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[mysqlctl] Restructure MetadataManager to reduce public API surface area #8152

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Merged
deepthi merged 1 commit into from
Jun 3, 2021
Merged

[mysqlctl] Restructure MetadataManager to reduce public API surface area #8152

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6 changes: 4 additions & 2 deletions go/vt/mysqlctl/backup.go
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Original file line number Diff line number Diff line change
Expand Up @@ -246,6 +246,8 @@ func Restore(ctx context.Context, params RestoreParams) (*BackupManifest, error)
return nil, vterrors.Wrap(err, "ListBackups failed")
}

metadataManager := &MetadataManager{}

if len(bhs) == 0 {
// There are no backups (not even broken/incomplete ones).
params.Logger.Errorf("no backup to restore on BackupStorage for directory %v. Starting up empty.", backupDir)
Expand All @@ -259,7 +261,7 @@ func Restore(ctx context.Context, params RestoreParams) (*BackupManifest, error)
params.Logger.Errorf("error resetting replication: %v. Continuing", err)
}

if err := PopulateMetadataTables(params.Mysqld, params.LocalMetadata, params.DbName); err != nil {
if err := metadataManager.PopulateMetadataTables(params.Mysqld, params.LocalMetadata, params.DbName); err != nil {
params.Logger.Errorf("error populating metadata tables: %v. Continuing", err)

}
Expand Down Expand Up @@ -308,7 +310,7 @@ func Restore(ctx context.Context, params RestoreParams) (*BackupManifest, error)
// Populate local_metadata before starting without --skip-networking,
// so it's there before we start announcing ourselves.
params.Logger.Infof("Restore: populating local_metadata")
err = PopulateMetadataTables(params.Mysqld, params.LocalMetadata, params.DbName)
err = metadataManager.PopulateMetadataTables(params.Mysqld, params.LocalMetadata, params.DbName)
if err != nil {
return nil, err
}
Expand Down
116 changes: 43 additions & 73 deletions go/vt/mysqlctl/metadata_tables.go
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Original file line number Diff line number Diff line change
Expand Up @@ -63,27 +63,8 @@ var (
// and _vt.shard_metadata tables.
type MetadataManager struct{}

// CreateMetadataTables creates the metadata tables. See the package-level
// function for more details.
func (m *MetadataManager) CreateMetadataTables(mysqld MysqlDaemon, dbName string) error {
return CreateMetadataTables(mysqld, dbName)
}

// PopulateMetadataTables creates and fills the metadata tables. See the
// package-level function for more details.
func (m *MetadataManager) PopulateMetadataTables(mysqld MysqlDaemon, localMetadata map[string]string, dbName string) error {
return PopulateMetadataTables(mysqld, localMetadata, dbName)
}

// UpsertLocalMetadata adds the given metadata map to the _vt.local_metadata
// table, updating any duplicate rows to the values in the map. See the package-
// level function for more details.
func (m *MetadataManager) UpsertLocalMetadata(mysqld MysqlDaemon, localMetadata map[string]string, dbName string) error {
return UpsertLocalMetadata(mysqld, localMetadata, dbName)
}

// CreateMetadataTables creates the _vt.local_metadata and _vt.shard_metadata
// tables.
// PopulateMetadataTables creates and fills the _vt.local_metadata table and
// creates the _vt.shard_metadata table.
//
// _vt.local_metadata table is a per-tablet table that is never replicated.
// This allows queries against local_metadata to return different values on
Expand All @@ -94,8 +75,45 @@ func (m *MetadataManager) UpsertLocalMetadata(mysqld MysqlDaemon, localMetadata
// created here to make it easier to create it on databases that were running
// old version of Vitess, or databases that are getting converted to run under
// Vitess.
func CreateMetadataTables(mysqld MysqlDaemon, dbName string) error {
log.Infof("Creating _vt.local_metadata and _vt.shard_metadata tables ...")
//
// This function is semantically equivalent to calling createMetadataTables
// followed immediately by upsertLocalMetadata.
func (m *MetadataManager) PopulateMetadataTables(mysqld MysqlDaemon, localMetadata map[string]string, dbName string) error {
log.Infof("Populating _vt.local_metadata table...")

// Get a non-pooled DBA connection.
conn, err := mysqld.GetDbaConnection(context.TODO())
if err != nil {
return err
}
defer conn.Close()

// Disable replication on this session. We close the connection after using
// it, so there's no need to re-enable replication when we're done.
if _, err := conn.ExecuteFetch("SET @@session.sql_log_bin = 0", 0, false); err != nil {
return err
}

// Create the database and table if necessary.
if err := createMetadataTables(conn, dbName); err != nil {
return err
}

// Populate local_metadata from the passed list of values.
return upsertLocalMetadata(conn, localMetadata, dbName)
}

// UpsertLocalMetadata adds the given metadata map to the _vt.local_metadata
// table, updating any rows that exist for a given `_vt.local_metadata.name`
// with the map value. The session that performs these upserts sets
// sql_log_bin=0, as the _vt.local_metadata table is meant to never be
// replicated.
//
// Callers are responsible for ensuring the _vt.local_metadata table exists
// before calling this function, usually by calling CreateMetadataTables at
// least once prior.
func (m *MetadataManager) UpsertLocalMetadata(mysqld MysqlDaemon, localMetadata map[string]string, dbName string) error {
log.Infof("Upserting _vt.local_metadata ...")

conn, err := mysqld.GetDbaConnection(context.TODO())
if err != nil {
Expand All @@ -109,7 +127,7 @@ func CreateMetadataTables(mysqld MysqlDaemon, dbName string) error {
return err
}

return createMetadataTables(conn, dbName)
return upsertLocalMetadata(conn, localMetadata, dbName)
}

func createMetadataTables(conn *dbconnpool.DBConnection, dbName string) error {
Expand Down Expand Up @@ -174,37 +192,7 @@ func createShardMetadataTable(conn *dbconnpool.DBConnection, dbName string) erro
return nil
}

// PopulateMetadataTables creates and fills the _vt.local_metadata table and
// creates _vt.shard_metadata table.
//
// This function is semantically equivalent to calling CreateMetadataTables
// followed immediately by UpsertLocalMetadata.
func PopulateMetadataTables(mysqld MysqlDaemon, localMetadata map[string]string, dbName string) error {
log.Infof("Populating _vt.local_metadata table...")

// Get a non-pooled DBA connection.
conn, err := mysqld.GetDbaConnection(context.TODO())
if err != nil {
return err
}
defer conn.Close()

// Disable replication on this session. We close the connection after using
// it, so there's no need to re-enable replication when we're done.
if _, err := conn.ExecuteFetch("SET @@session.sql_log_bin = 0", 0, false); err != nil {
return err
}

// Create the database and table if necessary.
if err := createMetadataTables(conn, dbName); err != nil {
return err
}

// Populate local_metadata from the passed list of values.
return upsertLocalMetadata(conn, localMetadata, dbName)
}

// UpsertLocalMetadata adds the given metadata map to the _vt.local_metadata
// upsertLocalMetadata adds the given metadata map to the _vt.local_metadata
// table, updating any rows that exist for a given `_vt.local_metadata.name`
// with the map value. The session that performs these upserts sets
// sql_log_bin=0, as the _vt.local_metadata table is meant to never be
Expand All @@ -213,24 +201,6 @@ func PopulateMetadataTables(mysqld MysqlDaemon, localMetadata map[string]string,
// Callers are responsible for ensuring the _vt.local_metadata table exists
// before calling this function, usually by calling CreateMetadataTables at
// least once prior.
func UpsertLocalMetadata(mysqld MysqlDaemon, localMetadata map[string]string, dbName string) error {
log.Infof("Upserting _vt.local_metadata ...")

conn, err := mysqld.GetDbaConnection(context.TODO())
if err != nil {
return err
}
defer conn.Close()

// Disable replication on this session. We close the connection after using
// it, so there's no need to re-enable replication when we're done.
if _, err := conn.ExecuteFetch("SET @@session.sql_log_bin = 0", 0, false); err != nil {
return err
}

return upsertLocalMetadata(conn, localMetadata, dbName)
}

func upsertLocalMetadata(conn *dbconnpool.DBConnection, localMetadata map[string]string, dbName string) error {
// Populate local_metadata from the passed list of values.
if _, err := conn.ExecuteFetch("BEGIN", 0, false); err != nil {
Expand Down
6 changes: 5 additions & 1 deletion go/vt/vttablet/tabletmanager/restore.go
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Original file line number Diff line number Diff line change
Expand Up @@ -184,7 +184,11 @@ func (tm *TabletManager) restoreDataLocked(ctx context.Context, logger logutil.L
}
if !ok {
params.Logger.Infof("Attempting to restore, but mysqld already contains data. Assuming vttablet was just restarted.")
return mysqlctl.PopulateMetadataTables(params.Mysqld, params.LocalMetadata, params.DbName)
// (NOTE:@ajm188) the legacy behavior is to always populate the metadata
// tables in this branch. Since tm.MetadataManager could be nil, we
// create a new instance for use here.
metadataManager := &mysqlctl.MetadataManager{}
return metadataManager.PopulateMetadataTables(params.Mysqld, params.LocalMetadata, params.DbName)
}
// We should not become master after restore, because that would incorrectly
// start a new master term, and it's likely our data dir will be out of date.
Expand Down