Make sure we finally release Handles

This is necessery for tests that restart the DBSync thread
For production the Handles were already closed on the OS level

Signed-off-by: Kostas Dermentzis <kostas.dermentzis@iohk.io>

Author: kderme

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

@@ -45,7 +45,8 @@ import Cardano.Slotting.Slot (EpochNo (..))
 
 import qualified Cardano.Db as DB
 import Cardano.DbSync.Api
-import Cardano.DbSync.Api.Types (InsertOptions (..), RunMigration, SyncEnv (..), SyncOptions (..), envLedgerEnv)
+import Cardano.DbSync.Api.Types (InsertOptions (..), LedgerEnv (..), RunMigration, SyncEnv (..), SyncOptions (..), envLedgerEnv)
+import Cardano.DbSync.Ledger.Types (HasLedgerEnv (..))
 import Cardano.DbSync.Config (configureLogging)
 import Cardano.DbSync.Config.Cardano
 import Cardano.DbSync.Config.Types
@@ -248,6 +249,10 @@ runSyncNode metricsSetters trce iomgr dbConnSetting runNearTipMigrationFnc syncN
 
           -- communication channel between datalayer thread and chainsync-client thread
           threadChannels <- liftIO newThreadChannels
+          -- 'finally' on the worker pool ensures the LSM session (and any other
+          -- backend resources) are closed even when db-sync is cancelled or
+          -- crashes — important for tests that restart db-sync in the same
+          -- process and need the OS file lock to be released.
           liftIO $
             mapConcurrently_
               id
@@ -257,6 +262,7 @@ runSyncNode metricsSetters trce iomgr dbConnSetting runNearTipMigrationFnc syncN
               , runFetchOffChainVoteThread syncEnv
               , runLedgerStateWriteThread (getTrace syncEnv) (envLedgerEnv syncEnv)
               ]
+              `finally` closeLedgerEnv syncEnv
     )
   where
     useShelleyInit :: SyncNodeConfig -> Bool
@@ -353,3 +359,14 @@ txOutConfigToTableType config = case config of
   TxOutConsumed _ (UseTxOutAddress flag) -> if flag then DB.TxOutVariantAddress else DB.TxOutVariantCore
   TxOutConsumedPrune _ (UseTxOutAddress flag) -> if flag then DB.TxOutVariantAddress else DB.TxOutVariantCore
   TxOutConsumedBootstrap _ (UseTxOutAddress flag) -> if flag then DB.TxOutVariantAddress else DB.TxOutVariantCore
+
+-- | Release backend resources held by the ledger environment.
+-- Currently this closes the LSM session (no-op for InMemory and NoLedger).
+closeLedgerEnv :: SyncEnv -> IO ()
+closeLedgerEnv syncEnv = case envLedgerEnv syncEnv of
+  HasLedger le -> do
+    let trce = leTrace le
+    logInfo trce "closeLedgerEnv: closing LSM session..."
+    leClose le
+    logInfo trce "closeLedgerEnv: closed."
+  NoLedger _ -> pure ()

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

@@ -206,7 +206,7 @@ mkHasLedgerEnv trce protoInfo dir nw maxLovelaceSupply systemStart syncOptions b
   let codecConfig = configCodec $ Consensus.pInfoConfig protoInfo
       someHasFS = SomeHasFS $ ioHasFS (MountPoint $ unLedgerStateDir dir)
       snapTracer = Tracer.nullTracer -- TODO: wire up snapshot tracing
-  (snapMgr, initGen, loadSnap) <- case backend of
+  (snapMgr, initGen, loadSnap, closeBackend) <- case backend of
     LedgerBackendInMemory -> do
       res <-
         runWithTempRegistry $
@@ -223,7 +223,7 @@ mkHasLedgerEnv trce protoInfo dir nw maxLovelaceSupply systemStart syncOptions b
             case eResult of
               Left err -> pure $ Left $ textShow err
               Right (cRef, _pt) -> pure $ Right cRef
-      pure (sm, ig, ld)
+      pure (sm, ig, ld, pure ())
     LedgerBackendLSM mPath -> do
       let lsmPath = fromMaybe (unLedgerStateDir dir </> "lsm") mPath
       salt <- fst . genWord64 <$> newStdGen
@@ -243,7 +243,13 @@ mkHasLedgerEnv trce protoInfo dir nw maxLovelaceSupply systemStart syncOptions b
             case eResult of
               Left err -> pure $ Left $ textShow err
               Right (cRef, _pt) -> pure $ Right cRef
-      pure (sm, ig, ld)
+      -- Close the LSM session on shutdown to release the file lock.
+      -- mkResources allocates the session via 'allocateTemp ... impossibleToNotTransfer',
+      -- which means it is intentionally NOT closed when runWithTempRegistry exits
+      -- (similar to bracketOnError). We release it explicitly here so the lock
+      -- is freed even when the same process restarts db-sync (test scenario).
+      let releaseLsm = releaseResources (Proxy @CardanoBlock) res
+      pure (sm, ig, ld, releaseLsm)
 
   pure
     HasLedgerEnv
@@ -264,6 +270,7 @@ mkHasLedgerEnv trce protoInfo dir nw maxLovelaceSupply systemStart syncOptions b
       , leSnapshotManager = snapMgr
       , leInitGenesis = initGen
       , leLoadSnapshot = loadSnap
+      , leClose = closeBackend
       }
 
 getTopLevelconfigHasLedger :: HasLedgerEnv -> TopLevelConfig CardanoBlock

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

@@ -87,6 +87,8 @@ data HasLedgerEnv = HasLedgerEnv
   -- ^ Create the initial consensus StateRef from genesis
   , leLoadSnapshot :: !(DiskSnapshot -> IO (Either Text ConsensusStateRef))
   -- ^ Load a snapshot from disk using the appropriate backend
+  , leClose :: !(IO ())
+  -- ^ Release backend resources (LSM session, registry, etc.). Call on shutdown.
   }
 
 -- | Pure ledger state, stored in LedgerDB checkpoints.