git-annex/Git/Tree.hs
Joey Hess 123f823ef7
no streaming
extractTree has to parse the whole input list in order to generate a tree,
so convert interface to non-streaming.

Some quick memory benchmarks in a repo with 60k files
don't look too bad despite not streaming.

To stream, without building up a whole tree object, one way would
be a new interface:

adjustTree :: MonadIO m :: (TreeItem -> m (Maybe TreeItem)) -> Ref -> Repo -> m Sha

This would only need to buffer tree objects from the current one down
to the root, in order to update trees when a TreeItem is changed.

But, while it supports changing items in the tree, and removing items,
it does not support adding new items, or moving items from one directory to
another.
2016-02-23 20:25:31 -04:00

121 lines
3.5 KiB
Haskell

{- git trees
-
- Copyright 2016 Joey Hess <id@joeyh.name>
-
- Licensed under the GNU GPL version 3 or higher.
-}
{-# LANGUAGE BangPatterns #-}
module Git.Tree (
Tree(..),
TreeContent(..),
getTree,
recordTree,
) where
import Common
import Git
import Git.FilePath
import Git.Types
import Git.Command
import Git.Sha
import qualified Git.LsTree as LsTree
import qualified Utility.CoProcess as CoProcess
import Numeric
import System.Posix.Types
newtype Tree = Tree [TreeContent]
deriving (Show)
data TreeContent
= TreeBlob TopFilePath FileMode Sha
-- A subtree that is already recorded in git, with a known sha.
| RecordedSubTree TopFilePath Sha [TreeContent]
-- A subtree that has not yet been recorded in git.
| NewSubTree TopFilePath [TreeContent]
deriving (Show)
{- Gets the Tree for a Ref. -}
getTree :: Ref -> Repo -> IO Tree
getTree r repo = do
-- Pass -t to get the tree object shas, which are normally omitted.
(l, cleanup) <- LsTree.lsTree' [Param "-t"] r repo
let !t = either (\e -> error ("ls-tree parse error:" ++ e)) id
(extractTree l)
void cleanup
return t
{- Assumes the list is ordered, with tree objects coming right before their
- contents. -}
extractTree :: [LsTree.TreeItem] -> Either String Tree
extractTree l = case go [] "" l of
Right (t, []) -> Right (Tree t)
Right _ -> parseerr "unexpected tree form"
Left e -> parseerr e
where
go t _ [] = Right (t, [])
go t prefix (i:is)
| prefix `isPrefixOf` getTopFilePath (LsTree.file i) =
case readObjectType (LsTree.typeobj i) of
Just BlobObject ->
let b = TreeBlob (LsTree.file i) (LsTree.mode i) (LsTree.sha i)
in go (b:t) prefix is
Just TreeObject -> case go [] (getTopFilePath (LsTree.file i) ++ "/") is of
Right (subtree, is') ->
let st = RecordedSubTree (LsTree.file i) (LsTree.sha i) subtree
in go (st:t) prefix is'
Left e -> Left e
_ -> parseerr ("unexpected object type \"" ++ LsTree.typeobj i ++ "\"")
| otherwise = Right (t, i:is)
parseerr = Left
{- Records a Tree in the Repo, returning its Sha.
-
- Efficiently handles subtrees, by only recording ones that have not
- already been recorded before. And even when many subtrees need to be
- recorded, it's done with a single call to git mktree, using its batch
- interface.
-}
recordTree :: Repo -> Tree -> IO Sha
recordTree repo t = do
h <- CoProcess.rawMode =<< gitCoProcessStart False ps repo
sha <- recordTree' h t
CoProcess.stop h
return sha
where
ps = [Param "mktree", Param "--batch", Param "-z"]
recordTree' :: CoProcess.CoProcessHandle -> Tree -> IO Sha
recordTree' h (Tree l) = mkTree h =<< mapM (recordSubTree h) l
recordSubTree :: CoProcess.CoProcessHandle -> TreeContent -> IO TreeContent
recordSubTree h (NewSubTree d l) = do
l' <- mapM (recordSubTree h) l
sha <- mkTree h l'
return (RecordedSubTree d sha l')
recordSubTree _ alreadyrecorded = return alreadyrecorded
mkTree :: CoProcess.CoProcessHandle -> [TreeContent] -> IO Sha
mkTree cp l = CoProcess.query cp send receive
where
send h = do
forM_ l $ \i -> hPutStr h $ case i of
TreeBlob f fm s -> mkTreeOutput fm BlobObject s f
RecordedSubTree f s _ -> mkTreeOutput 0o040000 TreeObject s f
NewSubTree _ _ -> error "recordSubTree internal error; unexpected NewSubTree"
hPutStr h "\NUL" -- signal end of tree to --batch
receive h = getSha "mktree" (hGetLine h)
mkTreeOutput :: FileMode -> ObjectType -> Sha -> TopFilePath -> String
mkTreeOutput fm ot s f = concat
[ showOct fm ""
, " "
, show ot
, " "
, fromRef s
, "\t"
, takeFileName (getTopFilePath f)
, "\NUL"
]