107 lines
3.5 KiB
Haskell
107 lines
3.5 KiB
Haskell
{- git-annex branch state management
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-
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- Runtime state about the git-annex branch, and a small cache.
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-
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- Copyright 2011-2020 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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module Annex.BranchState where
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import Annex.Common
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import Types.BranchState
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import qualified Annex
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import Logs
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import qualified Data.ByteString.Lazy as L
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getState :: Annex BranchState
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getState = Annex.getState Annex.branchstate
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changeState :: (BranchState -> BranchState) -> Annex ()
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changeState changer = Annex.changeState $ \s ->
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s { Annex.branchstate = changer (Annex.branchstate s) }
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{- Runs an action to check that the index file exists, if it's not been
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- checked before in this run of git-annex. -}
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checkIndexOnce :: Annex () -> Annex ()
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checkIndexOnce a = unlessM (indexChecked <$> getState) $ do
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a
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changeState $ \s -> s { indexChecked = True }
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{- Runs an action to update the branch, if it's not been updated before
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- in this run of git-annex.
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-
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- The action should return True if anything that was in the journal
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- before got staged (or if the journal was empty). That lets an opmisation
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- be done: The journal then does not need to be checked going forward,
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- until new information gets written to it.
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-}
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runUpdateOnce :: Annex Bool -> Annex BranchState
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runUpdateOnce a = do
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st <- getState
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if branchUpdated st
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then return st
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else do
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journalstaged <- a
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let stf = \st' -> st'
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{ branchUpdated = True
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, journalIgnorable = journalstaged
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&& not (needInteractiveAccess st')
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}
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changeState stf
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return (stf st)
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{- Avoids updating the branch. A useful optimisation when the branch
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- is known to have not changed, or git-annex won't be relying on info
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- queried from it being as up-to-date as possible. -}
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disableUpdate :: Annex ()
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disableUpdate = changeState $ \s -> s { branchUpdated = True }
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{- Called when a change is made to the journal. -}
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journalChanged :: Annex ()
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journalChanged = do
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-- Optimisation: Typically journalIgnorable will already be True
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-- (when one thing gets journalled, often other things do to),
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-- so avoid an unnecessary write to the MVar that changeState
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-- would do.
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--
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-- This assumes that another thread is not changing journalIgnorable
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-- at the same time, but since runUpdateOnce is the only
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-- thing that changes it, and it only runs once, that
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-- should not happen.
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st <- getState
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when (journalIgnorable st) $
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changeState $ \st' -> st' { journalIgnorable = False }
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{- When git-annex is somehow interactive, eg in --batch mode,
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- and needs to always notice changes made to the journal by other
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- processes, this disables optimisations that avoid normally reading the
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- journal.
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-
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- It also avoids using the cache, so changes committed by other processes
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- will be seen.
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-}
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enableInteractiveBranchAccess :: Annex ()
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enableInteractiveBranchAccess = changeState $
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\s -> s { needInteractiveAccess = True }
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setCache :: RawFilePath -> L.ByteString -> Annex ()
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setCache file content = changeState $ \s -> s
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{ cachedFileContents = add (cachedFileContents s) }
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where
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add l
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| length l < logFilesToCache = (file, content) : l
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| otherwise = (file, content) : Prelude.init l
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getCache :: RawFilePath -> Annex (Maybe L.ByteString)
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getCache file = (\st -> go (cachedFileContents st) st) <$> getState
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where
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go [] _ = Nothing
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go ((f,c):rest) state
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| f == file && not (needInteractiveAccess state) = Just c
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| otherwise = go rest state
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invalidateCache :: Annex ()
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invalidateCache = changeState $ \s -> s { cachedFileContents = [] }
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