From 1d50a136067b59ea8fc6b95b8b22a911f603a605 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Roman=20Smr=C5=BE?= <roman.smrz@seznam.cz>
Date: Sat, 4 May 2024 21:24:17 +0200
Subject: Network: wait with channel close after delivering all data

---
 src/Erebos/Network/Protocol.hs | 25 ++++++++++++++++++++-----
 1 file changed, 20 insertions(+), 5 deletions(-)

diff --git a/src/Erebos/Network/Protocol.hs b/src/Erebos/Network/Protocol.hs
index 59fcdca..3191f16 100644
--- a/src/Erebos/Network/Protocol.hs
+++ b/src/Erebos/Network/Protocol.hs
@@ -200,6 +200,7 @@ connAddWriteStream conn@Connection {..} = do
             sState <- newTVar StreamOpening
             (sFlowIn, sFlowOut) <- newFlow
             sNextSequence <- newTVar 0
+            sWaitingForAck <- newTVar 0
             let info = (n, Stream {..})
             return (info, info : streams)
         doInsert _ _ = throwError "all outbound streams in use"
@@ -217,10 +218,17 @@ connAddWriteStream conn@Connection {..} = do
                     _             -> retry
                 (,) <$> reservePacket conn
                     <*> readFlow (sFlowOut stream)
-            let (plain, cont, onAck) = case msg of
-                    StreamData {..} -> (stpData, True, return ())
-                    StreamClosed {} -> (BC.empty, False, streamClosed conn streamNumber)
-                    -- TODO: send channel closed only after delivering all previous data packets
+
+            (plain, cont, onAck) <- case msg of
+                StreamData {..} -> do
+                    return (stpData, True, return ())
+                StreamClosed {} -> do
+                    atomically $ do
+                        -- wait for ack on all sent stream data
+                        waits <- readTVar (sWaitingForAck stream)
+                        when (waits > 0) retry
+                    return (BC.empty, False, streamClosed conn streamNumber)
+
             let secure = True
                 plainAckedBy = []
                 mbReserved = Just reserved
@@ -247,9 +255,14 @@ connAddWriteStream conn@Connection {..} = do
 
             case mbs of
                 Just (bs, ackedBy) -> do
+                    atomically $ do
+                        modifyTVar' (sWaitingForAck stream) (+ 1)
                     let mbReserved' = (\rs -> rs
                             { rsAckedBy = guard (not $ null ackedBy) >> Just (`elem` ackedBy)
-                            , rsOnAck = rsOnAck rs >> onAck
+                            , rsOnAck = do
+                                rsOnAck rs
+                                onAck
+                                atomically $ modifyTVar' (sWaitingForAck stream) (subtract 1)
                             }) <$> mbReserved
                     sendBytes conn mbReserved' bs
                 Nothing -> return ()
@@ -266,6 +279,7 @@ connAddReadStream Connection {..} streamNumber = do
             sState <- newTVar StreamRunning
             (sFlowIn, sFlowOut) <- newFlow
             sNextSequence <- newTVar 0
+            sWaitingForAck <- newTVar 0
             let stream = Stream {..}
             return (stream, (streamNumber, stream) : streams)
     (stream, inStreams') <- doInsert inStreams
@@ -281,6 +295,7 @@ data Stream = Stream
     , sFlowIn :: Flow Void StreamPacket
     , sFlowOut :: Flow StreamPacket Void
     , sNextSequence :: TVar Word64
+    , sWaitingForAck :: TVar Word64
     }
 
 data StreamState = StreamOpening | StreamRunning
-- 
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