git-annex/Logs/Presence.hs
Joey Hess 6280af2901
generate more compact git-annex branch for imports
Especially from borg, where the content identifier logs
all end up being the same identical file!

But also, for other imports, the location tracking logs can,
in some cases, be identical files.

Bonus optimisation: Avoid looking up (and parsing when set)
GIT_ANNEX_VECTOR_CLOCK env var every time a log is written to.
Although the lookup does happen at startup even when no
log will be written now.
2020-12-23 15:25:16 -04:00

71 lines
2.1 KiB
Haskell

{- git-annex presence log
-
- This is used to store presence information in the git-annex branch in
- a way that can be union merged.
-
- A line of the log will look like: "date N INFO"
- Where N=1 when the INFO is present, 0 otherwise.
-
- Copyright 2010-2014 Joey Hess <id@joeyh.name>
-
- Licensed under the GNU AGPL version 3 or higher.
-}
module Logs.Presence (
module X,
addLog,
maybeAddLog,
readLog,
logNow,
currentLog,
currentLogInfo,
historicalLogInfo,
) where
import Logs.Presence.Pure as X
import Annex.Common
import Annex.VectorClock
import qualified Annex.Branch
import Git.Types (RefDate)
{- Adds a LogLine to the log, removing any LogLines that are obsoleted by
- adding it. -}
addLog :: RawFilePath -> LogLine -> Annex ()
addLog file line = Annex.Branch.change file $ \b ->
buildLog $ compactLog (line : parseLog b)
{- When a LogLine already exists with the same status and info, but an
- older timestamp, that LogLine is preserved, rather than updating the log
- with a newer timestamp.
-}
maybeAddLog :: RawFilePath -> LogLine -> Annex ()
maybeAddLog file line = Annex.Branch.maybeChange file $ \s -> do
m <- insertNewStatus line $ logMap $ parseLog s
return $ buildLog $ mapLog m
{- Reads a log file.
- Note that the LogLines returned may be in any order. -}
readLog :: RawFilePath -> Annex [LogLine]
readLog = parseLog <$$> Annex.Branch.get
{- Generates a new LogLine with the current time. -}
logNow :: LogStatus -> LogInfo -> Annex LogLine
logNow s i = do
c <- currentVectorClock
return $ LogLine c s i
{- Reads a log and returns only the info that is still in effect. -}
currentLogInfo :: RawFilePath -> Annex [LogInfo]
currentLogInfo file = map info <$> currentLog file
currentLog :: RawFilePath -> Annex [LogLine]
currentLog file = filterPresent <$> readLog file
{- Reads a historical version of a log and returns the info that was in
- effect at that time.
-
- The date is formatted as shown in gitrevisions man page.
-}
historicalLogInfo :: RefDate -> RawFilePath -> Annex [LogInfo]
historicalLogInfo refdate file = map info . filterPresent . parseLog
<$> Annex.Branch.getHistorical refdate file