5c960601aa
I want this as fast as possible, so it can be added to code paths without slowing them down. Avoid the set lookup, and rely on laziness, drops runtime from 14.37 ns to 11.03 ns according to this criterion benchmark: import Criterion.Main import qualified Types.Difference as New import qualified Types.DifferenceOld as Old main :: IO () main = defaultMain [ bgroup "hasDifference" [ bench "new" $ whnf (New.hasDifference New.OneLevelObjectHash) new , bench "old" $ whnf (Old.hasDifference Old.OneLevelObjectHash) old ] ] where s = "fromList [ObjectHashLower, OneLevelObjectHash, OneLevelBranchHash]" new = New.readDifferences s old = Old.readDifferences s A little bit of added boilerplate, but I suppose it's worth it to not need to worry about set lookup overhead. Note that adding more differences would slow down the old implementation; the new implementation will run the same speed.
126 lines
3.9 KiB
Haskell
126 lines
3.9 KiB
Haskell
{- git-annex repository differences
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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 Types.Difference (
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Difference(..),
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Differences(..),
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readDifferences,
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showDifferences,
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getDifferences,
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differenceConfigKey,
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differenceConfigVal,
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hasDifference,
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listDifferences,
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) where
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import Utility.PartialPrelude
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import qualified Git
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import qualified Git.Config
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import Data.Maybe
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import Data.Monoid
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import Prelude
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import qualified Data.Set as S
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-- Describes differences from the v5 repository format.
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--
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-- The serialization is stored in difference.log, so avoid changes that
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-- would break compatability.
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--
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-- Not breaking compatability is why a list of Differences is used, rather
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-- than a record type. With a record type, adding a new field for some future
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-- difference would serialize to a value that an older version could not
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-- parse, even if that new field was not used. With the Differences list,
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-- old versions can still parse it, unless the new Difference constructor
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-- is used.
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--
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-- The constructors intentionally do not have parameters; this is to
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-- ensure that any Difference that can be expressed is supported.
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-- So, a new repository version would be Version6, rather than Version Int.
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data Difference
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= ObjectHashLower
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| OneLevelObjectHash
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| OneLevelBranchHash
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deriving (Show, Read, Eq, Ord, Enum, Bounded)
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-- This type is used internally for efficient checking for differences,
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-- but converted to S.Set Difference for serialization.
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data Differences
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= Differences
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{ objectHashLower :: Bool
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, oneLevelObjectHash :: Bool
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, oneLevelBranchHash :: Bool
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}
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| UnknownDifferences
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-- UnknownDifferences cannot be equal
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instance Eq Differences where
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UnknownDifferences == _ = False
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_ == UnknownDifferences = False
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a == b = all (\f -> f a == f b)
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[ objectHashLower
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, oneLevelObjectHash
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, oneLevelBranchHash
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]
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instance Monoid Differences where
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mempty = Differences False False False
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mappend a@(Differences {}) b@(Differences {}) = a
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{ objectHashLower = objectHashLower a || objectHashLower b
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, oneLevelObjectHash = oneLevelObjectHash a || oneLevelObjectHash b
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, oneLevelBranchHash = oneLevelBranchHash a || oneLevelBranchHash b
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}
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mappend _ _ = UnknownDifferences
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readDifferences :: String -> Differences
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readDifferences = maybe UnknownDifferences mkDifferences . readish
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showDifferences :: Differences -> String
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showDifferences = show . S.fromList . listDifferences
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getDifferences :: Git.Repo -> Differences
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getDifferences r = mkDifferences $ S.fromList $
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mapMaybe getmaybe [minBound .. maxBound]
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where
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getmaybe d = case Git.Config.isTrue =<< Git.Config.getMaybe (differenceConfigKey d) r of
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Just True -> Just d
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_ -> Nothing
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differenceConfigKey :: Difference -> String
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differenceConfigKey ObjectHashLower = tunable "objecthashlower"
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differenceConfigKey OneLevelObjectHash = tunable "objecthash1"
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differenceConfigKey OneLevelBranchHash = tunable "branchhash1"
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differenceConfigVal :: Difference -> String
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differenceConfigVal _ = Git.Config.boolConfig True
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tunable :: String -> String
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tunable k = "annex.tune." ++ k
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hasDifference :: Difference -> Differences -> Bool
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hasDifference _ UnknownDifferences = False
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hasDifference ObjectHashLower ds = objectHashLower ds
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hasDifference OneLevelObjectHash ds = oneLevelObjectHash ds
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hasDifference OneLevelBranchHash ds = oneLevelBranchHash ds
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listDifferences :: Differences -> [Difference]
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listDifferences d@(Differences {}) = map snd $
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filter (\(f, _) -> f d)
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[ (objectHashLower, ObjectHashLower)
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, (oneLevelObjectHash, OneLevelObjectHash)
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, (oneLevelBranchHash, OneLevelBranchHash)
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]
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listDifferences UnknownDifferences = []
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mkDifferences :: S.Set Difference -> Differences
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mkDifferences s = Differences
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{ objectHashLower = check ObjectHashLower
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, oneLevelObjectHash = check OneLevelObjectHash
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, oneLevelBranchHash = check OneLevelBranchHash
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}
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where
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check f = f `S.member` s
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