git-annex/Logs/UUID.hs

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{- git-annex uuid log
-
- uuid.log stores a list of known uuids, and their descriptions.
-
- Copyright 2010-2019 Joey Hess <id@joeyh.name>
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-
- Licensed under the GNU AGPL version 3 or higher.
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-}
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module Logs.UUID (
uuidLog,
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describeUUID,
uuidDescMap,
uuidDescMapLoad,
uuidDescMapRaw,
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) where
import Types.UUID
import Annex.Common
import Annex.VectorClock
import qualified Annex
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import qualified Annex.Branch
import Logs
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import Logs.UUIDBased
import qualified Annex.UUID
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import qualified Data.Map.Strict as M
import qualified Data.ByteString.Lazy as L
import qualified Data.Attoparsec.ByteString.Lazy as A
{- Records a description for a uuid in the log. -}
describeUUID :: UUID -> UUIDDesc -> Annex ()
describeUUID uuid desc = do
c <- currentVectorClock
start implementing hidden git-annex repositories This adds a separate journal, which does not currently get committed to an index, but is planned to be committed to .git/annex/index-private. Changes that are regarding a UUID that is private will get written to this journal, and so will not be published into the git-annex branch. All log writing should have been made to indicate the UUID it's regarding, though I've not verified this yet. Currently, no UUIDs are treated as private yet, a way to configure that is needed. The implementation is careful to not add any additional IO work when privateUUIDsKnown is False. It will skip looking at the private journal at all. So this should be free, or nearly so, unless the feature is used. When it is used, all branch reads will be about twice as expensive. It is very lucky -- or very prudent design -- that Annex.Branch.change and maybeChange are the only ways to change a file on the branch, and Annex.Branch.set is only internal use. That let Annex.Branch.get always yield any private information that has been recorded, without the risk that Annex.Branch.set might be called, with a non-private UUID, and end up leaking the private information into the git-annex branch. And, this relies on the way git-annex union merges the git-annex branch. When reading a file, there can be a public and a private version, and they are just concacenated together. That will be handled the same as if there were two diverged git-annex branches that got union merged.
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Annex.Branch.change (Annex.Branch.RegardingUUID [uuid]) uuidLog $
buildLogOld buildUUIDDesc . changeLog c uuid desc . parseUUIDLog
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{- The map is cached for speed. -}
uuidDescMap :: Annex UUIDDescMap
uuidDescMap = maybe uuidDescMapLoad return =<< Annex.getState Annex.uuiddescmap
{- Read the uuidLog into a map, and cache it for later use.
-
- If the current repository has not been described, it is still included
- in the map with an empty description. -}
uuidDescMapLoad :: Annex UUIDDescMap
uuidDescMapLoad = do
m <- uuidDescMapRaw
u <- Annex.UUID.getUUID
let m' = M.insertWith preferold u mempty m
Annex.changeState $ \s -> s { Annex.uuiddescmap = Just m' }
return m'
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where
preferold = flip const
{- Read the uuidLog into a map. Includes only actually set descriptions. -}
uuidDescMapRaw :: Annex UUIDDescMap
uuidDescMapRaw = simpleMap . parseUUIDLog <$> Annex.Branch.get uuidLog
parseUUIDLog :: L.ByteString -> Log UUIDDesc
parseUUIDLog = parseLogOld (UUIDDesc <$> A.takeByteString)