Implement atomicReadIORef and use it in getEpochState

IntersectMBO · May 17, 2024 · 6c00851 · 6c00851
1 parent 662abc7
commit 6c00851
Showing 1 changed file with 5 additions and 1 deletion.
diff --git a/cardano-testnet/src/Testnet/Components/Query.hs b/cardano-testnet/src/Testnet/Components/Query.hs
@@ -121,8 +121,12 @@ getEpochState :: MonadTest m
 getEpochState EpochStateView{epochStateView} =
   withFrozenCallStack $
     H.byDurationM 0.5 15 "EpochStateView has not been initialized within 15 seconds" $
-      H.evalIO (readIORef epochStateView) >>= maybe H.failure pure
+      H.evalIO (atomicReadIORef epochStateView) >>= maybe H.failure pure
 
+-- | Reads the IORef and updates it with the initial read value
+atomicReadIORef :: IORef a -> IO a
+atomicReadIORef ref =
+  atomicModifyIORef' ref (\refCurrentValue -> (refCurrentValue, refCurrentValue))
 
 -- | Create a background thread listening for new epoch states. New epoch states are available to access
 -- through 'EpochStateView', using query functions.