cb375977a6
Including writing and parsing the metadata log files with bytestring-builder and attoparsec.
152 lines
4.9 KiB
Haskell
152 lines
4.9 KiB
Haskell
{- git-annex general metadata storage log and per-remote metadata storage log.
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-
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- A line of the log will look like "timestamp field [+-]value [...]"
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-
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- (In the per-remote log, each field is prefixed with "uuid:")
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-
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- Note that unset values are preserved. Consider this case:
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-
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- We have:
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-
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- 100 foo +x
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- 200 foo -x
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-
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- An unmerged remote has:
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-
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- 150 foo +x
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-
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- After union merge, because the foo -x was preserved, we know that
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- after the other remote redundantly set foo +x, it was unset,
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- and so foo currently has no value.
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-
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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 Logs.MetaData (
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getCurrentMetaData,
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getCurrentRemoteMetaData,
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addMetaData,
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addRemoteMetaData,
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addMetaDataClocked,
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currentMetaData,
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copyMetaData,
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) where
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import Annex.Common
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import Types.MetaData
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import Annex.MetaData.StandardFields
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import Annex.VectorClock
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import qualified Annex.Branch
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import qualified Annex
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import Logs
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import Utility.TimeStamp
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import Logs.MetaData.Pure
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import qualified Data.Set as S
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import qualified Data.Map as M
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{- Go through the log from oldest to newest, and combine it all
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- into a single MetaData representing the current state.
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-
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- Automatically generates a lastchanged metadata for each field that's
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- currently set, based on timestamps in the log.
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-}
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getCurrentMetaData :: Key -> Annex MetaData
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getCurrentMetaData = getCurrentMetaData' metaDataLogFile
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getCurrentMetaData' :: (GitConfig -> Key -> FilePath) -> Key -> Annex MetaData
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getCurrentMetaData' getlogfile k = do
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config <- Annex.getGitConfig
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ls <- S.toAscList <$> readLog (getlogfile config k)
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let loggedmeta = logToCurrentMetaData ls
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return $ currentMetaData $ unionMetaData loggedmeta
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(lastchanged ls loggedmeta)
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where
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lastchanged [] _ = emptyMetaData
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lastchanged ls (MetaData currentlyset) =
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let m = foldl' (flip M.union) M.empty (map genlastchanged ls)
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in MetaData $
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-- Add a overall lastchanged using the oldest log
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-- item (log is in ascending order).
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M.insert lastChangedField (lastchangedval $ Prelude.last ls) $
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M.mapKeys mkLastChangedField $
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-- Only include fields that are currently set.
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m `M.intersection` currentlyset
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-- Makes each field have the timestamp as its value.
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genlastchanged l =
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let MetaData m = value l
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ts = lastchangedval l
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in M.map (const ts) m
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lastchangedval l = S.singleton $ toMetaValue $ encodeBS $ showts $
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case changed l of
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VectorClock t -> t
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Unknown -> 0
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showts = formatPOSIXTime "%F@%H-%M-%S"
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getCurrentRemoteMetaData :: UUID -> Key -> Annex RemoteMetaData
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getCurrentRemoteMetaData u k = extractRemoteMetaData u <$>
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getCurrentMetaData' remoteMetaDataLogFile k
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{- Adds in some metadata, which can override existing values, or unset
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- them, but otherwise leaves any existing metadata as-is. -}
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addMetaData :: Key -> MetaData -> Annex ()
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addMetaData = addMetaData' metaDataLogFile
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addMetaData' :: (GitConfig -> Key -> FilePath) -> Key -> MetaData -> Annex ()
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addMetaData' getlogfile k metadata =
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addMetaDataClocked' getlogfile k metadata =<< liftIO currentVectorClock
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{- Reusing the same VectorClock when making changes to the metadata
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- of multiple keys is a nice optimisation. The same metadata lines
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- will tend to be generated across the different log files, and so
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- git will be able to pack the data more efficiently. -}
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addMetaDataClocked :: Key -> MetaData -> VectorClock -> Annex ()
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addMetaDataClocked = addMetaDataClocked' metaDataLogFile
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addMetaDataClocked' :: (GitConfig -> Key -> FilePath) -> Key -> MetaData -> VectorClock -> Annex ()
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addMetaDataClocked' getlogfile k d@(MetaData m) c
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| d == emptyMetaData = noop
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| otherwise = do
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config <- Annex.getGitConfig
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Annex.Branch.change (getlogfile config k) $
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buildLog . simplifyLog
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. S.insert (LogEntry c metadata)
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. parseLog
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where
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metadata = MetaData $ M.filterWithKey (\f _ -> not (isLastChangedField f)) m
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addRemoteMetaData :: Key -> RemoteMetaData -> Annex ()
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addRemoteMetaData k m = do
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addMetaData' remoteMetaDataLogFile k (fromRemoteMetaData m)
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getMetaDataLog :: Key -> Annex (Log MetaData)
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getMetaDataLog key = do
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config <- Annex.getGitConfig
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readLog $ metaDataLogFile config key
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{- Copies the metadata from the old key to the new key.
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-
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- The exact content of the metadata file is copied, so that the timestamps
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- remain the same, and because this is more space-efficient in the git
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- repository.
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-
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- Any metadata already attached to the new key is not preserved.
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-
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- Returns True when metadata was copied.
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-}
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copyMetaData :: Key -> Key -> Annex Bool
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copyMetaData oldkey newkey
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| oldkey == newkey = return False
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| otherwise = do
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l <- getMetaDataLog oldkey
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if logToCurrentMetaData (S.toAscList l) == emptyMetaData
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then return False
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else do
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config <- Annex.getGitConfig
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Annex.Branch.change (metaDataLogFile config newkey) $
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const $ buildLog l
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return True
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readLog :: FilePath -> Annex (Log MetaData)
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readLog = parseLog <$$> Annex.Branch.get
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