Merge pull request #2236 from urbit/bs/fix-log-replay

king: Fix log replay bug.

pkg/hs/urbit-king/lib/Urbit/Vere/Pier.hs

@@ -131,13 +131,19 @@ resumed :: (HasStderrLogFunc e, HasPierConfig e, HasLogFunc e)
         => Maybe Word64 -> Serf.Flags
         -> RAcquire e (Serf e, EventLog, SerfState)
 resumed event flags = do
+    rio $ logTrace "Resuming ship"
     top    <- view pierPathL
     tap    <- fmap (fromMaybe top) $ rio $ runMaybeT $ do
                 ev <- MaybeT (pure event)
                 MaybeT (getSnapshot top ev)
-    rio $ logTrace $ displayShow tap
+
+    rio $ logTrace $ display @Text ("pier: " <> pack top)
+    rio $ logTrace $ display @Text ("running serf in: " <> pack tap)
+
     log    <- Log.existing (top <> "/.urb/log")
+
     serf   <- Serf.run (Serf.Config tap flags)
+
     serfSt <- rio $ Serf.replay serf log event
 
     rio $ Serf.snapshot serf serfSt

pkg/hs/urbit-king/lib/Urbit/Vere/Serf.hs

@@ -270,7 +270,9 @@ cordText = T.strip . unCord
 --------------------------------------------------------------------------------
 
 snapshot :: HasLogFunc e => Serf e -> SerfState -> RIO e ()
-snapshot serf ss = sendOrder serf $ OSave $ ssLastEv ss
+snapshot serf ss = do
+    logTrace $ display ("Taking snapshot at event " <> tshow (ssLastEv ss))
+    sendOrder serf $ OSave $ ssLastEv ss
 
 shutdown :: HasLogFunc e => Serf e -> Word8 -> RIO e ()
 shutdown serf code = sendOrder serf (OExit code)
@@ -298,12 +300,20 @@ recvPlea w = do
 -}
 handshake :: HasLogFunc e => Serf e -> LogIdentity -> RIO e SerfState
 handshake serf ident = do
+    logTrace "Serf Handshake"
+
     ss@SerfState{..} <- recvPlea serf >>= \case
       PPlay e m -> pure $ SerfState e m
       x         -> throwIO (InvalidInitialPlea x)
 
+    logTrace $ display ("Handshake result: " <> tshow ss)
+
     when (ssNextEv == 1) $ do
-        sendOrder serf (OBoot (lifecycleLen ident))
+        let ev = OBoot (lifecycleLen ident)
+        logTrace $ display ("No snapshot. Sending boot event: " <> tshow ev)
+        sendOrder serf ev
+
+    logTrace "Finished handshake"
 
     pure ss
 
@@ -435,27 +445,43 @@ replayJobs serf lastEv = go Nothing
                 go pb played
 
     updatePb ss = do
-      let start = lastEv - (fromIntegral (ssNextEv ss))
-      let msg = pack ("Replaying events #" ++ (show (ssNextEv ss)) ++
-                      " to #" ++ (show lastEv))
+        let start = lastEv - fromIntegral (ssNextEv ss)
+        let msg   = pack ( "Replaying events #" ++ (show (ssNextEv ss))
+                        <> " to #" ++ (show lastEv)
+                         )
         updateProgressBar start msg
 
 
 replay :: (HasStderrLogFunc e, HasLogFunc e)
           => Serf e -> Log.EventLog -> Maybe Word64 -> RIO e SerfState
 replay serf log last = do
+    logTrace "Beginning event log replay"
+
+    last & \case
+        Nothing -> pure ()
+        Just lt -> logTrace $ display $
+                     "User requested to replay up to event #" <> tshow lt
+
     ss <- handshake serf (Log.identity log)
 
-    let numEvs = case last of
-                   Nothing -> ssNextEv ss
-                   Just la -> la - (ssNextEv ss) + 1
+    logLastEv :: Word64 <- fromIntegral <$> Log.lastEv log
 
-    lastEv <- last & maybe (Log.lastEv log) pure
+    let serfNextEv = ssNextEv ss
+        lastEventInSnap = serfNextEv - 1
 
-    runConduit $  Log.streamEvents log (ssNextEv ss)
+    logTrace $ display $ "Last event in event log is #" <> tshow logLastEv
+
+    let replayUpTo = fromMaybe logLastEv last
+
+    let numEvs :: Int = fromIntegral replayUpTo - fromIntegral lastEventInSnap
+
+    logTrace $ display $ "Replaying up to event #" <> tshow replayUpTo
+    logTrace $ display $ "Will replay " <> tshow numEvs <> " in total."
+
+    runConduit $ Log.streamEvents log serfNextEv
               .| CC.take (fromIntegral numEvs)
-               .| toJobs (Log.identity log) (ssNextEv ss)
-               .| replayJobs serf (fromIntegral lastEv) ss
+              .| toJobs (Log.identity log) serfNextEv
+              .| replayJobs serf (fromIntegral replayUpTo) ss
 
 toJobs :: HasLogFunc e
        => LogIdentity -> EventId -> ConduitT ByteString Job (RIO e) ()