e213ef310f
* Fix minor FD leak in journal code. Closes: #754608 * direct: Fix handling of case where a work tree subdirectory cannot be written to due to permissions. * migrate: Avoid re-checksumming when migrating from hashE to hash backend. * uninit: Avoid failing final removal in some direct mode repositories due to file modes. * S3: Deal with AWS ACL configurations that do not allow creating or checking the location of a bucket, but only reading and writing content to it. * resolvemerge: New plumbing command that runs the automatic merge conflict resolver. * Deal with change in git 2.0 that made indirect mode merge conflict resolution leave behind old files. * sync: Fix git sync with local git remotes even when they don't have an annex.uuid set. (The assistant already did so.) * Set gcrypt-publish-participants when setting up a gcrypt repository, to avoid unncessary passphrase prompts. This is a security/usability tradeoff. To avoid exposing the gpg key ids who can decrypt the repository, users can unset gcrypt-publish-participants. * Install nautilus hooks even when ~/.local/share/nautilus/ does not yet exist, since it is not automatically created for Gnome 3 users. * Windows: Move .vbs files out of git\bin, to avoid that being in the PATH, which caused some weird breakage. (Thanks, divB) * Windows: Fix locking issue that prevented the webapp starting (since 5.20140707). # imported from the archive
69 lines
2 KiB
Haskell
69 lines
2 KiB
Haskell
{- Transactional lists
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-
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- Based on DLists, a transactional list can quickly and efficiently
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- have items inserted at either end, or a whole list appended to it.
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-
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- Unlike a TQueue, the entire contents of a TList can be efficiently
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- read without modifying it.
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-
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- Copyright 2013 Joey Hess <joey@kitenet.net>
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-}
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{-# LANGUAGE BangPatterns #-}
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module Utility.TList where
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import Common
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import Control.Concurrent.STM
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import qualified Data.DList as D
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type TList a = TMVar (D.DList a)
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newTList :: STM (TList a)
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newTList = newEmptyTMVar
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{- Gets the contents of the TList. Blocks when empty.
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- TList is left empty. -}
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getTList :: TList a -> STM [a]
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getTList tlist = D.toList <$> getTDList tlist
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getTDList :: TList a -> STM (D.DList a)
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getTDList = takeTMVar
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{- Replaces the contents of the TList. -}
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setTList :: TList a -> [a] -> STM ()
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setTList tlist = setTDList tlist . D.fromList
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setTDList :: TList a -> D.DList a -> STM ()
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setTDList tlist = modifyTList tlist . const
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{- Takes anything currently in the TList, without blocking.
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- TList is left empty. -}
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takeTList :: TList a -> STM [a]
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takeTList tlist = maybe [] D.toList <$> tryTakeTMVar tlist
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{- Reads anything in the list, without modifying it, or blocking. -}
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readTList :: TList a -> STM [a]
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readTList tlist = maybe [] D.toList <$> tryReadTMVar tlist
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{- Mutates a TList. -}
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modifyTList :: TList a -> (D.DList a -> D.DList a) -> STM ()
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modifyTList tlist a = do
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dl <- fromMaybe D.empty <$> tryTakeTMVar tlist
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let !dl' = a dl
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{- The TMVar is left empty when the list is empty.
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- Thus attempts to read it automatically block. -}
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unless (emptyDList dl') $
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putTMVar tlist dl'
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where
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emptyDList = D.list True (\_ _ -> False)
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consTList :: TList a -> a -> STM ()
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consTList tlist v = modifyTList tlist $ \dl -> D.cons v dl
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snocTList :: TList a -> a -> STM ()
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snocTList tlist v = modifyTList tlist $ \dl -> D.snoc dl v
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appendTList :: TList a -> [a] -> STM ()
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appendTList tlist l = modifyTList tlist $ \dl -> D.append dl (D.fromList l)
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