app/Main.hs

@@ -21,8 +21,17 @@ main = do
     (serverSock, thisNode) <- fediChordInit conf
     -- currently no masking is necessary, as there is nothing to clean up
     cacheWriterThread <- forkIO $ cacheWriter thisNode
+    thisNodeSnap <- readTVarIO thisNode
+    realNode <- readTVarIO $ parentRealNode thisNodeSnap
     -- try joining the DHT using one of the provided bootstrapping nodes
-    joinedState <- tryBootstrapJoining thisNode
+    let
+        tryJoining (bn:bns) = do
+            j <- fediChordBootstrapJoin thisNode bn
+            case j of
+              Left err -> putStrLn ("join error: " <> err) >> tryJoining bns
+              Right joined -> pure $ Right joined
+        tryJoining [] = pure $ Left "Exhausted all bootstrap points for joining."
+    joinedState <- tryJoining $ bootstrapNodes realNode
     either (\err -> do
         -- handle unsuccessful join
 
@@ -50,5 +59,4 @@ readConfig = do
       , confDhtPort = read portString
       , confBootstrapNodes = [(bootstrapHost, read bootstrapPortString)]
       --, confStabiliseInterval = 60
-      , confBootstrapSamplingInterval = 180
                            }

src/Hash2Pub/FediChord.hs

@@ -40,7 +40,6 @@ module Hash2Pub.FediChord (
   , fediChordInit
   , fediChordJoin
   , fediChordBootstrapJoin
-  , tryBootstrapJoining
   , fediMainThreads
   , RealNode (..)
   , nodeStateInit
@@ -82,7 +81,6 @@ import           Network.Socket                hiding (recv, recvFrom, send,
                                                 sendTo)
 import           Network.Socket.ByteString
 import           Safe
-import           System.Random                 (randomRIO)
 
 import           Hash2Pub.DHTProtocol
 import           Hash2Pub.FediChordTypes
@@ -143,82 +141,17 @@ fediChordBootstrapJoin :: LocalNodeStateSTM              -- ^ the local 'NodeSta
                         -> (String, PortNumber)   -- ^ domain and port of a bootstrapping node
                         -> IO (Either String LocalNodeStateSTM) -- ^ the joined 'NodeState' after a
                                             -- successful join, otherwise an error message
-fediChordBootstrapJoin nsSTM bootstrapNode = do
+fediChordBootstrapJoin nsSTM (joinHost, joinPort) =
     -- can be invoked multiple times with all known bootstrapping nodes until successfully joined
-    ns <- readTVarIO nsSTM
-    runExceptT $ do
-        -- 1. get routed to the currently responsible node
-        lookupResp <- liftIO $ bootstrapQueryId nsSTM bootstrapNode $ getNid ns
-        currentlyResponsible <- liftEither lookupResp
-        liftIO . putStrLn $ "Trying to join on " <> show (getNid currentlyResponsible)
-        -- 2. then send a join to the currently responsible node
-        joinResult <- liftIO $ requestJoin currentlyResponsible nsSTM
-        liftEither joinResult
-
--- Periodically lookup own ID through a random bootstrapping node to discover and merge separated DHT clusters.
--- Unjoined try joining instead.
-convergenceSampleThread :: LocalNodeStateSTM -> IO ()
-convergenceSampleThread nsSTM = forever $ do
-    nsSnap <- readTVarIO nsSTM
-    parentNode <- readTVarIO $ parentRealNode nsSnap
-    if isJoined nsSnap
-       then
-        runExceptT (do
-            -- joined node: choose random node, do queryIDLoop, compare result with own responsibility
-            let bss = bootstrapNodes parentNode
-            randIndex <- liftIO $ randomRIO (0, length bss - 1)
-            chosenNode <- maybe (throwError "invalid bootstrapping node index") pure $ atMay bss randIndex
-            lookupResult <- liftIO $ bootstrapQueryId nsSTM chosenNode (getNid nsSnap)
-            currentlyResponsible <- liftEither lookupResult
-            if getNid currentlyResponsible /= getNid nsSnap
-               -- if mismatch, stabilise on the result, else do nothing
-               then do
-                   stabResult <- liftIO $ requestStabilise nsSnap currentlyResponsible
-                   (preds, succs) <- liftEither stabResult
-                   -- TODO: verify neighbours before adding, see #55
-                   liftIO . atomically $ do
-                       ns <- readTVar nsSTM
-                       writeTVar nsSTM $ addPredecessors preds ns
-               else pure ()
-                   ) >> pure ()
-    -- unjoined node: try joining through all bootstrapping nodes
-    else tryBootstrapJoining nsSTM >> pure ()
-    let delaySecs = confBootstrapSamplingInterval . nodeConfig $ parentNode
-    threadDelay $ delaySecs * 10^6
-
-
--- | Try joining the DHT through any of the bootstrapping nodes until it succeeds.
-tryBootstrapJoining :: LocalNodeStateSTM -> IO (Either String LocalNodeStateSTM)
-tryBootstrapJoining nsSTM = do
-    bss <- atomically $ do
-        nsSnap <- readTVar nsSTM
-        realNodeSnap <- readTVar $ parentRealNode nsSnap
-        pure $ bootstrapNodes realNodeSnap
-    tryJoining bss
-  where
-    tryJoining (bn:bns) = do
-        j <- fediChordBootstrapJoin nsSTM bn
-        case j of
-          Left err     -> putStrLn ("join error: " <> err) >> tryJoining bns
-          Right joined -> pure $ Right joined
-    tryJoining [] = pure $ Left "Exhausted all bootstrap points for joining."
-
-
--- | Look up a key just based on the responses of a single bootstrapping node.
-bootstrapQueryId :: LocalNodeStateSTM -> (String, PortNumber) -> NodeID -> IO (Either String RemoteNodeState)
-bootstrapQueryId nsSTM (bootstrapHost, bootstrapPort) targetID = do
-    ns <- readTVarIO nsSTM
-    bootstrapResponse <- bracket (mkSendSocket bootstrapHost bootstrapPort) close (
+    bracket (mkSendSocket joinHost joinPort) close (\sock -> do
+        putStrLn "BootstrapJoin"
+        -- 1. get routed to placement of own ID until FOUND:
         -- Initialise an empty cache only with the responses from a bootstrapping node
-        fmap Right . sendRequestTo 5000 3 (lookupMessage targetID ns Nothing)
-                                                                                  )
-       `catch` (\e -> pure . Left $ "Error at bootstrap QueryId: " <> displayException (e :: IOException))
-
-    case bootstrapResponse of
-      Left err -> pure $ Left err
-      Right resp
-        | resp == Set.empty -> pure . Left $ "Bootstrapping node " <> show bootstrapHost <> " gave no response."
-        | otherwise -> do
+        ns <- readTVarIO nsSTM
+        bootstrapResponse <- sendRequestTo 5000 3 (lookupMessage (getNid ns) ns Nothing) sock
+        if bootstrapResponse == Set.empty
+           then pure . Left $ "Bootstrapping node " <> show joinHost <> " gave no response."
+           else do
                now <- getPOSIXTime
                -- create new cache with all returned node responses
                let bootstrapCache =
@@ -228,20 +161,23 @@ bootstrapQueryId nsSTM (bootstrapHost, bootstrapPort) targetID = do
                            Just (FOUND result1) -> addCacheEntryPure now (RemoteCacheEntry result1 now) cacheAcc
                            Just (FORWARD resultset) -> foldr' (addCacheEntryPure now) cacheAcc resultset
                               )
-                           initCache resp
-               currentlyResponsible <- queryIdLookupLoop bootstrapCache ns 50 $ getNid ns
-               pure $ Right currentlyResponsible
+                           initCache bootstrapResponse
+               fediChordJoin bootstrapCache nsSTM
+                                                   )
+       `catch` (\e -> pure . Left $ "Error at bootstrap joining: " <> displayException (e :: IOException))
 
-
--- | join a node to the DHT using the global node cache
+-- | join a node to the DHT, using the provided cache snapshot for resolving the new
 -- node's position.
-fediChordJoin :: LocalNodeStateSTM                    -- ^ the local 'NodeState'
+fediChordJoin :: NodeCache                          -- ^ a snapshot of the NodeCache to
+                                                    -- use for ID lookup
+              -> LocalNodeStateSTM                    -- ^ the local 'NodeState'
               -> IO (Either String LocalNodeStateSTM)  -- ^ the joined 'NodeState' after a
                                                     -- successful join, otherwise an error message
-fediChordJoin nsSTM = do
+fediChordJoin cacheSnapshot nsSTM = do
     ns <- readTVarIO nsSTM
-    -- 1. get routed to the currently responsible node
-    currentlyResponsible <- requestQueryID ns $ getNid ns
+    -- get routed to the currently responsible node, based on the response
+    -- from the bootstrapping node
+    currentlyResponsible <- queryIdLookupLoop cacheSnapshot ns 50 $ getNid ns
     putStrLn $ "Trying to join on " <> show (getNid currentlyResponsible)
     -- 2. then send a join to the currently responsible node
     joinResult <- requestJoin currentlyResponsible nsSTM
@@ -270,7 +206,7 @@ joinOnNewEntriesThread nsSTM = loop
               pure ()
           -- otherwise try joining
           FORWARD _ -> do
-              joinResult <- fediChordJoin nsSTM
+              joinResult <- fediChordJoin cache  nsSTM
               either
                 -- on join failure, sleep and retry
                 -- TODO: make delay configurable
@@ -541,7 +477,6 @@ fediMainThreads sock nsSTM = do
         (fediMessageHandler sendQ recvQ nsSTM) $
         concurrently_ (stabiliseThread nsSTM) $
             concurrently_ (cacheVerifyThread nsSTM) $
-                concurrently_ (convergenceSampleThread nsSTM) $
                 concurrently_
                     (sendThread sock sendQ)
                     (recvThread sock recvQ)

src/Hash2Pub/FediChordTypes.hs

@@ -589,15 +589,10 @@ byteStringToUInteger bs = sum $ parsedBytes 0 bs
 -- | configuration values used for initialising the FediChord DHT
 data FediChordConf = FediChordConf
     { confDomain         :: String
-    -- ^ the domain/ hostname the node is reachable under
     , confIP             :: HostAddress6
-    -- ^ IP address of outgoing packets
     , confDhtPort        :: Int
-    -- ^ listening port for the FediChord DHT
     , confBootstrapNodes :: [(String, PortNumber)]
-    -- ^ list of potential bootstrapping nodes
-    , confBootstrapSamplingInterval :: Int
-    -- ^ pause between sampling the own ID through bootstrap nodes, in seconds
+    --, confStabiliseInterval :: Int
     }
     deriving (Show, Eq)