summaryrefslogtreecommitdiff
path: root/Annex/Journal.hs
blob: 0f0803aaac0c456a4d0d9414250f3b87567d550d (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
{- management of the git-annex journal
 -
 - The journal is used to queue up changes before they are committed to the
 - git-annex branch. Amoung other things, it ensures that if git-annex is
 - interrupted, its recorded data is not lost.
 -
 - Copyright 2011 Joey Hess <joey@kitenet.net>
 -
 - Licensed under the GNU GPL version 3 or higher.
 -}

{-# LANGUAGE CPP #-}

module Annex.Journal where

import System.IO.Binary

import Common.Annex
import Annex.Exception
import qualified Git
import Annex.Perms

{- Records content for a file in the branch to the journal.
 -
 - Using the journal, rather than immediatly staging content to the index
 - avoids git needing to rewrite the index after every change. -}
setJournalFile :: FilePath -> String -> Annex ()
setJournalFile file content = do
	createAnnexDirectory =<< fromRepo gitAnnexJournalDir
	createAnnexDirectory =<< fromRepo gitAnnexTmpDir
	-- journal file is written atomically
	jfile <- fromRepo $ journalFile file
	tmp <- fromRepo gitAnnexTmpDir
	let tmpfile = tmp </> takeFileName jfile
	liftIO $ do
		writeBinaryFile tmpfile content
		moveFile tmpfile jfile

{- Gets any journalled content for a file in the branch. -}
getJournalFile :: FilePath -> Annex (Maybe String)
getJournalFile file = inRepo $ \g -> catchMaybeIO $
	readFileStrict $ journalFile file g

{- List of files that have updated content in the journal. -}
getJournalledFiles :: Annex [FilePath]
getJournalledFiles = map fileJournal <$> getJournalFiles

{- List of existing journal files. -}
getJournalFiles :: Annex [FilePath]
getJournalFiles = do
	g <- gitRepo
	fs <- liftIO $ catchDefaultIO [] $
		getDirectoryContents $ gitAnnexJournalDir g
	return $ filter (`notElem` [".", ".."]) fs

{- Checks if there are changes in the journal. -}
journalDirty :: Annex Bool
journalDirty = not . null <$> getJournalFiles

{- Produces a filename to use in the journal for a file on the branch.
 -
 - The journal typically won't have a lot of files in it, so the hashing
 - used in the branch is not necessary, and all the files are put directly
 - in the journal directory.
 -}
journalFile :: FilePath -> Git.Repo -> FilePath
journalFile file repo = gitAnnexJournalDir repo </> concatMap mangle file
  where
	mangle c
		| c == pathSeparator = "_"
		| c == '_' = "__"
		| otherwise = [c]

{- Converts a journal file (relative to the journal dir) back to the
 - filename on the branch. -}
fileJournal :: FilePath -> FilePath
fileJournal = replace [pathSeparator, pathSeparator] "_" .
	replace "_" [pathSeparator]

{- Runs an action that modifies the journal, using locking to avoid
 - contention with other git-annex processes. -}
lockJournal :: Annex a -> Annex a
lockJournal a = do
	lockfile <- fromRepo gitAnnexJournalLock
	createAnnexDirectory $ takeDirectory lockfile
	mode <- annexFileMode
	bracketIO (lock lockfile mode) unlock (const a)
  where
	lock lockfile mode = do
#ifndef __WINDOWS__
		l <- noUmask mode $ createFile lockfile mode
		waitToSetLock l (WriteLock, AbsoluteSeek, 0, 0)
		return l
#else
		writeFile lockfile ""
		return lockfile
#endif
#ifndef __WINDOWS__
	unlock = closeFd
#else
	unlock = removeFile
#endif