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module Erebos.Storage.Merge (
Mergeable(..),
merge, storeMerge,
Generation,
showGeneration,
compareGeneration, generationMax,
storedGeneration,
generations,
ancestors,
precedes,
filterAncestors,
storedRoots,
walkAncestors,
findProperty,
findPropertyFirst,
) where
import Control.Concurrent.MVar
import Data.ByteString.Char8 qualified as BC
import Data.HashTable.IO qualified as HT
import Data.Kind
import Data.List
import Data.Maybe
import Data.Set (Set)
import Data.Set qualified as S
import System.IO.Unsafe (unsafePerformIO)
import Erebos.Storage
import Erebos.Storage.Internal
import Erebos.Util
class Storable (Component a) => Mergeable a where
type Component a :: Type
mergeSorted :: [Stored (Component a)] -> a
toComponents :: a -> [Stored (Component a)]
instance Mergeable [Stored Object] where
type Component [Stored Object] = Object
mergeSorted = id
toComponents = id
merge :: Mergeable a => [Stored (Component a)] -> a
merge [] = error "merge: empty list"
merge xs = mergeSorted $ filterAncestors xs
storeMerge :: (Mergeable a, Storable a) => [Stored (Component a)] -> IO (Stored a)
storeMerge [] = error "merge: empty list"
storeMerge xs@(Stored ref _ : _) = wrappedStore (refStorage ref) $ mergeSorted $ filterAncestors xs
previous :: Storable a => Stored a -> [Stored a]
previous (Stored ref _) = case load ref of
Rec items | Just (RecRef dref) <- lookup (BC.pack "SDATA") items
, Rec ditems <- load dref ->
map wrappedLoad $ catMaybes $ map (\case RecRef r -> Just r; _ -> Nothing) $
map snd $ filter ((`elem` [ BC.pack "SPREV", BC.pack "SBASE" ]) . fst) ditems
| otherwise ->
map wrappedLoad $ catMaybes $ map (\case RecRef r -> Just r; _ -> Nothing) $
map snd $ filter ((`elem` [ BC.pack "PREV", BC.pack "BASE" ]) . fst) items
_ -> []
nextGeneration :: [Generation] -> Generation
nextGeneration = foldl' helper (Generation 0)
where helper (Generation c) (Generation n) | c <= n = Generation (n + 1)
| otherwise = Generation c
showGeneration :: Generation -> String
showGeneration (Generation x) = show x
compareGeneration :: Generation -> Generation -> Maybe Ordering
compareGeneration (Generation x) (Generation y) = Just $ compare x y
generationMax :: Storable a => [Stored a] -> Maybe (Stored a)
generationMax (x : xs) = Just $ snd $ foldl' helper (storedGeneration x, x) xs
where helper (mg, mx) y = let yg = storedGeneration y
in case compareGeneration mg yg of
Just LT -> (yg, y)
_ -> (mg, mx)
generationMax [] = Nothing
storedGeneration :: Storable a => Stored a -> Generation
storedGeneration x =
unsafePerformIO $ withMVar (stRefGeneration $ refStorage $ storedRef x) $ \ht -> do
let doLookup y = HT.lookup ht (refDigest $ storedRef y) >>= \case
Just gen -> return gen
Nothing -> do
gen <- nextGeneration <$> mapM doLookup (previous y)
HT.insert ht (refDigest $ storedRef y) gen
return gen
doLookup x
generations :: Storable a => [Stored a] -> [Set (Stored a)]
generations = unfoldr gen . (,S.empty)
where gen (hs, cur) = case filter (`S.notMember` cur) $ previous =<< hs of
[] -> Nothing
added -> let next = foldr S.insert cur added
in Just (next, (added, next))
ancestors :: Storable a => [Stored a] -> Set (Stored a)
ancestors = last . (S.empty:) . generations
precedes :: Storable a => Stored a -> Stored a -> Bool
precedes x y = not $ x `elem` filterAncestors [x, y]
filterAncestors :: Storable a => [Stored a] -> [Stored a]
filterAncestors [x] = [x]
filterAncestors xs = let xs' = uniq $ sort xs
in helper xs' xs'
where helper remains walk = case generationMax walk of
Just x -> let px = previous x
remains' = filter (\r -> all (/=r) px) remains
in helper remains' $ uniq $ sort (px ++ filter (/=x) walk)
Nothing -> remains
storedRoots :: Storable a => Stored a -> [Stored a]
storedRoots x = do
let st = refStorage $ storedRef x
unsafePerformIO $ withMVar (stRefRoots st) $ \ht -> do
let doLookup y = HT.lookup ht (refDigest $ storedRef y) >>= \case
Just roots -> return roots
Nothing -> do
roots <- case previous y of
[] -> return [refDigest $ storedRef y]
ps -> map (refDigest . storedRef) . filterAncestors . map (wrappedLoad @Object . Ref st) . concat <$> mapM doLookup ps
HT.insert ht (refDigest $ storedRef y) roots
return roots
map (wrappedLoad . Ref st) <$> doLookup x
walkAncestors :: (Storable a, Monoid m) => (Stored a -> m) -> [Stored a] -> m
walkAncestors f = helper . sortBy cmp
where
helper (x : y : xs) | x == y = helper (x : xs)
helper (x : xs) = f x <> helper (mergeBy cmp (sortBy cmp (previous x)) xs)
helper [] = mempty
cmp x y = case compareGeneration (storedGeneration x) (storedGeneration y) of
Just LT -> GT
Just GT -> LT
_ -> compare x y
findProperty :: forall a b. Storable a => (a -> Maybe b) -> [Stored a] -> [b]
findProperty sel = map (fromJust . sel . fromStored) . filterAncestors . (findPropHeads sel =<<)
findPropertyFirst :: forall a b. Storable a => (a -> Maybe b) -> [Stored a] -> Maybe b
findPropertyFirst sel = fmap (fromJust . sel . fromStored) . listToMaybe . filterAncestors . (findPropHeads sel =<<)
findPropHeads :: forall a b. Storable a => (a -> Maybe b) -> Stored a -> [Stored a]
findPropHeads sel sobj | Just _ <- sel $ fromStored sobj = [sobj]
| otherwise = findPropHeads sel =<< previous sobj
|