store and initialise lookup cache

contributes to #24

src/Hash2Pub/FediChord.hs

@@ -94,10 +94,12 @@ import           Debug.Trace                   (trace)
 -- ToDo: load persisted state, thus this function already operates in IO
 fediChordInit :: FediChordConf -> IO (Socket, LocalNodeStateSTM)
 fediChordInit initConf = do
+    emptyLookupCache <- newTVarIO Map.empty
     let realNode = RealNode {
             vservers = []
           , nodeConfig = initConf
           , bootstrapNodes = confBootstrapNodes initConf
+          , lookupCacheSTM = emptyLookupCache
                             }
     realNodeSTM <- newTVarIO realNode
     initialState <- nodeStateInit realNodeSTM

src/Hash2Pub/FediChordTypes.hs

@@ -145,6 +145,8 @@ data RealNode = RealNode
     -- ^ holds the initial configuration read at program start
     , bootstrapNodes :: [(String, PortNumber)]
     -- ^ nodes to be used as bootstrapping points, new ones learned during operation
+    , lookupCacheSTM :: TVar LookupCache
+    -- ^ a global cache of looked up keys and their associated nodes
     }
 
 type RealNodeSTM = TVar RealNode
@@ -294,6 +296,9 @@ instance HasKeyID NodeID where
 type NodeCacheEntry = CacheEntry RemoteNodeState
 type NodeCache = RingMap NodeCacheEntry
 
+type LookupCacheEntry = CacheEntry (String, PortNumber)
+type LookupCache = Map.Map NodeID LookupCacheEntry
+
 -- | generic data structure for holding elements with a key and modular lookup
 newtype RingMap a = RingMap { getRingMap :: HasKeyID a => Map.Map NodeID (RingEntry a) }