channeldb+lncfg: add config flag to skip pending close cleanup

Add a new configuration option `db.skip-pending-close-cleanup` that
allows users to skip the cleanup of pending channel closes at startup.
This is useful when users want to start their node quickly and defer
the cleanup to a later restart.

The cleanup of closed channel data (revocation logs, forwarding
packages) can take a while if there are many channels pending cleanup.
By setting this flag, users can trade startup latency for a faster
boot time when needed.

Usage:
  lnd --db.skip-pending-close-cleanup=true

Or in lnd.conf:
  [db]
  skip-pending-close-cleanup=true

Author: ziggie1984

channeldb/db.go

@@ -439,12 +439,17 @@ func CreateWithBackend(backend kvdb.Backend, modifiers ...OptionModifier) (*DB,
 	// Clean up any channels that were closed but whose data has not yet
 	// been fully deleted. This is deferred to startup to avoid blocking
 	// the channel close operation.
-	err := chanDB.channelStateDB.CleanupPendingCloses()
-	if err != nil {
-		backend.Close()
+	if !opts.SkipPendingCloseCleanup {
+		err := chanDB.channelStateDB.CleanupPendingCloses()
+		if err != nil {
+			backend.Close()
 
-		return nil, fmt.Errorf("unable to cleanup pending "+
-			"channel closes: %w", err)
+			return nil, fmt.Errorf("unable to cleanup pending "+
+				"channel closes: %w", err)
+		}
+	} else {
+		log.Info("Skipping pending channel close cleanup as " +
+			"configured")
 	}
 
 	return chanDB, nil

channeldb/options.go

@@ -71,6 +71,12 @@ type Options struct {
 	// storeFinalHtlcResolutions determines whether to persistently store
 	// the final resolution of incoming htlcs.
 	storeFinalHtlcResolutions bool
+
+	// SkipPendingCloseCleanup when set to true, skips the cleanup of
+	// pending channel closes at startup. This can be useful if the user
+	// wants to start the node quickly and defer the cleanup to a later
+	// restart.
+	SkipPendingCloseCleanup bool
 }
 
 // DefaultOptions returns an Options populated with default values.
@@ -151,3 +157,11 @@ func OptionGcDecayedLog(noGc bool) OptionModifier {
 		o.OptionalMiragtionConfig.MigrationFlags[1] = !noGc
 	}
 }
+
+// OptionSkipPendingCloseCleanup controls whether to skip the cleanup of
+// pending channel closes at startup.
+func OptionSkipPendingCloseCleanup(skip bool) OptionModifier {
+	return func(o *Options) {
+		o.SkipPendingCloseCleanup = skip
+	}
+}

config_builder.go

@@ -1071,6 +1071,9 @@ func (d *DefaultDatabaseBuilder) BuildDatabase(
 		channeldb.OptionNoRevLogAmtData(cfg.DB.NoRevLogAmtData),
 		channeldb.OptionGcDecayedLog(cfg.DB.NoGcDecayedLog),
 		channeldb.OptionWithDecayedLogDB(dbs.DecayedLogDB),
+		channeldb.OptionSkipPendingCloseCleanup(
+			cfg.DB.SkipPendingCloseCleanup,
+		),
 	}
 
 	// Otherwise, we'll open two instances, one for the state we only need

lncfg/db.go

@@ -97,6 +97,8 @@ type DB struct {
 	NoRevLogAmtData bool `long:"no-rev-log-amt-data" description:"If set, the to-local and to-remote output amounts of revoked commitment transactions will not be stored in the revocation log. Note that once this data is lost, a watchtower client will not be able to back up the revoked state."`
 
 	NoGcDecayedLog bool `long:"no-gc-decayed-log" description:"Do not run the optional migration that garbage collects the decayed log to save disk space."`
+
+	SkipPendingCloseCleanup bool `long:"skip-pending-close-cleanup" description:"Skip cleanup of pending channel closes at startup. This can be useful for faster startup when there are many channels pending cleanup, deferring the cleanup to a later restart."`
 }
 
 // DefaultDB creates and returns a new default DB config.

sample-lnd.conf

@@ -1511,6 +1511,11 @@
 ; the future.
 ; db.no-rev-log-amt-data=false
 
+; If set to true, skip cleanup of pending channel closes at startup. This can
+; be useful for faster startup when there are many channels pending cleanup,
+; deferring the cleanup to a later restart.
+; db.skip-pending-close-cleanup=false
+
 ; If set to true, native SQL will be used instead of KV emulation for tables
 ; that support it.
 ; Subsystems which support native SQL tables: