Conway: also enable mempool ref script size limit (#1168)

Also implementing
#1166 (comment),
but in a more fine-grained fashion

The insight here is that `txRefScriptSize` is implemented using
`getBabbageTxDict` for Shelley-based blocks, see the usage sites of that
function in `Ouroboros.Consensus.Mempool.Impl.Common` and
`Ouroboros.Consensus.Mempool.Update`.

Author: amesgen

ouroboros-consensus-cardano/changelog.d/20240627_125444_alexander.esgen_conway_mempool_refscript_limit.md

@@ -0,0 +1,4 @@
+### Non-Breaking
+
+- Also enabled total ref script size limit in the mempool in Conway (it
+  continues to be enabled in Babbage).

ouroboros-consensus-cardano/src/shelley/Ouroboros/Consensus/Shelley/Eras.hs

@@ -211,6 +211,11 @@ defaultApplyShelleyBasedTx globals ledgerEnv mempoolState _wti tx = do
     refScriptPredicate = case getBabbageTxDict (Proxy @era) of
       Nothing -> pure ()
       Just (BabbageTxDict mkError)
+        -- The ledger rules of Conway (and later eras) already handle ref
+        -- scripts appropriately, so we only need to perform the checks below
+        -- for Babbage.
+        | not $ isBeforeConway (Proxy @era)
+        -> pure ()
         -- Reject it if it has more than 100 kibibytes of ref script.
         | refScriptsSize > totalRefScriptsSizeLimit
         -> throwError $ mkError
@@ -299,7 +304,12 @@ instance (Praos.PraosCrypto c) => ShelleyBasedEra (ConwayEra c) where
 
   getConwayEraGovDict _ = Just ConwayEraGovDict
 
-  getBabbageTxDict _ = Nothing
+  getBabbageTxDict _ = Just $ BabbageTxDict $ \a b ->
+      SL.ApplyTxError
+    $ pure
+    $ Conway.ConwayUtxowFailure
+    $ Conway.UtxoFailure
+    $ Conway.MaxTxSizeUTxO a b
 
 applyAlonzoBasedTx :: forall era.
   ( ShelleyBasedEra era,

ouroboros-consensus/changelog.d/20240820_160936_alexander.esgen_conway_mempool_refscript_limit.md

@@ -0,0 +1,4 @@
+### Non-Breaking
+
+- Mempool: also changed to use the more conservative value of Ledger's
+  `maxRefScriptSizePerBlock`, ie 1MiB, that was decided on for Conway.

ouroboros-consensus/src/ouroboros-consensus/Ouroboros/Consensus/Mempool/Update.hs

@@ -185,10 +185,11 @@ pureTryAddTx cfg txSize wti tx is
     -- mempool, and...
   | let curSize = msNumBytes  $ isMempoolSize is
   , curSize < getMempoolCapacityBytes (isCapacity is)
-    -- ... if the mempool has less than 2.5 mebibytes of ref scripts.
-  , let maxTotalRefScriptSize = 5 * 512 * 1024 -- 2.5 Mebibytes
-        curTotalRefScriptSize = isTotalRefScriptSize is
-  , curTotalRefScriptSize Prelude.< maxTotalRefScriptSize
+    -- ... if the mempool will have at most 1 mebibyte of ref scripts.
+  , let curTotalRefScriptSize = isTotalRefScriptSize is
+        newTxRefScriptSize    = txRefScriptSize cfg (isLedgerState is) tx
+        maxTotalRefScriptSize = 1024 * 1024 -- 1MiB
+  , curTotalRefScriptSize + newTxRefScriptSize Prelude.<= maxTotalRefScriptSize
   =
   case eVtx of
       -- We only extended the ValidationResult with a single transaction