make setPredecessors and setSuccessors enforce the ordering + size limit

closes #47

src/Hash2Pub/DHTProtocol.hs

@@ -228,8 +228,8 @@ respondLeave nsSTM msgSet = do
         writeTQueue (cacheWriteQueue nsSnap) $ deleteCacheEntry senderID
         writeTVar nsSTM $
             -- add predecessors and successors of leaving node to own lists
-            setPredecessors (take (kNeighbours nsSnap) . delete senderID . nub . sortBy (flip localCompare) $ requestPreds <> predecessors nsSnap)
-          . setSuccessors (take (kNeighbours nsSnap) . delete senderID . nub . sortBy localCompare $ requestSuccs <> successors nsSnap) $ nsSnap
+            setPredecessors (delete senderID $ requestPreds <> predecessors nsSnap)
+          . setSuccessors (delete senderID $ requestSuccs <> successors nsSnap) $ nsSnap
         -- TODO: handle handover of key data
         let leaveResponse = Response {
                 responseTo = requestID aRequestPart
@@ -301,7 +301,7 @@ respondJoin nsSTM msgSet = do
         then do
         -- if yes, adjust own predecessors/ successors and return those in a response
            let
-             newPreds = take (kNeighbours nsSnap) . nub . sortBy (flip localCompare) $ getNid senderNS:predecessors nsSnap
+             newPreds = getNid senderNS:predecessors nsSnap
              joinedNS = setPredecessors newPreds nsSnap
              responsePayload = JoinResponsePayload {
                 joinSuccessors = successors joinedNS

src/Hash2Pub/FediChordTypes.hs

@@ -32,6 +32,7 @@ module Hash2Pub.FediChordTypes (
                            ) where
 
 import           Control.Exception
+import           Data.List                     (delete, nub, sortBy)
 import qualified Data.Map.Strict               as Map
 import           Data.Maybe                    (fromMaybe, isJust, mapMaybe)
 import qualified Data.Set                      as Set
@@ -213,11 +214,11 @@ instance Typeable a => Show (TQueue a) where
 
 -- | convenience function that updates the successors of a 'LocalNodeState'
 setSuccessors :: [NodeID] -> LocalNodeState -> LocalNodeState
-setSuccessors succ' ns = ns {successors = succ'}
+setSuccessors succ' ns = ns {successors = take (kNeighbours ns) . nub . sortBy localCompare $ succ'}
 
 -- | convenience function that updates the predecessors of a 'LocalNodeState'
 setPredecessors :: [NodeID] -> LocalNodeState -> LocalNodeState
-setPredecessors pred' ns = ns {predecessors = pred'}
+setPredecessors pred' ns = ns {predecessors = take (kNeighbours ns) . nub . sortBy (flip localCompare)  $ pred'}
 
 type NodeCache = Map.Map NodeID CacheEntry