git-annex/Annex/GitOverlay.hs
2020-08-26 12:29:13 -04:00

136 lines
4.2 KiB
Haskell

{- Temporarily changing how git-annex runs git commands.
-
- Copyright 2014-2020 Joey Hess <id@joeyh.name>
-
- Licensed under the GNU AGPL version 3 or higher.
-}
{-# LANGUAGE CPP #-}
module Annex.GitOverlay (
module Annex.GitOverlay,
AltIndexFile(..),
) where
import qualified Control.Exception as E
import Annex.Common
import Types.IndexFiles
import Git
import Git.Types
import Git.Index
import Git.Env
import qualified Annex
import qualified Annex.Queue
#ifndef mingw32_HOST_OS
import qualified Utility.LockFile.PidLock as PidF
import qualified Utility.LockPool.PidLock as PidP
import Utility.LockPool (dropLock)
import Utility.Env
import Config
#endif
{- Runs an action using a different git index file. -}
withIndexFile :: AltIndexFile -> (FilePath -> Annex a) -> Annex a
withIndexFile i = withAltRepo usecachedgitenv restoregitenv
where
-- This is an optimisation. Since withIndexFile is run repeatedly,
-- typically with the same file, and addGitEnv uses the slow
-- getEnvironment when gitEnv is Nothing, and has to do a
-- nontrivial amount of work, we cache the modified environment
-- the first time, and reuse it in subsequent calls for the same
-- index file.
--
-- (This could be done at another level; eg when creating the
-- Git object in the first place, but it's more efficient to let
-- the environment be inherited in all calls to git where it
-- does not need to be modified.)
--
-- Also, the use of AltIndexFile avoids needing to construct
-- the FilePath each time, which saves enough time to be worth the
-- added complication.
usecachedgitenv g = case gitEnv g of
Nothing -> Annex.withState $ \s -> case Annex.cachedgitenv s of
Just (cachedi, cachedf, cachede) | i == cachedi ->
return (s, (g { gitEnv = Just cachede }, cachedf))
_ -> do
r@(g', f) <- addindex g
let cache = (,,)
<$> Just i
<*> Just f
<*> gitEnv g'
return (s { Annex.cachedgitenv = cache }, r)
Just _ -> liftIO $ addindex g
addindex g = do
f <- indexEnvVal $ case i of
AnnexIndexFile -> gitAnnexIndex g
ViewIndexFile -> gitAnnexViewIndex g
g' <- addGitEnv g indexEnv f
return (g', f)
restoregitenv g g' = g' { gitEnv = gitEnv g }
{- Runs an action using a different git work tree.
-
- Smudge and clean filters are disabled in this work tree. -}
withWorkTree :: FilePath -> Annex a -> Annex a
withWorkTree d a = withAltRepo
(\g -> return $ (g { location = modlocation (location g), gitGlobalOpts = gitGlobalOpts g ++ disableSmudgeConfig }, ()))
(\g g' -> g' { location = location g, gitGlobalOpts = gitGlobalOpts g })
(const a)
where
modlocation l@(Local {}) = l { worktree = Just (toRawFilePath d) }
modlocation _ = error "withWorkTree of non-local git repo"
disableSmudgeConfig = map Param
[ "-c", "filter.annex.smudge="
, "-c", "filter.annex.clean="
]
{- 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.
-
- Needs git 2.2.0 or newer.
-}
withWorkTreeRelated :: FilePath -> Annex a -> Annex a
withWorkTreeRelated d a = withAltRepo modrepo unmodrepo (const a)
where
modrepo g = liftIO $ do
g' <- addGitEnv g "GIT_COMMON_DIR"
=<< absPath (fromRawFilePath (localGitDir g))
g'' <- addGitEnv g' "GIT_DIR" d
return (g'' { gitEnvOverridesGitDir = True }, ())
unmodrepo g g' = g'
{ gitEnv = gitEnv g
, gitEnvOverridesGitDir = gitEnvOverridesGitDir g
}
withAltRepo
:: (Repo -> Annex (Repo, t))
-- ^ modify Repo
-> (Repo -> Repo -> Repo)
-- ^ undo modifications; first Repo is the original and second
-- is the one after running the action.
-> (t -> Annex a)
-> Annex a
withAltRepo modrepo unmodrepo a = do
g <- gitRepo
(g', t) <- modrepo g
q <- Annex.Queue.get
v <- tryNonAsync $ do
Annex.changeState $ \s -> s
{ Annex.repo = g'
-- Start a separate queue for any changes made
-- with the modified repo.
, Annex.repoqueue = Nothing
}
a t
void $ tryNonAsync Annex.Queue.flush
Annex.changeState $ \s -> s
{ Annex.repo = unmodrepo g (Annex.repo s)
, Annex.repoqueue = Just q
}
either E.throw return v