func (wr *Wrangler) reparentShardLocked(keyspace, shard string, masterElectTabletAlias topo.TabletAlias, leaveMasterReadOnly, forceReparentToCurrentMaster bool) error {
// critical read, we want up to date info (and the shard is locked).
shardInfo, err := wr.ts.GetShardCritical(keyspace, shard)
if err != nil {
return err
}
tabletMap, err := topo.GetTabletMapForShard(wr.ts, keyspace, shard)
if err != nil {
return err
}
slaveTabletMap, masterTabletMap := topotools.SortedTabletMap(tabletMap)
if shardInfo.MasterAlias == masterElectTabletAlias && !forceReparentToCurrentMaster {
return fmt.Errorf("master-elect tablet %v is already master - specify -force to override", masterElectTabletAlias)
}
masterElectTablet, ok := tabletMap[masterElectTabletAlias]
if !ok {
return fmt.Errorf("master-elect tablet %v not found in replication graph %v/%v %v", masterElectTabletAlias, keyspace, shard, topotools.MapKeys(tabletMap))
}
// Create reusable Reparent event with available info
ev := &events.Reparent{
ShardInfo: *shardInfo,
NewMaster: *masterElectTablet.Tablet,
}
if oldMasterTablet, ok := tabletMap[shardInfo.MasterAlias]; ok {
ev.OldMaster = *oldMasterTablet.Tablet
}
if !shardInfo.MasterAlias.IsZero() && !forceReparentToCurrentMaster {
err = wr.reparentShardGraceful(ev, shardInfo, slaveTabletMap, masterTabletMap, masterElectTablet, leaveMasterReadOnly)
} else {
err = wr.reparentShardBrutal(ev, shardInfo, slaveTabletMap, masterTabletMap, masterElectTablet, leaveMasterReadOnly, forceReparentToCurrentMaster)
}
if err == nil {
// only log if it works, if it fails we'll show the error
wr.Logger().Infof("reparentShard finished")
}
return err
}
func (wr *Wrangler) initShardMasterLocked(ctx context.Context, ev *events.Reparent, keyspace, shard string, masterElectTabletAlias *pb.TabletAlias, force bool, waitSlaveTimeout time.Duration) error {
shardInfo, err := wr.ts.GetShard(ctx, keyspace, shard)
if err != nil {
return err
}
ev.ShardInfo = *shardInfo
event.DispatchUpdate(ev, "reading tablet map")
tabletMap, err := wr.ts.GetTabletMapForShard(ctx, keyspace, shard)
if err != nil {
return err
}
// Check the master elect is in tabletMap
masterElectTabletInfo, ok := tabletMap[*masterElectTabletAlias]
if !ok {
return fmt.Errorf("master-elect tablet %v is not in the shard", topoproto.TabletAliasString(masterElectTabletAlias))
}
ev.NewMaster = *masterElectTabletInfo.Tablet
// Check the master is the only master is the shard, or -force was used.
_, masterTabletMap := topotools.SortedTabletMap(tabletMap)
if !topoproto.TabletAliasEqual(shardInfo.MasterAlias, masterElectTabletAlias) {
if !force {
return fmt.Errorf("master-elect tablet %v is not the shard master, use -force to proceed anyway", topoproto.TabletAliasString(masterElectTabletAlias))
}
wr.logger.Warningf("master-elect tablet %v is not the shard master, proceeding anyway as -force was used", topoproto.TabletAliasString(masterElectTabletAlias))
}
if _, ok := masterTabletMap[*masterElectTabletAlias]; !ok {
if !force {
return fmt.Errorf("master-elect tablet %v is not a master in the shard, use -force to proceed anyway", topoproto.TabletAliasString(masterElectTabletAlias))
}
wr.logger.Warningf("master-elect tablet %v is not a master in the shard, proceeding anyway as -force was used", topoproto.TabletAliasString(masterElectTabletAlias))
}
haveOtherMaster := false
for alias, ti := range masterTabletMap {
if !topoproto.TabletAliasEqual(&alias, masterElectTabletAlias) && ti.Type != pb.TabletType_SCRAP {
haveOtherMaster = true
}
}
if haveOtherMaster {
if !force {
return fmt.Errorf("master-elect tablet %v is not the only master in the shard, use -force to proceed anyway", topoproto.TabletAliasString(masterElectTabletAlias))
}
wr.logger.Warningf("master-elect tablet %v is not the only master in the shard, proceeding anyway as -force was used", topoproto.TabletAliasString(masterElectTabletAlias))
}
// First phase: reset replication on all tablets. If anyone fails,
// we stop. It is probably because it is unreachable, and may leave
// an unstable database process in the mix, with a database daemon
// at a wrong replication spot.
event.DispatchUpdate(ev, "resetting replication on all tablets")
wg := sync.WaitGroup{}
rec := concurrency.AllErrorRecorder{}
for alias, tabletInfo := range tabletMap {
wg.Add(1)
go func(alias pb.TabletAlias, tabletInfo *topo.TabletInfo) {
defer wg.Done()
wr.logger.Infof("resetting replication on tablet %v", topoproto.TabletAliasString(&alias))
if err := wr.TabletManagerClient().ResetReplication(ctx, tabletInfo); err != nil {
rec.RecordError(fmt.Errorf("Tablet %v ResetReplication failed (either fix it, or Scrap it): %v", topoproto.TabletAliasString(&alias), err))
}
}(alias, tabletInfo)
}
wg.Wait()
if err := rec.Error(); err != nil {
return err
}
// Tell the new master to break its slaves, return its replication
// position
wr.logger.Infof("initializing master on %v", topoproto.TabletAliasString(masterElectTabletAlias))
event.DispatchUpdate(ev, "initializing master")
rp, err := wr.TabletManagerClient().InitMaster(ctx, masterElectTabletInfo)
if err != nil {
return err
}
// Now tell the new master to insert the reparent_journal row,
// and tell everybody else to become a slave of the new master,
// and wait for the row in the reparent_journal table.
// We start all these in parallel, to handle the semi-sync
// case: for the master to be able to commit its row in the
// reparent_journal table, it needs connected slaves.
event.DispatchUpdate(ev, "reparenting all tablets")
now := time.Now().UnixNano()
wgMaster := sync.WaitGroup{}
wgSlaves := sync.WaitGroup{}
var masterErr error
for alias, tabletInfo := range tabletMap {
if topoproto.TabletAliasEqual(&alias, masterElectTabletAlias) {
wgMaster.Add(1)
go func(alias pb.TabletAlias, tabletInfo *topo.TabletInfo) {
defer wgMaster.Done()
wr.logger.Infof("populating reparent journal on new master %v", topoproto.TabletAliasString(&alias))
masterErr = wr.TabletManagerClient().PopulateReparentJournal(ctx, tabletInfo, now, initShardMasterOperation, &alias, rp)
}(alias, tabletInfo)
} else {
wgSlaves.Add(1)
go func(alias pb.TabletAlias, tabletInfo *topo.TabletInfo) {
defer wgSlaves.Done()
wr.logger.Infof("initializing slave %v", topoproto.TabletAliasString(&alias))
if err := wr.TabletManagerClient().InitSlave(ctx, tabletInfo, masterElectTabletAlias, rp, now); err != nil {
rec.RecordError(fmt.Errorf("Tablet %v InitSlave failed: %v", topoproto.TabletAliasString(&alias), err))
}
}(alias, tabletInfo)
}
}
// After the master is done, we can update the shard record
// (note with semi-sync, it also means at least one slave is done)
wgMaster.Wait()
if masterErr != nil {
wgSlaves.Wait()
return fmt.Errorf("failed to PopulateReparentJournal on master: %v", masterErr)
}
if !topoproto.TabletAliasEqual(shardInfo.MasterAlias, masterElectTabletAlias) {
shardInfo.MasterAlias = masterElectTabletAlias
if err := wr.ts.UpdateShard(ctx, shardInfo); err != nil {
wgSlaves.Wait()
return fmt.Errorf("failed to update shard master record: %v", err)
}
}
// Wait for the slaves to complete. If some of them fail, we
// don't want to rebuild the shard serving graph (the failure
// will most likely be a timeout, and our context will be
// expired, so the rebuild will fail anyway)
wgSlaves.Wait()
if err := rec.Error(); err != nil {
return err
}
// Then we rebuild the entire serving graph for the shard,
// to account for all changes.
event.DispatchUpdate(ev, "rebuilding shard graph")
_, err = wr.RebuildShardGraph(ctx, keyspace, shard, nil)
return err
}
func tabletExternallyReparentedLocked(ts topo.Server, tablet *topo.TabletInfo, actionTimeout, lockTimeout time.Duration, interrupted chan struct{}) (err error) {
// read the shard, make sure again the master is not already good.
// critical read, we want up to date info (and the shard is locked).
shardInfo, err := ts.GetShardCritical(tablet.Keyspace, tablet.Shard)
if err != nil {
return err
}
if shardInfo.MasterAlias == tablet.Alias {
return fmt.Errorf("this tablet is already the master")
}
// Read the tablets, make sure the master elect is known to the shard
// (it's this tablet, so it better be!).
// Note we will keep going with a partial tablet map, which usually
// happens when a cell is not reachable. After these checks, the
// guarantees we'll have are:
// - global cell is reachable (we just locked and read the shard)
// - the local cell that contains the new master is reachable
// (as we're going to check the new master is in the list)
// That should be enough.
tabletMap, err := topo.GetTabletMapForShard(ts, tablet.Keyspace, tablet.Shard)
switch err {
case nil:
// keep going
case topo.ErrPartialResult:
log.Warningf("Got topo.ErrPartialResult from GetTabletMapForShard, may need to re-init some tablets")
default:
return err
}
masterElectTablet, ok := tabletMap[tablet.Alias]
if !ok {
return fmt.Errorf("this master-elect tablet %v not found in replication graph %v/%v %v", tablet.Alias, tablet.Keyspace, tablet.Shard, topotools.MapKeys(tabletMap))
}
// Create reusable Reparent event with available info
ev := &events.Reparent{
ShardInfo: *shardInfo,
NewMaster: *tablet.Tablet,
}
if oldMasterTablet, ok := tabletMap[shardInfo.MasterAlias]; ok {
ev.OldMaster = *oldMasterTablet.Tablet
}
defer func() {
if err != nil {
event.DispatchUpdate(ev, "failed: "+err.Error())
}
}()
// sort the tablets, and handle them
slaveTabletMap, masterTabletMap := topotools.SortedTabletMap(tabletMap)
event.DispatchUpdate(ev, "starting external from tablet")
// we fix the new master in the replication graph
event.DispatchUpdate(ev, "mark ourself as new master")
err = updateReplicationGraphForPromotedSlave(ts, tablet)
if err != nil {
// This suggests we can't talk to topo server. This is bad.
return fmt.Errorf("updateReplicationGraphForPromotedSlave failed: %v", err)
}
// Once this tablet is promoted, remove it from our maps
delete(slaveTabletMap, tablet.Alias)
delete(masterTabletMap, tablet.Alias)
// Then fix all the slaves, including the old master. This
// last step is very likely to time out for some tablets (one
// random guy is dead, the old master is dead, ...). We
// execute them all in parallel until we get to
// wr.ActionTimeout(). After this, no other action with a
// timeout is executed, so even if we got to the timeout,
// we're still good.
event.DispatchUpdate(ev, "restarting slaves")
logger := logutil.NewConsoleLogger()
ai := initiator.NewActionInitiator(ts)
topotools.RestartSlavesExternal(ts, logger, slaveTabletMap, masterTabletMap, masterElectTablet.Alias, func(ti *topo.TabletInfo, swrd *actionnode.SlaveWasRestartedArgs) error {
return ai.RpcSlaveWasRestarted(ti, swrd, actionTimeout)
})
// Compute the list of Cells we need to rebuild: old master and
// all other cells if reparenting to another cell.
cells := []string{shardInfo.MasterAlias.Cell}
if shardInfo.MasterAlias.Cell != tablet.Alias.Cell {
cells = nil
}
// now update the master record in the shard object
event.DispatchUpdate(ev, "updating shard record")
log.Infof("Updating Shard's MasterAlias record")
shardInfo.MasterAlias = tablet.Alias
if err = topo.UpdateShard(ts, shardInfo); err != nil {
return err
}
// and rebuild the shard serving graph
event.DispatchUpdate(ev, "rebuilding shard serving graph")
log.Infof("Rebuilding shard serving graph data")
if err = topotools.RebuildShard(logger, ts, tablet.Keyspace, tablet.Shard, cells, lockTimeout, interrupted); err != nil {
return err
}
event.DispatchUpdate(ev, "finished")
return nil
}
func (wr *Wrangler) applySchemaShardComplex(statusArray []*TabletStatus, shardInfo *topo.ShardInfo, preflight *myproto.SchemaChangeResult, masterTabletAlias topo.TabletAlias, change string, newParentTabletAlias topo.TabletAlias, force bool) (*myproto.SchemaChangeResult, error) {
// apply the schema change to all replica / slave tablets
for _, status := range statusArray {
// if already applied, we skip this guy
diffs := myproto.DiffSchemaToArray("after", preflight.AfterSchema, status.ti.Alias.String(), status.beforeSchema)
if len(diffs) == 0 {
log.Infof("Tablet %v already has the AfterSchema, skipping", status.ti.Alias)
continue
}
// make sure the before schema matches
diffs = myproto.DiffSchemaToArray("master", preflight.BeforeSchema, status.ti.Alias.String(), status.beforeSchema)
if len(diffs) > 0 {
if force {
log.Warningf("Tablet %v has inconsistent schema, ignoring: %v", status.ti.Alias, strings.Join(diffs, "\n"))
} else {
return nil, fmt.Errorf("Tablet %v has inconsistent schema: %v", status.ti.Alias, strings.Join(diffs, "\n"))
}
}
// take this guy out of the serving graph if necessary
ti, err := wr.ts.GetTablet(status.ti.Alias)
if err != nil {
return nil, err
}
typeChangeRequired := ti.Tablet.IsInServingGraph()
if typeChangeRequired {
// note we want to update the serving graph there
err = wr.changeTypeInternal(ti.Alias, topo.TYPE_SCHEMA_UPGRADE)
if err != nil {
return nil, err
}
}
// apply the schema change
log.Infof("Applying schema change to slave %v in complex mode", status.ti.Alias)
sc := &myproto.SchemaChange{Sql: change, Force: force, AllowReplication: false, BeforeSchema: preflight.BeforeSchema, AfterSchema: preflight.AfterSchema}
_, err = wr.ApplySchema(status.ti.Alias, sc)
if err != nil {
return nil, err
}
// put this guy back into the serving graph
if typeChangeRequired {
err = wr.changeTypeInternal(ti.Alias, ti.Tablet.Type)
if err != nil {
return nil, err
}
}
}
// if newParentTabletAlias is passed in, use that as the new master
if !newParentTabletAlias.IsZero() {
log.Infof("Reparenting with new master set to %v", newParentTabletAlias)
tabletMap, err := topo.GetTabletMapForShard(wr.ts, shardInfo.Keyspace(), shardInfo.ShardName())
if err != nil {
return nil, err
}
slaveTabletMap, masterTabletMap := topotools.SortedTabletMap(tabletMap)
newMasterTablet, err := wr.ts.GetTablet(newParentTabletAlias)
if err != nil {
return nil, err
}
// Create reusable Reparent event with available info
ev := &events.Reparent{
ShardInfo: *shardInfo,
NewMaster: *newMasterTablet.Tablet,
}
if oldMasterTablet, ok := tabletMap[shardInfo.MasterAlias]; ok {
ev.OldMaster = *oldMasterTablet.Tablet
}
err = wr.reparentShardGraceful(ev, shardInfo, slaveTabletMap, masterTabletMap, newMasterTablet /*leaveMasterReadOnly*/, false)
if err != nil {
return nil, err
}
// Here we would apply the schema change to the old
// master, but after a reparent it's in Scrap state,
// so no need to. When/if reparent leaves the
// original master in a different state (like replica
// or rdonly), then we should apply the schema there
// too.
log.Infof("Skipping schema change on old master %v in complex mode, it's been Scrapped", masterTabletAlias)
}
return &myproto.SchemaChangeResult{BeforeSchema: preflight.BeforeSchema, AfterSchema: preflight.AfterSchema}, nil
}
func (wr *Wrangler) shardExternallyReparentedLocked(keyspace, shard string, masterElectTabletAlias topo.TabletAlias) (err error) {
// read the shard, make sure the master is not already good.
shardInfo, err := wr.ts.GetShard(keyspace, shard)
if err != nil {
return err
}
if shardInfo.MasterAlias == masterElectTabletAlias {
return fmt.Errorf("master-elect tablet %v is already master", masterElectTabletAlias)
}
// Read the tablets, make sure the master elect is known to us.
// Note we will keep going with a partial tablet map, which usually
// happens when a cell is not reachable. After these checks, the
// guarantees we'll have are:
// - global cell is reachable (we just locked and read the shard)
// - the local cell that contains the new master is reachable
// (as we're going to check the new master is in the list)
// That should be enough.
tabletMap, err := topo.GetTabletMapForShard(wr.ts, keyspace, shard)
switch err {
case nil:
// keep going
case topo.ErrPartialResult:
wr.logger.Warningf("Got topo.ErrPartialResult from GetTabletMapForShard, may need to re-init some tablets")
default:
return err
}
masterElectTablet, ok := tabletMap[masterElectTabletAlias]
if !ok {
return fmt.Errorf("master-elect tablet %v not found in replication graph %v/%v %v", masterElectTabletAlias, keyspace, shard, topotools.MapKeys(tabletMap))
}
// Create reusable Reparent event with available info
ev := &events.Reparent{
ShardInfo: *shardInfo,
NewMaster: *masterElectTablet.Tablet,
}
if oldMasterTablet, ok := tabletMap[shardInfo.MasterAlias]; ok {
ev.OldMaster = *oldMasterTablet.Tablet
}
defer func() {
if err != nil {
event.DispatchUpdate(ev, "failed: "+err.Error())
}
}()
// sort the tablets, and handle them
slaveTabletMap, masterTabletMap := topotools.SortedTabletMap(tabletMap)
err = wr.reparentShardExternal(ev, slaveTabletMap, masterTabletMap, masterElectTablet)
if err != nil {
wr.logger.Infof("Skipping shard rebuild with failed reparent")
return err
}
// Compute the list of Cells we need to rebuild: old master and
// all other cells if reparenting to another cell.
cells := []string{shardInfo.MasterAlias.Cell}
if shardInfo.MasterAlias.Cell != masterElectTabletAlias.Cell {
cells = nil
}
// now update the master record in the shard object
event.DispatchUpdate(ev, "updating shard record")
wr.logger.Infof("Updating Shard's MasterAlias record")
shardInfo.MasterAlias = masterElectTabletAlias
if err = topo.UpdateShard(wr.ts, shardInfo); err != nil {
return err
}
// and rebuild the shard serving graph
event.DispatchUpdate(ev, "rebuilding shard serving graph")
wr.logger.Infof("Rebuilding shard serving graph data")
if _, err = topotools.RebuildShard(wr.logger, wr.ts, masterElectTablet.Keyspace, masterElectTablet.Shard, cells, wr.lockTimeout, interrupted); err != nil {
return err
}
event.DispatchUpdate(ev, "finished")
return nil
}
func (wr *Wrangler) initShardMasterLocked(ctx context.Context, ev *events.Reparent, keyspace, shard string, masterElectTabletAlias *topodatapb.TabletAlias, force bool, waitSlaveTimeout time.Duration) error {
shardInfo, err := wr.ts.GetShard(ctx, keyspace, shard)
if err != nil {
return err
}
ev.ShardInfo = *shardInfo
event.DispatchUpdate(ev, "reading tablet map")
tabletMap, err := wr.ts.GetTabletMapForShard(ctx, keyspace, shard)
if err != nil {
return err
}
// Check the master elect is in tabletMap
masterElectTabletInfo, ok := tabletMap[*masterElectTabletAlias]
if !ok {
return fmt.Errorf("master-elect tablet %v is not in the shard", topoproto.TabletAliasString(masterElectTabletAlias))
}
ev.NewMaster = *masterElectTabletInfo.Tablet
// Check the master is the only master is the shard, or -force was used.
_, masterTabletMap := topotools.SortedTabletMap(tabletMap)
if !topoproto.TabletAliasEqual(shardInfo.MasterAlias, masterElectTabletAlias) {
if !force {
return fmt.Errorf("master-elect tablet %v is not the shard master, use -force to proceed anyway", topoproto.TabletAliasString(masterElectTabletAlias))
}
wr.logger.Warningf("master-elect tablet %v is not the shard master, proceeding anyway as -force was used", topoproto.TabletAliasString(masterElectTabletAlias))
}
if _, ok := masterTabletMap[*masterElectTabletAlias]; !ok {
if !force {
return fmt.Errorf("master-elect tablet %v is not a master in the shard, use -force to proceed anyway", topoproto.TabletAliasString(masterElectTabletAlias))
}
wr.logger.Warningf("master-elect tablet %v is not a master in the shard, proceeding anyway as -force was used", topoproto.TabletAliasString(masterElectTabletAlias))
}
haveOtherMaster := false
for alias := range masterTabletMap {
if !topoproto.TabletAliasEqual(&alias, masterElectTabletAlias) {
haveOtherMaster = true
}
}
if haveOtherMaster {
if !force {
return fmt.Errorf("master-elect tablet %v is not the only master in the shard, use -force to proceed anyway", topoproto.TabletAliasString(masterElectTabletAlias))
}
wr.logger.Warningf("master-elect tablet %v is not the only master in the shard, proceeding anyway as -force was used", topoproto.TabletAliasString(masterElectTabletAlias))
}
// First phase: reset replication on all tablets. If anyone fails,
// we stop. It is probably because it is unreachable, and may leave
// an unstable database process in the mix, with a database daemon
// at a wrong replication spot.
event.DispatchUpdate(ev, "resetting replication on all tablets")
wg := sync.WaitGroup{}
rec := concurrency.AllErrorRecorder{}
for alias, tabletInfo := range tabletMap {
wg.Add(1)
go func(alias topodatapb.TabletAlias, tabletInfo *topo.TabletInfo) {
defer wg.Done()
wr.logger.Infof("resetting replication on tablet %v", topoproto.TabletAliasString(&alias))
if err := wr.tmc.ResetReplication(ctx, tabletInfo.Tablet); err != nil {
rec.RecordError(fmt.Errorf("Tablet %v ResetReplication failed (either fix it, or Scrap it): %v", topoproto.TabletAliasString(&alias), err))
}
}(alias, tabletInfo)
}
wg.Wait()
if err := rec.Error(); err != nil {
return err
}
// Tell the new master to break its slaves, return its replication
// position
wr.logger.Infof("initializing master on %v", topoproto.TabletAliasString(masterElectTabletAlias))
event.DispatchUpdate(ev, "initializing master")
rp, err := wr.tmc.InitMaster(ctx, masterElectTabletInfo.Tablet)
if err != nil {
return err
}
// Now tell the new master to insert the reparent_journal row,
// and tell everybody else to become a slave of the new master,
// and wait for the row in the reparent_journal table.
// We start all these in parallel, to handle the semi-sync
// case: for the master to be able to commit its row in the
// reparent_journal table, it needs connected slaves.
event.DispatchUpdate(ev, "reparenting all tablets")
now := time.Now().UnixNano()
wgMaster := sync.WaitGroup{}
wgSlaves := sync.WaitGroup{}
var masterErr error
for alias, tabletInfo := range tabletMap {
if topoproto.TabletAliasEqual(&alias, masterElectTabletAlias) {
wgMaster.Add(1)
go func(alias topodatapb.TabletAlias, tabletInfo *topo.TabletInfo) {
defer wgMaster.Done()
wr.logger.Infof("populating reparent journal on new master %v", topoproto.TabletAliasString(&alias))
masterErr = wr.tmc.PopulateReparentJournal(ctx, tabletInfo.Tablet, now, initShardMasterOperation, &alias, rp)
}(alias, tabletInfo)
} else {
wgSlaves.Add(1)
go func(alias topodatapb.TabletAlias, tabletInfo *topo.TabletInfo) {
defer wgSlaves.Done()
wr.logger.Infof("initializing slave %v", topoproto.TabletAliasString(&alias))
if err := wr.tmc.InitSlave(ctx, tabletInfo.Tablet, masterElectTabletAlias, rp, now); err != nil {
rec.RecordError(fmt.Errorf("Tablet %v InitSlave failed: %v", topoproto.TabletAliasString(&alias), err))
}
}(alias, tabletInfo)
}
}
// After the master is done, we can update the shard record
// (note with semi-sync, it also means at least one slave is done)
wgMaster.Wait()
if masterErr != nil {
wgSlaves.Wait()
return fmt.Errorf("failed to PopulateReparentJournal on master: %v", masterErr)
}
if !topoproto.TabletAliasEqual(shardInfo.MasterAlias, masterElectTabletAlias) {
if _, err := wr.ts.UpdateShardFields(ctx, keyspace, shard, func(si *topo.ShardInfo) error {
si.MasterAlias = masterElectTabletAlias
return nil
}); err != nil {
wgSlaves.Wait()
return fmt.Errorf("failed to update shard master record: %v", err)
}
}
// Wait for the slaves to complete. If some of them fail, we
// don't want to rebuild the shard serving graph (the failure
// will most likely be a timeout, and our context will be
// expired, so the rebuild will fail anyway)
wgSlaves.Wait()
if err := rec.Error(); err != nil {
return err
}
// Create database if necessary on the master. Slaves will get it too through
// replication. Since the user called InitShardMaster, they've told us to
// assume that whatever data is on all the slaves is what they intended.
// If the database doesn't exist, it means the user intends for these tablets
// to begin serving with no data (i.e. first time initialization).
createDB := fmt.Sprintf("CREATE DATABASE IF NOT EXISTS `%s`", topoproto.TabletDbName(masterElectTabletInfo.Tablet))
if _, err := wr.tmc.ExecuteFetchAsDba(ctx, masterElectTabletInfo.Tablet, false, []byte(createDB), 1, false, true); err != nil {
return fmt.Errorf("failed to create database: %v", err)
}
return nil
}