1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
|
module Storage.Merge (
Mergeable(..),
merge, storeMerge,
Generation,
compareGeneration, generationMax,
storedGeneration,
generations,
ancestors,
precedes,
filterAncestors,
findProperty,
) where
import Control.Concurrent.MVar
import qualified Data.ByteString.Char8 as BC
import qualified Data.HashTable.IO as HT
import Data.List
import Data.Maybe
import Data.Set (Set)
import qualified Data.Set as S
import System.IO.Unsafe (unsafePerformIO)
import Storage
import Storage.Internal
import Util
class Storable a => Mergeable a where
mergeSorted :: [Stored a] -> a
merge :: Mergeable a => [Stored a] -> a
merge [] = error "merge: empty list"
merge [x] = fromStored x
merge xs = mergeSorted $ filterAncestors xs
storeMerge :: Mergeable a => [Stored a] -> IO (Stored a)
storeMerge [] = error "merge: empty list"
storeMerge [x] = return x
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 ((== BC.pack "SPREV") . fst) ditems
| otherwise ->
map wrappedLoad $ catMaybes $ map (\case RecRef r -> Just r; _ -> Nothing) $
map snd $ filter ((== BC.pack "PREV") . fst) items
_ -> []
nextGeneration :: [Generation] -> Generation
nextGeneration = foldl' helper (Generation 0)
where helper (Generation c) (Generation n) | c <= n = Generation (n + 1)
| otherwise = Generation c
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
findProperty :: forall a b. Storable a => (a -> Maybe b) -> [Stored a] -> [b]
findProperty sel = map (fromJust . sel . fromStored) . filterAncestors . (findPropHeads =<<)
where findPropHeads :: Stored a -> [Stored a]
findPropHeads sobj | Just _ <- sel $ fromStored sobj = [sobj]
| otherwise = findPropHeads =<< previous sobj
|