git-annex/Logs.hs
Joey Hess 3e68c1c2fd add remote state logs
This allows a remote to store a piece of arbitrary state associated with a
key. This is needed to support Tahoe, where the file-cap is calculated from
the data stored in it, and used to retrieve a key later. Glacier also would
be much improved by using this.

GETSTATE and SETSTATE are added to the external special remote protocol.

Note that the state is left as-is even when a key is removed from a remote.
It's up to the remote to decide when it wants to clear the state.

The remote state log, $KEY.log.rmt, is a UUID-based log. However,
rather than using the old UUID-based log format, I created a new variant
of that format. The new varient is more space efficient (since it lacks the
"timestamp=" hack, and easier to parse (and the parser doesn't mess with
whitespace in the value), and avoids compatability cruft in the old one.

This seemed worth cleaning up for these new files, since there could be a
lot of them, while before UUID-based logs were only used for a few log
files at the top of the git-annex branch. The transition code has also
been updated to handle these new UUID-based logs.

This commit was sponsored by Daniel Hofer.
2014-01-03 16:35:57 -04:00

129 lines
3.6 KiB
Haskell

{- git-annex log file names
-
- Copyright 2013 Joey Hess <joey@kitenet.net>
-
- Licensed under the GNU GPL version 3 or higher.
-}
module Logs where
import Common.Annex
import Types.Key
{- There are several varieties of log file formats. -}
data LogVariety = UUIDBasedLog | NewUUIDBasedLog | PresenceLog Key
deriving (Show)
{- Converts a path from the git-annex branch into one of the varieties
- of logs used by git-annex, if it's a known path. -}
getLogVariety :: FilePath -> Maybe LogVariety
getLogVariety f
| f `elem` topLevelUUIDBasedLogs = Just UUIDBasedLog
| isRemoteStateLog f = Just NewUUIDBasedLog
| otherwise = PresenceLog <$> firstJust (presenceLogs f)
{- All the uuid-based logs stored in the top of the git-annex branch. -}
topLevelUUIDBasedLogs :: [FilePath]
topLevelUUIDBasedLogs =
[ uuidLog
, remoteLog
, trustLog
, groupLog
, preferredContentLog
, scheduleLog
]
{- All the ways to get a key from a presence log file -}
presenceLogs :: FilePath -> [Maybe Key]
presenceLogs f =
[ urlLogFileKey f
, locationLogFileKey f
]
uuidLog :: FilePath
uuidLog = "uuid.log"
remoteLog :: FilePath
remoteLog = "remote.log"
trustLog :: FilePath
trustLog = "trust.log"
groupLog :: FilePath
groupLog = "group.log"
preferredContentLog :: FilePath
preferredContentLog = "preferred-content.log"
scheduleLog :: FilePath
scheduleLog = "schedule.log"
{- The pathname of the location log file for a given key. -}
locationLogFile :: Key -> String
locationLogFile key = hashDirLower key ++ keyFile key ++ ".log"
{- Converts a pathname into a key if it's a location log. -}
locationLogFileKey :: FilePath -> Maybe Key
locationLogFileKey path
| ["remote", "web"] `isPrefixOf` splitDirectories dir = Nothing
| ext == ".log" = fileKey base
| otherwise = Nothing
where
(dir, file) = splitFileName path
(base, ext) = splitAt (length file - 4) file
{- The filename of the url log for a given key. -}
urlLogFile :: Key -> FilePath
urlLogFile key = hashDirLower key </> keyFile key ++ urlLogExt
{- Old versions stored the urls elsewhere. -}
oldurlLogs :: Key -> [FilePath]
oldurlLogs key =
[ "remote/web" </> hashDirLower key </> key2file key ++ ".log"
, "remote/web" </> hashDirLower key </> keyFile key ++ ".log"
]
urlLogExt :: String
urlLogExt = ".log.web"
{- Converts a url log file into a key.
- (Does not work on oldurlLogs.) -}
urlLogFileKey :: FilePath -> Maybe Key
urlLogFileKey path
| ext == urlLogExt = fileKey base
| otherwise = Nothing
where
file = takeFileName path
(base, ext) = splitAt (length file - extlen) file
extlen = length urlLogExt
{- Does not work on oldurllogs. -}
isUrlLog :: FilePath -> Bool
isUrlLog file = urlLogExt `isSuffixOf` file
{- The filename of the remote state log for a given key. -}
remoteStateLogFile :: Key -> FilePath
remoteStateLogFile key = hashDirLower key </> keyFile key ++ remoteStateLogExt
remoteStateLogExt :: String
remoteStateLogExt = ".log.rmt"
isRemoteStateLog :: FilePath -> Bool
isRemoteStateLog path = remoteStateLogExt `isSuffixOf` path
prop_logs_sane :: Key -> Bool
prop_logs_sane dummykey = all id
[ isNothing (getLogVariety "unknown")
, expect isUUIDBasedLog (getLogVariety uuidLog)
, expect isPresenceLog (getLogVariety $ locationLogFile dummykey)
, expect isPresenceLog (getLogVariety $ urlLogFile dummykey)
, expect isNewUUIDBasedLog (getLogVariety $ remoteStateLogFile dummykey)
]
where
expect = maybe False
isUUIDBasedLog UUIDBasedLog = True
isUUIDBasedLog _ = False
isNewUUIDBasedLog NewUUIDBasedLog = True
isNewUUIDBasedLog _ = False
isPresenceLog (PresenceLog k) = k == dummykey
isPresenceLog _ = False