feature(cardano-db-sync): Replace DRep pulsing state in ledger state

Before retrieving the DRep pulsing state, force its evaluation, then
save it to the ledger state. This will prevent us from unnecessarily
recalculating it.

Author: sgillespie

cardano-db-sync/src/Cardano/DbSync/Ledger/State.hs

@@ -84,7 +84,7 @@ import qualified Data.Strict.Maybe as Strict
 import qualified Data.Text as Text
 import Data.Time.Clock (UTCTime, diffUTCTime, getCurrentTime)
 import GHC.IO.Exception (userError)
-import Lens.Micro ((^.))
+import Lens.Micro ((%~), (^.), (^?))
 import Ouroboros.Consensus.Block (
   CodecConfig,
   Point (..),
@@ -226,7 +226,7 @@ applyBlock env blk = do
     !result <- fromEitherSTM $ tickThenReapplyCheckHash (ExtLedgerCfg (getTopLevelconfigHasLedger env)) blk (clsState oldState)
     let ledgerEventsFull = mapMaybe (convertAuxLedgerEvent (leHasRewards env)) (lrEvents result)
     let (ledgerEvents, deposits) = splitDeposits ledgerEventsFull
-    let !newLedgerState = lrResult result
+    let !newLedgerState = finaliseDrepDistr (lrResult result)
     !details <- getSlotDetails env (ledgerState newLedgerState) time (cardanoBlockSlotNo blk)
     !newEpoch <- fromEitherSTM $ mkNewEpoch (clsState oldState) newLedgerState (findAdaPots ledgerEvents)
     let !newEpochBlockNo = applyToEpochBlockNo (isJust $ blockIsEBB blk) (isJust newEpoch) (clsEpochBlockNo oldState)
@@ -282,18 +282,19 @@ applyBlock env blk = do
     applyToEpochBlockNo _ _ GenesisEpochBlockNo = EpochBlockNo 0
     applyToEpochBlockNo _ _ EBBEpochBlockNo = EpochBlockNo 0
 
+    getDrepState :: ExtLedgerState CardanoBlock -> Maybe (DRepPulsingState StandardConway)
+    getDrepState ls = ls ^? newEpochStateT . Shelley.newEpochStateDRepPulsingStateL
+
+    finaliseDrepDistr :: ExtLedgerState CardanoBlock -> ExtLedgerState CardanoBlock
+    finaliseDrepDistr ledger =
+      ledger & newEpochStateT %~ forceDRepPulsingState @StandardConway
+
 getEnacted :: ExtLedgerState CardanoBlock -> Maybe (GovRelation StrictMaybe StandardConway)
 getEnacted ls = case ledgerState ls of
   LedgerStateConway cls ->
     Just $ govStatePrevGovActionIds $ Consensus.shelleyLedgerState cls ^. Shelley.newEpochStateGovStateL
   _ -> Nothing
 
-getDrepState :: ExtLedgerState CardanoBlock -> Maybe (DRepPulsingState StandardConway)
-getDrepState ls = case ledgerState ls of
-  LedgerStateConway cls ->
-    Just $ Consensus.shelleyLedgerState cls ^. Shelley.newEpochStateDRepPulsingStateL
-  _ -> Nothing
-
 getCommittee :: ExtLedgerState CardanoBlock -> Maybe (StrictMaybe (Committee StandardConway))
 getCommittee ls = case ledgerState ls of
   LedgerStateConway cls ->