Guard against overflow of exponential

Author: kderme

cardano-db-sync/src/Cardano/DbSync/OffChain/FetchQueue.hs

@@ -28,13 +28,18 @@ retryAgain fetchTime existingRetryCount =
   -- POSIXTime is in seconds.
   Retry
     { retryFetchTime = fetchTime
-    , retryRetryTime = fetchTime + min (24 * 60 * 60) (30 + (5 ^ nextRetryCount) * 60)
+    , retryRetryTime = fetchTime + retryDiff
     , retryCount = nextRetryCount
     }
   where
     nextRetryCount :: Word
     nextRetryCount = 1 + existingRetryCount
 
+    retryDiff =
+      if nextRetryCount >= 5
+        then 24 * 60 * 60
+        else min (24 * 60 * 60) (30 + (2 ^ nextRetryCount) * 60)
+
 -- A nice pretty printer for the retry.
 showRetryTimes :: Retry -> Text
 showRetryTimes retry =