git-annex/Logs/Transitions.hs
Joey Hess 2eadb6cd68
convert transitions.log to attoparsec and bytestring-builder
Not likely to be any speed gain here, but this completes porting every
log file over.

And, it let me get rid of code copied from ghc and modified, so
simplifying the licensing.
2019-01-10 17:13:30 -04:00

99 lines
3.3 KiB
Haskell

{- git-annex transitions log
-
- This is used to record transitions that have been performed on the
- git-annex branch, and when the transition was first started.
-
- We can quickly detect when the local branch has already had an transition
- done that is listed in the remote branch by checking that the local
- branch contains the same transition, with the same or newer start time.
-
- Copyright 2013-2019 Joey Hess <id@joeyh.name>
-
- Licensed under the GNU GPL version 3 or higher.
-}
module Logs.Transitions where
import Annex.Common
import Annex.VectorClock
import Logs.Line
import qualified Data.Set as S
import Data.Either
import Data.ByteString (ByteString)
import Data.ByteString.Builder
import qualified Data.ByteString.Lazy as L
import qualified Data.Attoparsec.ByteString.Lazy as A
import qualified Data.Attoparsec.ByteString.Char8 as A8
transitionsLog :: FilePath
transitionsLog = "transitions.log"
data Transition
= ForgetGitHistory
| ForgetDeadRemotes
deriving (Show, Ord, Eq, Read)
data TransitionLine = TransitionLine
{ transitionStarted :: VectorClock
-- New transitions that we don't know about yet are preserved.
, transition :: Either ByteString Transition
} deriving (Ord, Eq)
type Transitions = S.Set TransitionLine
describeTransition :: Transition -> String
describeTransition ForgetGitHistory = "forget git history"
describeTransition ForgetDeadRemotes = "forget dead remotes"
noTransitions :: Transitions
noTransitions = S.empty
addTransition :: VectorClock -> Transition -> Transitions -> Transitions
addTransition c t = S.insert $ TransitionLine c (Right t)
buildTransitions :: Transitions -> Builder
buildTransitions = mconcat . map genline . S.elems
where
genline tl = buildt (transition tl) <> charUtf8 ' '
<> buildVectorClock (transitionStarted tl) <> charUtf8 '\n'
buildt (Left b) = byteString b
buildt (Right t) = byteString (encodeBS (show t))
parseTransitions :: L.ByteString -> Transitions
parseTransitions = fromMaybe S.empty . A.maybeResult . A.parse
(S.fromList <$> parseLogLines transitionLineParser)
parseTransitionsStrictly :: String -> L.ByteString -> Transitions
parseTransitionsStrictly source b =
let ts = parseTransitions b
in if S.null $ S.filter (isLeft . transition) ts
then ts
else giveup $ "unknown transitions listed in " ++ source ++ "; upgrade git-annex!"
showTransitionLine :: TransitionLine -> String
showTransitionLine (TransitionLine c t) = unwords [show t, formatVectorClock c]
transitionLineParser :: A.Parser TransitionLine
transitionLineParser = do
t <- (parsetransition <$> A.takeByteString)
_ <- A8.char ' '
c <- vectorClockParser
return $ TransitionLine c t
where
parsetransition b = case readish (decodeBS b) of
Just t -> Right t
Nothing -> Left b
combineTransitions :: [Transitions] -> Transitions
combineTransitions = S.unions
{- Unknown types of transitions are omitted. -}
knownTransitionList :: Transitions -> [Transition]
knownTransitionList = nub . rights . map transition . S.elems
{- Typically ran with Annex.Branch.change, but we can't import Annex.Branch
- here since it depends on this module. -}
recordTransitions :: (FilePath -> (L.ByteString -> Builder) -> Annex ()) -> Transitions -> Annex ()
recordTransitions changer t = changer transitionsLog $
buildTransitions . S.union t . parseTransitionsStrictly "local"