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ConsistentHashing
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| module ConsistentHash where | |
| import Data.Map as M | |
| import Data.List as L | |
| import Data.ByteString.Lazy.Char8 | |
| import Data.Digest.Pure.MD5 hiding (hash) | |
| type Key = String | |
| type Node = Key | |
| type Nodes = [Node] | |
| type CH = (Map Key Node, Node) | |
| create :: Nodes -> CH | |
| create nodes = (circle, (L.head nodes)) | |
| where circle = M.fromList $ L.map (\n -> (hash n, n)) nodes | |
| hash :: Key -> String | |
| hash key = show $ md5 $ pack key | |
| get :: CH -> Key -> Node | |
| get (circle, firstNode) key = case M.lookupGE (hash key) circle of | |
| Just (k, n) -> n | |
| Nothing -> firstNode |
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| {-# LANGUAGE OverloadedStrings #-} | |
| import ConsistentHash | |
| import Data.List as L | |
| import Data.Map as M | |
| main = do | |
| let nodes = ["n1", "n2", "n3", "n4", "n5", "n6"] | |
| let ds = ['a'..'z'] | |
| let emptyStat = M.fromList $ L.map (\n -> (n, [])) nodes | |
| let ch = create nodes | |
| let foundNodes = L.map (\d -> (d, ((get ch).show) d)) ds | |
| print $ L.foldl (\st (d, n) -> M.adjust (++[d]) n st) emptyStat foundNodes |
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