a964012fc3
I had not realized what a memory leak the lazy state monad could be, although I have not seen much evidence of actual leaking in git-annex. However, if running git-annex on a great many files, this could matter. The additional Utility.State.changeState adds even more strictness, avoiding a problem I saw in github-backup where repeatedly modifying state built up a huge pile of thunks.
74 lines
1.9 KiB
Haskell
74 lines
1.9 KiB
Haskell
{- git cat-file interface
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-
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- Copyright 2011 Joey Hess <joey@kitenet.net>
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-
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- Licensed under the GNU GPL version 3 or higher.
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-}
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module Git.CatFile (
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CatFileHandle,
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catFileStart,
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catFileStop,
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catFile,
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catObject
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) where
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import System.Cmd.Utils
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import System.IO
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import qualified Data.ByteString.Char8 as S
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import qualified Data.ByteString.Lazy.Char8 as L
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import Common
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import Git
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import Git.Sha
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import Git.Command
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type CatFileHandle = (PipeHandle, Handle, Handle)
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{- Starts git cat-file running in batch mode in a repo and returns a handle. -}
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catFileStart :: Repo -> IO CatFileHandle
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catFileStart repo = hPipeBoth "git" $ toCommand $
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gitCommandLine [Param "cat-file", Param "--batch"] repo
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{- Stops git cat-file. -}
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catFileStop :: CatFileHandle -> IO ()
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catFileStop (pid, from, to) = do
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hClose to
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hClose from
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forceSuccess pid
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{- Reads a file from a specified branch. -}
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catFile :: CatFileHandle -> Branch -> FilePath -> IO L.ByteString
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catFile h branch file = catObject h $ Ref $ show branch ++ ":" ++ file
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{- Uses a running git cat-file read the content of an object.
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- Objects that do not exist will have "" returned. -}
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catObject :: CatFileHandle -> Ref -> IO L.ByteString
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catObject (_, from, to) object = do
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hPutStrLn to $ show object
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hFlush to
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header <- hGetLine from
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case words header of
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[sha, objtype, size]
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| length sha == shaSize &&
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validobjtype objtype -> handle size
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| otherwise -> dne
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_
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| header == show object ++ " missing" -> dne
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| otherwise -> error $ "unknown response from git cat-file " ++ header
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where
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handle size = case reads size of
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[(bytes, "")] -> readcontent bytes
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_ -> dne
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readcontent bytes = do
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content <- S.hGet from bytes
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c <- hGetChar from
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when (c /= '\n') $
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error "missing newline from git cat-file"
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return $ L.fromChunks [content]
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dne = return L.empty
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validobjtype t
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| t == "blob" = True
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| t == "commit" = True
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| t == "tree" = True
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| otherwise = False
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