67 lines
1.7 KiB
Haskell
67 lines
1.7 KiB
Haskell
{- git-annex concurrent state
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-
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- Copyright 2015 Joey Hess <id@joeyh.name>
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-
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- Licensed under the GNU GPL version 3 or higher.
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-}
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module Annex.Concurrent where
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import Annex.Common
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import Annex
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import Annex.CatFile
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import Annex.CheckAttr
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import Annex.CheckIgnore
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import qualified Annex.Queue
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import qualified Data.Map as M
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{- Allows forking off a thread that uses a copy of the current AnnexState
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- to run an Annex action.
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-
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- The returned IO action can be used to start the thread.
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- It returns an Annex action that must be run in the original
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- calling context to merge the forked AnnexState back into the
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- current AnnexState.
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-}
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forkState :: Annex a -> Annex (IO (Annex a))
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forkState a = do
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st <- dupState
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return $ do
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(ret, newst) <- run st a
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return $ do
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mergeState newst
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return ret
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{- Returns a copy of the current AnnexState that is safe to be
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- used when forking off a thread.
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-
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- After an Annex action is run using this AnnexState, it
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- should be merged back into the current Annex's state,
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- by calling mergeState.
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-}
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dupState :: Annex AnnexState
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dupState = do
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st <- Annex.getState id
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-- avoid sharing eg, open file handles
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return $ st
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{ Annex.workers = []
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, Annex.catfilehandles = M.empty
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, Annex.checkattrhandle = Nothing
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, Annex.checkignorehandle = Nothing
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}
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{- Merges the passed AnnexState into the current Annex state.
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- Also closes various handles in it. -}
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mergeState :: AnnexState -> Annex ()
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mergeState st = do
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st' <- liftIO $ snd <$> run st closehandles
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forM_ (M.toList $ Annex.cleanup st') $
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uncurry addCleanup
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Annex.Queue.mergeFrom st'
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changeState $ \s -> s { errcounter = errcounter s + errcounter st' }
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where
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closehandles = do
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catFileStop
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checkAttrStop
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checkIgnoreStop
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