LedgerDB.V2: adapt queries for DbChangelog of length >k

Author: amesgen

ouroboros-consensus/src/ouroboros-consensus/Ouroboros/Consensus/Storage/LedgerDB/V2.hs

@@ -267,10 +267,13 @@ implGetVolatileTip ::
 implGetVolatileTip = fmap current . readTVar . ldbSeq
 
 implGetImmutableTip ::
-  MonadSTM m =>
+  (MonadSTM m, GetTip l) =>
   LedgerDBEnv m l blk ->
   STM m (l EmptyMK)
-implGetImmutableTip = fmap anchor . readTVar . ldbSeq
+implGetImmutableTip env =
+  anchor . volatileSuffix k <$> readTVar (ldbSeq env)
+ where
+  k = ledgerDbCfgSecParam $ ldbCfg env
 
 implGetPastLedgerState ::
   ( MonadSTM m
@@ -280,7 +283,10 @@ implGetPastLedgerState ::
   , HeaderHash l ~ HeaderHash blk
   ) =>
   LedgerDBEnv m l blk -> Point blk -> STM m (Maybe (l EmptyMK))
-implGetPastLedgerState env point = getPastLedgerAt point <$> readTVar (ldbSeq env)
+implGetPastLedgerState env point =
+  getPastLedgerAt point . volatileSuffix k <$> readTVar (ldbSeq env)
+ where
+  k = ledgerDbCfgSecParam $ ldbCfg env
 
 implGetHeaderStateHistory ::
   ( MonadSTM m
@@ -304,7 +310,10 @@ implGetHeaderStateHistory env = do
   pure
     . HeaderStateHistory
     . AS.bimap mkHeaderStateWithTime' mkHeaderStateWithTime'
-    $ getLedgerSeq ldb
+    . getLedgerSeq
+    $ volatileSuffix k ldb
+ where
+  k = ledgerDbCfgSecParam $ ldbCfg env
 
 implValidate ::
   forall m l blk.
@@ -557,7 +566,7 @@ acquireAtTarget ::
   LDBLock ->
   m (Either GetForkerError (StateRef m l))
 acquireAtTarget ldbEnv target _ = runExceptT $ do
-  l <- lift $ readTVarIO (ldbSeq ldbEnv)
+  l <- lift $ volatileSuffix k <$> readTVarIO (ldbSeq ldbEnv)
   StateRef st tbs <- case target of
     Right VolatileTip -> pure $ currentHandle l
     Right ImmutableTip -> pure $ anchorHandle l
@@ -580,6 +589,8 @@ acquireAtTarget ldbEnv target _ = runExceptT $ do
       Just l' -> pure $ currentHandle l'
   tbs' <- lift $ duplicate tbs
   pure $ StateRef st tbs'
+ where
+  k = ledgerDbCfgSecParam $ ldbCfg ldbEnv
 
 newForkerAtTarget ::
   ( HeaderHash l ~ HeaderHash blk

ouroboros-consensus/src/ouroboros-consensus/Ouroboros/Consensus/Storage/LedgerDB/V2/LedgerSeq.hs

@@ -52,6 +52,7 @@ module Ouroboros.Consensus.Storage.LedgerDB.V2.LedgerSeq
   , snapshots
   , tip
   , volatileStatesBimap
+  , volatileSuffix
   ) where
 
 import Cardano.Ledger.BaseTypes
@@ -512,6 +513,13 @@ volatileStatesBimap f g =
   AS.bimap (f . state) (g . state)
     . getLedgerSeq
 
+-- | Take the suffix containing the @k@ most recent states. The 'LedgerSeq' can
+-- contain more than @k@ states if we adopted new blocks, but garbage collection
+-- has not yet been run.
+volatileSuffix :: GetTip l => SecurityParam -> LedgerSeq m l -> LedgerSeq m l
+volatileSuffix (SecurityParam k) =
+  LedgerSeq . AS.anchorNewest (unNonZero k) . getLedgerSeq
+
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