git-annex/Git/Ref.hs
Joey Hess 9eb10caa27
Some optimisations to string splitting code.
Turns out that Data.List.Utils.split is slow and makes a lot of
allocations. Here's a much simpler single character splitter that behaves
the same (even in wacky corner cases) while running in half the time and
75% the allocations.

As well as being an optimisation, this helps move toward eliminating use of
missingh.

(Data.List.Split.splitOn is nearly as slow as Data.List.Utils.split and
allocates even more.)

I have not benchmarked the effect on git-annex, but would not be surprised
to see some parsing of eg, large streams from git commands run twice as
fast, and possibly in less memory.

This commit was sponsored by Boyd Stephen Smith Jr. on Patreon.
2017-01-31 19:06:22 -04:00

149 lines
4.4 KiB
Haskell

{- git ref stuff
-
- Copyright 2011-2013 Joey Hess <id@joeyh.name>
-
- Licensed under the GNU GPL version 3 or higher.
-}
module Git.Ref where
import Common
import Git
import Git.Command
import Git.Sha
import Git.Types
import Data.Char (chr)
headRef :: Ref
headRef = Ref "HEAD"
headFile :: Repo -> FilePath
headFile r = localGitDir r </> "HEAD"
setHeadRef :: Ref -> Repo -> IO ()
setHeadRef ref r = writeFile (headFile r) ("ref: " ++ fromRef ref)
{- Converts a fully qualified git ref into a user-visible string. -}
describe :: Ref -> String
describe = fromRef . base
{- Often git refs are fully qualified
- (eg refs/heads/master or refs/remotes/origin/master).
- Converts such a fully qualified ref into a base ref
- (eg: master or origin/master). -}
base :: Ref -> Ref
base = Ref . remove "refs/heads/" . remove "refs/remotes/" . fromRef
where
remove prefix s
| prefix `isPrefixOf` s = drop (length prefix) s
| otherwise = s
{- Given a directory such as "refs/remotes/origin", and a ref such as
- refs/heads/master, yields a version of that ref under the directory,
- such as refs/remotes/origin/master. -}
underBase :: String -> Ref -> Ref
underBase dir r = Ref $ dir ++ "/" ++ fromRef (base r)
{- A Ref that can be used to refer to a file in the repository, as staged
- in the index.
-
- Prefixing the file with ./ makes this work even if in a subdirectory
- of a repo.
-}
fileRef :: FilePath -> Ref
fileRef f = Ref $ ":./" ++ f
{- Converts a Ref to refer to the content of the Ref on a given date. -}
dateRef :: Ref -> RefDate -> Ref
dateRef (Ref r) (RefDate d) = Ref $ r ++ "@" ++ d
{- A Ref that can be used to refer to a file in the repository as it
- appears in a given Ref. -}
fileFromRef :: Ref -> FilePath -> Ref
fileFromRef (Ref r) f = let (Ref fr) = fileRef f in Ref (r ++ fr)
{- Checks if a ref exists. -}
exists :: Ref -> Repo -> IO Bool
exists ref = runBool
[Param "show-ref", Param "--verify", Param "-q", Param $ fromRef ref]
{- The file used to record a ref. (Git also stores some refs in a
- packed-refs file.) -}
file :: Ref -> Repo -> FilePath
file ref repo = localGitDir repo </> fromRef ref
{- Checks if HEAD exists. It generally will, except for in a repository
- that was just created. -}
headExists :: Repo -> IO Bool
headExists repo = do
ls <- lines <$> pipeReadStrict [Param "show-ref", Param "--head"] repo
return $ any (" HEAD" `isSuffixOf`) ls
{- Get the sha of a fully qualified git ref, if it exists. -}
sha :: Branch -> Repo -> IO (Maybe Sha)
sha branch repo = process <$> showref repo
where
showref = pipeReadStrict [Param "show-ref",
Param "--hash", -- get the hash
Param $ fromRef branch]
process [] = Nothing
process s = Just $ Ref $ firstLine s
headSha :: Repo -> IO (Maybe Sha)
headSha = sha headRef
{- List of (shas, branches) matching a given ref or refs. -}
matching :: [Ref] -> Repo -> IO [(Sha, Branch)]
matching refs repo = matching' (map fromRef refs) repo
{- Includes HEAD in the output, if asked for it. -}
matchingWithHEAD :: [Ref] -> Repo -> IO [(Sha, Branch)]
matchingWithHEAD refs repo = matching' ("--head" : map fromRef refs) repo
{- List of (shas, branches) matching a given ref or refs. -}
matching' :: [String] -> Repo -> IO [(Sha, Branch)]
matching' ps repo = map gen . lines <$>
pipeReadStrict (Param "show-ref" : map Param ps) repo
where
gen l = let (r, b) = separate (== ' ') l
in (Ref r, Ref b)
{- List of (shas, branches) matching a given ref spec.
- Duplicate shas are filtered out. -}
matchingUniq :: [Ref] -> Repo -> IO [(Sha, Branch)]
matchingUniq refs repo = nubBy uniqref <$> matching refs repo
where
uniqref (a, _) (b, _) = a == b
{- Gets the sha of the tree a ref uses. -}
tree :: Ref -> Repo -> IO (Maybe Sha)
tree ref = extractSha <$$> pipeReadStrict
[ Param "rev-parse", Param (fromRef ref ++ ":") ]
{- Checks if a String is a legal git ref name.
-
- The rules for this are complex; see git-check-ref-format(1) -}
legal :: Bool -> String -> Bool
legal allowonelevel s = all (== False) illegal
where
illegal =
[ any ("." `isPrefixOf`) pathbits
, any (".lock" `isSuffixOf`) pathbits
, not allowonelevel && length pathbits < 2
, contains ".."
, any (\c -> contains [c]) illegalchars
, begins "/"
, ends "/"
, contains "//"
, ends "."
, contains "@{"
, null s
]
contains v = v `isInfixOf` s
ends v = v `isSuffixOf` s
begins v = v `isPrefixOf` s
pathbits = splitc '/' s
illegalchars = " ~^:?*[\\" ++ controlchars
controlchars = chr 0o177 : [chr 0 .. chr (0o40-1)]