b1d719f9d2
Capstone to this feature. Any transitions that have been performed on an unmerged remote ref but not on the local git-annex branch, or vice-versa have to be applied on the fly when reading files. Sponsored-by: Dartmouth College's Datalad project
110 lines
3.6 KiB
Haskell
110 lines
3.6 KiB
Haskell
{- git-annex transitions log
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-
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- This is used to record transitions that have been performed on the
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- git-annex branch, and when the transition was first started.
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-
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- We can quickly detect when the local branch has already had an transition
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- done that is listed in the remote branch by checking that the local
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- branch contains the same transition, with the same or newer start time.
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-
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- Copyright 2013-2021 Joey Hess <id@joeyh.name>
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-
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- Licensed under the GNU AGPL version 3 or higher.
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-}
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{-# LANGUAGE OverloadedStrings #-}
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module Logs.Transitions where
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import Annex.Common
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import Annex.VectorClock
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import Logs.Line
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import qualified Git
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import Git.Types (fromRef)
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import Annex.CatFile
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import qualified Data.Set as S
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import Data.Either
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import Data.ByteString (ByteString)
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import Data.ByteString.Builder
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import qualified Data.ByteString.Lazy as L
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import qualified Data.Attoparsec.ByteString.Lazy as A
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import qualified Data.Attoparsec.ByteString.Char8 as A8
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transitionsLog :: RawFilePath
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transitionsLog = "transitions.log"
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data Transition
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= ForgetGitHistory
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| ForgetDeadRemotes
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deriving (Show, Ord, Eq, Read)
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data TransitionLine = TransitionLine
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{ transitionStarted :: VectorClock
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-- New transitions that we don't know about yet are preserved.
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, transition :: Either ByteString Transition
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} deriving (Ord, Eq)
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type Transitions = S.Set TransitionLine
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describeTransition :: Transition -> String
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describeTransition ForgetGitHistory = "forget git history"
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describeTransition ForgetDeadRemotes = "forget dead remotes"
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noTransitions :: Transitions
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noTransitions = S.empty
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addTransition :: CandidateVectorClock -> Transition -> Transitions -> Transitions
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addTransition c t s = S.insert (TransitionLine c' (Right t)) s
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where
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oldcs = map transitionStarted $
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filter (\l -> transition l == Right t) (S.toList s)
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c' = advanceVectorClock c oldcs
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buildTransitions :: Transitions -> Builder
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buildTransitions = mconcat . map genline . S.elems
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where
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genline tl = buildt (transition tl) <> charUtf8 ' '
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<> buildVectorClock (transitionStarted tl) <> charUtf8 '\n'
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buildt (Left b) = byteString b
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buildt (Right t) = byteString (encodeBS (show t))
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parseTransitions :: L.ByteString -> Transitions
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parseTransitions = fromMaybe S.empty . A.maybeResult . A.parse
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(S.fromList <$> parseLogLines transitionLineParser)
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parseTransitionsStrictly :: String -> L.ByteString -> Transitions
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parseTransitionsStrictly source b =
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let ts = parseTransitions b
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in if S.null $ S.filter (isLeft . transition) ts
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then ts
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else giveup $ "unknown transitions listed in " ++ source ++ "; upgrade git-annex!"
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transitionLineParser :: A.Parser TransitionLine
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transitionLineParser = do
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t <- (parsetransition <$> A.takeByteString)
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_ <- A8.char ' '
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c <- vectorClockParser
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return $ TransitionLine c t
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where
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parsetransition b = case readish (decodeBS b) of
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Just t -> Right t
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Nothing -> Left b
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combineTransitions :: [Transitions] -> Transitions
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combineTransitions = S.unions
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{- Unknown types of transitions are omitted. -}
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knownTransitionList :: Transitions -> [Transition]
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knownTransitionList = nub . rights . map transition . S.elems
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{- Typically ran with Annex.Branch.change, but we can't import Annex.Branch
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- here since it depends on this module. -}
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recordTransitions :: (RawFilePath -> (L.ByteString -> Builder) -> Annex ()) -> Transitions -> Annex ()
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recordTransitions changer t = changer transitionsLog $
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buildTransitions . S.union t . parseTransitionsStrictly "local"
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getRefTransitions :: Git.Ref -> Annex Transitions
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getRefTransitions ref =
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parseTransitionsStrictly (fromRef ref)
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<$> catFile ref transitionsLog
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