Move tracer out of the modifyMVar block

Author: jasagredo

ouroboros-consensus/src/ouroboros-consensus/Ouroboros/Consensus/Storage/ImmutableDB/Impl/Index/Cache.hs

@@ -574,23 +574,27 @@ getChunkInfo ::
 getChunkInfo cacheEnv chunk = do
     lastUsed <- LastUsed <$> getMonotonicTime
     -- Make sure we don't leave an empty MVar in case of an exception.
-    mbCacheHit <- modifyMVar cacheVar $
+    (mbCacheHit, tr) <- modifyMVar cacheVar $
       \cached@Cached { currentChunk, currentChunkInfo, nbPastChunks } -> if
         | chunk == currentChunk -> do
           -- Cache hit for the current chunk
-          traceWith tracer $ TraceCurrentChunkHit chunk nbPastChunks
-          return (cached, Just $ Left currentChunkInfo)
+          return ( cached
+                 , (Just $ Left currentChunkInfo, TraceCurrentChunkHit chunk nbPastChunks)
+                 )
         | Just (pastChunkInfo, cached') <- lookupPastChunkInfo chunk lastUsed cached -> do
           -- Cache hit for an chunk in the past
-          traceWith tracer $ TracePastChunkHit chunk nbPastChunks
-          return (cached', Just $ Right pastChunkInfo)
+          return ( cached'
+                 , (Just $ Right pastChunkInfo, TracePastChunkHit chunk nbPastChunks)
+                 )
         | otherwise -> do
           -- Cache miss for an chunk in the past. We don't want to hold on to
           -- the 'cacheVar' MVar, blocking all other access to the cace, while
           -- we're reading things from disk, so put it back now and update the
           -- cache afterwards.
-          traceWith tracer $ TracePastChunkMiss chunk nbPastChunks
-          return (cached, Nothing)
+          return ( cached
+                 , (Nothing, TracePastChunkMiss chunk nbPastChunks)
+                 )
+    traceWith tracer tr
     case mbCacheHit of
       Just hit -> return hit
       Nothing  -> do