REBASEME: Add a trimLedgerState stub

Author: sgillespie

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

@@ -35,6 +35,7 @@ module Cardano.DbSync.Ledger.State (
   getStakeSlice,
   getSliceMeta,
   findProposedCommittee,
+  trimLedgerState,
 ) where
 
 import Cardano.BM.Trace (Trace, logInfo, logWarning)
@@ -89,6 +90,7 @@ import qualified Data.Set as Set
 import qualified Data.Strict.Maybe as Strict
 import qualified Data.Text as Text
 import Data.Time.Clock (UTCTime, diffUTCTime, getCurrentTime)
+import GHC.Conc (unsafeIOToSTM)
 import GHC.IO.Exception (userError)
 import Lens.Micro ((%~), (^.), (^?))
 import Ouroboros.Consensus.Block (
@@ -132,7 +134,7 @@ import qualified Ouroboros.Network.Point as Point
 import System.Directory (doesFileExist, listDirectory, removeFile)
 import System.FilePath (dropExtension, takeExtension, (</>))
 import System.Mem (performMajorGC)
-import Prelude (String, id)
+import Prelude (String, id, undefined)
 
 -- Note: The decision on whether a ledger-state is written to disk is based on the block number
 -- rather than the slot number because while the block number is fully populated (for every block
@@ -217,6 +219,7 @@ readStateUnsafe env = do
 applyBlockAndSnapshot :: HasLedgerEnv -> CardanoBlock -> Bool -> IO (ApplyResult, Bool)
 applyBlockAndSnapshot ledgerEnv blk isCons = do
   (oldState, appResult) <- applyBlock ledgerEnv blk
+
   tookSnapshot <- storeSnapshotAndCleanupMaybe ledgerEnv oldState appResult (blockNo blk) isCons (isSyncedWithinSeconds (apSlotDetails appResult) 600)
   pure (appResult, tookSnapshot)
 
@@ -233,10 +236,12 @@ applyBlock env blk = do
     let ledgerEventsFull = mapMaybe (convertAuxLedgerEvent (leHasRewards env)) (lrEvents result)
     let (ledgerEvents, deposits) = splitDeposits ledgerEventsFull
     let !newLedgerState = finaliseDrepDistr (lrResult result)
+
     !details <- getSlotDetails env (ledgerState newLedgerState) time (cardanoBlockSlotNo blk)
     !newEpoch <- fromEitherSTM $ mkOnNewEpoch (clsState oldState) newLedgerState (findAdaPots ledgerEvents)
     let !newEpochBlockNo = applyToEpochBlockNo (isJust $ blockIsEBB blk) (isJust newEpoch) (clsEpochBlockNo oldState)
     let !newState = CardanoLedgerState newLedgerState newEpochBlockNo
+    let !newState' = maybe newState (trimOnNewEpoch newState) newEpoch
     let !ledgerDB' = pushLedgerDB ledgerDB newState
     writeTVar (leStateVar env) (Strict.Just ledgerDB')
     let !appResult =
@@ -299,6 +304,9 @@ applyBlock env blk = do
     finaliseDrepDistr ledger =
       ledger & newEpochStateT %~ forceDRepPulsingState @StandardConway
 
+    trimOnNewEpoch :: CardanoLedgerState -> Generic.NewEpoch -> CardanoLedgerState
+    trimOnNewEpoch ls !_ = trimLedgerState ls
+
 getGovState :: ExtLedgerState CardanoBlock -> Maybe (ConwayGovState StandardConway)
 getGovState ls = case ledgerState ls of
   LedgerStateConway cls ->
@@ -889,3 +897,6 @@ findProposedCommittee gaId cgs = do
       UpdateCommittee _ toRemove toAdd q -> Right $ Ledger.SJust $ updatedCommittee toRemove toAdd q scommittee
       _ -> Left "Unexpected gov action." -- Should never happen since the accumulator only includes UpdateCommittee
     fromNothing err = maybe (Left err) Right
+
+trimLedgerState :: CardanoLedgerState -> CardanoLedgerState
+trimLedgerState = undefined