split fediChordJoin into general purpose and bootstrapping part

src/Hash2Pub/FediChord.hs

@@ -38,6 +38,7 @@ module Hash2Pub.FediChord (
   , FediChordConf(..)
   , fediChordInit
   , fediChordJoin
+  , fediChordBootstrapJoin
   , nodeStateInit
   , mkServerSocket
   , mkSendSocket
@@ -110,11 +111,13 @@ nodeStateInit conf = do
                                            }
     pure initialState
 
-fediChordJoin :: LocalNodeState              -- ^ the local 'NodeState'
-              -> (String, PortNumber)   -- ^ domain and port of a bootstrapping node
-              -> IO (Either String LocalNodeState) -- ^ the joined 'NodeState' after a
+-- | Join a new node into the DHT, using a provided bootstrap node as initial cache seed
+-- for resolving the new node's position.
+fediChordBootstrapJoin :: LocalNodeState              -- ^ the local 'NodeState'
+                        -> (String, PortNumber)   -- ^ domain and port of a bootstrapping node
+                        -> IO (Either String LocalNodeState) -- ^ the joined 'NodeState' after a
                                             -- successful join, otherwise an error message
-fediChordJoin ns (joinHost, joinPort) = do
+fediChordBootstrapJoin ns (joinHost, joinPort) = do
     -- can be invoked multiple times with all known bootstrapping nodes until successfully joined
     sock <- mkSendSocket joinHost joinPort
     -- 1. get routed to placement of own ID until FOUND:
@@ -133,18 +136,24 @@ fediChordJoin ns (joinHost, joinPort) = do
                        Just (FORWARD resultset) -> foldr' (addCacheEntryPure now) cacheAcc resultset
                           )
                        initCache bootstrapResponse
-           -- get routed to the currently responsible node, based on the response
-           -- from the bootstrapping node
-           currentlyResponsible <- queryIdLookupLoop bootstrapCache ns $ getNid ns
-           -- do actual join
-           joinResult <- requestJoin currentlyResponsible ns
-           case joinResult of
-             Nothing -> pure . Left $ "Error joining on " <> show currentlyResponsible
-             Just joinedNS -> pure . Right $ joinedNS
-
+           fediChordJoin bootstrapCache ns
 
+-- | join a node to the DHT, using the provided cache snapshot for resolving the new
+-- node's position.
+fediChordJoin :: NodeCache                          -- ^ a snapshot of the NodeCache to
+                                                    -- use for ID lookup
+              -> LocalNodeState                     -- ^ the local 'NodeState'
+              -> IO (Either String LocalNodeState)  -- ^ the joined 'NodeState' after a
+                                                    -- successful join, otherwise an error message
+fediChordJoin cacheSnapshot ns = do
+    -- get routed to the currently responsible node, based on the response
+    -- from the bootstrapping node
+    currentlyResponsible <- queryIdLookupLoop cacheSnapshot ns $ getNid ns
     -- 2. then send a join to the currently responsible node
-    -- after successful join, finally add own node to the cache
+    joinResult <- requestJoin currentlyResponsible ns
+    case joinResult of
+      Nothing -> pure . Left $ "Error joining on " <> show currentlyResponsible
+      Just joinedNS -> pure . Right $ joinedNS
 
 
 -- | cache updater thread that waits for incoming NodeCache update instructions on

src/Hash2Pub/Main.hs

@@ -18,7 +18,7 @@ main = do
     -- currently no masking is necessary, as there is nothing to clean up
     cacheWriterThread <- forkIO $ cacheWriter thisNode
     -- idea: list of bootstrapping nodes, try joining within a timeout
-    joinedState <- fediChordJoin thisNode $ head . confBootstrapNodes $ conf
+    joinedState <- fediChordBootstrapJoin thisNode $ head . confBootstrapNodes $ conf
     -- stop main thread from terminating during development
     getChar
     pure ()