catch and handle more join errors

src/Hash2Pub/DHTProtocol.hs

@@ -23,10 +23,10 @@ module Hash2Pub.DHTProtocol
         where
 
 import           Control.Concurrent.Async
-import           Control.Exception
 import           Control.Concurrent.STM
 import           Control.Concurrent.STM.TBQueue
 import           Control.Concurrent.STM.TQueue
+import           Control.Exception
 import           Control.Monad                  (foldM, forM, forM_)
 import qualified Data.ByteString                as BS
 import           Data.Either                    (rights)
@@ -146,7 +146,7 @@ markCacheEntryAsVerified timestamp = Map.adjust adjustFunc
 -- | send a join request and return the joined 'LocalNodeState' including neighbours
 requestJoin :: NodeState a => a             -- ^ currently responsible node to be contacted
             -> LocalNodeState               -- ^ joining NodeState
-            -> IO (Maybe LocalNodeState)    -- ^ node after join with all its new information
+            -> IO (Either String LocalNodeState)    -- ^ node after join with all its new information
 requestJoin toJoinOn ownState =
     bracket (mkSendSocket (getDomain toJoinOn) (getDhtPort toJoinOn)) close (\sock -> do
         responses <- sendRequestTo 5000 3 (\rid -> Request rid (toRemoteNodeState ownState) 1 1 Join (Just JoinRequestPayload)) sock
@@ -166,10 +166,11 @@ requestJoin toJoinOn ownState =
             (setPredecessors [] . setSuccessors [] $ ownState)
             responses
         if responses == Set.empty
-           then pure Nothing
+           then pure . Left $ "join error: got no response from " <> show (getNid toJoinOn)
             -- sort successors and predecessors
-           else pure . Just . setSuccessors (sortBy localCompare $ successors joinedStateUnsorted) . setPredecessors (sortBy localCompare $ predecessors joinedStateUnsorted) $ joinedStateUnsorted
+           else pure . Right . setSuccessors (sortBy localCompare $ successors joinedStateUnsorted) . setPredecessors (sortBy localCompare $ predecessors joinedStateUnsorted) $ joinedStateUnsorted
                                                                             )
+        `catch` (\e -> pure . Left $ displayException (e :: IOException))
 
 
 -- | Send a 'QueryID' 'Request' for getting the node that handles a certain key ID.

src/Hash2Pub/FediChord.hs

@@ -154,8 +154,8 @@ fediChordJoin cacheSnapshot ns = do
     -- 2. then send a join to the currently responsible node
     joinResult <- requestJoin currentlyResponsible ns
     case joinResult of
-      Nothing -> pure . Left $ "Error joining on " <> show currentlyResponsible
+      Left err       -> pure . Left $ "Error joining on " <> err
-      Just joinedNS -> pure . Right $ joinedNS
+      Right joinedNS -> pure . Right $ joinedNS
 
 
 -- | cache updater thread that waits for incoming NodeCache update instructions on

src/Hash2Pub/Main.hs

@@ -2,9 +2,9 @@ module Main where
 
 import           Control.Concurrent
 import           Control.Exception
+import           Data.Either
 import           Data.IP            (IPv6, toHostAddress6)
 import           System.Environment
-import           Data.Either
 
 import           Hash2Pub.FediChord