57 lines
1.5 KiB
Haskell
57 lines
1.5 KiB
Haskell
{- Caching a file's inode, size, and modification time to see when it's changed.
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-
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- Copyright 2013 Joey Hess <joey@kitenet.net>
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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 Utility.InodeCache where
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import Common
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import System.Posix.Types
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import Utility.QuickCheck
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data InodeCache = InodeCache FileID FileOffset EpochTime
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deriving (Eq, Show)
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{- Weak comparison of the inode caches, comparing the size and mtime, but
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- not the actual inode. Useful when inodes have changed, perhaps
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- due to some filesystems being remounted. -}
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compareWeak :: InodeCache -> InodeCache -> Bool
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compareWeak (InodeCache _ size1 mtime1) (InodeCache _ size2 mtime2) =
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size1 == size2 && mtime1 == mtime2
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showInodeCache :: InodeCache -> String
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showInodeCache (InodeCache inode size mtime) = unwords
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[ show inode
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, show size
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, show mtime
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]
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readInodeCache :: String -> Maybe InodeCache
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readInodeCache s = case words s of
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(inode:size:mtime:_) -> InodeCache
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<$> readish inode
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<*> readish size
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<*> readish mtime
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_ -> Nothing
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genInodeCache :: FilePath -> IO (Maybe InodeCache)
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genInodeCache f = catchDefaultIO Nothing $ toInodeCache <$> getFileStatus f
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toInodeCache :: FileStatus -> Maybe InodeCache
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toInodeCache s
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(fileID s)
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(fileSize s)
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(modificationTime s)
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| otherwise = Nothing
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instance Arbitrary InodeCache where
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arbitrary = InodeCache
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<$> arbitrary
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<*> arbitrary
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<*> arbitrary
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prop_read_show_inodecache :: InodeCache -> Bool
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prop_read_show_inodecache c = readInodeCache (showInodeCache c) == Just c
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