git-annex/Annex/AdjustedBranch.hs
2016-03-31 12:27:48 -04:00

363 lines
12 KiB
Haskell

{- adjusted branch
-
- Copyright 2016 Joey Hess <id@joeyh.name>
-
- Licensed under the GNU GPL version 3 or higher.
-}
module Annex.AdjustedBranch (
Adjustment(..),
OrigBranch,
AdjBranch,
originalToAdjusted,
adjustedToOriginal,
fromAdjustedBranch,
getAdjustment,
enterAdjustedBranch,
adjustToCrippledFileSystem,
updateAdjustedBranch,
propigateAdjustedCommits,
) where
import Annex.Common
import qualified Annex
import Git
import Git.Types
import qualified Git.Branch
import qualified Git.Ref
import qualified Git.Command
import qualified Git.Tree
import qualified Git.DiffTree
import Git.Tree (TreeItem(..))
import Git.Sha
import Git.Env
import Git.Index
import Git.FilePath
import qualified Git.LockFile
import Annex.CatFile
import Annex.Link
import Annex.AutoMerge
import Annex.Content
import qualified Database.Keys
import qualified Data.Map as M
data Adjustment
= UnlockAdjustment
| LockAdjustment
| HideMissingAdjustment
| ShowMissingAdjustment
deriving (Show, Eq)
reverseAdjustment :: Adjustment -> Adjustment
reverseAdjustment UnlockAdjustment = LockAdjustment
reverseAdjustment LockAdjustment = UnlockAdjustment
reverseAdjustment HideMissingAdjustment = ShowMissingAdjustment
reverseAdjustment ShowMissingAdjustment = HideMissingAdjustment
{- How to perform various adjustments to a TreeItem. -}
adjustTreeItem :: Adjustment -> TreeItem -> Annex (Maybe TreeItem)
adjustTreeItem UnlockAdjustment ti@(TreeItem f m s)
| toBlobType m == Just SymlinkBlob = do
mk <- catKey s
case mk of
Just k -> do
Database.Keys.addAssociatedFile k f
Just . TreeItem f (fromBlobType FileBlob)
<$> hashPointerFile k
Nothing -> return (Just ti)
| otherwise = return (Just ti)
adjustTreeItem LockAdjustment ti@(TreeItem f m s)
| toBlobType m /= Just SymlinkBlob = do
mk <- catKey s
case mk of
Just k -> do
absf <- inRepo $ \r -> absPath $
fromTopFilePath f r
linktarget <- calcRepo $ gitAnnexLink absf k
Just . TreeItem f (fromBlobType SymlinkBlob)
<$> hashSymlink linktarget
Nothing -> return (Just ti)
| otherwise = return (Just ti)
adjustTreeItem HideMissingAdjustment ti@(TreeItem _ _ s) = do
mk <- catKey s
case mk of
Just k -> ifM (inAnnex k)
( return (Just ti)
, return Nothing
)
Nothing -> return (Just ti)
adjustTreeItem ShowMissingAdjustment ti = return (Just ti)
type OrigBranch = Branch
type AdjBranch = Branch
adjustedBranchPrefix :: String
adjustedBranchPrefix = "refs/heads/adjusted/"
serialize :: Adjustment -> String
serialize UnlockAdjustment = "unlocked"
serialize LockAdjustment = "locked"
serialize HideMissingAdjustment = "present"
serialize ShowMissingAdjustment = "showmissing"
deserialize :: String -> Maybe Adjustment
deserialize "unlocked" = Just UnlockAdjustment
deserialize "locked" = Just UnlockAdjustment
deserialize "present" = Just HideMissingAdjustment
deserialize _ = Nothing
originalToAdjusted :: OrigBranch -> Adjustment -> AdjBranch
originalToAdjusted orig adj = Ref $
adjustedBranchPrefix ++ base ++ '(' : serialize adj ++ ")"
where
base = fromRef (Git.Ref.basename orig)
adjustedToOriginal :: AdjBranch -> Maybe (Adjustment, OrigBranch)
adjustedToOriginal b
| adjustedBranchPrefix `isPrefixOf` bs = do
let (base, as) = separate (== '(') (drop prefixlen bs)
adj <- deserialize (takeWhile (/= ')') as)
Just (adj, Git.Ref.under "refs/heads" (Ref base))
| otherwise = Nothing
where
bs = fromRef b
prefixlen = length adjustedBranchPrefix
getAdjustment :: Branch -> Maybe Adjustment
getAdjustment = fmap fst . adjustedToOriginal
fromAdjustedBranch :: Branch -> OrigBranch
fromAdjustedBranch b = maybe b snd (adjustedToOriginal b)
originalBranch :: Annex (Maybe OrigBranch)
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).
-
- Can fail, if no branch is checked out, or perhaps if staged changes
- conflict with the adjusted branch.
-}
enterAdjustedBranch :: Adjustment -> Annex ()
enterAdjustedBranch adj = go =<< originalBranch
where
go (Just origbranch) = do
adjbranch <- preventCommits $ const $
adjustBranch adj origbranch
inRepo $ Git.Command.run
[ Param "checkout"
, Param $ fromRef $ Git.Ref.base $ adjbranch
]
go Nothing = error "not on any branch!"
adjustToCrippledFileSystem :: Annex ()
adjustToCrippledFileSystem = do
warning "Entering an adjusted branch where files are unlocked as this filesystem does not support locked files."
whenM (isNothing <$> originalBranch) $
void $ inRepo $ Git.Branch.commitCommand Git.Branch.AutomaticCommit
[ Param "--quiet"
, Param "--allow-empty"
, Param "-m"
, Param "commit before entering adjusted unlocked branch"
]
enterAdjustedBranch UnlockAdjustment
adjustBranch :: Adjustment -> OrigBranch -> Annex AdjBranch
adjustBranch adj origbranch = do
sha <- adjust adj origbranch
inRepo $ Git.Branch.update "entering adjusted branch" adjbranch sha
return adjbranch
where
adjbranch = originalToAdjusted origbranch adj
adjust :: Adjustment -> Ref -> Annex Sha
adjust adj orig = do
treesha <- adjustTree adj orig
commitAdjustedTree treesha orig
adjustTree :: Adjustment -> Ref -> Annex Sha
adjustTree adj orig = do
let toadj = adjustTreeItem adj
treesha <- Git.Tree.adjustTree toadj [] [] orig =<< Annex.gitRepo
return treesha
type CommitsPrevented = Git.LockFile.LockHandle
{- Locks git's index file, preventing git from making a commit, merge,
- or otherwise changing the HEAD ref while the action is run.
-
- Throws an IO exception if the index file is already locked.
-}
preventCommits :: (CommitsPrevented -> Annex a) -> Annex a
preventCommits = bracket setup cleanup
where
setup = do
lck <- fromRepo indexFileLock
liftIO $ Git.LockFile.openLock lck
cleanup = liftIO . Git.LockFile.closeLock
{- Commits a given adjusted tree, with the provided parent ref.
-
- This should always yield the same value, even if performed in different
- clones of a repo, at different times. The commit message and other
- metadata is based on the parent.
-}
commitAdjustedTree :: Sha -> Ref -> Annex Sha
commitAdjustedTree treesha parent = go =<< catCommit parent
where
go Nothing = inRepo mkcommit
go (Just parentcommit) = inRepo $ commitWithMetaData
(commitAuthorMetaData parentcommit)
(commitCommitterMetaData parentcommit)
mkcommit
mkcommit = Git.Branch.commitTree Git.Branch.AutomaticCommit
adjustedBranchCommitMessage [parent] treesha
adjustedBranchCommitMessage :: String
adjustedBranchCommitMessage = "git-annex adjusted branch"
{- Update the currently checked out adjusted branch, merging the provided
- branch into it. -}
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
where
go commitsprevented (Just mergesha, Just currbranch) =
ifM (inRepo $ Git.Branch.changed currbranch mergesha)
( do
propigateAdjustedCommits' origbranch (adj, currbranch) commitsprevented
adjustedtomerge <- adjust adj mergesha
ifM (inRepo $ Git.Branch.changed currbranch adjustedtomerge)
( return $ do
-- Run after commit lock is dropped.
ifM (autoMergeFrom adjustedtomerge (Just currbranch) commitmode)
( preventCommits $ \commitsprevented' ->
recommit commitsprevented' currbranch mergesha =<< catCommit currbranch
, return False
)
, nochangestomerge
)
, nochangestomerge
)
go _ _ = return $ return False
nochangestomerge = return $ return True
{- Once a merge commit has been made, re-do it, removing
- the old version of the adjusted branch as a parent, and
- making the only parent be the branch that was merged in.
-
- Doing this ensures that the same commit Sha is
- always arrived at for a given commit from the merged in branch.
-}
recommit commitsprevented currbranch parent (Just commit) = do
commitsha <- commitAdjustedTree (commitTree commit) parent
inRepo $ Git.Branch.update "merging into adjusted branch" currbranch commitsha
propigateAdjustedCommits' origbranch (adj, currbranch) commitsprevented
return True
recommit _ _ _ 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.
-
- After propigating the commits back to the orig banch,
- rebase the adjusted branch on top of the updated orig branch.
-}
propigateAdjustedCommits :: OrigBranch -> (Adjustment, AdjBranch) -> Annex ()
propigateAdjustedCommits origbranch (adj, currbranch) =
preventCommits $ propigateAdjustedCommits' origbranch (adj, currbranch)
propigateAdjustedCommits' :: OrigBranch -> (Adjustment, AdjBranch) -> CommitsPrevented -> Annex ()
propigateAdjustedCommits' origbranch (adj, currbranch) _commitsprevented = do
ov <- inRepo $ Git.Ref.sha (Git.Ref.under "refs/heads" origbranch)
case ov of
Just origsha -> do
cv <- catCommit currbranch
case cv of
Just currcommit -> do
v <- newcommits >>= go origsha False
case v of
Left e -> do
warning e
return ()
Right newparent ->
rebase currcommit newparent
Nothing -> return ()
Nothing -> return ()
where
newcommits = inRepo $ Git.Branch.changedCommits origbranch currbranch
-- Get commits oldest first, so they can be processed
-- in order made.
[Param "--reverse"]
go parent _ [] = do
inRepo $ Git.Branch.update "updating adjusted branch" origbranch parent
return (Right parent)
go parent pastadjcommit (sha:l) = do
mc <- catCommit sha
case mc of
Just c
| commitMessage c == adjustedBranchCommitMessage ->
go parent True l
| pastadjcommit -> do
v <- reverseAdjustedCommit parent adj (sha, c) origbranch
case v of
Left e -> return (Left e)
Right commit -> go commit pastadjcommit l
_ -> go parent pastadjcommit l
rebase currcommit newparent = do
-- Reuse the current adjusted tree,
-- and reparent it on top of the new
-- version of the origbranch.
commitAdjustedTree (commitTree currcommit) newparent
>>= inRepo . Git.Branch.update "rebasing adjusted branch on top of updated original branch" currbranch
{- Reverses an adjusted commit, and commit on top of the provided newparent,
- yielding a commit sha.
-
- Adjust the tree of the newparent, changing only the files that the
- commit changed, and reverse adjusting those changes.
-
- Note that the commit message, and the author and committer metadata are
- copied over. However, any gpg signature will be lost, and any other
- headers are not copied either. -}
reverseAdjustedCommit :: Sha -> Adjustment -> (Sha, Commit) -> OrigBranch -> Annex (Either String Sha)
reverseAdjustedCommit newparent adj (csha, c) origbranch
-- commitDiff does not support merge commits
| length (commitParent c) > 1 = return $
Left $ "unable to propigate merge commit " ++ show csha ++ " back to " ++ show origbranch
| otherwise = do
(diff, cleanup) <- inRepo (Git.DiffTree.commitDiff csha)
let (adds, others) = partition (\dti -> Git.DiffTree.srcsha dti == nullSha) diff
let (removes, changes) = partition (\dti -> Git.DiffTree.dstsha dti == nullSha) others
adds' <- catMaybes <$>
mapM (adjustTreeItem reverseadj) (map diffTreeToTreeItem adds)
treesha <- Git.Tree.adjustTree
(propchanges changes)
adds'
(map Git.DiffTree.file removes)
newparent
=<< Annex.gitRepo
void $ liftIO cleanup
revadjcommit <- inRepo $ commitWithMetaData
(commitAuthorMetaData c)
(commitCommitterMetaData c) $
Git.Branch.commitTree Git.Branch.AutomaticCommit
(commitMessage c) [newparent] treesha
return (Right revadjcommit)
where
reverseadj = reverseAdjustment adj
propchanges changes ti@(TreeItem f _ _) =
case M.lookup f m of
Nothing -> return (Just ti) -- not changed
Just change -> adjustTreeItem reverseadj change
where
m = M.fromList $ map (\i@(TreeItem f' _ _) -> (f', i)) $
map diffTreeToTreeItem changes
diffTreeToTreeItem :: Git.DiffTree.DiffTreeItem -> TreeItem
diffTreeToTreeItem dti = TreeItem
(Git.DiffTree.file dti)
(Git.DiffTree.dstmode dti)
(Git.DiffTree.dstsha dti)