From 988144e9e7f9f9c22e4f43d5fdcac603d750a217 Mon Sep 17 00:00:00 2001
From: Trolli Schmittlauch <t.schmittlauch@orlives.de>
Date: Sun, 26 Jul 2020 18:55:23 +0200
Subject: [PATCH 01/35] further relax constrains on RingMap

key now needs to be explicitly given at insert, instead of
deriving it from the value. This makes it possible to store values where
a key cannot be extracted from (HasKeyID)

contributes to #62, #32, #41
---
 src/Hash2Pub/RingMap.hs | 155 +++++++++++++++++++++-------------------
 1 file changed, 80 insertions(+), 75 deletions(-)

diff --git a/src/Hash2Pub/RingMap.hs b/src/Hash2Pub/RingMap.hs
index 529a68b..9c7f63b 100644
--- a/src/Hash2Pub/RingMap.hs
+++ b/src/Hash2Pub/RingMap.hs
@@ -10,31 +10,31 @@ import           Data.Maybe      (fromJust, isJust, isNothing, mapMaybe)
 
 -- | Class for all types that can be identified via a EpiChord key.
 -- Used for restricting the types a 'RingMap' can store
-class (Eq a, Show a, Bounded k, Ord k) => HasKeyID a k where
+class (Eq a, Show a, Bounded k, Ord k) => HasKeyID k a where
     getKeyID :: a -> k
 
 
 -- | generic data structure for holding elements with a key and modular lookup
-newtype RingMap a k = RingMap { getRingMap :: (HasKeyID a k, Bounded k, Ord k) => Map.Map k (RingEntry a k) }
+newtype RingMap k a = RingMap { getRingMap :: (Bounded k, Ord k) => Map.Map k (RingEntry k a) }
 
-instance (HasKeyID a k, Bounded k, Ord k) => Eq (RingMap a k) where
+instance (Bounded k, Ord k, Eq a) => Eq (RingMap k a) where
     a == b = getRingMap a == getRingMap b
 
-instance (HasKeyID a k, Bounded k, Ord k, Show k) => Show (RingMap a k) where
+instance (Bounded k, Ord k, Show k, Show a) => Show (RingMap k a) where
     show rmap = shows "RingMap " (show $ getRingMap rmap)
 
 -- | 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 a k = KeyEntry a
-    | ProxyEntry (k, ProxyDirection) (Maybe (RingEntry a k))
+data RingEntry k a = KeyEntry a
+    | ProxyEntry (k, ProxyDirection) (Maybe (RingEntry k a))
     deriving (Show, Eq)
 
 -- | as a compromise, only KeyEntry components are ordered by their key
 -- while ProxyEntry components should never be tried to be ordered.
-instance (HasKeyID a k, Eq k, Ord a, Bounded k, Ord k) => Ord (RingEntry a k) where
+instance (HasKeyID k a, Eq k, Ord a, Bounded k, Ord k) => Ord (RingEntry k a) where
     a `compare` b = compare (extractID a) (extractID b)
         where
-            extractID :: (HasKeyID a k, Ord a, Bounded k, Ord k) => RingEntry a k -> k
+            extractID :: (HasKeyID k a, Ord a, Bounded k, Ord k) => RingEntry k a -> k
             extractID (KeyEntry e) = getKeyID e
             extractID ProxyEntry{} = error "proxy entries should never appear outside of the RingMap"
 
@@ -49,51 +49,51 @@ instance Enum ProxyDirection where
     fromEnum Backwards = - 1
     fromEnum Forwards  = 1
 
--- | helper function for getting the a from a RingEntry a k
-extractRingEntry :: (HasKeyID a k, Bounded k, Ord k) => RingEntry a k -> Maybe a
+-- | helper function for getting the a from a RingEntry k a
+extractRingEntry :: (Bounded k, Ord k) => RingEntry k a -> Maybe a
 extractRingEntry (KeyEntry entry)                       = Just entry
 extractRingEntry (ProxyEntry _ (Just (KeyEntry entry))) = Just entry
 extractRingEntry _                                      = Nothing
 
 -- | An empty 'RingMap' needs to be initialised with 2 proxy entries,
 -- linking the modular name space together by connecting @minBound@ and @maxBound@
-emptyRMap :: (HasKeyID a k, Bounded k, Ord k) => RingMap a k
+emptyRMap :: (Bounded k, Ord k) => RingMap k a
 emptyRMap = RingMap . Map.fromList $ proxyEntry <$> [(maxBound, (minBound, Forwards)), (minBound, (maxBound, Backwards))]
   where
     proxyEntry (from,to) = (from, ProxyEntry to Nothing)
 
 -- | Maybe returns the entry stored at given key
-rMapLookup :: (HasKeyID a k, Bounded k, Ord k)
+rMapLookup :: (Bounded k, Ord k)
            => k       -- ^lookup key
-           -> RingMap a k    -- ^lookup cache
+           -> RingMap k a    -- ^lookup cache
            -> Maybe a
 rMapLookup key rmap =  extractRingEntry =<< Map.lookup key (getRingMap rmap)
 
 -- | returns number of present 'KeyEntry' in a properly initialised 'RingMap'
-rMapSize :: (HasKeyID a k, Integral i, Bounded k, Ord k)
-         => RingMap a k
+rMapSize :: (Integral i, Bounded k, Ord k)
+         => RingMap k a
          -> i
 rMapSize rmap = fromIntegral $ Map.size innerMap - oneIfEntry rmap minBound - oneIfEntry rmap maxBound
   where
     innerMap = getRingMap rmap
-    oneIfEntry :: (HasKeyID a k, Integral i, Bounded k, Ord k) => RingMap a k -> k -> i
+    oneIfEntry :: (Integral i, Bounded k, Ord k) => RingMap k a -> k -> i
     oneIfEntry rmap' nid
       | isNothing (rMapLookup nid rmap') = 1
       | otherwise = 0
 
 -- | a wrapper around lookup functions, making the lookup redirectable by a @ProxyEntry@
 -- to simulate a modular ring
-lookupWrapper :: (HasKeyID a k, Bounded k, Ord k, Num k)
-              => (k -> Map.Map k (RingEntry a k) -> Maybe (k, RingEntry a k))
-              -> (k -> Map.Map k (RingEntry a k) -> Maybe (k, RingEntry a k))
+lookupWrapper :: (Bounded k, Ord k, Num k)
+              => (k -> Map.Map k (RingEntry k a) -> Maybe (k, RingEntry k a))
+              -> (k -> Map.Map k (RingEntry k a) -> Maybe (k, RingEntry k a))
               -> ProxyDirection
               -> k
-              -> RingMap a k
-              -> Maybe a
+              -> RingMap k a
+              -> Maybe (k, a)
 lookupWrapper f fRepeat direction key rmap =
     case f key $ getRingMap rmap of
         -- the proxy entry found holds a
-        Just (_, ProxyEntry _ (Just (KeyEntry entry))) -> Just entry
+        Just (foundKey, ProxyEntry _ (Just (KeyEntry entry))) -> Just (foundKey, entry)
         -- proxy entry holds another proxy entry, this should not happen
         Just (_, ProxyEntry _ (Just (ProxyEntry _ _))) -> Nothing
         -- proxy entry without own entry is a pointer on where to continue
@@ -106,10 +106,10 @@ lookupWrapper f fRepeat direction key rmap =
                then lookupWrapper fRepeat fRepeat direction newKey rmap
                else Nothing
         -- normal entries are returned
-        Just (_, KeyEntry entry) -> Just entry
+        Just (foundKey, KeyEntry entry) -> Just (foundKey, entry)
         Nothing -> Nothing
   where
-    rMapNotEmpty :: (HasKeyID a k, Bounded k, Ord k) => RingMap a k -> Bool
+    rMapNotEmpty :: (Bounded k, Ord k) => RingMap k a -> Bool
     rMapNotEmpty rmap' = (Map.size (getRingMap rmap') > 2)     -- there are more than the 2 ProxyEntries
                    || isJust (rMapLookup minBound rmap') -- or one of the ProxyEntries holds a node
                    || isJust (rMapLookup maxBound rmap')
@@ -117,32 +117,34 @@ lookupWrapper f fRepeat direction key rmap =
 -- | find the successor node to a given key on a modular EpiChord ring.
 -- Note: The EpiChord definition of "successor" includes the node at the key itself,
 -- if existing.
-rMapLookupSucc :: (HasKeyID a k, Bounded k, Ord k, Num k)
+rMapLookupSucc :: (Bounded k, Ord k, Num k)
                => k           -- ^lookup key
-               -> RingMap a k       -- ^ring cache
-               -> Maybe a
+               -> RingMap k a       -- ^ring cache
+               -> Maybe (k, a)
 rMapLookupSucc = lookupWrapper Map.lookupGE Map.lookupGE Forwards
 
 -- | find the predecessor node to a given key on a modular EpiChord ring.
-rMapLookupPred :: (HasKeyID a k, Bounded k, Ord k, Num k)
+rMapLookupPred :: (Bounded k, Ord k, Num k)
                => k           -- ^lookup key
-               -> RingMap a k        -- ^ring cache
-               -> Maybe a
+               -> RingMap k a        -- ^ring cache
+               -> Maybe (k, a)
 rMapLookupPred = lookupWrapper Map.lookupLT Map.lookupLE Backwards
 
-addRMapEntryWith :: (HasKeyID a k, Bounded k, Ord k)
-                 => (RingEntry a k -> RingEntry a k -> RingEntry a k)
-                 -> a
-                 -> RingMap a k
-                 -> RingMap a k
-addRMapEntryWith combineFunc entry = RingMap
-    . Map.insertWith combineFunc (getKeyID entry) (KeyEntry entry)
+addRMapEntryWith :: (Bounded k, Ord k)
+                 => (RingEntry k a -> RingEntry k a -> RingEntry k a)
+                 -> k   -- ^ key
+                 -> a   -- ^ value
+                 -> RingMap k a
+                 -> RingMap k a
+addRMapEntryWith combineFunc key entry = RingMap
+    . Map.insertWith combineFunc key (KeyEntry entry)
     . getRingMap
 
-addRMapEntry :: (HasKeyID a k, Bounded k, Ord k)
-             => a
-             -> RingMap a k
-             -> RingMap a k
+addRMapEntry :: (Bounded k, Ord k)
+             => k   -- ^ key
+             -> a   -- ^ value
+             -> RingMap k a
+             -> RingMap k a
 addRMapEntry = addRMapEntryWith insertCombineFunction
   where
     insertCombineFunction newVal oldVal =
@@ -151,30 +153,30 @@ addRMapEntry = addRMapEntryWith insertCombineFunction
           KeyEntry _     -> newVal
 
 
-addRMapEntries :: (Foldable t, HasKeyID a k, Bounded k, Ord k)
-               => t a
-               -> RingMap a k
-               -> RingMap a k
-addRMapEntries entries rmap = foldr' addRMapEntry rmap entries
+addRMapEntries :: (Foldable t, Bounded k, Ord k)
+               => t (k, a)
+               -> RingMap k a
+               -> RingMap k a
+addRMapEntries entries rmap = foldr' (\(k, v) rmap' -> addRMapEntry k v rmap') rmap entries
 
-setRMapEntries :: (Foldable t, HasKeyID a k, Bounded k, Ord k)
-               => t a
-               -> RingMap a k
+setRMapEntries :: (Foldable t, Bounded k, Ord k)
+               => t (k, a)
+               -> RingMap k a
 setRMapEntries entries = addRMapEntries entries emptyRMap
 
-deleteRMapEntry :: (HasKeyID a k, Bounded k, Ord k)
+deleteRMapEntry :: (Bounded k, Ord k)
                 => k
-                -> RingMap a k
-                -> RingMap a k
+                -> RingMap k a
+                -> RingMap k a
 deleteRMapEntry nid = RingMap . Map.update modifier nid . getRingMap
   where
     modifier (ProxyEntry idPointer _) = Just (ProxyEntry idPointer Nothing)
     modifier KeyEntry {}              = Nothing
 
-rMapToList :: (HasKeyID a k, Bounded k, Ord k) => RingMap a k -> [a]
+rMapToList :: (Bounded k, Ord k) => RingMap k a -> [a]
 rMapToList = mapMaybe extractRingEntry . Map.elems . getRingMap
 
-rMapFromList :: (HasKeyID a k, Bounded k, Ord k) => [a] -> RingMap a k
+rMapFromList :: (Bounded k, Ord k) => [(k, a)] -> RingMap k a
 rMapFromList = setRMapEntries
 
 -- | takes up to i entries from a 'RingMap' by calling a getter function on a
@@ -182,49 +184,52 @@ rMapFromList = setRMapEntries
 -- Stops once i entries have been taken or an entry has been encountered twice
 -- (meaning the ring has been traversed completely).
 -- Forms the basis for 'takeRMapSuccessors' and 'takeRMapPredecessors'.
-takeRMapEntries_ :: (HasKeyID a k, Integral i, Bounded k, Ord k)
-                 => (k -> RingMap a k -> Maybe a)
-                 -> k
-                 -> i
-                 -> RingMap a k
-                 -> [a]
+takeRMapEntries_ :: (Integral i, Bounded k, Ord k)
+                 => (k -> RingMap k a -> Maybe (k, a))   -- ^ parameterisable getter function to determine lookup direction
+                 -> k   -- ^ starting key
+                 -> i   -- ^ number of maximum values to take
+                 -> RingMap k a
+                 -> [a] -- ^ values taken
 -- TODO: might be more efficient with dlists
 takeRMapEntries_ getterFunc startAt num rmap = reverse $
     case getterFunc startAt rmap of
       Nothing -> []
-      Just anEntry -> takeEntriesUntil rmap getterFunc (getKeyID anEntry) (getKeyID anEntry) (num-1) [anEntry]
+      Just (foundKey, anEntry) -> takeEntriesUntil rmap getterFunc foundKey foundKey (num-1) [anEntry]
   where
     -- for some reason, just reusing the already-bound @rmap@ and @getterFunc@
     -- variables leads to a type error, these need to be passed explicitly
-    takeEntriesUntil :: (HasKeyID a k, Integral i, Bounded k, Ord k)
-                     => RingMap a k
-                     -> (k -> RingMap a k -> Maybe a) -- getter function
+    takeEntriesUntil :: (Integral i, Bounded k, Ord k)
+                     => RingMap k a
+                     -> (k -> RingMap k a -> Maybe (k, a)) -- getter function
                      -> k
                      -> k
                      -> i
                      -> [a]
                      -> [a]
     takeEntriesUntil rmap' getterFunc' havingReached previousEntry remaining takeAcc
+      -- length limit reached
       | remaining <= 0 = takeAcc
-      | getKeyID (fromJust $ getterFunc' previousEntry rmap') == havingReached = takeAcc
-      | otherwise = let (Just gotEntry) = getterFunc' previousEntry rmap'
-                    in takeEntriesUntil rmap' getterFunc' havingReached (getKeyID gotEntry) (remaining-1) (gotEntry:takeAcc)
+      --
+      | otherwise = case nextEntry of
+                      Just (fKey, gotEntry)
+                        | fKey == havingReached -> takeAcc
+                        | otherwise -> takeEntriesUntil rmap' getterFunc' havingReached fKey (remaining - 1) (gotEntry:takeAcc)
+                      Nothing -> takeAcc
+        where
+            nextEntry = getterFunc' previousEntry rmap'
 
-takeRMapPredecessors :: (HasKeyID a k, Integral i, Bounded k, Ord k, Num k)
+
+takeRMapPredecessors :: (Integral i, Bounded k, Ord k, Num k)
                  => k
                  -> i
-                 -> RingMap a k
+                 -> RingMap k a
                  -> [a]
 takeRMapPredecessors = takeRMapEntries_ rMapLookupPred
 
-takeRMapSuccessors :: (HasKeyID a k, Integral i, Bounded k, Ord k, Num k)
+takeRMapSuccessors :: (Integral i, Bounded k, Ord k, Num k)
                  => k
                  -> i
-                 -> RingMap a k
+                 -> RingMap k a
                  -> [a]
 takeRMapSuccessors = takeRMapEntries_ rMapLookupSucc
 
--- clean up cache entries: once now - entry > maxAge
--- transfer difference now - entry to other node
-
-

From 7878c67635d2e11ef2bcf81783b1ffe7e19cd8ca Mon Sep 17 00:00:00 2001
From: Trolli Schmittlauch <t.schmittlauch@orlives.de>
Date: Mon, 27 Jul 2020 00:37:17 +0200
Subject: [PATCH 02/35] adjust rest of code to refactored RingMap

---
 src/Hash2Pub/DHTProtocol.hs    | 21 ++++++++++++---------
 src/Hash2Pub/FediChordTypes.hs | 25 ++++++++++++++-----------
 src/Hash2Pub/PostService.hs    |  4 +++-
 src/Hash2Pub/RingMap.hs        |  4 +++-
 4 files changed, 32 insertions(+), 22 deletions(-)

diff --git a/src/Hash2Pub/DHTProtocol.hs b/src/Hash2Pub/DHTProtocol.hs
index d69d94c..546c10f 100644
--- a/src/Hash2Pub/DHTProtocol.hs
+++ b/src/Hash2Pub/DHTProtocol.hs
@@ -130,23 +130,25 @@ closestCachePredecessors remainingLookups lastID nCache
 -- Looks up the successor of the lookup key on a 'RingMap' representation of the
 -- predecessor list with the node itself added. If the result is the same as the node
 -- itself then it falls into the responsibility interval.
-isInOwnResponsibilitySlice :: HasKeyID a NodeID => a -> LocalNodeState -> Bool
-isInOwnResponsibilitySlice lookupTarget ownNs = (getKeyID <$> rMapLookupSucc (getKeyID lookupTarget :: NodeID) predecessorRMap) == pure (getNid ownNs)
+isInOwnResponsibilitySlice :: HasKeyID NodeID a => a -> LocalNodeState -> Bool
+isInOwnResponsibilitySlice lookupTarget ownNs = (fst <$> rMapLookupSucc (getKeyID lookupTarget :: NodeID) predecessorRMap) == pure (getNid ownNs)
   where
     predecessorList = predecessors ownNs
     -- add node itself to RingMap representation, to distinguish between
     -- responsibility of own node and predecessor
-    predecessorRMap = addRMapEntry (toRemoteNodeState ownNs) $ rMapFromList predecessorList
+    predecessorRMap = addRMapEntry (getKeyID ownRemote) ownRemote $ rMapFromList (keyValuePair <$> predecessorList) :: RingMap NodeID RemoteNodeState
+    ownRemote = toRemoteNodeState ownNs
     closestPredecessor = headMay predecessorList
 
-isPossiblePredecessor :: HasKeyID a NodeID => a -> LocalNodeState -> Bool
+isPossiblePredecessor :: HasKeyID NodeID a => a -> LocalNodeState -> Bool
 isPossiblePredecessor = isInOwnResponsibilitySlice
 
-isPossibleSuccessor :: HasKeyID a NodeID => a -> LocalNodeState -> Bool
-isPossibleSuccessor lookupTarget ownNs = (getKeyID <$> rMapLookupPred (getKeyID lookupTarget :: NodeID) successorRMap) == pure (getNid ownNs)
+isPossibleSuccessor :: HasKeyID NodeID a => a -> LocalNodeState -> Bool
+isPossibleSuccessor lookupTarget ownNs = (fst <$> rMapLookupPred (getKeyID lookupTarget :: NodeID) successorRMap) == pure (getNid ownNs)
   where
     successorList = successors ownNs
-    successorRMap = addRMapEntry (toRemoteNodeState ownNs) $ rMapFromList successorList
+    successorRMap = addRMapEntry (getKeyID ownRemote) ownRemote $ rMapFromList (keyValuePair <$> successorList)
+    ownRemote = toRemoteNodeState ownNs
     closestSuccessor = headMay successorList
 
 -- cache operations
@@ -169,7 +171,8 @@ addCacheEntryPure now (RemoteCacheEntry ns ts) cache =
     let
         -- TODO: limit diffSeconds to some maximum value to prevent malicious nodes from inserting entries valid nearly until eternity
         timestamp' = if ts <= now then ts else now
-        newCache = addRMapEntryWith insertCombineFunction (CacheEntry False ns timestamp') cache
+        newEntry = CacheEntry False ns timestamp'
+        newCache = addRMapEntryWith insertCombineFunction (getKeyID newEntry) newEntry cache
         insertCombineFunction newVal@(KeyEntry (CacheEntry newValidationState newNode newTimestamp)) oldVal =
             case oldVal of
               ProxyEntry n _ -> ProxyEntry n (Just newVal)
@@ -202,7 +205,7 @@ addNodeAsVerifiedPure :: POSIXTime
                       -> RemoteNodeState
                       -> NodeCache
                       -> NodeCache
-addNodeAsVerifiedPure now node = addRMapEntry (CacheEntry True node now)
+addNodeAsVerifiedPure now node = addRMapEntry (getKeyID node) (CacheEntry True node now)
 
 
 
diff --git a/src/Hash2Pub/FediChordTypes.hs b/src/Hash2Pub/FediChordTypes.hs
index 7652f4f..6e0bef6 100644
--- a/src/Hash2Pub/FediChordTypes.hs
+++ b/src/Hash2Pub/FediChordTypes.hs
@@ -1,5 +1,6 @@
 {-# LANGUAGE DataKinds                  #-}
 {-# LANGUAGE DerivingStrategies         #-}
+{-# LANGUAGE FlexibleContexts           #-}
 {-# LANGUAGE FlexibleInstances          #-}
 {-# LANGUAGE GeneralizedNewtypeDeriving #-}
 {-# LANGUAGE MultiParamTypeClasses      #-}
@@ -26,8 +27,7 @@ module Hash2Pub.FediChordTypes (
   , CacheEntry(..)
   , RingEntry(..)
   , RingMap(..)
-  , HasKeyID
-  , getKeyID
+  , HasKeyID(..)
   , rMapSize
   , rMapLookup
   , rMapLookupPred
@@ -271,31 +271,31 @@ instance Typeable a => Show (TQueue a) where
 
 -- | convenience function that replaces the predecessors of a 'LocalNodeState' with the k closest nodes from the provided list
 setPredecessors :: [RemoteNodeState] -> LocalNodeState -> LocalNodeState
-setPredecessors preds ns = ns {predecessors = takeRMapPredecessors (getNid ns) (kNeighbours ns) . rMapFromList . filter ((/=) (getNid ns) . getNid) $ preds}
+setPredecessors preds ns = ns {predecessors = takeRMapPredecessors (getNid ns) (kNeighbours ns) . rMapFromList . fmap keyValuePair . filter ((/=) (getNid ns) . getNid) $ preds}
 
 -- | convenience function that replaces the successors of a 'LocalNodeState' with the k closest nodes from the provided list
 setSuccessors :: [RemoteNodeState] -> LocalNodeState -> LocalNodeState
-setSuccessors succs ns = ns {successors = takeRMapSuccessors (getNid ns) (kNeighbours ns) . rMapFromList . filter ((/=) (getNid ns) . getNid) $ succs}
+setSuccessors succs ns = ns {successors = takeRMapSuccessors (getNid ns) (kNeighbours ns) . rMapFromList . fmap keyValuePair . filter ((/=) (getNid ns) . getNid) $ succs}
 
 -- | sets the predecessors of a 'LocalNodeState' to the closest k nodes of the current predecessors and the provided list, combined
 addPredecessors :: [RemoteNodeState] -> LocalNodeState -> LocalNodeState
-addPredecessors preds ns = ns {predecessors = takeRMapPredecessors (getNid ns) (kNeighbours ns) . addRMapEntries (filter ((/=) (getNid ns) . getNid) preds) . rMapFromList  $ predecessors ns}
+addPredecessors preds ns = ns {predecessors = takeRMapPredecessors (getNid ns) (kNeighbours ns) . addRMapEntries (keyValuePair <$> filter ((/=) (getNid ns) . getNid) preds) . rMapFromList . fmap keyValuePair  $ predecessors ns}
 
 -- | sets the successors of a 'LocalNodeState' to the closest k nodes of the current successors and the provided list, combined
 addSuccessors :: [RemoteNodeState] -> LocalNodeState -> LocalNodeState
-addSuccessors succs ns = ns {successors = takeRMapSuccessors (getNid ns) (kNeighbours ns) . addRMapEntries (filter ((/=) (getNid ns) . getNid) succs) . rMapFromList  $ successors ns}
+addSuccessors succs ns = ns {successors = takeRMapSuccessors (getNid ns) (kNeighbours ns) . addRMapEntries (keyValuePair <$> filter ((/=) (getNid ns) . getNid) succs) . rMapFromList . fmap keyValuePair $ successors ns}
 
-instance HasKeyID RemoteNodeState NodeID where
+instance HasKeyID NodeID RemoteNodeState where
     getKeyID = getNid
 
-instance HasKeyID a k => HasKeyID (CacheEntry a) k where
+instance HasKeyID k a => HasKeyID k (CacheEntry a) where
     getKeyID (CacheEntry _ obj _) = getKeyID obj
 
 instance HasKeyID NodeID NodeID where
     getKeyID = id
 
 type NodeCacheEntry = CacheEntry RemoteNodeState
-type NodeCache = RingMap NodeCacheEntry NodeID
+type NodeCache = RingMap NodeID NodeCacheEntry
 
 type LookupCacheEntry = CacheEntry (String, PortNumber)
 type LookupCache = Map.Map NodeID LookupCacheEntry
@@ -319,12 +319,15 @@ cacheLookup = rMapLookup
 cacheLookupSucc :: NodeID           -- ^lookup key
                 -> NodeCache        -- ^ring cache
                 -> Maybe NodeCacheEntry
-cacheLookupSucc = rMapLookupSucc
+cacheLookupSucc key cache = snd <$> rMapLookupSucc key cache
 
 cacheLookupPred :: NodeID           -- ^lookup key
                 -> NodeCache        -- ^ring cache
                 -> Maybe NodeCacheEntry
-cacheLookupPred = rMapLookupPred
+cacheLookupPred key cache = snd <$> rMapLookupPred key cache
+
+-- clean up cache entries: once now - entry > maxAge
+-- transfer difference now - entry to other node
 
 -- | return the @NodeState@ data from a cache entry without checking its validation status
 cacheGetNodeStateUnvalidated :: CacheEntry RemoteNodeState -> RemoteNodeState
diff --git a/src/Hash2Pub/PostService.hs b/src/Hash2Pub/PostService.hs
index e8b325b..21a7238 100644
--- a/src/Hash2Pub/PostService.hs
+++ b/src/Hash2Pub/PostService.hs
@@ -1,15 +1,16 @@
 {-# LANGUAGE DataKinds             #-}
 {-# LANGUAGE FlexibleInstances     #-}
+{-# LANGUAGE InstanceSigs          #-}
 {-# LANGUAGE MultiParamTypeClasses #-}
 {-# LANGUAGE OverloadedStrings     #-}
 {-# LANGUAGE RankNTypes            #-}
 {-# LANGUAGE TypeOperators         #-}
-{-# LANGUAGE InstanceSigs          #-}
 
 module Hash2Pub.PostService where
 
 import           Control.Concurrent
 import qualified Data.ByteString.Lazy.UTF8 as BSU
+import qualified Data.HashMap.Strict       as HMap
 import           Data.Maybe                (fromMaybe)
 import           Data.String               (fromString)
 import qualified Data.Text                 as Txt
@@ -18,6 +19,7 @@ import qualified Network.Wai.Handler.Warp  as Warp
 import           Servant
 
 import           Hash2Pub.FediChord
+import           Hash2Pub.RingMap
 import           Hash2Pub.ServiceTypes
 
 
diff --git a/src/Hash2Pub/RingMap.hs b/src/Hash2Pub/RingMap.hs
index 9c7f63b..016f9f1 100644
--- a/src/Hash2Pub/RingMap.hs
+++ b/src/Hash2Pub/RingMap.hs
@@ -5,13 +5,15 @@ module Hash2Pub.RingMap where
 
 import           Data.Foldable   (foldr')
 import qualified Data.Map.Strict as Map
-import           Data.Maybe      (fromJust, isJust, isNothing, mapMaybe)
+import           Data.Maybe      (isJust, isNothing, mapMaybe)
 
 
 -- | Class for all types that can be identified via a EpiChord key.
 -- Used for restricting the types a 'RingMap' can store
 class (Eq a, Show a, Bounded k, Ord k) => HasKeyID k a where
     getKeyID :: a -> k
+    keyValuePair :: a -> (k, a)
+    keyValuePair val = (getKeyID val, val)
 
 
 -- | generic data structure for holding elements with a key and modular lookup

From 04423171fdbc307b9c0d05d9f3ec16f6453ec5f9 Mon Sep 17 00:00:00 2001
From: Trolli Schmittlauch <t.schmittlauch@orlives.de>
Date: Mon, 27 Jul 2020 13:20:15 +0200
Subject: [PATCH 03/35] define data types for post and subscription storage

---
 Hash2Pub.cabal                 |  2 +-
 src/Hash2Pub/FediChordTypes.hs |  2 +-
 src/Hash2Pub/PostService.hs    | 22 ++++++++++++++++++++--
 src/Hash2Pub/ServiceTypes.hs   |  8 +++++++-
 4 files changed, 29 insertions(+), 5 deletions(-)

diff --git a/Hash2Pub.cabal b/Hash2Pub.cabal
index ebc9c7e..3ca520e 100644
--- a/Hash2Pub.cabal
+++ b/Hash2Pub.cabal
@@ -46,7 +46,7 @@ category:            Network
 extra-source-files:  CHANGELOG.md
 
 common deps
-  build-depends:       base ^>=4.12.0.0, containers ^>=0.6.0.1, bytestring, utf8-string ^>=1.0.1.1, network ^>=2.8.0.1, time ^>=1.8.0.2, cmdargs ^>= 0.10, cryptonite ^>= 0.25, memory, async, stm, asn1-encoding, asn1-types, asn1-parse, publicsuffix, network-byte-order, safe, iproute, mtl, random, servant, servant-server, servant-client, warp, text, unordered-containers
+  build-depends:       base ^>=4.12.0.0, containers ^>=0.6.0.1, bytestring, utf8-string ^>=1.0.1.1, network ^>=2.8.0.1, time ^>=1.8.0.2, cmdargs ^>= 0.10, cryptonite ^>= 0.25, memory, async, stm, asn1-encoding, asn1-types, asn1-parse, publicsuffix, network-byte-order, safe, iproute, mtl, random, servant, servant-server, servant-client, warp, text, unordered-containers, hashable
   ghc-options:         -Wall
 
 
diff --git a/src/Hash2Pub/FediChordTypes.hs b/src/Hash2Pub/FediChordTypes.hs
index 6e0bef6..d764b71 100644
--- a/src/Hash2Pub/FediChordTypes.hs
+++ b/src/Hash2Pub/FediChordTypes.hs
@@ -413,7 +413,7 @@ data FediChordConf = FediChordConf
 
 class DHT d where
     -- | lookup the responsible host handling a given key string,
-    -- possibly from a lookup cache
+    -- possiblggy from a lookup cache
     lookupKey :: d -> String -> IO (Maybe (String, PortNumber))
     -- | lookup the responsible host handling a given key string,
     -- but force the DHT to do a fresh lookup instead of returning a cached result.
diff --git a/src/Hash2Pub/PostService.hs b/src/Hash2Pub/PostService.hs
index 21a7238..bc1dc23 100644
--- a/src/Hash2Pub/PostService.hs
+++ b/src/Hash2Pub/PostService.hs
@@ -9,16 +9,21 @@
 module Hash2Pub.PostService where
 
 import           Control.Concurrent
+import           Control.Concurrent.STM
+import           Control.Concurrent.STM.TChan
+import           Control.Concurrent.STM.TVar
 import qualified Data.ByteString.Lazy.UTF8 as BSU
 import qualified Data.HashMap.Strict       as HMap
+import qualified Data.HashSet as HSet
 import           Data.Maybe                (fromMaybe)
 import           Data.String               (fromString)
 import qualified Data.Text                 as Txt
+import Data.Time.Clock.POSIX
 
 import qualified Network.Wai.Handler.Warp  as Warp
 import           Servant
 
-import           Hash2Pub.FediChord
+import           Hash2Pub.FediChordTypes
 import           Hash2Pub.RingMap
 import           Hash2Pub.ServiceTypes
 
@@ -29,6 +34,13 @@ data PostService d = PostService
     -- queues, other data structures
     , baseDHT       ::   (DHT d) => d
     , serviceThread :: ThreadId
+    , subscribers   :: TVar (RingMap NodeID TagSubscribers)
+    -- ^ for each tag store the subscribers + their queue
+    , ownSubscriptions :: TVar (HMap.HashMap NodeID POSIXTime)
+    -- ^ tags subscribed by the own node have an assigned lease time
+    , ownPosts :: TVar (HSet.HashSet Txt.Text)
+    -- ^ just store the existence of posts for saving memory,
+    -- always return the same placeholder
     }
 
 instance DHT d => Service PostService d where
@@ -45,12 +57,18 @@ instance DHT d => Service PostService d where
                            }
     getServicePort s = fromIntegral $ psPort s
 
+type PostContent = Txt.Text
+-- | For each handled tag, store its subscribers and provide a
+-- broadcast 'TChan' for enqueuing posts
+type RelayTags = RingMap NodeID (TagSubscribers, TChan PostContent)
+-- | each subscriber is identified by its contact data "hostname" "port"
+-- and holds a TChan duplicated from the broadcast TChan of the tag
+type TagSubscribers = HMap.HashMap (String, Int) (TChan PostContent)
 
 -- | return a WAI application
 postServiceApplication :: Application
 postServiceApplication = serve exposedPostServiceAPI postServer
 
-servicePort = 8081
 
 -- | needed for guiding type inference
 exposedPostServiceAPI :: Proxy PostServiceAPI
diff --git a/src/Hash2Pub/ServiceTypes.hs b/src/Hash2Pub/ServiceTypes.hs
index ab06052..430dc74 100644
--- a/src/Hash2Pub/ServiceTypes.hs
+++ b/src/Hash2Pub/ServiceTypes.hs
@@ -1,9 +1,15 @@
 {-# LANGUAGE MultiParamTypeClasses #-}
 module Hash2Pub.ServiceTypes where
 
-import           Hash2Pub.FediChord (DHT (..))
+import Data.Hashable (Hashable(..))
+
+import           Hash2Pub.FediChord (DHT (..), NodeID(..))
 
 class Service s d where
     -- | run the service
     runService :: (Integral i) => d -> String -> i -> IO (s d)
     getServicePort :: (Integral i) => s d -> i
+
+instance Hashable NodeID where
+    hashWithSalt salt = hashWithSalt salt . getNodeID
+    hash = hash . getNodeID

From daae9d0b38182985963f896018a46c2435e78a80 Mon Sep 17 00:00:00 2001
From: Trolli Schmittlauch <t.schmittlauch@orlives.de>
Date: Mon, 27 Jul 2020 21:39:33 +0200
Subject: [PATCH 04/35] process and enqueue incoming posts

---
 src/Hash2Pub/PostService.hs  | 146 ++++++++++++++++++++++-------------
 src/Hash2Pub/ServiceTypes.hs |   4 +-
 2 files changed, 94 insertions(+), 56 deletions(-)

diff --git a/src/Hash2Pub/PostService.hs b/src/Hash2Pub/PostService.hs
index bc1dc23..fc3e5e8 100644
--- a/src/Hash2Pub/PostService.hs
+++ b/src/Hash2Pub/PostService.hs
@@ -11,16 +11,20 @@ module Hash2Pub.PostService where
 import           Control.Concurrent
 import           Control.Concurrent.STM
 import           Control.Concurrent.STM.TChan
+import           Control.Concurrent.STM.TQueue
 import           Control.Concurrent.STM.TVar
-import qualified Data.ByteString.Lazy.UTF8 as BSU
-import qualified Data.HashMap.Strict       as HMap
-import qualified Data.HashSet as HSet
-import           Data.Maybe                (fromMaybe)
-import           Data.String               (fromString)
-import qualified Data.Text                 as Txt
-import Data.Time.Clock.POSIX
+import           Control.Monad                 (forM_, forever)
+import           Control.Monad.IO.Class        (liftIO)
+import qualified Data.ByteString.Lazy.UTF8     as BSU
+import qualified Data.HashMap.Strict           as HMap
+import qualified Data.HashSet                  as HSet
+import           Data.Maybe                    (fromMaybe)
+import           Data.String                   (fromString)
+import qualified Data.Text.Lazy                as Txt
+import           Data.Time.Clock.POSIX
+import           System.Random
 
-import qualified Network.Wai.Handler.Warp  as Warp
+import qualified Network.Wai.Handler.Warp      as Warp
 import           Servant
 
 import           Hash2Pub.FediChordTypes
@@ -29,34 +33,23 @@ import           Hash2Pub.ServiceTypes
 
 
 data PostService d = PostService
-    { psPort        :: Warp.Port
-    , psHost        :: String
+    { psPort           :: Warp.Port
+    , psHost           :: String
     -- queues, other data structures
-    , baseDHT       ::   (DHT d) => d
-    , serviceThread :: ThreadId
-    , subscribers   :: TVar (RingMap NodeID TagSubscribers)
+    , baseDHT          ::   (DHT d) => d
+    , serviceThread    :: TVar ThreadId
+    , subscribers      :: TVar (RingMap NodeID TagSubscribers)
     -- ^ for each tag store the subscribers + their queue
     , ownSubscriptions :: TVar (HMap.HashMap NodeID POSIXTime)
     -- ^ tags subscribed by the own node have an assigned lease time
-    , ownPosts :: TVar (HSet.HashSet Txt.Text)
+    , ownPosts         :: TVar (HSet.HashSet Txt.Text)
     -- ^ just store the existence of posts for saving memory,
-    -- always return the same placeholder
+    , relayInQueue     :: TQueue (Hashtag, PostID, PostContent)
+    -- ^ Queue for processing incoming posts of own instance asynchronously
     }
 
-instance DHT d => Service PostService d where
-    runService dht host port = do
-        let
-            port' = fromIntegral port
-            warpSettings = Warp.setPort port' . Warp.setHost (fromString host) $ Warp.defaultSettings
-        servThread <- forkIO $ Warp.runSettings warpSettings postServiceApplication
-        pure $ PostService {
-            psPort = port'
-          , psHost = host
-          , baseDHT = dht
-          , serviceThread = servThread
-                           }
-    getServicePort s = fromIntegral $ psPort s
-
+type Hashtag = Txt.Text
+type PostID = Txt.Text
 type PostContent = Txt.Text
 -- | For each handled tag, store its subscribers and provide a
 -- broadcast 'TChan' for enqueuing posts
@@ -65,9 +58,40 @@ type RelayTags = RingMap NodeID (TagSubscribers, TChan PostContent)
 -- and holds a TChan duplicated from the broadcast TChan of the tag
 type TagSubscribers = HMap.HashMap (String, Int) (TChan PostContent)
 
+
+instance DHT d => Service PostService d where
+    -- | initialise 'PostService' data structures and run server
+    runService dht host port = do
+        -- create necessary TVars
+        threadVar <- newTVarIO =<< myThreadId -- own thread ID as placeholder
+        subscriberVar <- newTVarIO emptyRMap
+        ownSubsVar <- newTVarIO HMap.empty
+        ownPostVar <- newTVarIO HSet.empty
+        relayInQueue' <- newTQueueIO
+        let
+            thisService = PostService {
+                psPort = port'
+              , psHost = host
+              , baseDHT = dht
+              , serviceThread = threadVar
+              , subscribers = subscriberVar
+              , ownSubscriptions = ownSubsVar
+              , ownPosts = ownPostVar
+              , relayInQueue = relayInQueue'
+                                      }
+            port' = fromIntegral port
+            warpSettings = Warp.setPort port' . Warp.setHost (fromString host) $ Warp.defaultSettings
+        servThreadID <- forkIO $ Warp.runSettings warpSettings $ postServiceApplication thisService
+        -- update thread ID after fork
+        atomically $ writeTVar threadVar servThreadID
+        pure thisService
+
+    getServicePort s = fromIntegral $ psPort s
+
+
 -- | return a WAI application
-postServiceApplication :: Application
-postServiceApplication = serve exposedPostServiceAPI postServer
+postServiceApplication :: PostService d -> Application
+postServiceApplication serv = serve exposedPostServiceAPI $ postServer serv
 
 
 -- | needed for guiding type inference
@@ -78,7 +102,7 @@ exposedPostServiceAPI = Proxy
 
 -- ========= HTTP API and handlers =============
 
-type PostServiceAPI = "relay" :> "inbox" :> ReqBody '[PlainText] Txt.Text :> PostCreated '[PlainText] Txt.Text
+type PostServiceAPI = "relay" :> "inbox" :> ReqBody '[PlainText] Txt.Text :> PutCreated '[PlainText] NoContent
                  -- ^ delivery endpoint of newly published posts of the relay's instance
                  :<|> "relay" :> "subscribers" :> ReqBody '[PlainText] Txt.Text :> Post '[PlainText] Txt.Text
                  -- ^ endpoint for delivering the subscriptions and outstanding queue
@@ -97,37 +121,51 @@ type PostServiceAPI = "relay" :> "inbox" :> ReqBody '[PlainText] Txt.Text :> Pos
                  -- the Origin header to $hashtag
 
 
-postServer :: Server PostServiceAPI
-postServer = relayInbox
-        :<|> subscriptionDelivery
-        :<|> postFetch
-        :<|> postMultiFetch
-        :<|> tagDelivery
-        :<|> tagSubscribe
-        :<|> tagUnsubscribe
+postServer :: PostService d -> Server PostServiceAPI
+postServer service = relayInbox service
+        :<|> subscriptionDelivery service
+        :<|> postFetch service
+        :<|> postMultiFetch service
+        :<|> tagDelivery service
+        :<|> tagSubscribe service
+        :<|> tagUnsubscribe service
 
 
-relayInbox :: Txt.Text -> Handler Txt.Text
-relayInbox post = pure $ "Here be InboxDragons with " <> post
+relayInbox :: PostService d -> Txt.Text -> Handler NoContent
+relayInbox serv post = do
+    -- extract contained hashtags
+    let
+        containedTags = fmap Txt.tail . filter ((==) '#' . Txt.head) . Txt.words $ post
+    -- generate post ID
+    postId <- liftIO $ Txt.pack . show <$> (randomRIO (0, 2^128-1) :: IO Integer)
+    -- add ID to own posts
+    liftIO . atomically $ modifyTVar' (ownPosts serv) (HSet.insert postId)
+    -- enqueue a relay job for each tag
+    liftIO $ forM_ (containedTags :: [Txt.Text]) (\tag ->
+        atomically $ writeTQueue (relayInQueue serv) (tag, postId,  post)
+                                 )
+    pure NoContent
 
-subscriptionDelivery :: Txt.Text -> Handler Txt.Text
-subscriptionDelivery subList = pure $ "Here be Subscription List dragons: " <> subList
 
-postFetch :: Txt.Text -> Handler Txt.Text
-postFetch postID = pure $ "Here be a post with dragon ID " <> postID
 
-postMultiFetch :: Txt.Text -> Handler Txt.Text
-postMultiFetch postIDs = pure $ "Here be multiple post dragons: "
+subscriptionDelivery :: PostService d -> Txt.Text -> Handler Txt.Text
+subscriptionDelivery serv subList = pure $ "Here be Subscription List dragons: " <> subList
+
+postFetch :: PostService d -> Txt.Text -> Handler Txt.Text
+postFetch serv postID = pure $ "Here be a post with dragon ID " <> postID
+
+postMultiFetch :: PostService d -> Txt.Text -> Handler Txt.Text
+postMultiFetch serv postIDs = pure $ "Here be multiple post dragons: "
                       <> (Txt.unwords . Txt.lines $ postIDs)
 
-tagDelivery :: Txt.Text -> Txt.Text -> Handler Txt.Text
-tagDelivery hashtag posts = pure $ "Here be #" <> hashtag <> " dragons with " <> posts
+tagDelivery :: PostService d -> Txt.Text -> Txt.Text -> Handler Txt.Text
+tagDelivery serv hashtag posts = pure $ "Here be #" <> hashtag <> " dragons with " <> posts
 
-tagSubscribe :: Txt.Text -> Maybe Txt.Text -> Handler Integer
-tagSubscribe hashtag origin = pure 42
+tagSubscribe :: PostService d -> Txt.Text -> Maybe Txt.Text -> Handler Integer
+tagSubscribe serv hashtag origin = pure 42
 
-tagUnsubscribe :: Txt.Text -> Maybe Txt.Text -> Handler Txt.Text
-tagUnsubscribe hashtag origin = pure $ "Here be a dragon unsubscription from " <> fromMaybe "Nothing" origin <> " to " <> hashtag
+tagUnsubscribe :: PostService d -> Txt.Text -> Maybe Txt.Text -> Handler Txt.Text
+tagUnsubscribe serv hashtag origin = pure $ "Here be a dragon unsubscription from " <> fromMaybe "Nothing" origin <> " to " <> hashtag
 
 
 -- | define how to convert all showable types to PlainText
diff --git a/src/Hash2Pub/ServiceTypes.hs b/src/Hash2Pub/ServiceTypes.hs
index 430dc74..5e2b37c 100644
--- a/src/Hash2Pub/ServiceTypes.hs
+++ b/src/Hash2Pub/ServiceTypes.hs
@@ -1,9 +1,9 @@
 {-# LANGUAGE MultiParamTypeClasses #-}
 module Hash2Pub.ServiceTypes where
 
-import Data.Hashable (Hashable(..))
+import           Data.Hashable      (Hashable (..))
 
-import           Hash2Pub.FediChord (DHT (..), NodeID(..))
+import           Hash2Pub.FediChord (DHT (..), NodeID (..))
 
 class Service s d where
     -- | run the service

From 736815ea831bc7fdecd0f9680f3218b70684b6ce Mon Sep 17 00:00:00 2001
From: Trolli Schmittlauch <t.schmittlauch@orlives.de>
Date: Mon, 27 Jul 2020 21:49:42 +0200
Subject: [PATCH 05/35] normalise hastag unicode representation of incoming
 posts

---
 Hash2Pub.cabal              | 2 +-
 src/Hash2Pub/PostService.hs | 4 +++-
 2 files changed, 4 insertions(+), 2 deletions(-)

diff --git a/Hash2Pub.cabal b/Hash2Pub.cabal
index 3ca520e..56441ad 100644
--- a/Hash2Pub.cabal
+++ b/Hash2Pub.cabal
@@ -46,7 +46,7 @@ category:            Network
 extra-source-files:  CHANGELOG.md
 
 common deps
-  build-depends:       base ^>=4.12.0.0, containers ^>=0.6.0.1, bytestring, utf8-string ^>=1.0.1.1, network ^>=2.8.0.1, time ^>=1.8.0.2, cmdargs ^>= 0.10, cryptonite ^>= 0.25, memory, async, stm, asn1-encoding, asn1-types, asn1-parse, publicsuffix, network-byte-order, safe, iproute, mtl, random, servant, servant-server, servant-client, warp, text, unordered-containers, hashable
+  build-depends:       base ^>=4.12.0.0, containers ^>=0.6.0.1, bytestring, utf8-string ^>=1.0.1.1, network ^>=2.8.0.1, time ^>=1.8.0.2, cmdargs ^>= 0.10, cryptonite ^>= 0.25, memory, async, stm, asn1-encoding, asn1-types, asn1-parse, publicsuffix, network-byte-order, safe, iproute, mtl, random, servant, servant-server, servant-client, warp, text, unordered-containers, hashable, unicode-transforms
   ghc-options:         -Wall
 
 
diff --git a/src/Hash2Pub/PostService.hs b/src/Hash2Pub/PostService.hs
index fc3e5e8..e44c8c6 100644
--- a/src/Hash2Pub/PostService.hs
+++ b/src/Hash2Pub/PostService.hs
@@ -21,6 +21,8 @@ import qualified Data.HashSet                  as HSet
 import           Data.Maybe                    (fromMaybe)
 import           Data.String                   (fromString)
 import qualified Data.Text.Lazy                as Txt
+import           Data.Text.Normalize           (NormalizationMode (NFC),
+                                                normalize)
 import           Data.Time.Clock.POSIX
 import           System.Random
 
@@ -135,7 +137,7 @@ relayInbox :: PostService d -> Txt.Text -> Handler NoContent
 relayInbox serv post = do
     -- extract contained hashtags
     let
-        containedTags = fmap Txt.tail . filter ((==) '#' . Txt.head) . Txt.words $ post
+        containedTags = fmap (Txt.fromStrict . normalize NFC . Txt.toStrict . Txt.tail) . filter ((==) '#' . Txt.head) . Txt.words $ post
     -- generate post ID
     postId <- liftIO $ Txt.pack . show <$> (randomRIO (0, 2^128-1) :: IO Integer)
     -- add ID to own posts

From 3b657574061700d83ab671cbaa8e6ce360c97094 Mon Sep 17 00:00:00 2001
From: Trolli Schmittlauch <t.schmittlauch@orlives.de>
Date: Tue, 28 Jul 2020 02:12:03 +0200
Subject: [PATCH 06/35] worker thread for processing incoming posts in
 background, started together with web server

---
 src/Hash2Pub/PostService.hs | 28 +++++++++++++++++++++++++++-
 1 file changed, 27 insertions(+), 1 deletion(-)

diff --git a/src/Hash2Pub/PostService.hs b/src/Hash2Pub/PostService.hs
index e44c8c6..8811080 100644
--- a/src/Hash2Pub/PostService.hs
+++ b/src/Hash2Pub/PostService.hs
@@ -9,6 +9,7 @@
 module Hash2Pub.PostService where
 
 import           Control.Concurrent
+import           Control.Concurrent.Async
 import           Control.Concurrent.STM
 import           Control.Concurrent.STM.TChan
 import           Control.Concurrent.STM.TQueue
@@ -83,7 +84,14 @@ instance DHT d => Service PostService d where
                                       }
             port' = fromIntegral port
             warpSettings = Warp.setPort port' . Warp.setHost (fromString host) $ Warp.defaultSettings
-        servThreadID <- forkIO $ Warp.runSettings warpSettings $ postServiceApplication thisService
+        -- Run 'concurrently_' from another thread to be able to return the
+        -- 'PostService'.
+        -- Terminating that parent thread will make all child threads terminate as well.
+        servThreadID <- forkIO $
+            concurrently_
+                -- web server
+                (Warp.runSettings warpSettings $ postServiceApplication thisService)
+                (processIncomingPosts thisService)
         -- update thread ID after fork
         atomically $ writeTVar threadVar servThreadID
         pure thisService
@@ -175,3 +183,21 @@ tagUnsubscribe serv hashtag origin = pure $ "Here be a dragon unsubscription fro
 -- TODO: figure out how this overlapping stuff actually works https://downloads.haskell.org/~ghc/latest/docs/html/users_guide/glasgow_exts.html#instance-overlap
 instance {-# OVERLAPPABLE #-} Show a => MimeRender PlainText a where
     mimeRender _ = BSU.fromString . show
+
+
+-- ====== worker threads ======
+
+-- | process the pending relays of incoming posts from the internal queue:
+-- Look up responsible relay node for given hashtag and forward post to it
+processIncomingPosts :: DHT d => PostService d -> IO ()
+processIncomingPosts serv = forever $ do
+    -- blocks until available
+    -- TODO: process multiple in parallel
+    (t, pID, pC) <- atomically . readTQueue $ relayInQueue serv
+    lookupRes <- lookupKey (baseDHT serv) (Txt.unpack t)
+    case lookupRes of
+      -- no vserver active => wait and retry
+      Nothing -> threadDelay $ 10 * 10^6
+      Just (responsibleHost, responsiblePort) -> do
+        -- TODO: do actual HTTP requests
+        pure ()

From 970c94ff0d51ce90d2d8b4d244087fe3536e1c31 Mon Sep 17 00:00:00 2001
From: Trolli Schmittlauch <t.schmittlauch@orlives.de>
Date: Tue, 28 Jul 2020 21:39:15 +0200
Subject: [PATCH 07/35] set up subscription data structures and transfer
 subscription endpoint

---
 src/Hash2Pub/PostService.hs | 74 +++++++++++++++++++++++++++++++++----
 1 file changed, 67 insertions(+), 7 deletions(-)

diff --git a/src/Hash2Pub/PostService.hs b/src/Hash2Pub/PostService.hs
index 8811080..9be7d1b 100644
--- a/src/Hash2Pub/PostService.hs
+++ b/src/Hash2Pub/PostService.hs
@@ -41,7 +41,7 @@ data PostService d = PostService
     -- queues, other data structures
     , baseDHT          ::   (DHT d) => d
     , serviceThread    :: TVar ThreadId
-    , subscribers      :: TVar (RingMap NodeID TagSubscribers)
+    , subscribers      :: TVar RelayTags
     -- ^ for each tag store the subscribers + their queue
     , ownSubscriptions :: TVar (HMap.HashMap NodeID POSIXTime)
     -- ^ tags subscribed by the own node have an assigned lease time
@@ -56,10 +56,10 @@ type PostID = Txt.Text
 type PostContent = Txt.Text
 -- | For each handled tag, store its subscribers and provide a
 -- broadcast 'TChan' for enqueuing posts
-type RelayTags = RingMap NodeID (TagSubscribers, TChan PostContent)
+type RelayTags = RingMap NodeID (TagSubscribers, TChan PostID, Hashtag)
 -- | each subscriber is identified by its contact data "hostname" "port"
 -- and holds a TChan duplicated from the broadcast TChan of the tag
-type TagSubscribers = HMap.HashMap (String, Int) (TChan PostContent)
+type TagSubscribers = TVar (HMap.HashMap (String, Int) (TChan PostID))
 
 
 instance DHT d => Service PostService d where
@@ -114,7 +114,7 @@ exposedPostServiceAPI = Proxy
 
 type PostServiceAPI = "relay" :> "inbox" :> ReqBody '[PlainText] Txt.Text :> PutCreated '[PlainText] NoContent
                  -- ^ delivery endpoint of newly published posts of the relay's instance
-                 :<|> "relay" :> "subscribers" :> ReqBody '[PlainText] Txt.Text :> Post '[PlainText] Txt.Text
+                 :<|> "relay" :> "subscribers" :> ReqBody '[PlainText] Txt.Text :> PostNoContent '[PlainText] NoContent
                  -- ^ endpoint for delivering the subscriptions and outstanding queue
                  :<|> "post" :> Capture "postid" Txt.Text :> Get '[PlainText] Txt.Text
                  -- ^ fetch endpoint for posts, full post ID is http://$domain/post/$postid
@@ -145,7 +145,7 @@ relayInbox :: PostService d -> Txt.Text -> Handler NoContent
 relayInbox serv post = do
     -- extract contained hashtags
     let
-        containedTags = fmap (Txt.fromStrict . normalize NFC . Txt.toStrict . Txt.tail) . filter ((==) '#' . Txt.head) . Txt.words $ post
+        containedTags = fmap (normaliseTag . Txt.tail) . filter ((==) '#' . Txt.head) . Txt.words $ post
     -- generate post ID
     postId <- liftIO $ Txt.pack . show <$> (randomRIO (0, 2^128-1) :: IO Integer)
     -- add ID to own posts
@@ -158,8 +158,25 @@ relayInbox serv post = do
 
 
 
-subscriptionDelivery :: PostService d -> Txt.Text -> Handler Txt.Text
-subscriptionDelivery serv subList = pure $ "Here be Subscription List dragons: " <> subList
+subscriptionDelivery :: PostService d -> Txt.Text -> Handler NoContent
+subscriptionDelivery serv subList = do
+    let
+        tagSubs = Txt.lines subList
+    liftIO $ forM_ tagSubs $ processTag (subscribers serv)
+    pure NoContent
+    -- TODO: check and only accept tags in own (future?) responsibility
+  where
+      processTag :: TVar RelayTags -> Txt.Text -> IO ()
+      processTag subscriberSTM tagData = do
+          let
+            tag:subText:posts:_ = Txt.splitOn "," tagData
+            sub = read . Txt.unpack $ subText :: (String, Int)
+            postList = Txt.words posts
+          enqueueSubscriptions subscriberSTM (normaliseTag tag) sub postList
+
+
+
+
 
 postFetch :: PostService d -> Txt.Text -> Handler Txt.Text
 postFetch serv postID = pure $ "Here be a post with dragon ID " <> postID
@@ -178,6 +195,49 @@ tagUnsubscribe :: PostService d -> Txt.Text -> Maybe Txt.Text -> Handler Txt.Tex
 tagUnsubscribe serv hashtag origin = pure $ "Here be a dragon unsubscription from " <> fromMaybe "Nothing" origin <> " to " <> hashtag
 
 
+-- ======= data structure manipulations =========
+
+-- | Write all pending posts of a subscriber-tag-combination to its queue.
+-- Sets up all necessary data structures if they are still missing.
+enqueueSubscriptions :: TVar RelayTags    -- tag-subscriber map
+                     -> Hashtag         -- hashtag of pending posts
+                     -> (String, Int)   -- subscriber's connection information
+                     -> [PostID]        -- pending posts
+                     -> IO ()
+enqueueSubscriptions tagMapSTM tag subscriber posts = do
+    -- get the tag output queue and, if necessary, create it
+    subChan <- atomically setupSubscriberChannel
+    forM_ posts (atomically . writeTChan subChan)
+  where
+      setupSubscriberChannel :: STM (TChan PostID)
+      setupSubscriberChannel = do
+          tagMap <- readTVar tagMapSTM
+          case rMapLookup (genKeyID . Txt.unpack $ tag) tagMap of
+            Nothing -> do
+              -- if no collision/ tag doesn't exist yet, just initialize a
+              -- new subscriber map
+              broadcastChan <- newBroadcastTChan
+              tagOutChan <- dupTChan broadcastChan
+              newSubMapSTM <- newTVar $ HMap.singleton subscriber tagOutChan
+              writeTVar tagMapSTM $ addRMapEntry (genKeyID . Txt.unpack $ tag) (newSubMapSTM, broadcastChan, tag) tagMap
+              pure tagOutChan
+            Just (foundSubMapSTM, broadcastChan, _) -> do
+              -- otherwise use the existing subscriber map
+              foundSubMap <- readTVar foundSubMapSTM
+              case HMap.lookup subscriber foundSubMap of
+                Nothing -> do
+                  -- for new subscribers, create new output channel
+                  tagOutChan <- dupTChan broadcastChan
+                  writeTVar foundSubMapSTM $ HMap.insert subscriber tagOutChan foundSubMap
+                  pure tagOutChan
+                -- existing subscriber's channels are just returned
+                Just tagOutChan -> pure tagOutChan
+
+
+-- normalise the unicode representation of a string to NFC
+normaliseTag :: Txt.Text -> Txt.Text
+normaliseTag = Txt.fromStrict . normalize NFC . Txt.toStrict
+
 -- | define how to convert all showable types to PlainText
 -- No idea what I'm doing with these overlappable instances though ¯\_(ツ)_/¯
 -- TODO: figure out how this overlapping stuff actually works https://downloads.haskell.org/~ghc/latest/docs/html/users_guide/glasgow_exts.html#instance-overlap

From 63bc06a88e3e6827c92a4ea51f4ec447de000dc5 Mon Sep 17 00:00:00 2001
From: Trolli Schmittlauch <t.schmittlauch@orlives.de>
Date: Tue, 28 Jul 2020 23:45:21 +0200
Subject: [PATCH 08/35] implement post fetch (with placeholder content)

---
 src/Hash2Pub/PostService.hs | 13 +++++++++----
 1 file changed, 9 insertions(+), 4 deletions(-)

diff --git a/src/Hash2Pub/PostService.hs b/src/Hash2Pub/PostService.hs
index 9be7d1b..ef22e29 100644
--- a/src/Hash2Pub/PostService.hs
+++ b/src/Hash2Pub/PostService.hs
@@ -108,7 +108,10 @@ postServiceApplication serv = serve exposedPostServiceAPI $ postServer serv
 exposedPostServiceAPI :: Proxy PostServiceAPI
 exposedPostServiceAPI = Proxy
 
+-- ========= constants ===========
 
+placeholderPost :: Txt.Text
+placeholderPost = Txt.take 5120 . Txt.repeat $ 'O' -- size 5KiB
 
 -- ========= HTTP API and handlers =============
 
@@ -175,11 +178,13 @@ subscriptionDelivery serv subList = do
           enqueueSubscriptions subscriberSTM (normaliseTag tag) sub postList
 
 
-
-
-
 postFetch :: PostService d -> Txt.Text -> Handler Txt.Text
-postFetch serv postID = pure $ "Here be a post with dragon ID " <> postID
+postFetch serv postID = do
+    postSet <- liftIO . readTVarIO . ownPosts $ serv
+    if HSet.member postID postSet
+       -- decision: always return the same placeholder post
+       then pure placeholderPost
+       else throwError $ err404 { errBody = "No post found with this ID" }
 
 postMultiFetch :: PostService d -> Txt.Text -> Handler Txt.Text
 postMultiFetch serv postIDs = pure $ "Here be multiple post dragons: "

From bd70e2dff02ea98b7d892d3a97d92f6df84fd4fe Mon Sep 17 00:00:00 2001
From: Trolli Schmittlauch <t.schmittlauch@orlives.de>
Date: Wed, 29 Jul 2020 00:06:16 +0200
Subject: [PATCH 09/35] implement multiple post fetch (with placeholder
 content)

---
 src/Hash2Pub/PostService.hs | 16 ++++++++++++----
 1 file changed, 12 insertions(+), 4 deletions(-)

diff --git a/src/Hash2Pub/PostService.hs b/src/Hash2Pub/PostService.hs
index ef22e29..169d2b7 100644
--- a/src/Hash2Pub/PostService.hs
+++ b/src/Hash2Pub/PostService.hs
@@ -14,7 +14,7 @@ import           Control.Concurrent.STM
 import           Control.Concurrent.STM.TChan
 import           Control.Concurrent.STM.TQueue
 import           Control.Concurrent.STM.TVar
-import           Control.Monad                 (forM_, forever)
+import           Control.Monad                 (foldM, forM_, forever)
 import           Control.Monad.IO.Class        (liftIO)
 import qualified Data.ByteString.Lazy.UTF8     as BSU
 import qualified Data.HashMap.Strict           as HMap
@@ -150,7 +150,7 @@ relayInbox serv post = do
     let
         containedTags = fmap (normaliseTag . Txt.tail) . filter ((==) '#' . Txt.head) . Txt.words $ post
     -- generate post ID
-    postId <- liftIO $ Txt.pack . show <$> (randomRIO (0, 2^128-1) :: IO Integer)
+    postId <- liftIO $ Txt.pack . show <$> (randomRIO (0, 2^(128::Integer)-1) :: IO Integer)
     -- add ID to own posts
     liftIO . atomically $ modifyTVar' (ownPosts serv) (HSet.insert postId)
     -- enqueue a relay job for each tag
@@ -186,9 +186,17 @@ postFetch serv postID = do
        then pure placeholderPost
        else throwError $ err404 { errBody = "No post found with this ID" }
 
+
 postMultiFetch :: PostService d -> Txt.Text -> Handler Txt.Text
-postMultiFetch serv postIDs = pure $ "Here be multiple post dragons: "
-                      <> (Txt.unwords . Txt.lines $ postIDs)
+postMultiFetch serv postIDs = do
+    let idList = Txt.lines postIDs
+    postSet <- liftIO . readTVarIO . ownPosts $ serv
+    -- look up existence of all given post IDs, fail if even one is missing
+    foldM (\response postID ->
+        if HSet.member postID postSet
+           then pure $ placeholderPost <> "\n" <> response
+           else throwError $ err404 { errBody = "No post found with this ID" }
+          ) "" idList
 
 tagDelivery :: PostService d -> Txt.Text -> Txt.Text -> Handler Txt.Text
 tagDelivery serv hashtag posts = pure $ "Here be #" <> hashtag <> " dragons with " <> posts

From ad52a017aa18c92188ddf89a3edc8e16340d1132 Mon Sep 17 00:00:00 2001
From: Trolli Schmittlauch <t.schmittlauch@orlives.de>
Date: Wed, 29 Jul 2020 22:15:14 +0200
Subject: [PATCH 10/35] add relay inbox endpoint

---
 src/Hash2Pub/PostService.hs | 74 ++++++++++++++++++++++++++++---------
 1 file changed, 56 insertions(+), 18 deletions(-)

diff --git a/src/Hash2Pub/PostService.hs b/src/Hash2Pub/PostService.hs
index 169d2b7..059ebe5 100644
--- a/src/Hash2Pub/PostService.hs
+++ b/src/Hash2Pub/PostService.hs
@@ -56,10 +56,11 @@ type PostID = Txt.Text
 type PostContent = Txt.Text
 -- | For each handled tag, store its subscribers and provide a
 -- broadcast 'TChan' for enqueuing posts
-type RelayTags = RingMap NodeID (TagSubscribers, TChan PostID, Hashtag)
+type RelayTags = RingMap NodeID (TagSubscribersSTM, TChan PostID, Hashtag)
+type TagSubscribersSTM = TVar TagSubscribers
 -- | each subscriber is identified by its contact data "hostname" "port"
 -- and holds a TChan duplicated from the broadcast TChan of the tag
-type TagSubscribers = TVar (HMap.HashMap (String, Int) (TChan PostID))
+type TagSubscribers = (HMap.HashMap (String, Int) (TChan PostID))
 
 
 instance DHT d => Service PostService d where
@@ -115,7 +116,7 @@ placeholderPost = Txt.take 5120 . Txt.repeat $ 'O' -- size 5KiB
 
 -- ========= HTTP API and handlers =============
 
-type PostServiceAPI = "relay" :> "inbox" :> ReqBody '[PlainText] Txt.Text :> PutCreated '[PlainText] NoContent
+type PostServiceAPI = "relay" :> "inbox" :> Capture "hashtag" Txt.Text :> ReqBody '[PlainText] Txt.Text :> PutCreated '[PlainText] NoContent
                  -- ^ delivery endpoint of newly published posts of the relay's instance
                  :<|> "relay" :> "subscribers" :> ReqBody '[PlainText] Txt.Text :> PostNoContent '[PlainText] NoContent
                  -- ^ endpoint for delivering the subscriptions and outstanding queue
@@ -123,6 +124,8 @@ type PostServiceAPI = "relay" :> "inbox" :> ReqBody '[PlainText] Txt.Text :> Put
                  -- ^ fetch endpoint for posts, full post ID is http://$domain/post/$postid
                  :<|> "posts" :> ReqBody '[PlainText] Txt.Text :> Post '[PlainText] Txt.Text
                  -- ^ endpoint for fetching multiple posts at once
+                 :<|> "posts" :> "inbox" :> ReqBody '[PlainText] Txt.Text :> PutCreated '[PlainText] NoContent
+                 -- ^ delivery endpoint of newly published posts of the relay's instance
                  :<|> "tags" :> Capture "hashtag" Txt.Text :> ReqBody '[PlainText] Txt.Text :> PostCreated '[PlainText] Txt.Text
                  -- ^ delivery endpoint for posts of $tag at subscribing instance
                  :<|> "tags" :> Capture "hashtag" Txt.Text :> "subscribe" :> Header "Origin" Txt.Text :> Get '[PlainText] Integer
@@ -139,28 +142,28 @@ postServer service = relayInbox service
         :<|> subscriptionDelivery service
         :<|> postFetch service
         :<|> postMultiFetch service
+        :<|> postInbox service
         :<|> tagDelivery service
         :<|> tagSubscribe service
         :<|> tagUnsubscribe service
 
 
-relayInbox :: PostService d -> Txt.Text -> Handler NoContent
-relayInbox serv post = do
-    -- extract contained hashtags
+relayInbox :: PostService d -> Hashtag -> Txt.Text -> Handler NoContent
+relayInbox serv tag posts = do
     let
-        containedTags = fmap (normaliseTag . Txt.tail) . filter ((==) '#' . Txt.head) . Txt.words $ post
-    -- generate post ID
-    postId <- liftIO $ Txt.pack . show <$> (randomRIO (0, 2^(128::Integer)-1) :: IO Integer)
-    -- add ID to own posts
-    liftIO . atomically $ modifyTVar' (ownPosts serv) (HSet.insert postId)
-    -- enqueue a relay job for each tag
-    liftIO $ forM_ (containedTags :: [Txt.Text]) (\tag ->
-        atomically $ writeTQueue (relayInQueue serv) (tag, postId,  post)
-                                 )
+    -- skip checking whether the post actually contains the tag, just drop full post
+        postIDs = head . Txt.splitOn "," <$> Txt.lines posts
+    broadcastChan <- liftIO $ atomically $ getTagBroadcastChannel serv tag
+    -- if tag is not in own responsibility, return a 410 Gone
+    maybe
+        (throwError $ err410 { errBody = "Relay is not responsible for this tag"})
+    -- otherwise enqueue posts into broadcast queue of the tag
+        (\queue ->
+            liftIO $ forM_ postIDs (atomically . writeTChan queue)
+        )
+        broadcastChan
     pure NoContent
 
-
-
 subscriptionDelivery :: PostService d -> Txt.Text -> Handler NoContent
 subscriptionDelivery serv subList = do
     let
@@ -198,6 +201,23 @@ postMultiFetch serv postIDs = do
            else throwError $ err404 { errBody = "No post found with this ID" }
           ) "" idList
 
+
+postInbox :: PostService d -> Txt.Text -> Handler NoContent
+postInbox serv post = do
+    -- extract contained hashtags
+    let
+        containedTags = fmap (normaliseTag . Txt.tail) . filter ((==) '#' . Txt.head) . Txt.words $ post
+    -- generate post ID
+    postId <- liftIO $ Txt.pack . show <$> (randomRIO (0, 2^(128::Integer)-1) :: IO Integer)
+    -- add ID to own posts
+    liftIO . atomically $ modifyTVar' (ownPosts serv) (HSet.insert postId)
+    -- enqueue a relay job for each tag
+    liftIO $ forM_ (containedTags :: [Txt.Text]) (\tag ->
+        atomically $ writeTQueue (relayInQueue serv) (tag, postId,  post)
+                                 )
+    pure NoContent
+
+
 tagDelivery :: PostService d -> Txt.Text -> Txt.Text -> Handler Txt.Text
 tagDelivery serv hashtag posts = pure $ "Here be #" <> hashtag <> " dragons with " <> posts
 
@@ -225,7 +245,7 @@ enqueueSubscriptions tagMapSTM tag subscriber posts = do
       setupSubscriberChannel :: STM (TChan PostID)
       setupSubscriberChannel = do
           tagMap <- readTVar tagMapSTM
-          case rMapLookup (genKeyID . Txt.unpack $ tag) tagMap of
+          case lookupRelayTags tag tagMap of
             Nothing -> do
               -- if no collision/ tag doesn't exist yet, just initialize a
               -- new subscriber map
@@ -247,6 +267,24 @@ enqueueSubscriptions tagMapSTM tag subscriber posts = do
                 Just tagOutChan -> pure tagOutChan
 
 
+-- | returns the broadcast channel of a hashtag if there are any subscribers to it
+getTagBroadcastChannel :: PostService d -> Hashtag -> STM (Maybe (TChan PostID))
+getTagBroadcastChannel serv tag = do
+    tagMap <- readTVar $ subscribers serv
+    case lookupRelayTags tag tagMap of
+      Nothing -> pure Nothing
+      Just (subscriberSTM, broadcastChan, _) -> do
+          subscriberMap <- readTVar subscriberSTM
+          if HMap.null subscriberMap
+             then pure Nothing
+             else pure (Just broadcastChan)
+
+
+-- | look up the subscription data of a tag
+lookupRelayTags :: Hashtag -> RelayTags -> Maybe (TagSubscribersSTM, TChan PostID, Hashtag)
+lookupRelayTags tag = rMapLookup (genKeyID . Txt.unpack $ tag)
+
+
 -- normalise the unicode representation of a string to NFC
 normaliseTag :: Txt.Text -> Txt.Text
 normaliseTag = Txt.fromStrict . normalize NFC . Txt.toStrict

From da47f8062fc155f3d4b163b4fb9770969f423c23 Mon Sep 17 00:00:00 2001
From: Trolli Schmittlauch <t.schmittlauch@orlives.de>
Date: Wed, 29 Jul 2020 23:06:07 +0200
Subject: [PATCH 11/35] add lease time to subscription entries

---
 src/Hash2Pub/PostService.hs | 67 ++++++++++++++++++++-----------------
 1 file changed, 37 insertions(+), 30 deletions(-)

diff --git a/src/Hash2Pub/PostService.hs b/src/Hash2Pub/PostService.hs
index 059ebe5..81b00a3 100644
--- a/src/Hash2Pub/PostService.hs
+++ b/src/Hash2Pub/PostService.hs
@@ -60,7 +60,8 @@ type RelayTags = RingMap NodeID (TagSubscribersSTM, TChan PostID, Hashtag)
 type TagSubscribersSTM = TVar TagSubscribers
 -- | each subscriber is identified by its contact data "hostname" "port"
 -- and holds a TChan duplicated from the broadcast TChan of the tag
-type TagSubscribers = (HMap.HashMap (String, Int) (TChan PostID))
+-- + an expiration timestamp
+type TagSubscribers = (HMap.HashMap (String, Int) (TChan PostID, POSIXTime))
 
 
 instance DHT d => Service PostService d where
@@ -175,10 +176,12 @@ subscriptionDelivery serv subList = do
       processTag :: TVar RelayTags -> Txt.Text -> IO ()
       processTag subscriberSTM tagData = do
           let
-            tag:subText:posts:_ = Txt.splitOn "," tagData
+            tag:subText:lease:posts:_ = Txt.splitOn "," tagData
+            -- ignore checking of lease time
+            leaseTime = fromIntegral (read . Txt.unpack $ lease :: Integer)
             sub = read . Txt.unpack $ subText :: (String, Int)
             postList = Txt.words posts
-          enqueueSubscriptions subscriberSTM (normaliseTag tag) sub postList
+          enqueueSubscription subscriberSTM (normaliseTag tag) sub postList leaseTime
 
 
 postFetch :: PostService d -> Txt.Text -> Handler Txt.Text
@@ -232,39 +235,43 @@ tagUnsubscribe serv hashtag origin = pure $ "Here be a dragon unsubscription fro
 
 -- | Write all pending posts of a subscriber-tag-combination to its queue.
 -- Sets up all necessary data structures if they are still missing.
-enqueueSubscriptions :: TVar RelayTags    -- tag-subscriber map
+enqueueSubscription :: TVar RelayTags    -- tag-subscriber map
                      -> Hashtag         -- hashtag of pending posts
                      -> (String, Int)   -- subscriber's connection information
                      -> [PostID]        -- pending posts
+                     -> POSIXTime       -- lease expiry time
                      -> IO ()
-enqueueSubscriptions tagMapSTM tag subscriber posts = do
+enqueueSubscription tagMapSTM tag subscriber posts leaseTime = do
     -- get the tag output queue and, if necessary, create it
-    subChan <- atomically setupSubscriberChannel
+    subChan <- atomically $ setupSubscriberChannel tagMapSTM tag subscriber leaseTime
     forM_ posts (atomically . writeTChan subChan)
-  where
-      setupSubscriberChannel :: STM (TChan PostID)
-      setupSubscriberChannel = do
-          tagMap <- readTVar tagMapSTM
-          case lookupRelayTags tag tagMap of
-            Nothing -> do
-              -- if no collision/ tag doesn't exist yet, just initialize a
-              -- new subscriber map
-              broadcastChan <- newBroadcastTChan
-              tagOutChan <- dupTChan broadcastChan
-              newSubMapSTM <- newTVar $ HMap.singleton subscriber tagOutChan
-              writeTVar tagMapSTM $ addRMapEntry (genKeyID . Txt.unpack $ tag) (newSubMapSTM, broadcastChan, tag) tagMap
-              pure tagOutChan
-            Just (foundSubMapSTM, broadcastChan, _) -> do
-              -- otherwise use the existing subscriber map
-              foundSubMap <- readTVar foundSubMapSTM
-              case HMap.lookup subscriber foundSubMap of
-                Nothing -> do
-                  -- for new subscribers, create new output channel
-                  tagOutChan <- dupTChan broadcastChan
-                  writeTVar foundSubMapSTM $ HMap.insert subscriber tagOutChan foundSubMap
-                  pure tagOutChan
-                -- existing subscriber's channels are just returned
-                Just tagOutChan -> pure tagOutChan
+
+
+-- | STM operation to return the outgoing post queue of a tag to a specified subscriber.
+-- If the queue doesn't exist yet, all necessary data structures are set up accordingly.
+setupSubscriberChannel :: TVar RelayTags -> Hashtag -> (String, Int) -> POSIXTime -> STM (TChan PostID)
+setupSubscriberChannel tagMapSTM tag subscriber leaseTime = do
+    tagMap <- readTVar tagMapSTM
+    case lookupRelayTags tag tagMap of
+      Nothing -> do
+        -- if no collision/ tag doesn't exist yet, just initialize a
+        -- new subscriber map
+        broadcastChan <- newBroadcastTChan
+        tagOutChan <- dupTChan broadcastChan
+        newSubMapSTM <- newTVar $ HMap.singleton subscriber (tagOutChan, leaseTime)
+        writeTVar tagMapSTM $ addRMapEntry (genKeyID . Txt.unpack $ tag) (newSubMapSTM, broadcastChan, tag) tagMap
+        pure tagOutChan
+      Just (foundSubMapSTM, broadcastChan, _) -> do
+        -- otherwise use the existing subscriber map
+        foundSubMap <- readTVar foundSubMapSTM
+        case HMap.lookup subscriber foundSubMap of
+          Nothing -> do
+            -- for new subscribers, create new output channel
+            tagOutChan <- dupTChan broadcastChan
+            writeTVar foundSubMapSTM $ HMap.insert subscriber (tagOutChan, leaseTime) foundSubMap
+            pure tagOutChan
+          -- existing subscriber's channels are just returned
+          Just (tagOutChan, _) -> pure tagOutChan
 
 
 -- | returns the broadcast channel of a hashtag if there are any subscribers to it

From 98ca0ff13e2996aa45d7bcfab695143689ae8650 Mon Sep 17 00:00:00 2001
From: Trolli Schmittlauch <t.schmittlauch@orlives.de>
Date: Thu, 30 Jul 2020 01:21:56 +0200
Subject: [PATCH 12/35] service config, integrate service launch into DHT
 launch

TODO: hold a reference from DHT to service
---
 Hash2Pub.cabal                 |  2 +-
 app/Main.hs                    | 20 +++++++++++++++-----
 src/Hash2Pub/FediChord.hs      | 11 +++++++++--
 src/Hash2Pub/FediChordTypes.hs | 25 +++++++++++++++++++++++++
 src/Hash2Pub/PostService.hs    | 15 ++++++---------
 src/Hash2Pub/ServiceTypes.hs   | 15 ---------------
 6 files changed, 56 insertions(+), 32 deletions(-)
 delete mode 100644 src/Hash2Pub/ServiceTypes.hs

diff --git a/Hash2Pub.cabal b/Hash2Pub.cabal
index 56441ad..54cb29d 100644
--- a/Hash2Pub.cabal
+++ b/Hash2Pub.cabal
@@ -55,7 +55,7 @@ library
   import: deps
 
   -- Modules exported by the library.
-  exposed-modules:     Hash2Pub.FediChord, Hash2Pub.FediChordTypes, Hash2Pub.DHTProtocol, Hash2Pub.ASN1Coding, Hash2Pub.ProtocolTypes, Hash2Pub.PostService, Hash2Pub.ServiceTypes, Hash2Pub.RingMap
+  exposed-modules:     Hash2Pub.FediChord, Hash2Pub.FediChordTypes, Hash2Pub.DHTProtocol, Hash2Pub.ASN1Coding, Hash2Pub.ProtocolTypes, Hash2Pub.PostService, Hash2Pub.RingMap
 
   -- Modules included in this library but not exported.
   other-modules: Hash2Pub.Utils
diff --git a/app/Main.hs b/app/Main.hs
index 8887ee8..98961c0 100644
--- a/app/Main.hs
+++ b/app/Main.hs
@@ -10,15 +10,17 @@ import           Data.IP                     (IPv6, toHostAddress6)
 import           System.Environment
 
 import           Hash2Pub.FediChord
+import           Hash2Pub.FediChordTypes
+import           Hash2Pub.PostService        (PostService (..))
 
 main :: IO ()
 main = do
     -- ToDo: parse and pass config
     -- probably use `tomland` for that
-    conf <- readConfig
+    (fConf, sConf) <- readConfig
     -- TODO: first initialise 'RealNode', then the vservers
     -- ToDo: load persisted caches, bootstrapping nodes …
-    (serverSock, thisNode) <- fediChordInit conf
+    (serverSock, thisNode) <- fediChordInit fConf (runService sConf :: DHT d => d -> IO (PostService d))
     -- currently no masking is necessary, as there is nothing to clean up
     nodeCacheWriterThread <- forkIO $ nodeCacheWriter thisNode
     -- try joining the DHT using one of the provided bootstrapping nodes
@@ -41,10 +43,11 @@ main = do
     pure ()
 
 
-readConfig :: IO FediChordConf
+readConfig :: IO (FediChordConf, ServiceConf)
 readConfig = do
-    confDomainString : ipString : portString : bootstrapHost : bootstrapPortString : _ <- getArgs
-    pure $ FediChordConf {
+    confDomainString : ipString : portString : bootstrapHost : bootstrapPortString : servicePortString : speedup : _ <- getArgs
+    let
+        fConf = FediChordConf {
         confDomain = confDomainString
       , confIP = toHostAddress6 . read $ ipString
       , confDhtPort = read portString
@@ -53,3 +56,10 @@ readConfig = do
       , confBootstrapSamplingInterval = 180
       , confMaxLookupCacheAge = 300
                            }
+        sConf = ServiceConf {
+        confSubscriptionExpiryTime = 2*3600 `div` read speedup
+                            , confServicePort = read servicePortString
+                            , confServiceHost = confDomainString
+                            }
+    pure (fConf, sConf)
+
diff --git a/src/Hash2Pub/FediChord.hs b/src/Hash2Pub/FediChord.hs
index 26a373c..7a5abb0 100644
--- a/src/Hash2Pub/FediChord.hs
+++ b/src/Hash2Pub/FediChord.hs
@@ -95,16 +95,23 @@ import           Debug.Trace                   (trace)
 
 -- | initialise data structures, compute own IDs and bind to listening socket
 -- ToDo: load persisted state, thus this function already operates in IO
-fediChordInit :: FediChordConf -> IO (Socket, LocalNodeStateSTM)
-fediChordInit initConf = do
+--fediChordInit :: (DHT d, Service s d)
+--              => FediChordConf
+--              -> (d -> s d)     -- ^ runner function for service
+--              -> IO (Socket, LocalNodeStateSTM)
+fediChordInit initConf serviceRunner = do
     emptyLookupCache <- newTVarIO Map.empty
     let realNode = RealNode {
             vservers = []
           , nodeConfig = initConf
           , bootstrapNodes = confBootstrapNodes initConf
           , lookupCacheSTM = emptyLookupCache
+          --, service = undefined
                             }
     realNodeSTM <- newTVarIO realNode
+    -- launch service and set the reference in the RealNode
+    serv <- serviceRunner realNodeSTM
+    --atomically . writeTVar $ realNode { service = serv }
     initialState <- nodeStateInit realNodeSTM
     initialStateSTM <- newTVarIO initialState
     serverSock <- mkServerSocket (getIpAddr initialState) (getDhtPort initialState)
diff --git a/src/Hash2Pub/FediChordTypes.hs b/src/Hash2Pub/FediChordTypes.hs
index d764b71..604519e 100644
--- a/src/Hash2Pub/FediChordTypes.hs
+++ b/src/Hash2Pub/FediChordTypes.hs
@@ -58,11 +58,14 @@ module Hash2Pub.FediChordTypes (
   , bsAsIpAddr
   , FediChordConf(..)
   , DHT(..)
+  , Service(..)
+  , ServiceConf(..)
                            ) where
 
 import           Control.Exception
 import           Data.Foldable                 (foldr')
 import           Data.Function                 (on)
+import qualified Data.Hashable                 as Hashable
 import           Data.List                     (delete, nub, sortBy)
 import qualified Data.Map.Strict               as Map
 import           Data.Maybe                    (fromJust, fromMaybe, isJust,
@@ -144,6 +147,7 @@ a `localCompare` b
 -- | Data for managing the virtual server nodes of this real node.
 -- Also contains shared data and config values.
 -- TODO: more data structures for k-choices bookkeeping
+--data RealNode s = RealNode
 data RealNode = RealNode
     { vservers       :: [LocalNodeStateSTM]
     -- ^ references to all active versers
@@ -155,6 +159,7 @@ data RealNode = RealNode
     -- ^ a global cache of looked up keys and their associated nodes
     }
 
+--type RealNodeSTM s = TVar (RealNode s)
 type RealNodeSTM = TVar RealNode
 
 -- | represents a node and all its important state
@@ -411,6 +416,26 @@ data FediChordConf = FediChordConf
     }
     deriving (Show, Eq)
 
+-- ====== Service Types ============
+
+class Service s d where
+    -- | run the service
+    runService :: ServiceConf -> d -> IO (s d)
+    getServicePort' :: (Integral i) => s d -> i
+
+instance Hashable.Hashable NodeID where
+    hashWithSalt salt = Hashable.hashWithSalt salt . getNodeID
+    hash = Hashable.hash . getNodeID
+
+data ServiceConf = ServiceConf
+    { confSubscriptionExpiryTime :: Integer
+    -- ^ subscription lease expiration in seconds
+    , confServicePort            :: Int
+    -- ^ listening port for service
+    , confServiceHost            :: String
+    -- ^ hostname of service
+    }
+
 class DHT d where
     -- | lookup the responsible host handling a given key string,
     -- possiblggy from a lookup cache
diff --git a/src/Hash2Pub/PostService.hs b/src/Hash2Pub/PostService.hs
index 81b00a3..264bccb 100644
--- a/src/Hash2Pub/PostService.hs
+++ b/src/Hash2Pub/PostService.hs
@@ -32,12 +32,10 @@ import           Servant
 
 import           Hash2Pub.FediChordTypes
 import           Hash2Pub.RingMap
-import           Hash2Pub.ServiceTypes
 
 
 data PostService d = PostService
-    { psPort           :: Warp.Port
-    , psHost           :: String
+    { serviceConf      :: ServiceConf
     -- queues, other data structures
     , baseDHT          ::   (DHT d) => d
     , serviceThread    :: TVar ThreadId
@@ -66,7 +64,7 @@ type TagSubscribers = (HMap.HashMap (String, Int) (TChan PostID, POSIXTime))
 
 instance DHT d => Service PostService d where
     -- | initialise 'PostService' data structures and run server
-    runService dht host port = do
+    runService conf dht = do
         -- create necessary TVars
         threadVar <- newTVarIO =<< myThreadId -- own thread ID as placeholder
         subscriberVar <- newTVarIO emptyRMap
@@ -75,8 +73,7 @@ instance DHT d => Service PostService d where
         relayInQueue' <- newTQueueIO
         let
             thisService = PostService {
-                psPort = port'
-              , psHost = host
+                serviceConf = conf
               , baseDHT = dht
               , serviceThread = threadVar
               , subscribers = subscriberVar
@@ -84,8 +81,8 @@ instance DHT d => Service PostService d where
               , ownPosts = ownPostVar
               , relayInQueue = relayInQueue'
                                       }
-            port' = fromIntegral port
-            warpSettings = Warp.setPort port' . Warp.setHost (fromString host) $ Warp.defaultSettings
+            port' = fromIntegral (confServicePort conf)
+            warpSettings = Warp.setPort port' . Warp.setHost (fromString . confServiceHost $ conf) $ Warp.defaultSettings
         -- Run 'concurrently_' from another thread to be able to return the
         -- 'PostService'.
         -- Terminating that parent thread will make all child threads terminate as well.
@@ -98,7 +95,7 @@ instance DHT d => Service PostService d where
         atomically $ writeTVar threadVar servThreadID
         pure thisService
 
-    getServicePort s = fromIntegral $ psPort s
+    getServicePort' = fromIntegral . confServicePort . serviceConf
 
 
 -- | return a WAI application
diff --git a/src/Hash2Pub/ServiceTypes.hs b/src/Hash2Pub/ServiceTypes.hs
deleted file mode 100644
index 5e2b37c..0000000
--- a/src/Hash2Pub/ServiceTypes.hs
+++ /dev/null
@@ -1,15 +0,0 @@
-{-# LANGUAGE MultiParamTypeClasses #-}
-module Hash2Pub.ServiceTypes where
-
-import           Data.Hashable      (Hashable (..))
-
-import           Hash2Pub.FediChord (DHT (..), NodeID (..))
-
-class Service s d where
-    -- | run the service
-    runService :: (Integral i) => d -> String -> i -> IO (s d)
-    getServicePort :: (Integral i) => s d -> i
-
-instance Hashable NodeID where
-    hashWithSalt salt = hashWithSalt salt . getNodeID
-    hash = hash . getNodeID

From 4bf80911432da8db7b1d5bc9278885310c1517c7 Mon Sep 17 00:00:00 2001
From: Trolli Schmittlauch <t.schmittlauch@orlives.de>
Date: Thu, 30 Jul 2020 01:30:42 +0200
Subject: [PATCH 13/35] fix type signature of fediChordInit

---
 src/Hash2Pub/FediChord.hs | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/src/Hash2Pub/FediChord.hs b/src/Hash2Pub/FediChord.hs
index 7a5abb0..70c9ff7 100644
--- a/src/Hash2Pub/FediChord.hs
+++ b/src/Hash2Pub/FediChord.hs
@@ -95,10 +95,10 @@ import           Debug.Trace                   (trace)
 
 -- | initialise data structures, compute own IDs and bind to listening socket
 -- ToDo: load persisted state, thus this function already operates in IO
---fediChordInit :: (DHT d, Service s d)
---              => FediChordConf
---              -> (d -> s d)     -- ^ runner function for service
---              -> IO (Socket, LocalNodeStateSTM)
+fediChordInit :: (Service s RealNodeSTM)
+              => FediChordConf
+              -> (RealNodeSTM -> IO (s RealNodeSTM))     -- ^ runner function for service
+              -> IO (Socket, LocalNodeStateSTM)
 fediChordInit initConf serviceRunner = do
     emptyLookupCache <- newTVarIO Map.empty
     let realNode = RealNode {

From 5ffe1b074e723f8ffaa29716baf066fe08f79a7d Mon Sep 17 00:00:00 2001
From: Trolli Schmittlauch <t.schmittlauch@orlives.de>
Date: Thu, 30 Jul 2020 02:19:26 +0200
Subject: [PATCH 14/35] add reference from RealNode to Service

This required to make both RealNode(STM) and LocalNodeState(STM) parameterisable
polymorphic types
---
 src/Hash2Pub/DHTProtocol.hs    | 44 +++++++++++++-------------
 src/Hash2Pub/FediChord.hs      | 57 ++++++++++++++++------------------
 src/Hash2Pub/FediChordTypes.hs | 30 +++++++++---------
 src/Hash2Pub/PostService.hs    |  2 ++
 test/FediChordSpec.hs          |  2 +-
 5 files changed, 68 insertions(+), 67 deletions(-)

diff --git a/src/Hash2Pub/DHTProtocol.hs b/src/Hash2Pub/DHTProtocol.hs
index 546c10f..f962d58 100644
--- a/src/Hash2Pub/DHTProtocol.hs
+++ b/src/Hash2Pub/DHTProtocol.hs
@@ -92,7 +92,7 @@ import           Debug.Trace                    (trace)
 
 -- TODO: evaluate more fine-grained argument passing to allow granular locking
 -- | look up an ID to either claim responsibility for it or return the closest l nodes from the local cache
-queryLocalCache :: LocalNodeState -> NodeCache -> Int -> NodeID -> QueryResponse
+queryLocalCache :: LocalNodeState s -> NodeCache -> Int -> NodeID -> QueryResponse
 queryLocalCache ownState nCache lBestNodes targetID
     -- as target ID falls between own ID and first predecessor, it is handled by this node
     -- This only makes sense if the node is part of the DHT by having joined.
@@ -130,7 +130,7 @@ closestCachePredecessors remainingLookups lastID nCache
 -- Looks up the successor of the lookup key on a 'RingMap' representation of the
 -- predecessor list with the node itself added. If the result is the same as the node
 -- itself then it falls into the responsibility interval.
-isInOwnResponsibilitySlice :: HasKeyID NodeID a => a -> LocalNodeState -> Bool
+isInOwnResponsibilitySlice :: HasKeyID NodeID a => a -> LocalNodeState s -> Bool
 isInOwnResponsibilitySlice lookupTarget ownNs = (fst <$> rMapLookupSucc (getKeyID lookupTarget :: NodeID) predecessorRMap) == pure (getNid ownNs)
   where
     predecessorList = predecessors ownNs
@@ -140,10 +140,10 @@ isInOwnResponsibilitySlice lookupTarget ownNs = (fst <$> rMapLookupSucc (getKeyI
     ownRemote = toRemoteNodeState ownNs
     closestPredecessor = headMay predecessorList
 
-isPossiblePredecessor :: HasKeyID NodeID a => a -> LocalNodeState -> Bool
+isPossiblePredecessor :: HasKeyID NodeID a => a -> LocalNodeState s -> Bool
 isPossiblePredecessor = isInOwnResponsibilitySlice
 
-isPossibleSuccessor :: HasKeyID NodeID a => a -> LocalNodeState -> Bool
+isPossibleSuccessor :: HasKeyID NodeID a => a -> LocalNodeState s -> Bool
 isPossibleSuccessor lookupTarget ownNs = (fst <$> rMapLookupPred (getKeyID lookupTarget :: NodeID) successorRMap) == pure (getNid ownNs)
   where
     successorList = successors ownNs
@@ -224,7 +224,7 @@ markCacheEntryAsVerified timestamp nid = RingMap . Map.adjust adjustFunc nid . g
 
 -- | uses the successor and predecessor list of a node as an indicator for whether a
 -- node has properly joined the DHT
-isJoined :: LocalNodeState -> Bool
+isJoined :: LocalNodeState s -> Bool
 isJoined ns = not . all null $ [successors ns, predecessors ns]
 
 -- | the size limit to be used when serialising messages for sending
@@ -248,7 +248,7 @@ ackRequest _ _ = Map.empty
 
 -- | Dispatch incoming requests to the dedicated handling and response function, and enqueue
 -- the response to be sent.
-handleIncomingRequest :: LocalNodeStateSTM                     -- ^ the handling node
+handleIncomingRequest :: LocalNodeStateSTM s                     -- ^ the handling node
                       -> TQueue (BS.ByteString, SockAddr)   -- ^ send queue
                       -> Set.Set FediChordMessage           -- ^ all parts of the request to handle
                       -> SockAddr                           -- ^ source address of the request
@@ -287,7 +287,7 @@ handleIncomingRequest nsSTM sendQ msgSet sourceAddr = do
 
 
 -- | execute a key ID lookup on local cache and respond with the result
-respondQueryID :: LocalNodeStateSTM -> Set.Set FediChordMessage -> IO (Map.Map Integer BS.ByteString)
+respondQueryID :: LocalNodeStateSTM s -> Set.Set FediChordMessage -> IO (Map.Map Integer BS.ByteString)
 respondQueryID nsSTM msgSet = do
     putStrLn "responding to a QueryID request"
     -- this message cannot be split reasonably, so just
@@ -328,7 +328,7 @@ respondQueryID nsSTM msgSet = do
 -- | Respond to a Leave request by removing the leaving node from local data structures
 -- and confirming with response.
 -- TODO: copy over key data from leaver and confirm
-respondLeave :: LocalNodeStateSTM -> Set.Set FediChordMessage -> IO (Map.Map Integer BS.ByteString)
+respondLeave :: LocalNodeStateSTM s -> Set.Set FediChordMessage -> IO (Map.Map Integer BS.ByteString)
 respondLeave nsSTM msgSet = do
     -- combine payload of all parts
     let (requestPreds, requestSuccs) = foldr' (\msg (predAcc, succAcc) ->
@@ -359,7 +359,7 @@ respondLeave nsSTM msgSet = do
     pure $ serialiseMessage sendMessageSize responseMsg
 
 -- | respond to stabilise requests by returning successor and predecessor list
-respondStabilise :: LocalNodeStateSTM -> Set.Set FediChordMessage -> IO (Map.Map Integer BS.ByteString)
+respondStabilise :: LocalNodeStateSTM s -> Set.Set FediChordMessage -> IO (Map.Map Integer BS.ByteString)
 respondStabilise nsSTM msgSet = do
     nsSnap <- readTVarIO nsSTM
     let
@@ -381,7 +381,7 @@ respondStabilise nsSTM msgSet = do
 
 
 -- | respond to Ping request by returning all active vserver NodeStates
-respondPing :: LocalNodeStateSTM -> Set.Set FediChordMessage -> IO (Map.Map Integer BS.ByteString)
+respondPing :: LocalNodeStateSTM s -> Set.Set FediChordMessage -> IO (Map.Map Integer BS.ByteString)
 respondPing nsSTM msgSet = do
     -- TODO: respond with all active VS when implementing k-choices
     nsSnap <- readTVarIO nsSTM
@@ -400,7 +400,7 @@ respondPing nsSTM msgSet = do
 
 -- this modifies node state, so locking and IO seems to be necessary.
 -- Still try to keep as much code as possible pure
-respondJoin :: LocalNodeStateSTM -> Set.Set FediChordMessage -> IO (Map.Map Integer BS.ByteString)
+respondJoin :: LocalNodeStateSTM s -> Set.Set FediChordMessage -> IO (Map.Map Integer BS.ByteString)
 respondJoin nsSTM msgSet = do
     -- atomically read and modify the node state according to the parsed request
     responseMsg <- atomically $ do
@@ -451,8 +451,8 @@ respondJoin nsSTM msgSet = do
 
 -- | send a join request and return the joined 'LocalNodeState' including neighbours
 requestJoin :: NodeState a => a             -- ^ currently responsible node to be contacted
-            -> LocalNodeStateSTM               -- ^ joining NodeState
-            -> IO (Either String LocalNodeStateSTM)    -- ^ node after join with all its new information
+            -> LocalNodeStateSTM s               -- ^ joining NodeState
+            -> IO (Either String (LocalNodeStateSTM s))    -- ^ node after join with all its new information
 requestJoin toJoinOn ownStateSTM = do
     ownState <- readTVarIO ownStateSTM
     prn <- readTVarIO $ parentRealNode ownState
@@ -500,7 +500,7 @@ requestJoin toJoinOn ownStateSTM = do
 
 
 -- | Send a 'QueryID' 'Request' for getting the node that handles a certain key ID.
-requestQueryID :: LocalNodeState        -- ^ NodeState of the querying node
+requestQueryID :: LocalNodeState s        -- ^ NodeState of the querying node
                -> NodeID                -- ^ target key ID to look up
                -> IO RemoteNodeState    -- ^ the node responsible for handling that key
 -- 1. do a local lookup for the l closest nodes
@@ -515,7 +515,7 @@ requestQueryID ns targetID = do
     queryIdLookupLoop firstCacheSnapshot ns 50 targetID
 
 -- | like 'requestQueryID, but allows passing of a custom cache, e.g. for joining
-queryIdLookupLoop :: NodeCache -> LocalNodeState -> Int -> NodeID -> IO RemoteNodeState
+queryIdLookupLoop :: NodeCache -> LocalNodeState s -> Int -> NodeID -> IO RemoteNodeState
 -- return node itself as default fallback value against infinite recursion.
 -- TODO: consider using an Either instead of a default value
 queryIdLookupLoop _ ns 0 _ = pure $ toRemoteNodeState ns
@@ -541,7 +541,7 @@ queryIdLookupLoop cacheSnapshot ns maxAttempts targetID = do
 
 sendQueryIdMessages :: (Integral i)
                     => NodeID                        -- ^ target key ID to look up
-                    -> LocalNodeState                -- ^ node state of the node doing the query
+                    -> LocalNodeState s                -- ^ node state of the node doing the query
                     -> Maybe i                       -- ^ optionally provide an explicit @l@ parameter of number of nodes to be returned
                    -> [RemoteNodeState]             -- ^ nodes to query
                    -> IO QueryResponse -- ^ accumulated response
@@ -579,7 +579,7 @@ sendQueryIdMessages targetID ns lParam targets = do
 -- | Create a QueryID message to be supplied to 'sendRequestTo'
 lookupMessage :: Integral i
               => NodeID         -- ^ target ID
-              -> LocalNodeState -- ^ sender node state
+              -> LocalNodeState s -- ^ sender node state
               -> Maybe i        -- ^ optionally provide a different l parameter
               ->  (Integer -> FediChordMessage)
 lookupMessage targetID ns lParam = \rID -> Request rID (toRemoteNodeState ns) 1 True QueryID (Just $ pl ns targetID)
@@ -589,7 +589,7 @@ lookupMessage targetID ns lParam = \rID -> Request rID (toRemoteNodeState ns) 1
 
 -- | Send a stabilise request to provided 'RemoteNode' and, if successful,
 -- return parsed neighbour lists
-requestStabilise :: LocalNodeState      -- ^ sending node
+requestStabilise :: LocalNodeState s      -- ^ sending node
                  -> RemoteNodeState     -- ^ neighbour node to send to
                  -> IO (Either String ([RemoteNodeState], [RemoteNodeState]))   -- ^ (predecessors, successors) of responding node
 requestStabilise ns neighbour = do
@@ -624,7 +624,7 @@ requestStabilise ns neighbour = do
         ) responses
 
 
-requestPing :: LocalNodeState      -- ^ sending node
+requestPing :: LocalNodeState s      -- ^ sending node
                  -> RemoteNodeState     -- ^ node to be PINGed
                  -> IO (Either String [RemoteNodeState])   -- ^ all active vServers of the pinged node
 requestPing ns target = do
@@ -723,7 +723,7 @@ sendRequestTo timeoutMillis numAttempts msgIncomplete sock = do
 
 -- | enqueue a list of RemoteCacheEntries to be added to the global NodeCache
 queueAddEntries :: Foldable c => c RemoteCacheEntry
-                -> LocalNodeState
+                -> LocalNodeState s
                 -> IO ()
 queueAddEntries entries ns = do
     now <- getPOSIXTime
@@ -733,14 +733,14 @@ queueAddEntries entries ns = do
 -- | enque a list of node IDs to be deleted from the global NodeCache
 queueDeleteEntries :: Foldable c
                    => c NodeID
-                   -> LocalNodeState
+                   -> LocalNodeState s
                    -> IO ()
 queueDeleteEntries ids ns = forM_ ids $ atomically . writeTQueue (cacheWriteQueue ns) . deleteCacheEntry
 
 
 -- | enque a single node ID to be deleted from the global NodeCache
 queueDeleteEntry :: NodeID
-                 -> LocalNodeState
+                 -> LocalNodeState s
                  -> IO ()
 queueDeleteEntry toDelete = queueDeleteEntries $ Identity toDelete
 
diff --git a/src/Hash2Pub/FediChord.hs b/src/Hash2Pub/FediChord.hs
index 70c9ff7..914ea57 100644
--- a/src/Hash2Pub/FediChord.hs
+++ b/src/Hash2Pub/FediChord.hs
@@ -78,7 +78,6 @@ import           Data.Maybe                    (catMaybes, fromJust, fromMaybe,
                                                 isJust, isNothing, mapMaybe)
 import qualified Data.Set                      as Set
 import           Data.Time.Clock.POSIX
-import           Data.Typeable                 (Typeable (..), typeOf)
 import           Data.Word
 import qualified Network.ByteOrder             as NetworkBytes
 import           Network.Socket                hiding (recv, recvFrom, send,
@@ -95,10 +94,10 @@ import           Debug.Trace                   (trace)
 
 -- | initialise data structures, compute own IDs and bind to listening socket
 -- ToDo: load persisted state, thus this function already operates in IO
-fediChordInit :: (Service s RealNodeSTM)
+fediChordInit :: (Service s (RealNodeSTM s))
               => FediChordConf
-              -> (RealNodeSTM -> IO (s RealNodeSTM))     -- ^ runner function for service
-              -> IO (Socket, LocalNodeStateSTM)
+              -> (RealNodeSTM s -> IO (s (RealNodeSTM s)))     -- ^ runner function for service
+              -> IO (Socket, LocalNodeStateSTM s)
 fediChordInit initConf serviceRunner = do
     emptyLookupCache <- newTVarIO Map.empty
     let realNode = RealNode {
@@ -119,7 +118,7 @@ fediChordInit initConf serviceRunner = do
 
 -- | initialises the 'NodeState' for this local node.
 -- Separated from 'fediChordInit' to be usable in tests.
-nodeStateInit :: RealNodeSTM -> IO LocalNodeState
+nodeStateInit :: RealNodeSTM s -> IO (LocalNodeState s)
 nodeStateInit realNodeSTM = do
     realNode <- readTVarIO realNodeSTM
     cacheSTM <- newTVarIO initCache
@@ -151,9 +150,9 @@ nodeStateInit realNodeSTM = do
 
 -- | Join a new node into the DHT, using a provided bootstrap node as initial cache seed
 -- for resolving the new node's position.
-fediChordBootstrapJoin :: LocalNodeStateSTM              -- ^ the local 'NodeState'
+fediChordBootstrapJoin :: LocalNodeStateSTM s            -- ^ the local 'NodeState'
                         -> (String, PortNumber)   -- ^ domain and port of a bootstrapping node
-                        -> IO (Either String LocalNodeStateSTM) -- ^ the joined 'NodeState' after a
+                        -> IO (Either String (LocalNodeStateSTM s)) -- ^ the joined 'NodeState' after a
                                             -- successful join, otherwise an error message
 fediChordBootstrapJoin nsSTM bootstrapNode = do
     -- can be invoked multiple times with all known bootstrapping nodes until successfully joined
@@ -169,7 +168,7 @@ fediChordBootstrapJoin nsSTM bootstrapNode = do
 
 -- Periodically lookup own ID through a random bootstrapping node to discover and merge separated DHT clusters.
 -- Unjoined try joining instead.
-convergenceSampleThread :: LocalNodeStateSTM -> IO ()
+convergenceSampleThread :: LocalNodeStateSTM s -> IO ()
 convergenceSampleThread nsSTM = forever $ do
     nsSnap <- readTVarIO nsSTM
     parentNode <- readTVarIO $ parentRealNode nsSnap
@@ -200,7 +199,7 @@ convergenceSampleThread nsSTM = forever $ do
 
 
 -- | Try joining the DHT through any of the bootstrapping nodes until it succeeds.
-tryBootstrapJoining :: LocalNodeStateSTM -> IO (Either String LocalNodeStateSTM)
+tryBootstrapJoining :: LocalNodeStateSTM s -> IO (Either String (LocalNodeStateSTM s))
 tryBootstrapJoining nsSTM = do
     bss <- atomically $ do
         nsSnap <- readTVar nsSTM
@@ -217,7 +216,7 @@ tryBootstrapJoining nsSTM = do
 
 
 -- | Look up a key just based on the responses of a single bootstrapping node.
-bootstrapQueryId :: LocalNodeStateSTM -> (String, PortNumber) -> NodeID -> IO (Either String RemoteNodeState)
+bootstrapQueryId :: LocalNodeStateSTM s -> (String, PortNumber) -> NodeID -> IO (Either String RemoteNodeState)
 bootstrapQueryId nsSTM (bootstrapHost, bootstrapPort) targetID = do
     ns <- readTVarIO nsSTM
     srcAddr <- confIP . nodeConfig <$> readTVarIO (parentRealNode ns)
@@ -248,8 +247,8 @@ bootstrapQueryId nsSTM (bootstrapHost, bootstrapPort) targetID = do
 
 -- | join a node to the DHT using the global node cache
 -- node's position.
-fediChordJoin :: LocalNodeStateSTM                    -- ^ the local 'NodeState'
-              -> IO (Either String LocalNodeStateSTM)  -- ^ the joined 'NodeState' after a
+fediChordJoin :: LocalNodeStateSTM s                    -- ^ the local 'NodeState'
+              -> IO (Either String (LocalNodeStateSTM s))  -- ^ the joined 'NodeState' after a
                                                     -- successful join, otherwise an error message
 fediChordJoin nsSTM = do
     ns <- readTVarIO nsSTM
@@ -265,7 +264,7 @@ fediChordJoin nsSTM = do
 
 -- | Wait for new cache entries to appear and then try joining on them.
 -- Exits after successful joining.
-joinOnNewEntriesThread :: LocalNodeStateSTM -> IO ()
+joinOnNewEntriesThread :: LocalNodeStateSTM s -> IO ()
 joinOnNewEntriesThread nsSTM = loop
   where
     loop = do
@@ -278,8 +277,7 @@ joinOnNewEntriesThread nsSTM = loop
               result                   -> pure (result, cache)
         case lookupResult of
           -- already joined
-          FOUND _ -> do
-              print =<< readTVarIO nsSTM
+          FOUND _ ->
               pure ()
           -- otherwise try joining
           FORWARD _ -> do
@@ -295,7 +293,7 @@ joinOnNewEntriesThread nsSTM = loop
 
 -- | cache updater thread that waits for incoming NodeCache update instructions on
 -- the node's cacheWriteQueue and then modifies the NodeCache as the single writer.
-nodeCacheWriter :: LocalNodeStateSTM -> IO ()
+nodeCacheWriter :: LocalNodeStateSTM s -> IO ()
 nodeCacheWriter nsSTM =
     forever $ atomically $ do
         ns <- readTVar nsSTM
@@ -309,7 +307,7 @@ maxEntryAge = 600
 
 
 -- | Periodically iterate through cache, clean up expired entries and verify unverified ones
-nodeCacheVerifyThread :: LocalNodeStateSTM -> IO ()
+nodeCacheVerifyThread :: LocalNodeStateSTM s -> IO ()
 nodeCacheVerifyThread nsSTM = forever $ do
     putStrLn "cache verify run: begin"
     -- get cache
@@ -370,7 +368,7 @@ nodeCacheVerifyThread nsSTM = forever $ do
 -- | Checks the invariant of at least @jEntries@ per cache slice.
 -- If this invariant does not hold, the middle of the slice is returned for
 -- making lookups to that ID
-checkCacheSliceInvariants :: LocalNodeState
+checkCacheSliceInvariants :: LocalNodeState s
                           -> NodeCache
                           -> [NodeID]   -- ^ list of middle IDs of slices not
                                         -- ^ fulfilling the invariant
@@ -426,12 +424,11 @@ checkCacheSliceInvariants ns
 -- | Periodically send @StabiliseRequest' s to the closest neighbour nodes, until
 -- one responds, and get their neighbours for maintaining the own neighbour lists.
 -- If necessary, request new neighbours.
-stabiliseThread :: LocalNodeStateSTM -> IO ()
+stabiliseThread :: LocalNodeStateSTM s -> IO ()
 stabiliseThread nsSTM = forever $ do
     ns <- readTVarIO nsSTM
 
     putStrLn "stabilise run: begin"
-    print ns
 
     -- iterate through the same snapshot, collect potential new neighbours
     -- and nodes to be deleted, and modify these changes only at the end of
@@ -489,8 +486,8 @@ stabiliseThread nsSTM = forever $ do
     -- with the n+1-th neighbour.
     -- On success, return 2 lists: The failed nodes and the potential neighbours
     -- returned by the queried node.
-    stabiliseClosestResponder :: LocalNodeState     -- ^ own node
-                              -> (LocalNodeState -> [RemoteNodeState])  -- ^ getter function for either predecessors or successors
+    stabiliseClosestResponder :: LocalNodeState s    -- ^ own node
+                              -> (LocalNodeState s -> [RemoteNodeState])  -- ^ getter function for either predecessors or successors
                               -> Int    -- ^ index of neighbour to query
                               -> [RemoteNodeState]     -- ^ delete accumulator
                               -> IO (Either String ([RemoteNodeState], [RemoteNodeState])) -- ^ (nodes to be deleted, successfully pinged potential neighbours)
@@ -514,7 +511,7 @@ stabiliseThread nsSTM = forever $ do
 
     currentNeighbour ns neighbourGetter = atMay $ neighbourGetter ns
 
-    checkReachability :: LocalNodeState         -- ^ this node
+    checkReachability :: LocalNodeState s       -- ^ this node
                       -> RemoteNodeState        -- ^ node to Ping for reachability
                       -> IO (Maybe RemoteNodeState)     -- ^ if the Pinged node handles the requested node state then that one
     checkReachability ns toCheck = do
@@ -543,10 +540,10 @@ sendThread sock sendQ = forever $ do
     sendAllTo sock packet addr
 
 -- | Sets up and manages the main server threads of FediChord
-fediMainThreads :: Socket -> LocalNodeStateSTM -> IO ()
+fediMainThreads :: Socket -> LocalNodeStateSTM s -> IO ()
 fediMainThreads sock nsSTM = do
     ns <- readTVarIO nsSTM
-    putStrLn $ "launching threads, ns: " <> show ns
+    putStrLn $ "launching threads"
     sendQ <- newTQueueIO
     recvQ <- newTQueueIO
     -- concurrently launch all handler threads, if one of them throws an exception
@@ -588,7 +585,7 @@ requestMapPurge mapVar = forever $ do
 -- and pass them to their specific handling function.
 fediMessageHandler :: TQueue (BS.ByteString, SockAddr)  -- ^ send queue
                    -> TQueue (BS.ByteString, SockAddr)  -- ^ receive queue
-                   -> LocalNodeStateSTM                    -- ^ acting NodeState
+                   -> LocalNodeStateSTM s                  -- ^ acting NodeState
                    -> IO ()
 fediMessageHandler sendQ recvQ nsSTM = do
     -- Read node state just once, assuming that all relevant data for this function does
@@ -653,14 +650,14 @@ fediMessageHandler sendQ recvQ nsSTM = do
 
 -- ==== interface to service layer ====
 
-instance DHT RealNodeSTM where
+instance DHT (RealNodeSTM s) where
     lookupKey nodeSTM keystring = getKeyResponsibility nodeSTM $ genKeyID keystring
     forceLookupKey nodeSTM keystring = updateLookupCache nodeSTM $ genKeyID keystring
 
 -- | Returns the hostname and port of the host responsible for a key.
 -- Information is provided from a cache, only on a cache miss a new DHT lookup
 -- is triggered.
-getKeyResponsibility :: RealNodeSTM -> NodeID -> IO (Maybe (String, PortNumber))
+getKeyResponsibility :: RealNodeSTM s -> NodeID -> IO (Maybe (String, PortNumber))
 getKeyResponsibility nodeSTM lookupKey = do
     node <- readTVarIO nodeSTM
     cache <- readTVarIO $ lookupCacheSTM node
@@ -676,7 +673,7 @@ getKeyResponsibility nodeSTM lookupKey = do
 -- | Triggers a new DHT lookup for a key, updates the lookup cache and returns the
 -- new entry.
 -- If no vserver is active in the DHT, 'Nothing' is returned.
-updateLookupCache :: RealNodeSTM -> NodeID -> IO (Maybe (String, PortNumber))
+updateLookupCache :: RealNodeSTM s -> NodeID -> IO (Maybe (String, PortNumber))
 updateLookupCache nodeSTM lookupKey = do
     (node, lookupSource) <- atomically $ do
         node <- readTVar nodeSTM
@@ -703,7 +700,7 @@ updateLookupCache nodeSTM lookupKey = do
 
 
 -- | Periodically clean the lookup cache from expired entries.
-lookupCacheCleanup :: RealNodeSTM -> IO ()
+lookupCacheCleanup :: RealNodeSTM s -> IO ()
 lookupCacheCleanup nodeSTM = do
     node <- readTVarIO nodeSTM
     forever $ do
diff --git a/src/Hash2Pub/FediChordTypes.hs b/src/Hash2Pub/FediChordTypes.hs
index 604519e..5b8ef17 100644
--- a/src/Hash2Pub/FediChordTypes.hs
+++ b/src/Hash2Pub/FediChordTypes.hs
@@ -147,9 +147,8 @@ a `localCompare` b
 -- | Data for managing the virtual server nodes of this real node.
 -- Also contains shared data and config values.
 -- TODO: more data structures for k-choices bookkeeping
---data RealNode s = RealNode
-data RealNode = RealNode
-    { vservers       :: [LocalNodeStateSTM]
+data RealNode s = RealNode
+    { vservers       :: [LocalNodeStateSTM s]
     -- ^ references to all active versers
     , nodeConfig     :: FediChordConf
     -- ^ holds the initial configuration read at program start
@@ -157,10 +156,10 @@ data RealNode = RealNode
     -- ^ 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
+    , nodeService    :: s (RealNodeSTM s)
     }
 
---type RealNodeSTM s = TVar (RealNode s)
-type RealNodeSTM = TVar RealNode
+type RealNodeSTM s = TVar (RealNode s)
 
 -- | represents a node and all its important state
 data RemoteNodeState = RemoteNodeState
@@ -182,7 +181,7 @@ instance Ord RemoteNodeState where
     a `compare` b = nid a `compare` nid b
 
 -- | represents a node and encapsulates all data and parameters that are not present for remote nodes
-data LocalNodeState = LocalNodeState
+data LocalNodeState s = LocalNodeState
     { nodeState           :: RemoteNodeState
     -- ^ represents common data present both in remote and local node representations
     , nodeCacheSTM        :: TVar NodeCache
@@ -201,13 +200,13 @@ data LocalNodeState = LocalNodeState
     -- ^ number of parallel sent queries
     , jEntriesPerSlice    :: Int
     -- ^ number of desired entries per cache slice
-    , parentRealNode      :: RealNodeSTM
+    , parentRealNode      :: RealNodeSTM s
     -- ^ the parent node managing this vserver instance
     }
     deriving (Show, Eq)
 
 -- | for concurrent access, LocalNodeState is wrapped in a TVar
-type LocalNodeStateSTM = TVar LocalNodeState
+type LocalNodeStateSTM s = TVar (LocalNodeState s)
 
 -- | class for various NodeState representations, providing
 -- getters and setters for common values
@@ -244,14 +243,14 @@ instance NodeState RemoteNodeState where
     toRemoteNodeState = id
 
 -- | helper function for setting values on the 'RemoteNodeState' contained in the 'LocalNodeState'
-propagateNodeStateSet_ :: (RemoteNodeState -> RemoteNodeState) -> LocalNodeState -> LocalNodeState
+propagateNodeStateSet_ :: (RemoteNodeState -> RemoteNodeState) -> LocalNodeState s -> LocalNodeState s
 propagateNodeStateSet_ func ns = let
         newNs = func $ nodeState ns
     in
         ns {nodeState = newNs}
 
 
-instance NodeState LocalNodeState where
+instance NodeState (LocalNodeState s) where
     getNid = getNid . nodeState
     getDomain = getDomain . nodeState
     getIpAddr = getIpAddr . nodeState
@@ -273,21 +272,24 @@ instance Typeable a => Show (TVar a) where
 instance Typeable a => Show (TQueue a) where
     show x = show (typeOf x)
 
+instance Typeable a => Show (TChan a) where
+    show x = show (typeOf x)
+
 
 -- | convenience function that replaces the predecessors of a 'LocalNodeState' with the k closest nodes from the provided list
-setPredecessors :: [RemoteNodeState] -> LocalNodeState -> LocalNodeState
+setPredecessors :: [RemoteNodeState] -> LocalNodeState s -> LocalNodeState s
 setPredecessors preds ns = ns {predecessors = takeRMapPredecessors (getNid ns) (kNeighbours ns) . rMapFromList . fmap keyValuePair . filter ((/=) (getNid ns) . getNid) $ preds}
 
 -- | convenience function that replaces the successors of a 'LocalNodeState' with the k closest nodes from the provided list
-setSuccessors :: [RemoteNodeState] -> LocalNodeState -> LocalNodeState
+setSuccessors :: [RemoteNodeState] -> LocalNodeState s -> LocalNodeState s
 setSuccessors succs ns = ns {successors = takeRMapSuccessors (getNid ns) (kNeighbours ns) . rMapFromList . fmap keyValuePair . filter ((/=) (getNid ns) . getNid) $ succs}
 
 -- | sets the predecessors of a 'LocalNodeState' to the closest k nodes of the current predecessors and the provided list, combined
-addPredecessors :: [RemoteNodeState] -> LocalNodeState -> LocalNodeState
+addPredecessors :: [RemoteNodeState] -> LocalNodeState s -> LocalNodeState s
 addPredecessors preds ns = ns {predecessors = takeRMapPredecessors (getNid ns) (kNeighbours ns) . addRMapEntries (keyValuePair <$> filter ((/=) (getNid ns) . getNid) preds) . rMapFromList . fmap keyValuePair  $ predecessors ns}
 
 -- | sets the successors of a 'LocalNodeState' to the closest k nodes of the current successors and the provided list, combined
-addSuccessors :: [RemoteNodeState] -> LocalNodeState -> LocalNodeState
+addSuccessors :: [RemoteNodeState] -> LocalNodeState s -> LocalNodeState s
 addSuccessors succs ns = ns {successors = takeRMapSuccessors (getNid ns) (kNeighbours ns) . addRMapEntries (keyValuePair <$> filter ((/=) (getNid ns) . getNid) succs) . rMapFromList . fmap keyValuePair $ successors ns}
 
 instance HasKeyID NodeID RemoteNodeState where
diff --git a/src/Hash2Pub/PostService.hs b/src/Hash2Pub/PostService.hs
index 264bccb..d5dd30d 100644
--- a/src/Hash2Pub/PostService.hs
+++ b/src/Hash2Pub/PostService.hs
@@ -25,6 +25,7 @@ import qualified Data.Text.Lazy                as Txt
 import           Data.Text.Normalize           (NormalizationMode (NFC),
                                                 normalize)
 import           Data.Time.Clock.POSIX
+import           Data.Typeable                 (Typeable)
 import           System.Random
 
 import qualified Network.Wai.Handler.Warp      as Warp
@@ -48,6 +49,7 @@ data PostService d = PostService
     , relayInQueue     :: TQueue (Hashtag, PostID, PostContent)
     -- ^ Queue for processing incoming posts of own instance asynchronously
     }
+    deriving (Typeable)
 
 type Hashtag = Txt.Text
 type PostID = Txt.Text
diff --git a/test/FediChordSpec.hs b/test/FediChordSpec.hs
index 1cace7a..bcc2eaf 100644
--- a/test/FediChordSpec.hs
+++ b/test/FediChordSpec.hs
@@ -292,7 +292,7 @@ exampleNodeState = RemoteNodeState {
   , vServerID = 0
                    }
 
-exampleLocalNode :: IO LocalNodeState
+exampleLocalNode :: IO (LocalNodeState s)
 exampleLocalNode = nodeStateInit =<< (newTVarIO $ RealNode {
             vservers = []
           , nodeConfig = exampleFediConf

From e3c7faa80bbecbfda11901e45e9d673b62122eb0 Mon Sep 17 00:00:00 2001
From: Trolli Schmittlauch <t.schmittlauch@orlives.de>
Date: Fri, 31 Jul 2020 16:54:19 +0200
Subject: [PATCH 15/35] properly initialise RealNode with service and vserver
 data, set up reference

---
 src/Hash2Pub/FediChord.hs      | 13 ++++++++-----
 src/Hash2Pub/FediChordTypes.hs |  2 +-
 src/Hash2Pub/PostService.hs    |  2 +-
 3 files changed, 10 insertions(+), 7 deletions(-)

diff --git a/src/Hash2Pub/FediChord.hs b/src/Hash2Pub/FediChord.hs
index 914ea57..858b38e 100644
--- a/src/Hash2Pub/FediChord.hs
+++ b/src/Hash2Pub/FediChord.hs
@@ -105,20 +105,23 @@ fediChordInit initConf serviceRunner = do
           , nodeConfig = initConf
           , bootstrapNodes = confBootstrapNodes initConf
           , lookupCacheSTM = emptyLookupCache
-          --, service = undefined
+          , nodeService = undefined
                             }
     realNodeSTM <- newTVarIO realNode
     -- launch service and set the reference in the RealNode
     serv <- serviceRunner realNodeSTM
-    --atomically . writeTVar $ realNode { service = serv }
+    atomically . modifyTVar' realNodeSTM $ \rn -> rn { nodeService = serv }
+    -- initialise a single vserver
     initialState <- nodeStateInit realNodeSTM
     initialStateSTM <- newTVarIO initialState
+    -- add vserver to list at RealNode
+    atomically . modifyTVar' realNodeSTM $ \rn -> rn { vservers = initialStateSTM:vservers rn }
     serverSock <- mkServerSocket (getIpAddr initialState) (getDhtPort initialState)
     pure (serverSock, initialStateSTM)
 
 -- | initialises the 'NodeState' for this local node.
 -- Separated from 'fediChordInit' to be usable in tests.
-nodeStateInit :: RealNodeSTM s -> IO (LocalNodeState s)
+nodeStateInit :: Service s (RealNodeSTM s) => RealNodeSTM s -> IO (LocalNodeState s)
 nodeStateInit realNodeSTM = do
     realNode <- readTVarIO realNodeSTM
     cacheSTM <- newTVarIO initCache
@@ -131,7 +134,7 @@ nodeStateInit realNodeSTM = do
           , ipAddr = confIP conf
           , nid = genNodeID (confIP conf) (confDomain conf) $ fromInteger vsID
           , dhtPort = toEnum $ confDhtPort conf
-          , servicePort = 0
+          , servicePort = getListeningPortFromService $ nodeService realNode
           , vServerID = vsID
                                           }
         initialState = LocalNodeState {
@@ -543,7 +546,7 @@ sendThread sock sendQ = forever $ do
 fediMainThreads :: Socket -> LocalNodeStateSTM s -> IO ()
 fediMainThreads sock nsSTM = do
     ns <- readTVarIO nsSTM
-    putStrLn $ "launching threads"
+    putStrLn "launching threads"
     sendQ <- newTQueueIO
     recvQ <- newTQueueIO
     -- concurrently launch all handler threads, if one of them throws an exception
diff --git a/src/Hash2Pub/FediChordTypes.hs b/src/Hash2Pub/FediChordTypes.hs
index 5b8ef17..e73e7f5 100644
--- a/src/Hash2Pub/FediChordTypes.hs
+++ b/src/Hash2Pub/FediChordTypes.hs
@@ -423,7 +423,7 @@ data FediChordConf = FediChordConf
 class Service s d where
     -- | run the service
     runService :: ServiceConf -> d -> IO (s d)
-    getServicePort' :: (Integral i) => s d -> i
+    getListeningPortFromService :: (Integral i) => s d -> i
 
 instance Hashable.Hashable NodeID where
     hashWithSalt salt = Hashable.hashWithSalt salt . getNodeID
diff --git a/src/Hash2Pub/PostService.hs b/src/Hash2Pub/PostService.hs
index d5dd30d..ae122e2 100644
--- a/src/Hash2Pub/PostService.hs
+++ b/src/Hash2Pub/PostService.hs
@@ -97,7 +97,7 @@ instance DHT d => Service PostService d where
         atomically $ writeTVar threadVar servThreadID
         pure thisService
 
-    getServicePort' = fromIntegral . confServicePort . serviceConf
+    getListeningPortFromService = fromIntegral . confServicePort . serviceConf
 
 
 -- | return a WAI application

From 50044673a65d0ba0afcc4abc104fa19a70b67757 Mon Sep 17 00:00:00 2001
From: Trolli Schmittlauch <t.schmittlauch@orlives.de>
Date: Fri, 31 Jul 2020 17:46:33 +0200
Subject: [PATCH 16/35] server endpoint for tag-post delivery

---
 src/Hash2Pub/PostService.hs | 23 +++++++++++++++++------
 1 file changed, 17 insertions(+), 6 deletions(-)

diff --git a/src/Hash2Pub/PostService.hs b/src/Hash2Pub/PostService.hs
index ae122e2..cab4350 100644
--- a/src/Hash2Pub/PostService.hs
+++ b/src/Hash2Pub/PostService.hs
@@ -19,7 +19,7 @@ import           Control.Monad.IO.Class        (liftIO)
 import qualified Data.ByteString.Lazy.UTF8     as BSU
 import qualified Data.HashMap.Strict           as HMap
 import qualified Data.HashSet                  as HSet
-import           Data.Maybe                    (fromMaybe)
+import           Data.Maybe                    (fromMaybe, isJust)
 import           Data.String                   (fromString)
 import qualified Data.Text.Lazy                as Txt
 import           Data.Text.Normalize           (NormalizationMode (NFC),
@@ -48,6 +48,7 @@ data PostService d = PostService
     -- ^ just store the existence of posts for saving memory,
     , relayInQueue     :: TQueue (Hashtag, PostID, PostContent)
     -- ^ Queue for processing incoming posts of own instance asynchronously
+    , postFetchQueue   :: TQueue PostID
     }
     deriving (Typeable)
 
@@ -73,6 +74,7 @@ instance DHT d => Service PostService d where
         ownSubsVar <- newTVarIO HMap.empty
         ownPostVar <- newTVarIO HSet.empty
         relayInQueue' <- newTQueueIO
+        postFetchQueue' <- newTQueueIO
         let
             thisService = PostService {
                 serviceConf = conf
@@ -82,6 +84,7 @@ instance DHT d => Service PostService d where
               , ownSubscriptions = ownSubsVar
               , ownPosts = ownPostVar
               , relayInQueue = relayInQueue'
+              , postFetchQueue = postFetchQueue'
                                       }
             port' = fromIntegral (confServicePort conf)
             warpSettings = Warp.setPort port' . Warp.setHost (fromString . confServiceHost $ conf) $ Warp.defaultSettings
@@ -221,7 +224,15 @@ postInbox serv post = do
 
 
 tagDelivery :: PostService d -> Txt.Text -> Txt.Text -> Handler Txt.Text
-tagDelivery serv hashtag posts = pure $ "Here be #" <> hashtag <> " dragons with " <> posts
+tagDelivery serv hashtag posts = do
+    let postIDs = Txt.lines posts
+    subscriptions <- liftIO . readTVarIO . ownSubscriptions $ serv
+    if isJust (HMap.lookup (genKeyID . Txt.unpack $ hashtag) subscriptions)
+       then -- TODO: increase a counter/ statistics for received posts of this tag
+            liftIO $ forM_ postIDs $ atomically . writeTQueue (postFetchQueue serv)
+        else -- silently drop posts from unsubscribed tags
+            pure ()
+    pure $ "Received a postID for tag " <> hashtag
 
 tagSubscribe :: PostService d -> Txt.Text -> Maybe Txt.Text -> Handler Integer
 tagSubscribe serv hashtag origin = pure 42
@@ -251,7 +262,7 @@ enqueueSubscription tagMapSTM tag subscriber posts leaseTime = do
 setupSubscriberChannel :: TVar RelayTags -> Hashtag -> (String, Int) -> POSIXTime -> STM (TChan PostID)
 setupSubscriberChannel tagMapSTM tag subscriber leaseTime = do
     tagMap <- readTVar tagMapSTM
-    case lookupRelayTags tag tagMap of
+    case lookupTagSubscriptions tag tagMap of
       Nothing -> do
         -- if no collision/ tag doesn't exist yet, just initialize a
         -- new subscriber map
@@ -277,7 +288,7 @@ setupSubscriberChannel tagMapSTM tag subscriber leaseTime = do
 getTagBroadcastChannel :: PostService d -> Hashtag -> STM (Maybe (TChan PostID))
 getTagBroadcastChannel serv tag = do
     tagMap <- readTVar $ subscribers serv
-    case lookupRelayTags tag tagMap of
+    case lookupTagSubscriptions tag tagMap of
       Nothing -> pure Nothing
       Just (subscriberSTM, broadcastChan, _) -> do
           subscriberMap <- readTVar subscriberSTM
@@ -287,8 +298,8 @@ getTagBroadcastChannel serv tag = do
 
 
 -- | look up the subscription data of a tag
-lookupRelayTags :: Hashtag -> RelayTags -> Maybe (TagSubscribersSTM, TChan PostID, Hashtag)
-lookupRelayTags tag = rMapLookup (genKeyID . Txt.unpack $ tag)
+lookupTagSubscriptions :: Hashtag -> RingMap NodeID a -> Maybe a
+lookupTagSubscriptions tag = rMapLookup (genKeyID . Txt.unpack $ tag)
 
 
 -- normalise the unicode representation of a string to NFC

From 7d7fa3b52a745d57cefc4fb7f24aac798e39bce4 Mon Sep 17 00:00:00 2001
From: Trolli Schmittlauch <t.schmittlauch@orlives.de>
Date: Fri, 31 Jul 2020 17:49:52 +0200
Subject: [PATCH 17/35] fix haddock parsing

---
 src/Hash2Pub/PostService.hs | 16 ++++++++--------
 1 file changed, 8 insertions(+), 8 deletions(-)

diff --git a/src/Hash2Pub/PostService.hs b/src/Hash2Pub/PostService.hs
index cab4350..dc2164a 100644
--- a/src/Hash2Pub/PostService.hs
+++ b/src/Hash2Pub/PostService.hs
@@ -120,23 +120,23 @@ placeholderPost = Txt.take 5120 . Txt.repeat $ 'O' -- size 5KiB
 -- ========= HTTP API and handlers =============
 
 type PostServiceAPI = "relay" :> "inbox" :> Capture "hashtag" Txt.Text :> ReqBody '[PlainText] Txt.Text :> PutCreated '[PlainText] NoContent
-                 -- ^ delivery endpoint of newly published posts of the relay's instance
+                 -- delivery endpoint of newly published posts of the relay's instance
                  :<|> "relay" :> "subscribers" :> ReqBody '[PlainText] Txt.Text :> PostNoContent '[PlainText] NoContent
-                 -- ^ endpoint for delivering the subscriptions and outstanding queue
+                 -- endpoint for delivering the subscriptions and outstanding queue
                  :<|> "post" :> Capture "postid" Txt.Text :> Get '[PlainText] Txt.Text
-                 -- ^ fetch endpoint for posts, full post ID is http://$domain/post/$postid
+                 -- fetch endpoint for posts, full post ID is http://$domain/post/$postid
                  :<|> "posts" :> ReqBody '[PlainText] Txt.Text :> Post '[PlainText] Txt.Text
-                 -- ^ endpoint for fetching multiple posts at once
+                 -- endpoint for fetching multiple posts at once
                  :<|> "posts" :> "inbox" :> ReqBody '[PlainText] Txt.Text :> PutCreated '[PlainText] NoContent
-                 -- ^ delivery endpoint of newly published posts of the relay's instance
+                 -- delivery endpoint of newly published posts of the relay's instance
                  :<|> "tags" :> Capture "hashtag" Txt.Text :> ReqBody '[PlainText] Txt.Text :> PostCreated '[PlainText] Txt.Text
-                 -- ^ delivery endpoint for posts of $tag at subscribing instance
+                 -- delivery endpoint for posts of $tag at subscribing instance
                  :<|> "tags" :> Capture "hashtag" Txt.Text :> "subscribe" :> Header "Origin" Txt.Text :> Get '[PlainText] Integer
-                 -- ^ endpoint for subscribing the instance specified in
+                 -- endpoint for subscribing the instance specified in
                  -- the Origin header to $hashtag.
                  -- Returns subscription lease time in seconds.
                  :<|> "tags" :> Capture "hashtag" Txt.Text :> "unsubscribe" :> Header "Origin" Txt.Text :> Get '[PlainText] Txt.Text
-                 -- ^ endpoint for unsubscribing the instance specified in
+                 -- endpoint for unsubscribing the instance specified in
                  -- the Origin header to $hashtag
 
 

From 7280f251b5015fed7e76e1c01dcf19145f77cf83 Mon Sep 17 00:00:00 2001
From: Trolli Schmittlauch <t.schmittlauch@orlives.de>
Date: Sat, 1 Aug 2020 11:00:29 +0200
Subject: [PATCH 18/35] server endpoint for tag subscription

---
 Hash2Pub.cabal                 |  2 +-
 app/Main.hs                    |  2 +-
 src/Hash2Pub/FediChordTypes.hs |  2 +-
 src/Hash2Pub/PostService.hs    | 19 ++++++++++++++++---
 4 files changed, 19 insertions(+), 6 deletions(-)

diff --git a/Hash2Pub.cabal b/Hash2Pub.cabal
index 54cb29d..251c60d 100644
--- a/Hash2Pub.cabal
+++ b/Hash2Pub.cabal
@@ -46,7 +46,7 @@ category:            Network
 extra-source-files:  CHANGELOG.md
 
 common deps
-  build-depends:       base ^>=4.12.0.0, containers ^>=0.6.0.1, bytestring, utf8-string ^>=1.0.1.1, network ^>=2.8.0.1, time ^>=1.8.0.2, cmdargs ^>= 0.10, cryptonite ^>= 0.25, memory, async, stm, asn1-encoding, asn1-types, asn1-parse, publicsuffix, network-byte-order, safe, iproute, mtl, random, servant, servant-server, servant-client, warp, text, unordered-containers, hashable, unicode-transforms
+  build-depends:       base ^>=4.12.0.0, containers ^>=0.6.0.1, bytestring, utf8-string ^>=1.0.1.1, network ^>=2.8.0.1, time ^>=1.8.0.2, cmdargs ^>= 0.10, cryptonite ^>= 0.25, memory, async, stm, asn1-encoding, asn1-types, asn1-parse, publicsuffix, network-byte-order, safe, iproute, mtl, random, servant, servant-server, servant-client, warp, text, unordered-containers, hashable, unicode-transforms, http-client
   ghc-options:         -Wall
 
 
diff --git a/app/Main.hs b/app/Main.hs
index 98961c0..3bdb4d4 100644
--- a/app/Main.hs
+++ b/app/Main.hs
@@ -57,7 +57,7 @@ readConfig = do
       , confMaxLookupCacheAge = 300
                            }
         sConf = ServiceConf {
-        confSubscriptionExpiryTime = 2*3600 `div` read speedup
+        confSubscriptionExpiryTime = fromIntegral $ 2*3600 `div` (read speedup :: Integer)
                             , confServicePort = read servicePortString
                             , confServiceHost = confDomainString
                             }
diff --git a/src/Hash2Pub/FediChordTypes.hs b/src/Hash2Pub/FediChordTypes.hs
index e73e7f5..91b3822 100644
--- a/src/Hash2Pub/FediChordTypes.hs
+++ b/src/Hash2Pub/FediChordTypes.hs
@@ -430,7 +430,7 @@ instance Hashable.Hashable NodeID where
     hash = Hashable.hash . getNodeID
 
 data ServiceConf = ServiceConf
-    { confSubscriptionExpiryTime :: Integer
+    { confSubscriptionExpiryTime :: POSIXTime
     -- ^ subscription lease expiration in seconds
     , confServicePort            :: Int
     -- ^ listening port for service
diff --git a/src/Hash2Pub/PostService.hs b/src/Hash2Pub/PostService.hs
index dc2164a..d56eb4c 100644
--- a/src/Hash2Pub/PostService.hs
+++ b/src/Hash2Pub/PostService.hs
@@ -16,7 +16,8 @@ import           Control.Concurrent.STM.TQueue
 import           Control.Concurrent.STM.TVar
 import           Control.Monad                 (foldM, forM_, forever)
 import           Control.Monad.IO.Class        (liftIO)
-import qualified Data.ByteString.Lazy.UTF8     as BSU
+import qualified Data.ByteString.Lazy.UTF8     as BSUL
+import qualified Data.ByteString.UTF8          as BSU
 import qualified Data.HashMap.Strict           as HMap
 import qualified Data.HashSet                  as HSet
 import           Data.Maybe                    (fromMaybe, isJust)
@@ -26,6 +27,7 @@ import           Data.Text.Normalize           (NormalizationMode (NFC),
                                                 normalize)
 import           Data.Time.Clock.POSIX
 import           Data.Typeable                 (Typeable)
+import qualified Network.HTTP.Client           as HTTP
 import           System.Random
 
 import qualified Network.Wai.Handler.Warp      as Warp
@@ -235,7 +237,18 @@ tagDelivery serv hashtag posts = do
     pure $ "Received a postID for tag " <> hashtag
 
 tagSubscribe :: PostService d -> Txt.Text -> Maybe Txt.Text -> Handler Integer
-tagSubscribe serv hashtag origin = pure 42
+tagSubscribe serv hashtag origin = do
+    originURL <- maybe
+        (throwError $ err400 { errBody = "Missing Origin header" })
+        pure
+        origin
+    req <- HTTP.parseUrlThrow (Txt.unpack originURL)
+    now <- liftIO getPOSIXTime
+    let leaseTime = now + confSubscriptionExpiryTime (serviceConf serv)
+    -- setup subscription entry
+    _ <- liftIO . atomically $ setupSubscriberChannel (subscribers serv) hashtag (BSU.toString $ HTTP.host req, HTTP.port req) leaseTime
+    pure $ round leaseTime
+
 
 tagUnsubscribe :: PostService d -> Txt.Text -> Maybe Txt.Text -> Handler Txt.Text
 tagUnsubscribe serv hashtag origin = pure $ "Here be a dragon unsubscription from " <> fromMaybe "Nothing" origin <> " to " <> hashtag
@@ -310,7 +323,7 @@ normaliseTag = Txt.fromStrict . normalize NFC . Txt.toStrict
 -- No idea what I'm doing with these overlappable instances though ¯\_(ツ)_/¯
 -- TODO: figure out how this overlapping stuff actually works https://downloads.haskell.org/~ghc/latest/docs/html/users_guide/glasgow_exts.html#instance-overlap
 instance {-# OVERLAPPABLE #-} Show a => MimeRender PlainText a where
-    mimeRender _ = BSU.fromString . show
+    mimeRender _ = BSUL.fromString . show
 
 
 -- ====== worker threads ======

From 89706f688a332f2966d8c48a12c9a2e983424310 Mon Sep 17 00:00:00 2001
From: Trolli Schmittlauch <t.schmittlauch@orlives.de>
Date: Sat, 1 Aug 2020 11:18:16 +0200
Subject: [PATCH 19/35] server endpoint for tag unsubscription

---
 src/Hash2Pub/PostService.hs | 29 +++++++++++++++++++++++++++--
 1 file changed, 27 insertions(+), 2 deletions(-)

diff --git a/src/Hash2Pub/PostService.hs b/src/Hash2Pub/PostService.hs
index d56eb4c..838b2c8 100644
--- a/src/Hash2Pub/PostService.hs
+++ b/src/Hash2Pub/PostService.hs
@@ -251,8 +251,14 @@ tagSubscribe serv hashtag origin = do
 
 
 tagUnsubscribe :: PostService d -> Txt.Text -> Maybe Txt.Text -> Handler Txt.Text
-tagUnsubscribe serv hashtag origin = pure $ "Here be a dragon unsubscription from " <> fromMaybe "Nothing" origin <> " to " <> hashtag
-
+tagUnsubscribe serv hashtag origin = do
+    originURL <- maybe
+        (throwError $ err400 { errBody = "Missing Origin header" })
+        pure
+        origin
+    req <- HTTP.parseUrlThrow (Txt.unpack originURL)
+    liftIO . atomically $ deleteSubscription (subscribers serv) hashtag (BSU.toString $ HTTP.host req, HTTP.port req)
+    pure "bye bye"
 
 -- ======= data structure manipulations =========
 
@@ -297,6 +303,25 @@ setupSubscriberChannel tagMapSTM tag subscriber leaseTime = do
           Just (tagOutChan, _) -> pure tagOutChan
 
 
+-- | deletes a subscription from the passed subscriber map
+deleteSubscription :: TVar RelayTags -> Hashtag -> (String, Int) -> STM ()
+deleteSubscription tagMapSTM tag subscriber = do
+    tagMap <- readTVar tagMapSTM
+    case lookupTagSubscriptions tag tagMap of
+      -- no subscribers to that tag, just return
+      Nothing -> pure ()
+      Just (foundSubMapSTM, _, _) -> do
+          foundSubMap <- readTVar foundSubMapSTM
+          let newSubMap = HMap.delete subscriber foundSubMap
+          -- if there are no subscriptions for the tag anymore, remove its
+          -- data sttructure altogether
+          if HMap.null newSubMap
+             then writeTVar tagMapSTM $ deleteRMapEntry (genKeyID . Txt.unpack $ tag) tagMap
+          -- otherwise just remove the subscription of that node
+             else writeTVar foundSubMapSTM newSubMap
+
+
+
 -- | returns the broadcast channel of a hashtag if there are any subscribers to it
 getTagBroadcastChannel :: PostService d -> Hashtag -> STM (Maybe (TChan PostID))
 getTagBroadcastChannel serv tag = do

From 8faa9dc0164162d1f2b5ba558faf36a7defee250 Mon Sep 17 00:00:00 2001
From: Trolli Schmittlauch <t.schmittlauch@orlives.de>
Date: Sat, 1 Aug 2020 18:58:30 +0200
Subject: [PATCH 20/35] fix test by providing a MockService

---
 test/FediChordSpec.hs | 19 +++++++++++++++----
 1 file changed, 15 insertions(+), 4 deletions(-)

diff --git a/test/FediChordSpec.hs b/test/FediChordSpec.hs
index bcc2eaf..ed1f3c8 100644
--- a/test/FediChordSpec.hs
+++ b/test/FediChordSpec.hs
@@ -1,4 +1,6 @@
-{-# LANGUAGE OverloadedStrings #-}
+{-# LANGUAGE FlexibleInstances     #-}
+{-# LANGUAGE MultiParamTypeClasses #-}
+{-# LANGUAGE OverloadedStrings     #-}
 module FediChordSpec where
 
 import           Control.Concurrent.STM.TVar
@@ -292,12 +294,15 @@ exampleNodeState = RemoteNodeState {
   , vServerID = 0
                    }
 
-exampleLocalNode :: IO (LocalNodeState s)
-exampleLocalNode = nodeStateInit =<< (newTVarIO $ RealNode {
+exampleLocalNode :: IO (LocalNodeState MockService)
+exampleLocalNode = do
+    realNode <- newTVarIO $ RealNode {
             vservers = []
           , nodeConfig = exampleFediConf
           , bootstrapNodes = confBootstrapNodes exampleFediConf
-                                                        })
+          , nodeService = MockService
+                                                        }
+    nodeStateInit realNode
 
 
 exampleFediConf :: FediChordConf
@@ -313,3 +318,9 @@ exampleVs :: (Integral i) => i
 exampleVs = 4
 exampleIp :: HostAddress6
 exampleIp = tupleToHostAddress6 (0x2001, 0x16b8, 0x755a, 0xb110, 0x7d6a, 0x12ab, 0xf0c5, 0x386e)
+
+data MockService d = MockService
+
+instance DHT d => Service MockService d where
+    runService _ _ = pure MockService
+    getListeningPortFromService = const 1337

From 20e51ecca43b4453fbea7902c83e00fccf92576e Mon Sep 17 00:00:00 2001
From: Trolli Schmittlauch <t.schmittlauch@orlives.de>
Date: Sun, 2 Aug 2020 14:58:53 +0200
Subject: [PATCH 21/35] define API client functions

---
 src/Hash2Pub/PostService.hs | 13 +++++++++++++
 1 file changed, 13 insertions(+)

diff --git a/src/Hash2Pub/PostService.hs b/src/Hash2Pub/PostService.hs
index 838b2c8..76dab47 100644
--- a/src/Hash2Pub/PostService.hs
+++ b/src/Hash2Pub/PostService.hs
@@ -29,9 +29,12 @@ import           Data.Time.Clock.POSIX
 import           Data.Typeable                 (Typeable)
 import qualified Network.HTTP.Client           as HTTP
 import           System.Random
+import           Text.Read                     (readEither)
 
 import qualified Network.Wai.Handler.Warp      as Warp
 import           Servant
+import           Servant.Client
+import           Servant.Server
 
 import           Hash2Pub.FediChordTypes
 import           Hash2Pub.RingMap
@@ -260,6 +263,14 @@ tagUnsubscribe serv hashtag origin = do
     liftIO . atomically $ deleteSubscription (subscribers serv) hashtag (BSU.toString $ HTTP.host req, HTTP.port req)
     pure "bye bye"
 
+-- client/ request functions
+
+clientAPI :: Proxy PostServiceAPI
+clientAPI = Proxy
+
+
+relayInboxClient :<|> subscriptionDeliveryClient :<|> postFetchClient :<|> postMultiFetchClient :<|> postInboxClient :<|> tagDeliveryClient :<|> tagSubscribeClient :<|> tagUnsubscribeClient = client clientAPI
+
 -- ======= data structure manipulations =========
 
 -- | Write all pending posts of a subscriber-tag-combination to its queue.
@@ -350,6 +361,8 @@ normaliseTag = Txt.fromStrict . normalize NFC . Txt.toStrict
 instance {-# OVERLAPPABLE #-} Show a => MimeRender PlainText a where
     mimeRender _ = BSUL.fromString . show
 
+instance {-# OVERLAPPABLE #-} Read a => MimeUnrender PlainText a where
+    mimeUnrender _ = readEither . BSUL.toString
 
 -- ====== worker threads ======
 

From 7036867ae002db82e0ec39341c4dca52676f6960 Mon Sep 17 00:00:00 2001
From: Trolli Schmittlauch <t.schmittlauch@orlives.de>
Date: Mon, 3 Aug 2020 22:50:48 +0200
Subject: [PATCH 22/35] implemented first Servant client query

---
 src/Hash2Pub/PostService.hs | 23 +++++++++++++++++++----
 1 file changed, 19 insertions(+), 4 deletions(-)

diff --git a/src/Hash2Pub/PostService.hs b/src/Hash2Pub/PostService.hs
index 76dab47..e9144df 100644
--- a/src/Hash2Pub/PostService.hs
+++ b/src/Hash2Pub/PostService.hs
@@ -271,6 +271,18 @@ clientAPI = Proxy
 
 relayInboxClient :<|> subscriptionDeliveryClient :<|> postFetchClient :<|> postMultiFetchClient :<|> postInboxClient :<|> tagDeliveryClient :<|> tagSubscribeClient :<|> tagUnsubscribeClient = client clientAPI
 
+
+
+-- currently this is unused code
+getClients :: String -> Int -> HTTP.Manager -> Client IO PostServiceAPI
+getClients hostname' port' httpMan = hoistClient clientAPI
+    (fmap (either (error . show) id)
+    . flip runClientM clientEnv
+    )
+    (client clientAPI)
+  where
+      clientEnv = mkClientEnv httpMan (BaseUrl Http hostname' port' "")
+
 -- ======= data structure manipulations =========
 
 -- | Write all pending posts of a subscriber-tag-combination to its queue.
@@ -372,11 +384,14 @@ processIncomingPosts :: DHT d => PostService d -> IO ()
 processIncomingPosts serv = forever $ do
     -- blocks until available
     -- TODO: process multiple in parallel
-    (t, pID, pC) <- atomically . readTQueue $ relayInQueue serv
-    lookupRes <- lookupKey (baseDHT serv) (Txt.unpack t)
+    (tag, pID, pContent) <- atomically . readTQueue $ relayInQueue serv
+    lookupRes <- lookupKey (baseDHT serv) (Txt.unpack tag)
     case lookupRes of
       -- no vserver active => wait and retry
       Nothing -> threadDelay $ 10 * 10^6
       Just (responsibleHost, responsiblePort) -> do
-        -- TODO: do actual HTTP requests
-        pure ()
+        httpMan <- HTTP.newManager HTTP.defaultManagerSettings
+        resp <- runClientM (relayInboxClient tag (pID <> "," <> pContent)) (mkClientEnv httpMan (BaseUrl Http responsibleHost (fromIntegral responsiblePort) ""))
+        case resp of
+          Left err -> putStrLn $ "Error: " <> show err
+          Right yay -> putStrLn $ "Yay! " <> show yay

From 96c1963a4f350f617820d96afae2d44d7ffdd749 Mon Sep 17 00:00:00 2001
From: Trolli Schmittlauch <t.schmittlauch@orlives.de>
Date: Tue, 11 Aug 2020 00:07:45 +0200
Subject: [PATCH 23/35] actually check own responsibility for tags before
 accepting posts

---
 src/Hash2Pub/DHTProtocol.hs    |  1 +
 src/Hash2Pub/FediChord.hs      | 19 +++++++++++
 src/Hash2Pub/FediChordTypes.hs |  2 ++
 src/Hash2Pub/PostService.hs    | 61 +++++++++++++++++++++++++---------
 src/Hash2Pub/RingMap.hs        | 58 +++++++++++++++++++-------------
 5 files changed, 102 insertions(+), 39 deletions(-)

diff --git a/src/Hash2Pub/DHTProtocol.hs b/src/Hash2Pub/DHTProtocol.hs
index f962d58..a071132 100644
--- a/src/Hash2Pub/DHTProtocol.hs
+++ b/src/Hash2Pub/DHTProtocol.hs
@@ -34,6 +34,7 @@ module Hash2Pub.DHTProtocol
     , ackRequest
     , isPossibleSuccessor
     , isPossiblePredecessor
+    , isInOwnResponsibilitySlice
     , isJoined
     , closestCachePredecessors
     )
diff --git a/src/Hash2Pub/FediChord.hs b/src/Hash2Pub/FediChord.hs
index 858b38e..7911f3c 100644
--- a/src/Hash2Pub/FediChord.hs
+++ b/src/Hash2Pub/FediChord.hs
@@ -656,6 +656,25 @@ fediMessageHandler sendQ recvQ nsSTM = do
 instance DHT (RealNodeSTM s) where
     lookupKey nodeSTM keystring = getKeyResponsibility nodeSTM $ genKeyID keystring
     forceLookupKey nodeSTM keystring = updateLookupCache nodeSTM $ genKeyID keystring
+    -- potential better implementation: put all neighbours of all vservers and the vservers on a ringMap, look the key up and see whether it results in a LocalNodeState
+    isResponsibleFor nodeSTM key = do
+        node <- readTVarIO nodeSTM
+        foldM (\responsible vsSTM -> do
+            vs <- readTVarIO vsSTM
+            pure $ responsible || isInOwnResponsibilitySlice key vs
+              )
+              False
+              $ vservers node
+    isResponsibleForSTM nodeSTM key = do
+        node <- readTVar nodeSTM
+        foldM (\responsible vsSTM -> do
+            vs <- readTVar vsSTM
+            pure $ responsible || isInOwnResponsibilitySlice key vs
+              )
+              False
+              $ vservers node
+
+
 
 -- | Returns the hostname and port of the host responsible for a key.
 -- Information is provided from a cache, only on a cache miss a new DHT lookup
diff --git a/src/Hash2Pub/FediChordTypes.hs b/src/Hash2Pub/FediChordTypes.hs
index 91b3822..20d65fe 100644
--- a/src/Hash2Pub/FediChordTypes.hs
+++ b/src/Hash2Pub/FediChordTypes.hs
@@ -446,3 +446,5 @@ class DHT d where
     -- but force the DHT to do a fresh lookup instead of returning a cached result.
     -- Also invalidates old cache entries.
     forceLookupKey :: d -> String -> IO (Maybe (String, PortNumber))
+    isResponsibleFor :: d -> NodeID -> IO Bool
+    isResponsibleForSTM :: d -> NodeID -> STM Bool
diff --git a/src/Hash2Pub/PostService.hs b/src/Hash2Pub/PostService.hs
index e9144df..8f47227 100644
--- a/src/Hash2Pub/PostService.hs
+++ b/src/Hash2Pub/PostService.hs
@@ -12,10 +12,13 @@ import           Control.Concurrent
 import           Control.Concurrent.Async
 import           Control.Concurrent.STM
 import           Control.Concurrent.STM.TChan
+import           Control.Concurrent.STM.TChan
 import           Control.Concurrent.STM.TQueue
 import           Control.Concurrent.STM.TVar
-import           Control.Monad                 (foldM, forM_, forever)
+import           Control.Exception             (Exception (..))
+import           Control.Monad                 (foldM, forM, forM_, forever)
 import           Control.Monad.IO.Class        (liftIO)
+import           Control.Monad.STM
 import qualified Data.ByteString.Lazy.UTF8     as BSUL
 import qualified Data.ByteString.UTF8          as BSU
 import qualified Data.HashMap.Strict           as HMap
@@ -109,7 +112,7 @@ instance DHT d => Service PostService d where
 
 
 -- | return a WAI application
-postServiceApplication :: PostService d -> Application
+postServiceApplication :: DHT d => PostService d -> Application
 postServiceApplication serv = serve exposedPostServiceAPI $ postServer serv
 
 
@@ -126,7 +129,7 @@ placeholderPost = Txt.take 5120 . Txt.repeat $ 'O' -- size 5KiB
 
 type PostServiceAPI = "relay" :> "inbox" :> Capture "hashtag" Txt.Text :> ReqBody '[PlainText] Txt.Text :> PutCreated '[PlainText] NoContent
                  -- delivery endpoint of newly published posts of the relay's instance
-                 :<|> "relay" :> "subscribers" :> ReqBody '[PlainText] Txt.Text :> PostNoContent '[PlainText] NoContent
+                 :<|> "relay" :> "subscribers" :> ReqBody '[PlainText] Txt.Text :> PostNoContent '[PlainText] Txt.Text
                  -- endpoint for delivering the subscriptions and outstanding queue
                  :<|> "post" :> Capture "postid" Txt.Text :> Get '[PlainText] Txt.Text
                  -- fetch endpoint for posts, full post ID is http://$domain/post/$postid
@@ -145,7 +148,7 @@ type PostServiceAPI = "relay" :> "inbox" :> Capture "hashtag" Txt.Text :> ReqBod
                  -- the Origin header to $hashtag
 
 
-postServer :: PostService d -> Server PostServiceAPI
+postServer :: DHT d => PostService d -> Server PostServiceAPI
 postServer service = relayInbox service
         :<|> subscriptionDelivery service
         :<|> postFetch service
@@ -156,15 +159,21 @@ postServer service = relayInbox service
         :<|> tagUnsubscribe service
 
 
-relayInbox :: PostService d -> Hashtag -> Txt.Text -> Handler NoContent
+relayInbox :: DHT d => PostService d -> Hashtag -> Txt.Text -> Handler NoContent
 relayInbox serv tag posts = do
     let
     -- skip checking whether the post actually contains the tag, just drop full post
         postIDs = head . Txt.splitOn "," <$> Txt.lines posts
-    broadcastChan <- liftIO $ atomically $ getTagBroadcastChannel serv tag
     -- if tag is not in own responsibility, return a 410 Gone
-    maybe
+    responsible <- liftIO $ isResponsibleFor (baseDHT serv) (genKeyID . Txt.unpack $ tag)
+    if responsible
+       then pure ()
+       else
         (throwError $ err410 { errBody = "Relay is not responsible for this tag"})
+    broadcastChan <- liftIO $ atomically $ getTagBroadcastChannel serv tag
+    maybe
+    -- if noone subscribed to the tag, nothing needs to be done
+        (pure ())
     -- otherwise enqueue posts into broadcast queue of the tag
         (\queue ->
             liftIO $ forM_ postIDs (atomically . writeTChan queue)
@@ -172,15 +181,35 @@ relayInbox serv tag posts = do
         broadcastChan
     pure NoContent
 
-subscriptionDelivery :: PostService d -> Txt.Text -> Handler NoContent
+-- exception to be thrown when a tag is not in the responsibility of a relay
+newtype UnhandledTagException = UnhandledTagException String
+    deriving (Show, Typeable)
+
+instance Exception UnhandledTagException
+
+subscriptionDelivery :: DHT d => PostService d -> Txt.Text -> Handler Txt.Text
 subscriptionDelivery serv subList = do
     let
         tagSubs = Txt.lines subList
-    liftIO $ forM_ tagSubs $ processTag (subscribers serv)
-    pure NoContent
+    -- In favor of having the convenience of rolling back the transaction once a
+    -- not-handled tag occurs, this results in a single large transaction.
+    -- Hopefully the performance isn't too bad.
+    res <- liftIO . atomically $ (foldM (\_ tag' -> do
+        responsible <- isResponsibleForSTM (baseDHT serv) (genKeyID . Txt.unpack $ tag')
+        if responsible
+           then processTag (subscribers serv) tag'
+           else throwSTM $ UnhandledTagException (Txt.unpack tag' <> " not handled by this relay")
+        pure $ Right ()
+           ) (pure ()) tagSubs
+           `catchSTM` (\e -> pure . Left $ show (e :: UnhandledTagException))
+           -- TODO: potentially log this
+                          :: STM (Either String ()))
+    case res of
+      Left err -> throwError err410 {errBody = BSUL.fromString err}
+      Right _  -> pure ""
     -- TODO: check and only accept tags in own (future?) responsibility
   where
-      processTag :: TVar RelayTags -> Txt.Text -> IO ()
+      processTag :: TVar RelayTags -> Txt.Text -> STM ()
       processTag subscriberSTM tagData = do
           let
             tag:subText:lease:posts:_ = Txt.splitOn "," tagData
@@ -292,11 +321,11 @@ enqueueSubscription :: TVar RelayTags    -- tag-subscriber map
                      -> (String, Int)   -- subscriber's connection information
                      -> [PostID]        -- pending posts
                      -> POSIXTime       -- lease expiry time
-                     -> IO ()
+                     -> STM ()
 enqueueSubscription tagMapSTM tag subscriber posts leaseTime = do
     -- get the tag output queue and, if necessary, create it
-    subChan <- atomically $ setupSubscriberChannel tagMapSTM tag subscriber leaseTime
-    forM_ posts (atomically . writeTChan subChan)
+    subChan <- setupSubscriberChannel tagMapSTM tag subscriber leaseTime
+    forM_ posts (writeTChan subChan)
 
 
 -- | STM operation to return the outgoing post queue of a tag to a specified subscriber.
@@ -391,7 +420,7 @@ processIncomingPosts serv = forever $ do
       Nothing -> threadDelay $ 10 * 10^6
       Just (responsibleHost, responsiblePort) -> do
         httpMan <- HTTP.newManager HTTP.defaultManagerSettings
-        resp <- runClientM (relayInboxClient tag (pID <> "," <> pContent)) (mkClientEnv httpMan (BaseUrl Http responsibleHost (fromIntegral responsiblePort) ""))
+        resp <- runClientM (relayInboxClient tag $ pID <> "," <> pContent) (mkClientEnv httpMan (BaseUrl Http responsibleHost (fromIntegral responsiblePort) ""))
         case resp of
-          Left err -> putStrLn $ "Error: " <> show err
+          Left err  -> putStrLn $ "Error: " <> show err
           Right yay -> putStrLn $ "Yay! " <> show yay
diff --git a/src/Hash2Pub/RingMap.hs b/src/Hash2Pub/RingMap.hs
index 016f9f1..9b439e9 100644
--- a/src/Hash2Pub/RingMap.hs
+++ b/src/Hash2Pub/RingMap.hs
@@ -196,29 +196,28 @@ takeRMapEntries_ :: (Integral i, Bounded k, Ord k)
 takeRMapEntries_ getterFunc startAt num rmap = reverse $
     case getterFunc startAt rmap of
       Nothing -> []
-      Just (foundKey, anEntry) -> takeEntriesUntil rmap getterFunc foundKey foundKey (num-1) [anEntry]
-  where
-    -- for some reason, just reusing the already-bound @rmap@ and @getterFunc@
-    -- variables leads to a type error, these need to be passed explicitly
-    takeEntriesUntil :: (Integral i, Bounded k, Ord k)
-                     => RingMap k a
-                     -> (k -> RingMap k a -> Maybe (k, a)) -- getter function
-                     -> k
-                     -> k
-                     -> i
-                     -> [a]
-                     -> [a]
-    takeEntriesUntil rmap' getterFunc' havingReached previousEntry remaining takeAcc
-      -- length limit reached
-      | remaining <= 0 = takeAcc
-      --
-      | otherwise = case nextEntry of
-                      Just (fKey, gotEntry)
-                        | fKey == havingReached -> takeAcc
-                        | otherwise -> takeEntriesUntil rmap' getterFunc' havingReached fKey (remaining - 1) (gotEntry:takeAcc)
-                      Nothing -> takeAcc
-        where
-            nextEntry = getterFunc' previousEntry rmap'
+      Just (foundKey, anEntry) -> takeEntriesUntil_ rmap getterFunc foundKey foundKey (Just $ num-1) [anEntry]
+
+
+takeEntriesUntil_ :: (Integral i, Bounded k, Ord k)
+                 => RingMap k a
+                 -> (k -> RingMap k a -> Maybe (k, a)) -- getter function
+                 -> k           -- limit value
+                 -> k           -- start value
+                 -> Maybe i     -- possible number limit
+                 -> [a]
+                 -> [a]
+takeEntriesUntil_ rmap' getterFunc' havingReached previousEntry (Just remaining) takeAcc
+  -- length limit reached
+  | remaining <= 0 = takeAcc
+takeEntriesUntil_ rmap' getterFunc' havingReached previousEntry numLimit takeAcc =
+    case nextEntry of
+                  Just (fKey, gotEntry)
+                    | fKey == havingReached -> takeAcc
+                    | otherwise -> takeEntriesUntil_ rmap' getterFunc' havingReached fKey (fmap pred numLimit) (gotEntry:takeAcc)
+                  Nothing -> takeAcc
+    where
+        nextEntry = getterFunc' previousEntry rmap'
 
 
 takeRMapPredecessors :: (Integral i, Bounded k, Ord k, Num k)
@@ -235,3 +234,16 @@ takeRMapSuccessors :: (Integral i, Bounded k, Ord k, Num k)
                  -> [a]
 takeRMapSuccessors = takeRMapEntries_ rMapLookupSucc
 
+takeRMapPredecessorsFromTo :: (Bounded k, Ord k, Num k)
+                           => k     -- start value for taking
+                           -> k     -- stop value for taking
+                           -> RingMap k a
+                           -> [a]
+takeRMapPredecessorsFromTo fromVal toVal rmap = takeEntriesUntil_ rmap rMapLookupPred toVal fromVal Nothing []
+
+takeRMapSuccesorsFromTo :: (Bounded k, Ord k, Num k)
+                           => k     -- start value for taking
+                           -> k     -- stop value for taking
+                           -> RingMap k a
+                           -> [a]
+takeRMapSuccesorsFromTo fromVal toVal rmap = takeEntriesUntil_ rmap rMapLookupSucc toVal fromVal Nothing []

From 1258f673da285148c23dd66c43aaffa970f1e4cd Mon Sep 17 00:00:00 2001
From: Trolli Schmittlauch <t.schmittlauch@orlives.de>
Date: Wed, 12 Aug 2020 12:07:41 +0200
Subject: [PATCH 24/35] flush responsibility cache and retry in post queue
 delivery

---
 src/Hash2Pub/PostService.hs | 24 ++++++++++++++++++++++--
 1 file changed, 22 insertions(+), 2 deletions(-)

diff --git a/src/Hash2Pub/PostService.hs b/src/Hash2Pub/PostService.hs
index 8f47227..ab3f317 100644
--- a/src/Hash2Pub/PostService.hs
+++ b/src/Hash2Pub/PostService.hs
@@ -301,6 +301,20 @@ clientAPI = Proxy
 relayInboxClient :<|> subscriptionDeliveryClient :<|> postFetchClient :<|> postMultiFetchClient :<|> postInboxClient :<|> tagDeliveryClient :<|> tagSubscribeClient :<|> tagUnsubscribeClient = client clientAPI
 
 
+---- | Deliver the subscriber list of all hashtags in the interval [fromTag, toTag]
+---- and their outstanding delivery queue to another instance.
+---- If the transfer succeeds, the transfered subscribers are removed from the local list.
+--clientDeliverSubscriptions :: PostService
+--                           -> Hashtag -- ^ fromTag
+--                           -> Hashtag -- ^ toTag
+--                           -> (String, Int)     -- ^ hostname and port of instance to deliver to
+--                           -> IO (Either String ())     -- Either signals success or failure
+--clientDeliverSubscriptions serv fromTag toTag (toHost, toPort) = do
+--    -- collect tag intearval
+--    intervalTags <- takeRMapSuccesorsFromTo (genKeyID $ Txt.unpack fromTag) (genKeyID $ Txt.unpack fromTag) =<< readTVarIO $ subscribers serv
+--    -- extract subscribers and posts
+--    -- send subscribers
+--    -- on failure return a Left, otherwise flush remaining queues atomically, schedule all newly arrived posts to still be relayed and delete subscription entry
 
 -- currently this is unused code
 getClients :: String -> Int -> HTTP.Manager -> Client IO PostServiceAPI
@@ -407,7 +421,7 @@ instance {-# OVERLAPPABLE #-} Read a => MimeUnrender PlainText a where
 
 -- ====== worker threads ======
 
--- | process the pending relays of incoming posts from the internal queue:
+-- | process the pending relay inbox of incoming posts from the internal queue:
 -- Look up responsible relay node for given hashtag and forward post to it
 processIncomingPosts :: DHT d => PostService d -> IO ()
 processIncomingPosts serv = forever $ do
@@ -422,5 +436,11 @@ processIncomingPosts serv = forever $ do
         httpMan <- HTTP.newManager HTTP.defaultManagerSettings
         resp <- runClientM (relayInboxClient tag $ pID <> "," <> pContent) (mkClientEnv httpMan (BaseUrl Http responsibleHost (fromIntegral responsiblePort) ""))
         case resp of
-          Left err  -> putStrLn $ "Error: " <> show err
+          Left err  -> do
+              putStrLn $ "Error: " <> show err
+              -- 410 error indicates outdated responsibility mapping
+              -- Simplification: just invalidate the mapping entry on all errors, force a re-lookup and re-queue the post
+              -- TODO: keep track of maximum retries
+              _ <- forceLookupKey (baseDHT serv) (Txt.unpack tag)
+              atomically . writeTQueue (relayInQueue serv) $ (tag, pID, pContent)
           Right yay -> putStrLn $ "Yay! " <> show yay

From 1d808b6776c048c06fbf3f202db1a591df843578 Mon Sep 17 00:00:00 2001
From: Trolli Schmittlauch <t.schmittlauch@orlives.de>
Date: Wed, 12 Aug 2020 12:16:20 +0200
Subject: [PATCH 25/35] fix typo

---
 src/Hash2Pub/RingMap.hs | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/src/Hash2Pub/RingMap.hs b/src/Hash2Pub/RingMap.hs
index 9b439e9..e99f8b2 100644
--- a/src/Hash2Pub/RingMap.hs
+++ b/src/Hash2Pub/RingMap.hs
@@ -241,9 +241,9 @@ takeRMapPredecessorsFromTo :: (Bounded k, Ord k, Num k)
                            -> [a]
 takeRMapPredecessorsFromTo fromVal toVal rmap = takeEntriesUntil_ rmap rMapLookupPred toVal fromVal Nothing []
 
-takeRMapSuccesorsFromTo :: (Bounded k, Ord k, Num k)
+takeRMapSuccessorsFromTo :: (Bounded k, Ord k, Num k)
                            => k     -- start value for taking
                            -> k     -- stop value for taking
                            -> RingMap k a
                            -> [a]
-takeRMapSuccesorsFromTo fromVal toVal rmap = takeEntriesUntil_ rmap rMapLookupSucc toVal fromVal Nothing []
+takeRMapSuccessorsFromTo fromVal toVal rmap = takeEntriesUntil_ rmap rMapLookupSucc toVal fromVal Nothing []

From 2e88a4079b0c36888fe924c8aa72592f93926e89 Mon Sep 17 00:00:00 2001
From: Trolli Schmittlauch <t.schmittlauch@orlives.de>
Date: Wed, 12 Aug 2020 14:07:19 +0200
Subject: [PATCH 26/35] extract and build subscriber payload for sending

---
 src/Hash2Pub/PostService.hs | 55 +++++++++++++++++++++++++++----------
 1 file changed, 41 insertions(+), 14 deletions(-)

diff --git a/src/Hash2Pub/PostService.hs b/src/Hash2Pub/PostService.hs
index ab3f317..11562d4 100644
--- a/src/Hash2Pub/PostService.hs
+++ b/src/Hash2Pub/PostService.hs
@@ -301,20 +301,47 @@ clientAPI = Proxy
 relayInboxClient :<|> subscriptionDeliveryClient :<|> postFetchClient :<|> postMultiFetchClient :<|> postInboxClient :<|> tagDeliveryClient :<|> tagSubscribeClient :<|> tagUnsubscribeClient = client clientAPI
 
 
----- | Deliver the subscriber list of all hashtags in the interval [fromTag, toTag]
----- and their outstanding delivery queue to another instance.
----- If the transfer succeeds, the transfered subscribers are removed from the local list.
---clientDeliverSubscriptions :: PostService
---                           -> Hashtag -- ^ fromTag
---                           -> Hashtag -- ^ toTag
---                           -> (String, Int)     -- ^ hostname and port of instance to deliver to
---                           -> IO (Either String ())     -- Either signals success or failure
---clientDeliverSubscriptions serv fromTag toTag (toHost, toPort) = do
---    -- collect tag intearval
---    intervalTags <- takeRMapSuccesorsFromTo (genKeyID $ Txt.unpack fromTag) (genKeyID $ Txt.unpack fromTag) =<< readTVarIO $ subscribers serv
---    -- extract subscribers and posts
---    -- send subscribers
---    -- on failure return a Left, otherwise flush remaining queues atomically, schedule all newly arrived posts to still be relayed and delete subscription entry
+-- | Deliver the subscriber list of all hashtags in the interval [fromTag, toTag]
+-- and their outstanding delivery queue to another instance.
+-- If the transfer succeeds, the transfered subscribers are removed from the local list.
+clientDeliverSubscriptions :: PostService d
+                           -> Hashtag -- ^ fromTag
+                           -> Hashtag -- ^ toTag
+                           -> (String, Int)     -- ^ hostname and port of instance to deliver to
+                           -> IO (Either String ())     -- Either signals success or failure
+clientDeliverSubscriptions serv fromTag toTag (toHost, toPort) = do
+    -- collect tag intearval
+    intervalTags <- takeRMapSuccessorsFromTo (genKeyID $ Txt.unpack fromTag) (genKeyID $ Txt.unpack fromTag) <$> readTVarIO (subscribers serv)
+    -- returns a [ (TagSubscribersSTM, TChan PostID, Hashtag) ]
+    -- extract subscribers and posts
+    -- no need for extracting as a single atomic operation, as newly incoming posts are supposed to be rejected because of already having re-positioned on the DHT
+    subscriberData <- foldM (\response (subSTM, _, tag) -> do
+        subMap <- readTVarIO subSTM
+        thisTagsData <- foldM (\tagResponse (subscriber, (subChan, lease)) -> do
+            -- duplicate the pending queue to work on a copy, in case of a delivery error
+            pending <- atomically $ do
+                queueCopy <- cloneTChan subChan
+                channelGetAll queueCopy
+            if null pending
+               then pure tagResponse
+               else pure $ tag <> "," <> Txt.pack (show subscriber) <> "," <> Txt.pack (show lease) <> "," <> Txt.unwords pending <> "\n"
+              )
+            ""
+            (HMap.toList subMap)
+        pure $ thisTagsData <> response
+            )
+        ""
+        intervalTags
+    -- send subscribers
+    -- on failure return a Left, otherwise flush remaining queues atomically, schedule all newly arrived posts to still be relayed and delete subscription entry
+    pure . Right $ ()
+  where
+      channelGetAll :: TChan a -> STM [a]
+      channelGetAll chan = channelGetAll' chan []
+      channelGetAll' :: TChan a -> [a] -> STM [a]
+      channelGetAll' chan acc = do
+          haveRead <- tryReadTChan chan
+          maybe (pure acc) (\x -> channelGetAll' chan (x:acc)) haveRead
 
 -- currently this is unused code
 getClients :: String -> Int -> HTTP.Manager -> Client IO PostServiceAPI

From c1ce386b6599931b9e45268c18674457fd4f6ab0 Mon Sep 17 00:00:00 2001
From: Trolli Schmittlauch <t.schmittlauch@orlives.de>
Date: Wed, 12 Aug 2020 15:23:10 +0200
Subject: [PATCH 27/35] send prepared subscriptions and clean up on success

---
 src/Hash2Pub/PostService.hs | 14 +++++++++++---
 1 file changed, 11 insertions(+), 3 deletions(-)

diff --git a/src/Hash2Pub/PostService.hs b/src/Hash2Pub/PostService.hs
index 11562d4..17d585b 100644
--- a/src/Hash2Pub/PostService.hs
+++ b/src/Hash2Pub/PostService.hs
@@ -311,7 +311,7 @@ clientDeliverSubscriptions :: PostService d
                            -> IO (Either String ())     -- Either signals success or failure
 clientDeliverSubscriptions serv fromTag toTag (toHost, toPort) = do
     -- collect tag intearval
-    intervalTags <- takeRMapSuccessorsFromTo (genKeyID $ Txt.unpack fromTag) (genKeyID $ Txt.unpack fromTag) <$> readTVarIO (subscribers serv)
+    intervalTags <- takeRMapSuccessorsFromTo (genKeyID $ Txt.unpack fromTag) (genKeyID $ Txt.unpack toTag) <$> readTVarIO (subscribers serv)
     -- returns a [ (TagSubscribersSTM, TChan PostID, Hashtag) ]
     -- extract subscribers and posts
     -- no need for extracting as a single atomic operation, as newly incoming posts are supposed to be rejected because of already having re-positioned on the DHT
@@ -333,8 +333,16 @@ clientDeliverSubscriptions serv fromTag toTag (toHost, toPort) = do
         ""
         intervalTags
     -- send subscribers
-    -- on failure return a Left, otherwise flush remaining queues atomically, schedule all newly arrived posts to still be relayed and delete subscription entry
-    pure . Right $ ()
+    httpMan <- HTTP.newManager HTTP.defaultManagerSettings
+    resp <- runClientM (subscriptionDeliveryClient subscriberData) (mkClientEnv httpMan (BaseUrl Http toHost (fromIntegral toPort) ""))
+    -- on failure return a Left, otherwise delete subscription entry
+    case resp of
+      Left err -> pure . Left . show $ err
+      Right _ -> do
+          atomically $
+              modifyTVar' (subscribers serv) $ \tagMap ->
+                  foldr deleteRMapEntry tagMap ((\(_, _, t) -> genKeyID . Txt.unpack $ t) <$> intervalTags) 
+          pure . Right $ ()
   where
       channelGetAll :: TChan a -> STM [a]
       channelGetAll chan = channelGetAll' chan []

From 580410e0b4c78150bedfe51d3e5c27a24d02b550 Mon Sep 17 00:00:00 2001
From: Trolli Schmittlauch <t.schmittlauch@orlives.de>
Date: Thu, 13 Aug 2020 13:07:50 +0200
Subject: [PATCH 28/35] simple post fetch worker thread

---
 Hash2Pub.cabal              |  2 +-
 src/Hash2Pub/PostService.hs | 32 +++++++++++++++++++++++++++++---
 2 files changed, 30 insertions(+), 4 deletions(-)

diff --git a/Hash2Pub.cabal b/Hash2Pub.cabal
index 251c60d..5ffff0d 100644
--- a/Hash2Pub.cabal
+++ b/Hash2Pub.cabal
@@ -46,7 +46,7 @@ category:            Network
 extra-source-files:  CHANGELOG.md
 
 common deps
-  build-depends:       base ^>=4.12.0.0, containers ^>=0.6.0.1, bytestring, utf8-string ^>=1.0.1.1, network ^>=2.8.0.1, time ^>=1.8.0.2, cmdargs ^>= 0.10, cryptonite ^>= 0.25, memory, async, stm, asn1-encoding, asn1-types, asn1-parse, publicsuffix, network-byte-order, safe, iproute, mtl, random, servant, servant-server, servant-client, warp, text, unordered-containers, hashable, unicode-transforms, http-client
+  build-depends:       base ^>=4.12.0.0, containers ^>=0.6.0.1, bytestring, utf8-string ^>=1.0.1.1, network ^>=2.8.0.1, time ^>=1.8.0.2, cmdargs ^>= 0.10, cryptonite ^>= 0.25, memory, async, stm, asn1-encoding, asn1-types, asn1-parse, publicsuffix, network-byte-order, safe, iproute, mtl, random, servant, servant-server, servant-client, warp, text, unordered-containers, hashable, unicode-transforms, http-client, http-types
   ghc-options:         -Wall
 
 
diff --git a/src/Hash2Pub/PostService.hs b/src/Hash2Pub/PostService.hs
index 17d585b..47a4059 100644
--- a/src/Hash2Pub/PostService.hs
+++ b/src/Hash2Pub/PostService.hs
@@ -1,4 +1,4 @@
-{-# LANGUAGE DataKinds             #-}
+{-# laNGUAGE DataKinds             #-}
 {-# LANGUAGE FlexibleInstances     #-}
 {-# LANGUAGE InstanceSigs          #-}
 {-# LANGUAGE MultiParamTypeClasses #-}
@@ -15,7 +15,7 @@ import           Control.Concurrent.STM.TChan
 import           Control.Concurrent.STM.TChan
 import           Control.Concurrent.STM.TQueue
 import           Control.Concurrent.STM.TVar
-import           Control.Exception             (Exception (..))
+import           Control.Exception             (Exception (..), try)
 import           Control.Monad                 (foldM, forM, forM_, forever)
 import           Control.Monad.IO.Class        (liftIO)
 import           Control.Monad.STM
@@ -31,6 +31,7 @@ import           Data.Text.Normalize           (NormalizationMode (NFC),
 import           Data.Time.Clock.POSIX
 import           Data.Typeable                 (Typeable)
 import qualified Network.HTTP.Client           as HTTP
+import qualified Network.HTTP.Types            as HTTPT
 import           System.Random
 import           Text.Read                     (readEither)
 
@@ -341,7 +342,7 @@ clientDeliverSubscriptions serv fromTag toTag (toHost, toPort) = do
       Right _ -> do
           atomically $
               modifyTVar' (subscribers serv) $ \tagMap ->
-                  foldr deleteRMapEntry tagMap ((\(_, _, t) -> genKeyID . Txt.unpack $ t) <$> intervalTags) 
+                  foldr deleteRMapEntry tagMap ((\(_, _, t) -> genKeyID . Txt.unpack $ t) <$> intervalTags)
           pure . Right $ ()
   where
       channelGetAll :: TChan a -> STM [a]
@@ -479,3 +480,28 @@ processIncomingPosts serv = forever $ do
               _ <- forceLookupKey (baseDHT serv) (Txt.unpack tag)
               atomically . writeTQueue (relayInQueue serv) $ (tag, pID, pContent)
           Right yay -> putStrLn $ "Yay! " <> show yay
+
+
+-- | process the pending fetch jobs of delivered post IDs: Delivered posts are tried to be fetched from their URI-ID
+fetchTagPosts :: DHT d => PostService d -> IO ()
+fetchTagPosts serv = forever $ do
+    -- blocks until available
+    -- TODO: batching, retry
+    -- TODO: process multiple in parallel
+    pIdUri <- atomically . readTQueue $ postFetchQueue serv
+    httpMan <- HTTP.newManager HTTP.defaultManagerSettings
+    fetchReq <- HTTP.parseRequest . Txt.unpack $pIdUri
+    resp <- try $ HTTP.httpLbs fetchReq httpMan :: IO (Either HTTP.HttpException (HTTP.Response BSUL.ByteString))
+    case resp of
+      Right response ->
+          if HTTPT.statusCode (HTTP.responseStatus response) == 200
+             then
+             -- success, TODO: statistics
+             putStrLn "post fetch success"
+             else
+             -- TODO error handling, retry
+             pure ()
+      Left _ ->
+             -- TODO error handling, retry
+             pure ()
+

From dcd4a7b563a046f6e05cac27f6abc4c2160189b9 Mon Sep 17 00:00:00 2001
From: Trolli Schmittlauch <t.schmittlauch@orlives.de>
Date: Thu, 13 Aug 2020 13:08:38 +0200
Subject: [PATCH 29/35] add nix shell environment without HIE for smaller foot
 print

---
 shell-minimal.nix | 1 +
 1 file changed, 1 insertion(+)
 create mode 100644 shell-minimal.nix

diff --git a/shell-minimal.nix b/shell-minimal.nix
new file mode 100644
index 0000000..15cd4fb
--- /dev/null
+++ b/shell-minimal.nix
@@ -0,0 +1 @@
+(import ./default.nix {withHIE = false;}).shell

From 375014812ac41480f347b7e891713f928dc60ad9 Mon Sep 17 00:00:00 2001
From: Trolli Schmittlauch <t.schmittlauch@orlives.de>
Date: Thu, 13 Aug 2020 19:05:28 +0200
Subject: [PATCH 30/35] use a shared HTTP manager for requests

---
 src/Hash2Pub/PostService.hs | 14 +++++++-------
 1 file changed, 7 insertions(+), 7 deletions(-)

diff --git a/src/Hash2Pub/PostService.hs b/src/Hash2Pub/PostService.hs
index 47a4059..92cd772 100644
--- a/src/Hash2Pub/PostService.hs
+++ b/src/Hash2Pub/PostService.hs
@@ -1,4 +1,4 @@
-{-# laNGUAGE DataKinds             #-}
+{-# LANGUAGE DataKinds             #-}
 {-# LANGUAGE FlexibleInstances     #-}
 {-# LANGUAGE InstanceSigs          #-}
 {-# LANGUAGE MultiParamTypeClasses #-}
@@ -58,6 +58,7 @@ data PostService d = PostService
     , relayInQueue     :: TQueue (Hashtag, PostID, PostContent)
     -- ^ Queue for processing incoming posts of own instance asynchronously
     , postFetchQueue   :: TQueue PostID
+    , httpMan          :: HTTP.Manager
     }
     deriving (Typeable)
 
@@ -84,6 +85,7 @@ instance DHT d => Service PostService d where
         ownPostVar <- newTVarIO HSet.empty
         relayInQueue' <- newTQueueIO
         postFetchQueue' <- newTQueueIO
+        httpMan' <- HTTP.newManager HTTP.defaultManagerSettings
         let
             thisService = PostService {
                 serviceConf = conf
@@ -94,6 +96,7 @@ instance DHT d => Service PostService d where
               , ownPosts = ownPostVar
               , relayInQueue = relayInQueue'
               , postFetchQueue = postFetchQueue'
+              , httpMan = httpMan'
                                       }
             port' = fromIntegral (confServicePort conf)
             warpSettings = Warp.setPort port' . Warp.setHost (fromString . confServiceHost $ conf) $ Warp.defaultSettings
@@ -334,8 +337,7 @@ clientDeliverSubscriptions serv fromTag toTag (toHost, toPort) = do
         ""
         intervalTags
     -- send subscribers
-    httpMan <- HTTP.newManager HTTP.defaultManagerSettings
-    resp <- runClientM (subscriptionDeliveryClient subscriberData) (mkClientEnv httpMan (BaseUrl Http toHost (fromIntegral toPort) ""))
+    resp <- runClientM (subscriptionDeliveryClient subscriberData) (mkClientEnv (httpMan serv) (BaseUrl Http toHost (fromIntegral toPort) ""))
     -- on failure return a Left, otherwise delete subscription entry
     case resp of
       Left err -> pure . Left . show $ err
@@ -469,8 +471,7 @@ processIncomingPosts serv = forever $ do
       -- no vserver active => wait and retry
       Nothing -> threadDelay $ 10 * 10^6
       Just (responsibleHost, responsiblePort) -> do
-        httpMan <- HTTP.newManager HTTP.defaultManagerSettings
-        resp <- runClientM (relayInboxClient tag $ pID <> "," <> pContent) (mkClientEnv httpMan (BaseUrl Http responsibleHost (fromIntegral responsiblePort) ""))
+        resp <- runClientM (relayInboxClient tag $ pID <> "," <> pContent) (mkClientEnv (httpMan serv) (BaseUrl Http responsibleHost (fromIntegral responsiblePort) ""))
         case resp of
           Left err  -> do
               putStrLn $ "Error: " <> show err
@@ -489,9 +490,8 @@ fetchTagPosts serv = forever $ do
     -- TODO: batching, retry
     -- TODO: process multiple in parallel
     pIdUri <- atomically . readTQueue $ postFetchQueue serv
-    httpMan <- HTTP.newManager HTTP.defaultManagerSettings
     fetchReq <- HTTP.parseRequest . Txt.unpack $pIdUri
-    resp <- try $ HTTP.httpLbs fetchReq httpMan :: IO (Either HTTP.HttpException (HTTP.Response BSUL.ByteString))
+    resp <- try $ HTTP.httpLbs fetchReq (httpMan serv) :: IO (Either HTTP.HttpException (HTTP.Response BSUL.ByteString))
     case resp of
       Right response ->
           if HTTPT.statusCode (HTTP.responseStatus response) == 200

From e9ae258ddeec73b424528639c379c18d7c3d3e2c Mon Sep 17 00:00:00 2001
From: Trolli Schmittlauch <t.schmittlauch@orlives.de>
Date: Thu, 13 Aug 2020 21:12:22 +0200
Subject: [PATCH 31/35] subscribe to tag

---
 src/Hash2Pub/PostService.hs | 15 +++++++++++++++
 1 file changed, 15 insertions(+)

diff --git a/src/Hash2Pub/PostService.hs b/src/Hash2Pub/PostService.hs
index 92cd772..15901e0 100644
--- a/src/Hash2Pub/PostService.hs
+++ b/src/Hash2Pub/PostService.hs
@@ -354,6 +354,21 @@ clientDeliverSubscriptions serv fromTag toTag (toHost, toPort) = do
           haveRead <- tryReadTChan chan
           maybe (pure acc) (\x -> channelGetAll' chan (x:acc)) haveRead
 
+
+-- | Subscribe the client to the given hashtag. On success it returns the given lease time.
+clientSubscribeTo :: DHT d => PostService d -> Hashtag -> IO (Either String Integer)
+clientSubscribeTo serv tag = do
+    lookupRes <- lookupKey (baseDHT serv) (Txt.unpack tag)
+    maybe
+        (pure . Left $ "No node found")
+        (\(foundHost, foundPort) -> do
+            resp <- runClientM (tagSubscribeClient tag (Just . fromString . confServiceHost . serviceConf $ serv)) (mkClientEnv (httpMan serv) (BaseUrl Http foundHost (fromIntegral foundPort) ""))
+            case resp of
+              Left err    -> pure . Left . show $ err
+              Right lease -> pure . Right $ lease
+        )
+        lookupRes
+
 -- currently this is unused code
 getClients :: String -> Int -> HTTP.Manager -> Client IO PostServiceAPI
 getClients hostname' port' httpMan = hoistClient clientAPI

From e646045ab294ef88e08598e9c2f3ea3427425358 Mon Sep 17 00:00:00 2001
From: Trolli Schmittlauch <t.schmittlauch@orlives.de>
Date: Thu, 13 Aug 2020 21:57:28 +0200
Subject: [PATCH 32/35] include port in Origin header

---
 src/Hash2Pub/PostService.hs | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/src/Hash2Pub/PostService.hs b/src/Hash2Pub/PostService.hs
index 15901e0..1de7302 100644
--- a/src/Hash2Pub/PostService.hs
+++ b/src/Hash2Pub/PostService.hs
@@ -359,10 +359,11 @@ clientDeliverSubscriptions serv fromTag toTag (toHost, toPort) = do
 clientSubscribeTo :: DHT d => PostService d -> Hashtag -> IO (Either String Integer)
 clientSubscribeTo serv tag = do
     lookupRes <- lookupKey (baseDHT serv) (Txt.unpack tag)
+    let origin = "http://" <> Txt.pack (confServiceHost $ serviceConf serv) <> ":" <> Txt.pack (show (getListeningPortFromService serv :: Integer))
     maybe
         (pure . Left $ "No node found")
         (\(foundHost, foundPort) -> do
-            resp <- runClientM (tagSubscribeClient tag (Just . fromString . confServiceHost . serviceConf $ serv)) (mkClientEnv (httpMan serv) (BaseUrl Http foundHost (fromIntegral foundPort) ""))
+            resp <- runClientM (tagSubscribeClient tag (Just origin)) (mkClientEnv (httpMan serv) (BaseUrl Http foundHost (fromIntegral foundPort) ""))
             case resp of
               Left err    -> pure . Left . show $ err
               Right lease -> pure . Right $ lease

From 402378a78bd94c351c1bab77fd6b8d1bc985ed18 Mon Sep 17 00:00:00 2001
From: Trolli Schmittlauch <t.schmittlauch@orlives.de>
Date: Thu, 13 Aug 2020 23:44:24 +0200
Subject: [PATCH 33/35] signal and handle non-responsibility to subscriptions

---
 src/Hash2Pub/PostService.hs | 34 +++++++++++++++++++++++-----------
 1 file changed, 23 insertions(+), 11 deletions(-)

diff --git a/src/Hash2Pub/PostService.hs b/src/Hash2Pub/PostService.hs
index 1de7302..26c473b 100644
--- a/src/Hash2Pub/PostService.hs
+++ b/src/Hash2Pub/PostService.hs
@@ -272,8 +272,13 @@ tagDelivery serv hashtag posts = do
             pure ()
     pure $ "Received a postID for tag " <> hashtag
 
-tagSubscribe :: PostService d -> Txt.Text -> Maybe Txt.Text -> Handler Integer
+tagSubscribe :: DHT d => PostService d -> Txt.Text -> Maybe Txt.Text -> Handler Integer
 tagSubscribe serv hashtag origin = do
+    responsible <- liftIO $ isResponsibleFor (baseDHT serv) (genKeyID . Txt.unpack $ hashtag)
+    if not responsible
+       -- GONE if not responsible
+       then throwError err410 { errBody = "not responsible for this tag" }
+       else pure ()
     originURL <- maybe
         (throwError $ err400 { errBody = "Missing Origin header" })
         pure
@@ -359,16 +364,23 @@ clientDeliverSubscriptions serv fromTag toTag (toHost, toPort) = do
 clientSubscribeTo :: DHT d => PostService d -> Hashtag -> IO (Either String Integer)
 clientSubscribeTo serv tag = do
     lookupRes <- lookupKey (baseDHT serv) (Txt.unpack tag)
-    let origin = "http://" <> Txt.pack (confServiceHost $ serviceConf serv) <> ":" <> Txt.pack (show (getListeningPortFromService serv :: Integer))
-    maybe
-        (pure . Left $ "No node found")
-        (\(foundHost, foundPort) -> do
-            resp <- runClientM (tagSubscribeClient tag (Just origin)) (mkClientEnv (httpMan serv) (BaseUrl Http foundHost (fromIntegral foundPort) ""))
-            case resp of
-              Left err    -> pure . Left . show $ err
-              Right lease -> pure . Right $ lease
-        )
-        lookupRes
+    doSubscribe lookupRes True
+  where
+      doSubscribe lookupResponse allowRetry = maybe
+          (pure . Left $ "No node found")
+          (\(foundHost, foundPort) -> do
+              let origin = "http://" <> Txt.pack (confServiceHost $ serviceConf serv) <> ":" <> Txt.pack (show (getListeningPortFromService serv :: Integer))
+              resp <- runClientM (tagSubscribeClient tag (Just origin)) (mkClientEnv (httpMan serv) (BaseUrl Http foundHost (fromIntegral foundPort) ""))
+              case resp of
+                Left (FailureResponse _ fresp)
+                  |(HTTPT.statusCode . responseStatusCode $ fresp) == 410 && allowRetry -> do  -- responsibility gone, force new lookup
+                      newRes <- forceLookupKey (baseDHT serv) (Txt.unpack tag)
+                      doSubscribe newRes False
+                Left err    -> pure . Left . show $ err
+                Right lease -> pure . Right $ lease
+          )
+          lookupResponse
+
 
 -- currently this is unused code
 getClients :: String -> Int -> HTTP.Manager -> Client IO PostServiceAPI

From bf277c5a730f92f669929f2f015aa6b471758b59 Mon Sep 17 00:00:00 2001
From: Trolli Schmittlauch <t.schmittlauch@orlives.de>
Date: Thu, 13 Aug 2020 23:50:33 +0200
Subject: [PATCH 34/35] unsubsribe from tag

---
 src/Hash2Pub/PostService.hs | 29 ++++++++++++++++++++++++++++-
 1 file changed, 28 insertions(+), 1 deletion(-)

diff --git a/src/Hash2Pub/PostService.hs b/src/Hash2Pub/PostService.hs
index 26c473b..99a9efb 100644
--- a/src/Hash2Pub/PostService.hs
+++ b/src/Hash2Pub/PostService.hs
@@ -291,8 +291,13 @@ tagSubscribe serv hashtag origin = do
     pure $ round leaseTime
 
 
-tagUnsubscribe :: PostService d -> Txt.Text -> Maybe Txt.Text -> Handler Txt.Text
+tagUnsubscribe :: DHT d => PostService d -> Txt.Text -> Maybe Txt.Text -> Handler Txt.Text
 tagUnsubscribe serv hashtag origin = do
+    responsible <- liftIO $ isResponsibleFor (baseDHT serv) (genKeyID . Txt.unpack $ hashtag)
+    if not responsible
+       -- GONE if not responsible
+       then throwError err410 { errBody = "not responsible for this tag" }
+       else pure ()
     originURL <- maybe
         (throwError $ err400 { errBody = "Missing Origin header" })
         pure
@@ -382,6 +387,28 @@ clientSubscribeTo serv tag = do
           lookupResponse
 
 
+-- | Unsubscribe the client from the given hashtag.
+clientUnsubscribeFrom :: DHT d => PostService d -> Hashtag -> IO (Either String ())
+clientUnsubscribeFrom serv tag = do
+    lookupRes <- lookupKey (baseDHT serv) (Txt.unpack tag)
+    doUnsubscribe lookupRes True
+  where
+      doUnsubscribe lookupResponse allowRetry = maybe
+          (pure . Left $ "No node found")
+          (\(foundHost, foundPort) -> do
+              let origin = "http://" <> Txt.pack (confServiceHost $ serviceConf serv) <> ":" <> Txt.pack (show (getListeningPortFromService serv :: Integer))
+              resp <- runClientM (tagUnsubscribeClient tag (Just origin)) (mkClientEnv (httpMan serv) (BaseUrl Http foundHost (fromIntegral foundPort) ""))
+              case resp of
+                Left (FailureResponse _ fresp)
+                  |(HTTPT.statusCode . responseStatusCode $ fresp) == 410 && allowRetry -> do  -- responsibility gone, force new lookup
+                      newRes <- forceLookupKey (baseDHT serv) (Txt.unpack tag)
+                      doUnsubscribe newRes False
+                Left err    -> pure . Left . show $ err
+                Right _ -> pure . Right $ ()
+          )
+          lookupResponse
+
+
 -- currently this is unused code
 getClients :: String -> Int -> HTTP.Manager -> Client IO PostServiceAPI
 getClients hostname' port' httpMan = hoistClient clientAPI

From 4339cace201193d11842b95a502ccc6c7bef4742 Mon Sep 17 00:00:00 2001
From: Trolli Schmittlauch <t.schmittlauch@orlives.de>
Date: Fri, 14 Aug 2020 11:06:58 +0200
Subject: [PATCH 35/35] function for initially publishing a post

---
 src/Hash2Pub/PostService.hs | 15 +++++++++++++++
 1 file changed, 15 insertions(+)

diff --git a/src/Hash2Pub/PostService.hs b/src/Hash2Pub/PostService.hs
index 99a9efb..797a9e6 100644
--- a/src/Hash2Pub/PostService.hs
+++ b/src/Hash2Pub/PostService.hs
@@ -19,6 +19,7 @@ import           Control.Exception             (Exception (..), try)
 import           Control.Monad                 (foldM, forM, forM_, forever)
 import           Control.Monad.IO.Class        (liftIO)
 import           Control.Monad.STM
+import           Data.Bifunctor
 import qualified Data.ByteString.Lazy.UTF8     as BSUL
 import qualified Data.ByteString.UTF8          as BSU
 import qualified Data.HashMap.Strict           as HMap
@@ -409,6 +410,20 @@ clientUnsubscribeFrom serv tag = do
           lookupResponse
 
 
+-- | publish a new post to the inbox of a specified relay instance. This
+-- instance will then be the originating instance of the post and will forward
+-- the post to the responsible relays.
+-- As the initial publishing isn't done by a specific relay (but *to* a specific relay
+-- instead), the function does *not* take a PostService as argument.
+clientPublishPost :: HTTP.Manager   -- for better performance, a shared HTTP manager has to be provided
+                  -> String         -- hostname
+                  -> Int            -- port
+                  -> PostContent    -- post content
+                  -> IO (Either String ())  -- error or success
+clientPublishPost httpman hostname port postC = do
+    resp <- runClientM (postInboxClient postC) (mkClientEnv httpman (BaseUrl Http hostname port ""))
+    pure . bimap show (const ()) $ resp
+
 -- currently this is unused code
 getClients :: String -> Int -> HTTP.Manager -> Client IO PostServiceAPI
 getClients hostname' port' httpMan = hoistClient clientAPI