMessage :: String
adjustedBranchCommitMessage = "git-annex adjusted branch"
{- Update the currently checked out adjusted branch, merging the provided
- branch into it. -}
- branch into it. Note that the provided branch should be a non-adjusted
- branch. -}
updateAdjustedBranch :: Branch -> (OrigBranch, Adjustment) -> Git.Branch.CommitMode -> Annex Bool
updateAdjustedBranch tomerge (origbranch, adj) commitmode = catchBoolIO $
join $ preventCommits $ \commitsprevented -> go commitsprevented =<< (,)
<$> inRepo (Git.Ref.sha tomerge)
<*> inRepo Git.Branch.current
join $ preventCommits $ \commitsprevented ->
go commitsprevented =<< inRepo Git.Branch.current
where
go commitsprevented (Just mergesha, Just currbranch) =
ifM (inRepo $ Git.Branch.changed currbranch mergesha)
go commitsprevented (Just currbranch) =
ifM (inRepo $ Git.Branch.changed currbranch tomerge)
( do
void $ propigateAdjustedCommits' origbranch (adj, currbranch) commitsprevented
adjustedtomerge <- adjust adj mergesha
ifM (inRepo $ Git.Branch.changed currbranch adjustedtomerge)
( return $ do
-- Run after commit lock is dropped.
liftIO $ print ("autoMergeFrom", adjustedtomerge, (Just currbranch))
ifM (autoMergeFrom adjustedtomerge (Just currbranch) commitmode)
( preventCommits $ \_ ->
recommit currbranch mergesha =<< catCommit currbranch
, return False
)
, nochangestomerge
)
(updatedorig, _) <- propigateAdjustedCommits' origbranch (adj, currbranch) commitsprevented
changestomerge updatedorig currbranch
, nochangestomerge
)
go _ _ = return $ return False
nochangestomerge = return $ return True
{- A merge commit has been made on the adjusted branch.
- Now, re-do it, removing the old version of the adjusted branch
- from its history.
{- Since the adjusted branch changes files, merging tomerge
- directly into it would likely result in unncessary merge
- conflicts. To avoid those conflicts, instead merge tomerge into
- updatedorig. The result of the merge can the be
- adjusted to yield the final adjusted branch.
-
- There are two possible scenarios; either some commits
- were made on top of the adjusted branch's adjusting commit,
- or not. Those commits have already been propigated to the
- orig branch, so we can just check if there are commits in the
- orig branch that are not present in tomerge.
- In order to do a merge into a branch that is not checked out,
- set the work tree to a temp directory, and set GIT_DIR
- to another temp directory, in which HEAD contains the
- updatedorig sha. GIT_COMMON_DIR is set to point to the real
- git directory, and so git can read and write objects from there,
- but will use GIT_DIR for HEAD and index.
-
- (Doing the merge this way also lets it run even though the main
- index file is currently locked.)
-}
recommit currbranch mergedsha (Just mergecommit) =
ifM (inRepo $ Git.Branch.changed tomerge origbranch)
( remerge currbranch mergedsha mergecommit
=<< inRepo (Git.Ref.sha origbranch)
, fastforward currbranch mergedsha mergecommit
changestomerge (Just updatedorig) currbranch = do
misctmpdir <- fromRepo gitAnnexTmpMiscDir
void $ createAnnexDirectory misctmpdir
tmpwt <- fromRepo gitAnnexMergeDir
withTmpDirIn misctmpdir "git" $ \tmpgit -> withWorkTreeRelated tmpgit $
withemptydir tmpwt $ withWorkTree tmpwt $ do
liftIO $ writeFile (tmpgit </> "HEAD") (fromRef updatedorig)
showAction $ "Merging into " ++ fromRef (Git.Ref.base origbranch)
ifM (autoMergeFrom tomerge (Just updatedorig) commitmode)
( do
!mergecommit <- liftIO $ extractSha <$> readFile (tmpgit </> "HEAD")
-- This is run after the commit lock is dropped.
return $ postmerge currbranch mergecommit
, return $ return False
)
recommit _ _ Nothing = return False
changestomerge Nothing _ = return $ return False
{- Fast-forward scenario. The mergecommit is changed to a non-merge
- commit, with its parent being the mergedsha.
- The orig branch can simply be pointed at the mergedsha.
withemptydir d a = bracketIO setup cleanup (const a)
where
setup = do
whenM (doesDirectoryExist d) $
removeDirectoryRecursive d
createDirectoryIfMissing True d
cleanup _ = removeDirectoryRecursive d
{- A merge commit has been made between the origbranch and
- tomerge. Update origbranch to point to that commit, adjust
- it to get the new adjusted branch, and check it out.
-
- But, there may be unstaged work tree changes that conflict,
- so the check out is done by making a normal merge of
- the new adjusted branch.
-}
fastforward currbranch mergedsha mergecommit = do
commitsha <- commitAdjustedTree (commitTree mergecommit) mergedsha
inRepo $ Git.Branch.update "fast-forward update of adjusted branch" currbranch commitsha
inRepo $ Git.Branch.update "updating original branch" origbranch mergedsha
postmerge currbranch (Just mergecommit) = do
inRepo $ Git.Branch.update "updating original branch" origbranch mergecommit
adjtree <- adjustTree adj mergecommit
-- Make currbranch be a parent, so that merging
-- this commit will be a fast-forward.
adjmergecommit <- commitAdjustedTree' adjtree mergecommit
[mergecommit, currbranch]
showAction "Merging into adjusted branch"
ifM (autoMergeFrom adjmergecommit (Just currbranch) commitmode)
-- The adjusted branch has a merge commit on top;
-- clean that up and propigate any changes made
-- in that merge to the origbranch.
( do
propigateAdjustedCommits origbranch (adj, currbranch)
return True
{- True merge scenario. -}
remerge currbranch mergedsha mergecommit (Just origsha) = do
-- Update origbranch by reverse adjusting the mergecommit,
-- yielding a merge between orig and tomerge.
treesha <- reverseAdjustedTree origsha adj
-- get 1-parent commit because
-- reverseAdjustedTree does not support merges
=<< commitAdjustedTree (commitTree mergecommit) origsha
revadjcommit <- inRepo $
Git.Branch.commitTree Git.Branch.AutomaticCommit
("Merge branch " ++ fromRef tomerge) [origsha, mergedsha] treesha
inRepo $ Git.Branch.update "updating original branch" origbranch revadjcommit
-- Update currbranch, reusing mergedsha, but making its
-- parent be the updated origbranch.
adjcommit <- commitAdjustedTree' (commitTree mergecommit) revadjcommit [revadjcommit]
inRepo $ Git.Branch.update rebaseOnTopMsg currbranch adjcommit
return True
remerge _ _ _ Nothing = return False
, return False
)
postmerge _ Nothing = return False
{- Check for any commits present on the adjusted branch that have not yet
- been propigated to the orig branch, and propigate them.
@ -308,16 +324,16 @@ updateAdjustedBranch tomerge (origbranch, adj) commitmode = catchBoolIO $
-}
propigateAdjustedCommits :: OrigBranch -> (Adjustment, AdjBranch) -> Annex ()
propigateAdjustedCommits origbranch (adj, currbranch) =
preventCommits $ \commitsprevented -> do
join $ propigateAdjustedCommits' origbranch (adj, currbranch) commitsprevented
preventCommits $ \commitsprevented ->
join $ snd <$> propigateAdjustedCommits' origbranch (adj, currbranch) commitsprevented
{- Returns action which will rebase the adjusted branch on top of the
- updated orig branch. -}
{- Returns sha of updated orig branch, and action which will rebase
- the adjusted branch on top of the updated orig branch. -}
propigateAdjustedCommits'
:: OrigBranch
-> (Adjustment, AdjBranch)
-> CommitsPrevented
-> Annex (Annex ())
-> Annex (Maybe Sha, Annex ())
propigateAdjustedCommits' origbranch (adj, currbranch) _commitsprevented = do
ov <- inRepo $ Git.Ref.sha (Git.Ref.under "refs/heads" origbranch)
case ov of
@ -329,11 +345,13 @@ propigateAdjustedCommits' origbranch (adj, currbranch) _commitsprevented = do
case v of
Left e -> do
warning e
return $ return ()
Right newparent -> return $
rebase currcommit newparent
Nothing -> return $ return ()
Nothing -> return $ return ()
return (Nothing, return ())
Right newparent -> return
( Just newparent
, rebase currcommit newparent
)
Nothing -> return (Nothing, return ())
Nothing -> return (Nothing, return ())
where
newcommits = inRepo $ Git.Branch.changedCommits origbranch currbranch
-- Get commits oldest first, so they can be processed

2
Annex/Branch.hs
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@ -35,7 +35,7 @@ import Control.Concurrent (threadDelay)
import Annex.Common
import Annex.BranchState
import Annex.Journal
import Annex.Index
import Annex.GitOverlay
import qualified Git
import qualified Git.Command
import qualified Git.Ref

2
Annex/Direct.hs
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@ -37,7 +37,7 @@ import Annex.Perms
import Annex.ReplaceFile
import Annex.VariantFile
import Git.Index
import Annex.Index
import Annex.GitOverlay
import Annex.LockFile
import Annex.InodeSentinal

63
Annex/GitOverlay.hs Normal file
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@ -0,0 +1,63 @@
{- Temporarily changing the files git uses.
-
- Copyright 2014-2016 Joey Hess <id@joeyh.name>
-
- Licensed under the GNU GPL version 3 or higher.
-}
module Annex.GitOverlay where
import qualified Control.Exception as E
import Annex.Common
import Git
import Git.Types
import Git.Env
import qualified Annex
{- Runs an action using a different git index file. -}
withIndexFile :: FilePath -> Annex a -> Annex a
withIndexFile f = withAltRepo
(\g -> addGitEnv g "GIT_INDEX_FILE" f)
(\g g' -> g' { gitEnv = gitEnv g })
{- Runs an action using a different git work tree. -}
withWorkTree :: FilePath -> Annex a -> Annex a
withWorkTree d = withAltRepo
(\g -> return $ g { location = modlocation (location g) })
(\g g' -> g' { location = location g })
where
modlocation l@(Local {}) = l { worktree = Just d }
modlocation _ = error "withWorkTree of non-local git repo"
{- Runs an action with the git index file and HEAD, and a few other
- files that are related to the work tree coming from an overlay
- directory other than the usual. This is done by pointing
- GIT_COMMON_DIR at the regular git directory, and GIT_DIR at the
- overlay directory. -}
withWorkTreeRelated :: FilePath -> Annex a -> Annex a
withWorkTreeRelated d = withAltRepo modrepo unmodrepo
where
modrepo g = do
let g' = g { location = modlocation (location g) }
addGitEnv g' "GIT_COMMON_DIR" =<< absPath (localGitDir g)
unmodrepo g g' = g' { gitEnv = gitEnv g, location = location g }
modlocation l@(Local {}) = l { gitdir = d }
modlocation _ = error "withWorkTreeRelated of non-local git repo"
withAltRepo
:: (Repo -> IO Repo)
-- ^ modify Repo
-> (Repo -> Repo -> Repo)
-- ^ undo modifications; first Repo is the original and second
-- is the one after running the action.
-> Annex a
-> Annex a
withAltRepo modrepo unmodrepo a = do
g <- gitRepo
g' <- liftIO $ modrepo g
r <- tryNonAsync $ do
Annex.changeState $ \s -> s { Annex.repo = g' }
a
Annex.changeState $ \s -> s { Annex.repo = unmodrepo g (Annex.repo s) }
either E.throw return r

27
Annex/Index.hs
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@ -1,27 +0,0 @@
{- Using other git index files
-
- Copyright 2014 Joey Hess <id@joeyh.name>
-
- Licensed under the GNU GPL version 3 or higher.
-}
module Annex.Index (withIndexFile) where
import qualified Control.Exception as E
import Annex.Common
import Git.Types
import Git.Env
import qualified Annex
{- Runs an action using a different git index file. -}
withIndexFile :: FilePath -> Annex a -> Annex a
withIndexFile f a = do
g <- gitRepo
g' <- liftIO $ addGitEnv g "GIT_INDEX_FILE" f
r <- tryNonAsync $ do
Annex.changeState $ \s -> s { Annex.repo = g' }
a
Annex.changeState $ \s -> s { Annex.repo = (Annex.repo s) { gitEnv = gitEnv g} }
either E.throw return r

3
Annex/Locations.hs
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@ -291,7 +291,8 @@ gitAnnexFeedStateDir r = addTrailingPathSeparator $ gitAnnexDir r </> "feedstate
gitAnnexFeedState :: Key -> Git.Repo -> FilePath
gitAnnexFeedState k r = gitAnnexFeedStateDir r </> keyFile k
{- .git/annex/merge/ is used for direct mode merges. -}
{- .git/annex/merge/ is used as a empty work tree for direct mode merges and
- merges in adjusted branches. -}
gitAnnexMergeDir :: Git.Repo -> FilePath
gitAnnexMergeDir r = addTrailingPathSeparator $ gitAnnexDir r </> "merge"

2
Annex/View.hs
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@ -23,7 +23,7 @@ import Annex.HashObject
import Git.Types
import Git.FilePath
import Annex.WorkTree
import Annex.Index
import Annex.GitOverlay
import Annex.Link
import Annex.CatFile
import Logs.MetaData

188
doc/design/adjusted_branches.mdwn
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@ -104,67 +104,54 @@ that are merged in, for object add/remove to work as described below.
When merging, there should never be any commits present on the
adjusted/master branch that have not yet been propigated back to the master
branch. If there are any such commits, just propigate them into master before
beginning the merge. There may be staged changes, or changes in the work tree.
branch. If there are any such commits, just propigate them into master
before beginning the merge. There may be staged changes, or changes in the
work tree.
First adjust the new commit:
First, merge origin/master into master. This is done in a temp work
tree and with a temp index, so does not affect the checked out adjusted
branch.
origin/master adjusted/master master
A A
|--------------->A' |
| | |
(Note that the reason this is done, rather than adjusting origin/master
and merging it into the work tree, is that merge conflicts would be very
common with the naive approach, because the adjusted branch often changes
files, and origin/master may change the same files.)
origin/master master adjusted/master
A------------->A- - - ->A'
| |
B
B------------->C
While a fast-forward merge is shown here, other merges work the same way.
There may be merge conflicts; if so they're auto-resolved.
Then, adjust merge commit C, and merge that into adjusted/master.
origin/master master adjusted/master
A------------->A- - - ->A'
| | |
B------------->C- - C'->D'
This merge is done in-worktree, so the work tree gets updated.
There may be more merge conflicts here; they're also auto-resolved.
Now, D' is a merge commit, between A' and C'.
To finish, change that commit so it does not have A' as its parent.
This can be accomplished by propigating the reverse-adjusted D'
back to master, and then adjusting master to yield the final
adjusted/master.
origin/master master adjusted/master
A------------->A
| |
B------------->C
|
|---------->B'
D - - -> D'
Then, merge that into adjusted/master:
origin/master adjusted/master master
A A
|--------------->A' |
| | |
| |
B |
| |
|----------->B'->B''
That merge will take care of updating the work tree.
(What if there is a merge conflict between A' and B'? Normally such a merge
conflict should only affect the work tree/index, so can be resolved without
making a commit, but B'' may end up being made to resolve a merge
conflict.)
Once the merge is done, we have a merge commit B'' on adjusted/master.
To finish, redo that commit so it does not have A' as its parent.
origin/master adjusted/master master
A A
|--------------->A' |
| | |
| |
B
|
|--------------->B''
| |
Finally, update master, by reverse adjusting B''.
origin/master adjusted/master master
A A
|--------------->A' |
| | |
| | |
B |
| |
|--------------->B'' - - - - - - -> B
| |
Notice how similar this is to the commit graph. So, "fast-forward"
Notice how similar this is to the commit graph. Indeed, "fast-forward"
merging the same B commit from origin/master will lead to an identical
sha for B' as the original committer got.
sha for B' as the original committer got!
Since the adjusted/master branch is not present on the remote, if the user
does a `git pull`, it won't merge in changes from origin/master. Which is
@ -180,91 +167,6 @@ between the adjusted work tree and pulled changes. A post-merge hook would
be needed to re-adjust the work tree, and there would be a window where eg,
not present files would appear in the work tree.]
## another merge scenario
Another merge scenario is when there's a new commit C on adjusted/master,
and also a new commit B on origin/master.
Start by adjusting B':
origin/master adjusted/master master
A A
|--------------->A' |
| | |
| C'
B
|
|---------->B'
Then, merge B' into adjusted/master:
origin/master adjusted/master master
A A
|--------------->A' |
| | |
| C'
B |
| |
|----------->B'->M'
Here M' is the correct tree, but it has A' as its grandparent,
which is the adjusted branch commit, so needs to be dropped in order to
get a commit that can be put on master.
We don't want to lose commit C', but it's an adjusted
commit, so needs to be de-adjusted.
origin/master adjusted/master master
A A
|--------------->A' |
| | |
| C'- - - - - - - - > C
B |
| |
|----------->B'->M'
|
Now, we generate a merge commit, between B and C, with known result M'
(so no actual merging done here).
origin/master adjusted/master master
A A
|--------------->A' |
| | |
| C'- - - - - - - - > C
B |
| |
|--------------->M'<-----------------|
|
Finally, update master, by reverse adjusting M'. The resulting commit
on master will also be a merge between B and C.
### avoiding conflicted merge
When merging origin/master with adjusted/master, origin/master is
adjusted first, and then merged into the checked out adjusted/master
branch.
This can lead to merge conflicts, when files in origin/master have
been renamed or modified.
This is because adjusted/master and origin/master (and also its adjusted
form) will both modify a file; the former by eg, unlocking it and
the latter by eg, deleting it.
This may need an out of work-tree merge to resolve. In an empty temp work
tree, merge the de-adjusted form of adjusted/master and origin/master. If
that has (real) merge conflicts, auto-resolve them.
The resulting merge commit can then be adjusted to yield the adjusted
merge commit. The parents of the adjusted merge commit also need to be
adjusted, to be the same as if adjusted(origin/master) was merged into
adjusted/master.
Finally, check out the adjusted merge commit, to update the real working
tree.
## annex object add/remove
When objects are added/removed from the annex, the associated file has to
@ -377,13 +279,16 @@ into adjusted view worktrees.]
will make copies of the content of annexed files, so this would need
to checkout the adjusted branch some other way. Maybe generalize so this
more efficient checkout is available as a git-annex command?
* sync in adjusted branch runs merge in overlay worktree,
but the merge conflict resolution code does not know to use that
worktree.
* sync in adjusted branch can trigger merge conflict detection where
there should be no conflict.
git init a
cd a
git annex init --version=6
touch f
echo hi > f
git annex add f
git annex sync
cd ..
@ -391,6 +296,7 @@ into adjusted view worktrees.]
git clone a b
cd b
git annex init --version=6
git annex get
git annex adjust --unlock
cd ..