multi: pass in a MigrationConfig to all optional migrations

Define a MigrationConfig interface that should be used to pass the
config of an optional migration function. An implementation of this
interface is added for migration30 (the only current optional
migration).

channeldb/db.go

@@ -63,12 +63,24 @@ type mandatoryVersion struct {
 	migration migration
 }
 
+// MigrationConfig is an interface combines the config interfaces of all
+// optional migrations.
+type MigrationConfig interface {
+	migration30.MigrateRevLogConfig
+}
+
+// MigrationConfigImpl is a super set of all the various migration configs and
+// an implementation of MigrationConfig.
+type MigrationConfigImpl struct {
+	migration30.MigrateRevLogConfigImpl
+}
+
 // optionalMigration defines an optional migration function. When a migration
 // is optional, it usually involves a large scale of changes that might touch
 // millions of keys. Due to OOM concern, the update cannot be safely done
 // within one db transaction. Thus, for optional migrations, they must take the
 // db backend and construct transactions as needed.
-type optionalMigration func(db kvdb.Backend) error
+type optionalMigration func(db kvdb.Backend, cfg MigrationConfig) error
 
 // optionalVersion defines a db version that can be optionally applied. When
 // applying migrations, we must apply all the mandatory migrations first before
@@ -273,8 +285,12 @@ var (
 	// to determine its state.
 	optionalVersions = []optionalVersion{
 		{
-			name:      "prune revocation log",
+			name: "prune revocation log",
-			migration: migration30.MigrateRevocationLog,
+			migration: func(db kvdb.Backend,
+				cfg MigrationConfig) error {
+
+				return migration30.MigrateRevocationLog(db, cfg)
+			},
 		},
 	}
 
@@ -1545,8 +1561,12 @@ func (d *DB) applyOptionalVersions(cfg OptionalMiragtionConfig) error {
 	version := optionalVersions[0]
 	log.Infof("Performing database optional migration: %s", version.name)
 
+	migrationCfg := &MigrationConfigImpl{
+		migration30.MigrateRevLogConfigImpl{},
+	}
+
 	// Migrate the data.
-	if err := version.migration(d); err != nil {
+	if err := version.migration(d, migrationCfg); err != nil {
 		log.Errorf("Unable to apply optional migration: %s, error: %v",
 			version.name, err)
 		return err

channeldb/meta_test.go

@@ -530,7 +530,9 @@ func TestApplyOptionalVersions(t *testing.T) {
 	// Overwrite the migration function so we can count how many times the
 	// migration has happened.
 	migrateCount := 0
-	optionalVersions[0].migration = func(_ kvdb.Backend) error {
+	optionalVersions[0].migration = func(_ kvdb.Backend,
+		_ MigrationConfig) error {
+
 		migrateCount++
 		return nil
 	}

channeldb/migration30/migration.go

@@ -23,10 +23,17 @@ import (
 // indexes.
 const recordsPerTx = 20_000
 
+// MigrateRevLogConfig is an interface that defines the config that should be
+// passed to the MigrateRevocationLog function.
+type MigrateRevLogConfig interface{}
+
+// MigrateRevLogConfigImpl implements the MigrationRevLogConfig interface.
+type MigrateRevLogConfigImpl struct{}
+
 // MigrateRevocationLog migrates the old revocation logs into the newer format
 // and deletes them once finished, with the deletion only happens once ALL the
 // old logs have been migrates.
-func MigrateRevocationLog(db kvdb.Backend) error {
+func MigrateRevocationLog(db kvdb.Backend, _ MigrateRevLogConfig) error {
 	log.Infof("Migrating revocation logs, might take a while...")
 
 	var (

channeldb/migration30/migration_test.go

@@ -103,11 +103,15 @@ func TestMigrateRevocationLog(t *testing.T) {
 				return nil
 			}
 
+			cfg := &MigrateRevLogConfigImpl{}
+
 			migtest.ApplyMigrationWithDB(
 				t,
 				beforeMigration,
 				afterMigration,
-				MigrateRevocationLog,
+				func(db kvdb.Backend) error {
+					return MigrateRevocationLog(db, cfg)
+				},
 				false,
 			)
 		})
@@ -559,6 +563,8 @@ func BenchmarkMigration(b *testing.B) {
 		return setupTestLogs(db, c, oldLogs, nil)
 	}
 
+	cfg := &MigrateRevLogConfigImpl{}
+
 	// Run the migration test.
 	migtest.ApplyMigrationWithDB(
 		b,
@@ -568,7 +574,7 @@ func BenchmarkMigration(b *testing.B) {
 			b.StartTimer()
 			defer b.StopTimer()
 
-			return MigrateRevocationLog(db)
+			return MigrateRevocationLog(db, cfg)
 		},
 		false,
 	)

channeldb/migtest/migtest.go

@@ -89,7 +89,8 @@ func ApplyMigration(t *testing.T,
 // function. This function differs from ApplyMigration as it requires the
 // supplied migration functions to take a db instance and construct their own
 // database transactions.
-func ApplyMigrationWithDB(t testing.TB, beforeMigration, afterMigration,
+func ApplyMigrationWithDB(t testing.TB, beforeMigration,
+	afterMigration func(db kvdb.Backend) error,
 	migrationFunc func(db kvdb.Backend) error, shouldFail bool) {
 
 	t.Helper()