actually implement simple relaying of posts

was still missing for #41

src/Hash2Pub/DHTProtocol.hs

@@ -587,7 +587,6 @@ sendQueryIdMessages targetID ns lParam targets = do
 
           nodeConf <- nodeConfig <$> readTVarIO (parentRealNode ns)
           let srcAddr = confIP nodeConf
-          -- ToDo: make attempts and timeout configurable
           queryThreads <- mapM (\resultNode -> async $ bracket (mkSendSocket srcAddr (getDomain resultNode) (getDhtPort resultNode)) close (
               sendRequestTo (confRequestTimeout nodeConf) (confRequestRetries nodeConf) (lookupMessage targetID ns Nothing)
                                                                                                                                    )) targets

src/Hash2Pub/PostService.hs

@@ -17,6 +17,7 @@ import           Control.Monad.IO.Class    (liftIO)
 import           Data.Bifunctor
 import qualified Data.ByteString.Lazy.UTF8 as BSUL
 import qualified Data.ByteString.UTF8      as BSU
+import           Data.Either               (rights)
 import qualified Data.HashMap.Strict       as HMap
 import qualified Data.HashSet              as HSet
 import           Data.Maybe                (fromJust, isJust)
@@ -611,6 +612,33 @@ fetchTagPosts serv = forever $ do
              pure ()
 
 
+-- TODO: paralellelisation
+-- TODO: make sure it doesn't busy-wait
+relayWorker :: PostService d -> IO ()
+relayWorker serv = forever $ do
+    subscriptionMap <- readTVarIO $ subscribers serv
+    -- for each tag, try to deliver some posts to subscriber
+    forM_ subscriptionMap (\(subscriberMapSTM, _, tag) -> do
+        subscriberMap <- readTVarIO subscriberMapSTM
+        forM_ (HMap.toList subscriberMap) (\((subHost, subPort), (postChan, _)) -> do
+            postsToDeliver <- readUpTo 500 postChan
+            response <- runClientM (tagDeliveryClient tag (Txt.unlines postsToDeliver)) (mkClientEnv (httpMan serv) (BaseUrl Http subHost (fromIntegral subPort) ""))
+            -- so far just dropping failed attempts, TODO: retry mechanism
+            -- TODO: stats
+            pure ()
+            )
+        )
+  where
+      readUpTo :: Int -> TChan a -> IO [a]
+      readUpTo 0 _ = pure []
+      readUpTo n chan = do
+          readFromChan <- atomically (tryReadTChan chan)
+          case readFromChan of
+               Nothing -> pure []
+               Just val -> do
+                   moreReads <- readUpTo (pred n) chan
+                   pure (val:moreReads)
+
 -- ======= statistics/measurement and logging =======
 
 data StatsEventType = PostPublishEvent
@@ -713,8 +741,8 @@ evaluateStats timeInterval summedStats =
     -- first sum all event numbers, then divide through number of seconds passed to
     -- get rate per second
     RelayStats
-    { relayReceiveRates = mapRMap (/ intervalSeconds) $ relayReceiveRates summedStats
-    , relayDeliveryRates = mapRMap (/ intervalSeconds) $ relayDeliveryRates summedStats
+    { relayReceiveRates = (/ intervalSeconds) <$> relayReceiveRates summedStats
+    , relayDeliveryRates = (/ intervalSeconds) <$> relayDeliveryRates summedStats
     , postPublishRate = postPublishRate summedStats / intervalSeconds
     , postFetchRate = postFetchRate summedStats / intervalSeconds
     }

src/Hash2Pub/RingMap.hs

@@ -25,6 +25,29 @@ instance (Bounded k, Ord k, Eq a) => Eq (RingMap k a) where
 instance (Bounded k, Ord k, Show k, Show a) => Show (RingMap k a) where
     show rmap = shows ("RingMap " :: String) (show $ getRingMap rmap)
 
+
+instance (Bounded k, Ord k) => Functor (RingMap k) where
+    -- | map a function over all payload values of a 'RingMap'
+    fmap f = RingMap . Map.map traversingF . getRingMap
+      where
+          traversingF (KeyEntry a) = KeyEntry (f a)
+          traversingF (ProxyEntry pointer (Just entry)) = ProxyEntry pointer (Just $ traversingF entry)
+          traversingF (ProxyEntry pointer Nothing) = ProxyEntry pointer Nothing
+
+
+instance (Bounded k, Ord k) => Foldable (RingMap k) where
+    foldr f initVal = Map.foldr traversingFR initVal . getRingMap
+      where
+          traversingFR (KeyEntry a) acc = f a acc
+          traversingFR (ProxyEntry _ Nothing) acc = acc
+          traversingFR (ProxyEntry _ (Just entry)) acc = traversingFR entry acc
+    foldl f initVal = Map.foldl traversingFL initVal . getRingMap
+      where
+          traversingFL acc (KeyEntry a) = f acc a
+          traversingFL acc (ProxyEntry _ Nothing) = acc
+          traversingFL acc (ProxyEntry _ (Just entry)) = traversingFL acc entry
+
+
 -- | entry of a 'RingMap' that holds a value and can also
 -- wrap around the lookup direction at the edges of the name space.
 data RingEntry k a = KeyEntry a
@@ -247,14 +270,3 @@ takeRMapSuccessorsFromTo :: (Bounded k, Ord k, Num k)
                            -> RingMap k a
                            -> [a]
 takeRMapSuccessorsFromTo fromVal toVal rmap = takeEntriesUntil_ rmap rMapLookupSucc toVal fromVal Nothing []
-
-
--- | map a function over all payload values of a 'RingMap'
-mapRMap :: (Bounded k, Ord k, Num k)
-        => (a -> b) -> RingMap k a -> RingMap k b
-mapRMap f = RingMap . Map.map traversingF . getRingMap
-  where
-      --traversingF :: RingEntry k a -> RingEntry k b
-      traversingF (KeyEntry a) = KeyEntry (f a)
-      traversingF (ProxyEntry pointer (Just entry)) = ProxyEntry pointer (Just $ traversingF entry)
-      traversingF (ProxyEntry pointer Nothing) = ProxyEntry pointer Nothing