resume properly when copying a file to/from a local git remote is interrupted
Probably this fixes a reversion, but I don't know what version broke it. This does use withOtherTmp for a temp file that could be quite large. Though albeit a reflink copy that will not actually take up any space as long as the file it was copied from still exists. So if the copy cow succeeds but git-annex is interrupted just before that temp file gets renamed into the usual .git/annex/tmp/ location, there is a risk that the other temp directory ends up cluttered with a larger temp file than later. It will eventually be cleaned up, and the changes of this being a problem are small, so this seems like an acceptable thing to do. Sponsored-by: Shae Erisson on Patreon
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5 changed files with 48 additions and 10 deletions
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@ -15,6 +15,8 @@ import Utility.CopyFile
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import Utility.FileMode
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import Utility.Touch
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import Utility.Hash (IncrementalVerifier(..))
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import Annex.Tmp
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import Utility.Tmp
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import Control.Concurrent
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import qualified Data.ByteString as S
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@ -28,23 +30,34 @@ newCopyCoWTried :: IO CopyCoWTried
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newCopyCoWTried = CopyCoWTried <$> newEmptyMVar
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{- Copies a file is copy-on-write is supported. Otherwise, returns False. -}
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tryCopyCoW :: CopyCoWTried -> FilePath -> FilePath -> MeterUpdate -> IO Bool
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tryCopyCoW :: CopyCoWTried -> FilePath -> FilePath -> MeterUpdate -> Annex Bool
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tryCopyCoW (CopyCoWTried copycowtried) src dest meterupdate =
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-- If multiple threads reach this at the same time, they
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-- will both try CoW, which is acceptable.
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ifM (isEmptyMVar copycowtried)
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ifM (liftIO $ isEmptyMVar copycowtried)
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( do
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ok <- docopycow
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void $ tryPutMVar copycowtried ok
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void $ liftIO $ tryPutMVar copycowtried ok
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return ok
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, ifM (readMVar copycowtried)
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, ifM (liftIO $ readMVar copycowtried)
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( docopycow
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, return False
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)
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)
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where
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docopycow = watchFileSize dest meterupdate $
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copyCoW CopyTimeStamps src dest
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-- copyCow needs a destination file that does not exist,
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-- but the dest file might already. So use it with another
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-- temp file, and if it succeeds, rename it into place. If it fails,
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-- the dest file is left as-is, to support resuming.
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docopycow = withOtherTmp $ \othertmp -> liftIO $
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withTmpFileIn (fromRawFilePath othertmp) (takeFileName dest) $ \tmpdest _h -> do
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copied <- watchFileSize tmpdest meterupdate $
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copyCoW CopyTimeStamps src tmpdest
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if copied
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then liftIO $ catchBoolIO $ do
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rename tmpdest dest
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return True
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else return False
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data CopyMethod = CopiedCoW | Copied
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@ -70,7 +83,7 @@ fileCopier :: CopyCoWTried -> FilePath -> FilePath -> MeterUpdate -> Maybe Incre
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fileCopier _ src dest meterupdate iv = docopy
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#else
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fileCopier copycowtried src dest meterupdate iv =
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ifM (liftIO $ tryCopyCoW copycowtried src dest meterupdate)
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ifM (tryCopyCoW copycowtried src dest meterupdate)
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( do
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liftIO $ maybe noop unableIncremental iv
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return CopiedCoW
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