// RefreshTablesByShard calls RefreshState on all the tables of a
// given type in a shard. It would work for the master, but the
// discovery wouldn't be very efficient.
func (wr *Wrangler) RefreshTablesByShard(si *topo.ShardInfo, tabletType topo.TabletType, cells []string) error {
wr.Logger().Infof("RefreshTablesByShard called on shard %v/%v", si.Keyspace(), si.ShardName())
tabletMap, err := topo.GetTabletMapForShardByCell(context.TODO(), wr.ts, si.Keyspace(), si.ShardName(), cells)
switch err {
case nil:
// keep going
case topo.ErrPartialResult:
wr.Logger().Warningf("RefreshTablesByShard: got partial result for shard %v/%v, may not refresh all tablets everywhere", si.Keyspace(), si.ShardName())
default:
return err
}
// ignore errors in this phase
wg := sync.WaitGroup{}
for _, ti := range tabletMap {
if ti.Type != tabletType {
continue
}
wg.Add(1)
go func(ti *topo.TabletInfo) {
wr.Logger().Infof("Calling RefreshState on tablet %v", ti.Alias)
if err := wr.tmc.RefreshState(wr.ctx, ti); err != nil {
wr.Logger().Warningf("RefreshTablesByShard: failed to refresh %v: %v", ti.Alias, err)
}
wg.Done()
}(ti)
}
wg.Wait()
return nil
}
// replicaMigrateServedFrom handles the slave (replica, rdonly) migration.
func (wr *Wrangler) replicaMigrateServedFrom(ki *topo.KeyspaceInfo, sourceShard *topo.ShardInfo, destinationShard *topo.ShardInfo, servedType topo.TabletType, cells []string, reverse bool, tables []string, ev *events.MigrateServedFrom) error {
// Save the destination keyspace (its ServedFrom has been changed)
event.DispatchUpdate(ev, "updating keyspace")
if err := topo.UpdateKeyspace(wr.ts, ki); err != nil {
return err
}
// Save the source shard (its blacklisted tables field has changed)
event.DispatchUpdate(ev, "updating source shard")
if err := sourceShard.UpdateSourceBlacklistedTables(servedType, cells, reverse, tables); err != nil {
return fmt.Errorf("UpdateSourceBlacklistedTables(%v/%v) failed: %v", sourceShard.Keyspace(), sourceShard.ShardName(), err)
}
if err := topo.UpdateShard(context.TODO(), wr.ts, sourceShard); err != nil {
return fmt.Errorf("UpdateShard(%v/%v) failed: %v", sourceShard.Keyspace(), sourceShard.ShardName(), err)
}
// Now refresh the source servers so they reload their
// blacklisted table list
event.DispatchUpdate(ev, "refreshing sources tablets state so they update their blacklisted tables")
if err := wr.RefreshTablesByShard(sourceShard, servedType, cells); err != nil {
return err
}
return nil
}
// updateShardCellsAndMaster will update the 'Cells' and possibly
// MasterAlias records for the shard, if needed.
func (wr *Wrangler) updateShardCellsAndMaster(si *topo.ShardInfo, tabletAlias topo.TabletAlias, tabletType topo.TabletType, force bool) error {
// See if we need to update the Shard:
// - add the tablet's cell to the shard's Cells if needed
// - change the master if needed
shardUpdateRequired := false
if !si.HasCell(tabletAlias.Cell) {
shardUpdateRequired = true
}
if tabletType == topo.TYPE_MASTER && si.MasterAlias != tabletAlias {
shardUpdateRequired = true
}
if !shardUpdateRequired {
return nil
}
actionNode := actionnode.UpdateShard()
keyspace := si.Keyspace()
shard := si.ShardName()
lockPath, err := wr.lockShard(keyspace, shard, actionNode)
if err != nil {
return err
}
// re-read the shard with the lock
si, err = wr.ts.GetShard(keyspace, shard)
if err != nil {
return wr.unlockShard(keyspace, shard, actionNode, lockPath, err)
}
// update it
wasUpdated := false
if !si.HasCell(tabletAlias.Cell) {
si.Cells = append(si.Cells, tabletAlias.Cell)
wasUpdated = true
}
if tabletType == topo.TYPE_MASTER && si.MasterAlias != tabletAlias {
if !si.MasterAlias.IsZero() && !force {
return wr.unlockShard(keyspace, shard, actionNode, lockPath, fmt.Errorf("creating this tablet would override old master %v in shard %v/%v", si.MasterAlias, keyspace, shard))
}
si.MasterAlias = tabletAlias
wasUpdated = true
}
if wasUpdated {
// write it back
if err := topo.UpdateShard(context.TODO(), wr.ts, si); err != nil {
return wr.unlockShard(keyspace, shard, actionNode, lockPath, err)
}
}
// and unlock
return wr.unlockShard(keyspace, shard, actionNode, lockPath, err)
}
func (wr *Wrangler) migrateServedFrom(ki *topo.KeyspaceInfo, destinationShard *topo.ShardInfo, servedType topo.TabletType, cells []string, reverse bool) (err error) {
// re-read and update keyspace info record
ki, err = wr.ts.GetKeyspace(ki.KeyspaceName())
if err != nil {
return err
}
if reverse {
ki.UpdateServedFromMap(servedType, cells, destinationShard.SourceShards[0].Keyspace, false, nil)
} else {
ki.UpdateServedFromMap(servedType, cells, destinationShard.SourceShards[0].Keyspace, true, destinationShard.Cells)
}
// re-read and check the destination shard
destinationShard, err = wr.ts.GetShard(destinationShard.Keyspace(), destinationShard.ShardName())
if err != nil {
return err
}
if len(destinationShard.SourceShards) != 1 {
return fmt.Errorf("Destination shard %v/%v is not a vertical split target", destinationShard.Keyspace(), destinationShard.ShardName())
}
tables := destinationShard.SourceShards[0].Tables
// read the source shard, we'll need its master, and we'll need to
// update the blacklisted tables.
var sourceShard *topo.ShardInfo
sourceShard, err = wr.ts.GetShard(destinationShard.SourceShards[0].Keyspace, destinationShard.SourceShards[0].Shard)
if err != nil {
return err
}
ev := &events.MigrateServedFrom{
Keyspace: *ki,
SourceShard: *sourceShard,
DestinationShard: *destinationShard,
ServedType: servedType,
Reverse: reverse,
}
event.DispatchUpdate(ev, "start")
defer func() {
if err != nil {
event.DispatchUpdate(ev, "failed: "+err.Error())
}
}()
if servedType == topo.TYPE_MASTER {
err = wr.masterMigrateServedFrom(ki, sourceShard, destinationShard, tables, ev)
} else {
err = wr.replicaMigrateServedFrom(ki, sourceShard, destinationShard, servedType, cells, reverse, tables, ev)
}
event.DispatchUpdate(ev, "finished")
return
}
func (zkts *Server) UpdateShard(si *topo.ShardInfo, existingVersion int64) (int64, error) {
shardPath := path.Join(globalKeyspacesPath, si.Keyspace(), "shards", si.ShardName())
stat, err := zkts.zconn.Set(shardPath, jscfg.ToJson(si.Shard), int(existingVersion))
if err != nil {
if zookeeper.IsError(err, zookeeper.ZNONODE) {
err = topo.ErrNoNode
}
return -1, err
}
event.Dispatch(&events.ShardChange{
ShardInfo: *si,
Status: "updated",
})
return int64(stat.Version()), nil
}
func (wr *Wrangler) shardReplicationStatuses(shardInfo *topo.ShardInfo) ([]*topo.TabletInfo, []*myproto.ReplicationStatus, error) {
// FIXME(msolomon) this assumes no hierarchical replication, which is currently the case.
tabletMap, err := topo.GetTabletMapForShard(context.TODO(), wr.ts, shardInfo.Keyspace(), shardInfo.ShardName())
if err != nil {
return nil, nil, err
}
tablets := topotools.CopyMapValues(tabletMap, []*topo.TabletInfo{}).([]*topo.TabletInfo)
stats, err := wr.tabletReplicationStatuses(tablets)
return tablets, stats, err
}
// rebuildCellSrvShard computes and writes the serving graph data to a
// single cell
func rebuildCellSrvShard(ctx context.Context, log logutil.Logger, ts topo.Server, shardInfo *topo.ShardInfo, cell string, tablets map[topo.TabletAlias]*topo.TabletInfo) error {
log.Infof("rebuildCellSrvShard %v/%v in cell %v", shardInfo.Keyspace(), shardInfo.ShardName(), cell)
// Get all existing db types so they can be removed if nothing
// had been edited.
existingTabletTypes, err := ts.GetSrvTabletTypesPerShard(cell, shardInfo.Keyspace(), shardInfo.ShardName())
if err != nil {
if err != topo.ErrNoNode {
return err
}
}
// Update db type addresses in the serving graph
//
// locationAddrsMap is a map:
// key: tabletType
// value: EndPoints (list of server records)
locationAddrsMap := make(map[topo.TabletType]*topo.EndPoints)
for _, tablet := range tablets {
if !tablet.IsInReplicationGraph() {
// only valid case is a scrapped master in the
// catastrophic reparent case
if tablet.Parent.Uid != topo.NO_TABLET {
log.Warningf("Tablet %v should not be in the replication graph, please investigate (it is being ignored in the rebuild)", tablet.Alias)
}
continue
}
// Check IsInServingGraph, we don't want to add tablets that
// are not serving
if !tablet.IsInServingGraph() {
continue
}
// Check the Keyspace and Shard for the tablet are right
if tablet.Keyspace != shardInfo.Keyspace() || tablet.Shard != shardInfo.ShardName() {
return fmt.Errorf("CRITICAL: tablet %v is in replication graph for shard %v/%v but belongs to shard %v:%v", tablet.Alias, shardInfo.Keyspace(), shardInfo.ShardName(), tablet.Keyspace, tablet.Shard)
}
// Add the tablet to the list
addrs, ok := locationAddrsMap[tablet.Type]
if !ok {
addrs = topo.NewEndPoints()
locationAddrsMap[tablet.Type] = addrs
}
entry, err := tablet.Tablet.EndPoint()
if err != nil {
log.Warningf("EndPointForTablet failed for tablet %v: %v", tablet.Alias, err)
continue
}
addrs.Entries = append(addrs.Entries, *entry)
}
// we're gonna parallelize a lot here:
// - writing all the tabletTypes records
// - removing the unused records
// - writing SrvShard
rec := concurrency.AllErrorRecorder{}
wg := sync.WaitGroup{}
// write all the EndPoints nodes everywhere we want them
for tabletType, addrs := range locationAddrsMap {
wg.Add(1)
go func(tabletType topo.TabletType, addrs *topo.EndPoints) {
log.Infof("saving serving graph for cell %v shard %v/%v tabletType %v", cell, shardInfo.Keyspace(), shardInfo.ShardName(), tabletType)
span := trace.NewSpanFromContext(ctx)
span.StartClient("TopoServer.UpdateEndPoints")
span.Annotate("tablet_type", string(tabletType))
if err := ts.UpdateEndPoints(cell, shardInfo.Keyspace(), shardInfo.ShardName(), tabletType, addrs); err != nil {
rec.RecordError(fmt.Errorf("writing endpoints for cell %v shard %v/%v tabletType %v failed: %v", cell, shardInfo.Keyspace(), shardInfo.ShardName(), tabletType, err))
}
span.Finish()
wg.Done()
}(tabletType, addrs)
}
// Delete any pre-existing paths that were not updated by this process.
// That's the existingTabletTypes - locationAddrsMap
for _, tabletType := range existingTabletTypes {
if _, ok := locationAddrsMap[tabletType]; !ok {
wg.Add(1)
go func(tabletType topo.TabletType) {
log.Infof("removing stale db type from serving graph: %v", tabletType)
span := trace.NewSpanFromContext(ctx)
span.StartClient("TopoServer.DeleteEndPoints")
span.Annotate("tablet_type", string(tabletType))
if err := ts.DeleteEndPoints(cell, shardInfo.Keyspace(), shardInfo.ShardName(), tabletType); err != nil {
log.Warningf("unable to remove stale db type %v from serving graph: %v", tabletType, err)
}
span.Finish()
wg.Done()
}(tabletType)
}
}
// Update srvShard object
wg.Add(1)
go func() {
log.Infof("updating shard serving graph in cell %v for %v/%v", cell, shardInfo.Keyspace(), shardInfo.ShardName())
srvShard := &topo.SrvShard{
Name: shardInfo.ShardName(),
KeyRange: shardInfo.KeyRange,
ServedTypes: shardInfo.GetServedTypesPerCell(cell),
MasterCell: shardInfo.MasterAlias.Cell,
TabletTypes: make([]topo.TabletType, 0, len(locationAddrsMap)),
}
for tabletType := range locationAddrsMap {
srvShard.TabletTypes = append(srvShard.TabletTypes, tabletType)
}
span := trace.NewSpanFromContext(ctx)
span.StartClient("TopoServer.UpdateSrvShard")
span.Annotate("keyspace", shardInfo.Keyspace())
span.Annotate("shard", shardInfo.ShardName())
span.Annotate("cell", cell)
if err := ts.UpdateSrvShard(cell, shardInfo.Keyspace(), shardInfo.ShardName(), srvShard); err != nil {
rec.RecordError(fmt.Errorf("writing serving data in cell %v for %v/%v failed: %v", cell, shardInfo.Keyspace(), shardInfo.ShardName(), err))
}
span.Finish()
wg.Done()
}()
wg.Wait()
return rec.Error()
}
func (wr *Wrangler) validateReplication(shardInfo *topo.ShardInfo, tabletMap map[topo.TabletAlias]*topo.TabletInfo, results chan<- error) {
masterTablet, ok := tabletMap[shardInfo.MasterAlias]
if !ok {
results <- fmt.Errorf("master %v not in tablet map", shardInfo.MasterAlias)
return
}
slaveList, err := wr.tmc.GetSlaves(wr.ctx, masterTablet)
if err != nil {
results <- fmt.Errorf("GetSlaves(%v) failed: %v", masterTablet, err)
return
}
if len(slaveList) == 0 {
results <- fmt.Errorf("no slaves of tablet %v found", shardInfo.MasterAlias)
return
}
tabletIpMap := make(map[string]*topo.Tablet)
slaveIpMap := make(map[string]bool)
for _, tablet := range tabletMap {
tabletIpMap[normalizeIP(tablet.IPAddr)] = tablet.Tablet
}
// See if every slave is in the replication graph.
for _, slaveAddr := range slaveList {
if tabletIpMap[normalizeIP(slaveAddr)] == nil {
results <- fmt.Errorf("slave %v not in replication graph for shard %v/%v (mysql instance without vttablet?)", slaveAddr, shardInfo.Keyspace(), shardInfo.ShardName())
}
slaveIpMap[normalizeIP(slaveAddr)] = true
}
// See if every entry in the replication graph is connected to the master.
for _, tablet := range tabletMap {
if !tablet.IsSlaveType() {
continue
}
if !slaveIpMap[normalizeIP(tablet.IPAddr)] {
results <- fmt.Errorf("slave %v not replicating: %v %q", tablet.Alias, tablet.IPAddr, slaveList)
}
}
}
func (tee *Tee) UpdateShard(si *topo.ShardInfo, existingVersion int64) (newVersion int64, err error) {
if newVersion, err = tee.primary.UpdateShard(si, existingVersion); err != nil {
// failed on primary, not updating secondary
return
}
// if we have a mapping between shard version in first topo
// and shard version in second topo, replace the version number.
// if not, this will probably fail and log.
tee.mu.Lock()
svm, ok := tee.shardVersionMapping[si.Keyspace()+"/"+si.ShardName()]
if ok && svm.readFromVersion == existingVersion {
existingVersion = svm.readFromSecondVersion
delete(tee.shardVersionMapping, si.Keyspace()+"/"+si.ShardName())
}
tee.mu.Unlock()
if newVersion2, serr := tee.secondary.UpdateShard(si, existingVersion); serr != nil {
// not critical enough to fail
if serr == topo.ErrNoNode {
// the shard doesn't exist on the secondary, let's
// just create it
if serr = tee.secondary.CreateShard(si.Keyspace(), si.ShardName(), si.Shard); serr != nil {
log.Warningf("secondary.CreateShard(%v,%v) failed (after UpdateShard returned ErrNoNode): %v", si.Keyspace(), si.ShardName(), serr)
} else {
log.Infof("secondary.UpdateShard(%v, %v) failed with ErrNoNode, CreateShard then worked.", si.Keyspace(), si.ShardName())
si, gerr := tee.secondary.GetShard(si.Keyspace(), si.ShardName())
if gerr != nil {
log.Warningf("Failed to re-read shard(%v, %v) after creating it on secondary: %v", si.Keyspace(), si.ShardName(), gerr)
} else {
tee.mu.Lock()
tee.shardVersionMapping[si.Keyspace()+"/"+si.ShardName()] = versionMapping{
readFromVersion: newVersion,
readFromSecondVersion: si.Version(),
}
tee.mu.Unlock()
}
}
} else {
log.Warningf("secondary.UpdateShard(%v, %v) failed: %v", si.Keyspace(), si.ShardName(), serr)
}
} else {
tee.mu.Lock()
tee.shardVersionMapping[si.Keyspace()+"/"+si.ShardName()] = versionMapping{
readFromVersion: newVersion,
readFromSecondVersion: newVersion2,
}
tee.mu.Unlock()
}
return
}
// masterMigrateServedFrom handles the master migration. The ordering is
// a bit different than for rdonly / replica to guarantee a smooth transition.
//
// The order is as follows:
// - Add BlacklistedTables on the source shard map for master
// - Refresh the source master, so it stops writing on the tables
// - Get the source master position, wait until destination master reaches it
// - Clear SourceShard on the destination Shard
// - Refresh the destination master, so its stops its filtered
// replication and starts accepting writes
func (wr *Wrangler) masterMigrateServedFrom(ki *topo.KeyspaceInfo, sourceShard *topo.ShardInfo, destinationShard *topo.ShardInfo, tables []string, ev *events.MigrateServedFrom) error {
// Read the data we need
sourceMasterTabletInfo, err := wr.ts.GetTablet(sourceShard.MasterAlias)
if err != nil {
return err
}
destinationMasterTabletInfo, err := wr.ts.GetTablet(destinationShard.MasterAlias)
if err != nil {
return err
}
// Update source shard (more blacklisted tables)
event.DispatchUpdate(ev, "updating source shard")
if err := sourceShard.UpdateSourceBlacklistedTables(topo.TYPE_MASTER, nil, false, tables); err != nil {
return fmt.Errorf("UpdateSourceBlacklistedTables(%v/%v) failed: %v", sourceShard.Keyspace(), sourceShard.ShardName(), err)
}
if err := topo.UpdateShard(context.TODO(), wr.ts, sourceShard); err != nil {
return fmt.Errorf("UpdateShard(%v/%v) failed: %v", sourceShard.Keyspace(), sourceShard.ShardName(), err)
}
// Now refresh the blacklisted table list on the source master
event.DispatchUpdate(ev, "refreshing source master so it updates its blacklisted tables")
if err := wr.tmc.RefreshState(wr.ctx, sourceMasterTabletInfo); err != nil {
return err
}
// get the position
event.DispatchUpdate(ev, "getting master position")
masterPosition, err := wr.tmc.MasterPosition(wr.ctx, sourceMasterTabletInfo)
if err != nil {
return err
}
// wait for it
event.DispatchUpdate(ev, "waiting for destination master to catch up to source master")
if err := wr.tmc.WaitBlpPosition(context.TODO(), destinationMasterTabletInfo, blproto.BlpPosition{
Uid: 0,
Position: masterPosition,
}, wr.ActionTimeout()); err != nil {
return err
}
// Update the destination keyspace (its ServedFrom has changed)
event.DispatchUpdate(ev, "updating keyspace")
if err = topo.UpdateKeyspace(wr.ts, ki); err != nil {
return err
}
// Update the destination shard (no more source shard)
event.DispatchUpdate(ev, "updating destination shard")
destinationShard.SourceShards = nil
if err := topo.UpdateShard(context.TODO(), wr.ts, destinationShard); err != nil {
return err
}
// Tell the new shards masters they can now be read-write.
// Invoking a remote action will also make the tablet stop filtered
// replication.
event.DispatchUpdate(ev, "setting destination shard masters read-write")
if err := wr.refreshMasters([]*topo.ShardInfo{destinationShard}); err != nil {
return err
}
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(context.TODO(), 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) applySchemaShard(shardInfo *topo.ShardInfo, preflight *myproto.SchemaChangeResult, masterTabletAlias topo.TabletAlias, change string, newParentTabletAlias topo.TabletAlias, simple, force bool) (*myproto.SchemaChangeResult, error) {
// find all the shards we need to handle
aliases, err := topo.FindAllTabletAliasesInShard(context.TODO(), wr.ts, shardInfo.Keyspace(), shardInfo.ShardName())
if err != nil {
return nil, err
}
// build the array of TabletStatus we're going to use
statusArray := make([]*TabletStatus, 0, len(aliases)-1)
for _, alias := range aliases {
if alias == masterTabletAlias {
// we skip the master
continue
}
ti, err := wr.ts.GetTablet(alias)
if err != nil {
return nil, err
}
if ti.Type == topo.TYPE_LAG {
// lag tablets are usually behind, not replicating,
// and a general pain. So let's just skip them
// all together.
// TODO(alainjobart) figure out other types to skip:
// ValidateSchemaShard only does the serving types.
// We do everything in the replication graph
// but LAG. This seems fine for now.
log.Infof("Skipping tablet %v as it is LAG", ti.Alias)
continue
}
statusArray = append(statusArray, &TabletStatus{ti: ti})
}
// get schema on all tablets.
log.Infof("Getting schema on all tablets for shard %v/%v", shardInfo.Keyspace(), shardInfo.ShardName())
wg := &sync.WaitGroup{}
for _, status := range statusArray {
wg.Add(1)
go func(status *TabletStatus) {
status.beforeSchema, status.lastError = wr.tmc.GetSchema(wr.ctx, status.ti, nil, nil, false)
wg.Done()
}(status)
}
wg.Wait()
// quick check for errors
for _, status := range statusArray {
if status.lastError != nil {
return nil, fmt.Errorf("Error getting schema on tablet %v: %v", status.ti.Alias, status.lastError)
}
}
// simple or complex?
if simple {
return wr.applySchemaShardSimple(statusArray, preflight, masterTabletAlias, change, force)
}
return wr.applySchemaShardComplex(statusArray, shardInfo, preflight, masterTabletAlias, change, newParentTabletAlias, force)
}
// reparentShardBrutal executes a brutal reparent.
//
// Assume the master is dead and not coming back. Just push your way
// forward. Force means we are reparenting to the same master
// (assuming the data has been externally synched).
//
// The ev parameter is an event struct prefilled with information that the
// caller has on hand, which would be expensive for us to re-query.
func (wr *Wrangler) reparentShardBrutal(ev *events.Reparent, si *topo.ShardInfo, slaveTabletMap, masterTabletMap map[topo.TabletAlias]*topo.TabletInfo, masterElectTablet *topo.TabletInfo, leaveMasterReadOnly, force bool) (err error) {
event.DispatchUpdate(ev, "starting brutal")
defer func() {
if err != nil {
event.DispatchUpdate(ev, "failed: "+err.Error())
}
}()
wr.logger.Infof("Skipping ValidateShard - not a graceful situation")
if _, ok := slaveTabletMap[masterElectTablet.Alias]; !ok && !force {
return fmt.Errorf("master elect tablet not in replication graph %v %v/%v %v", masterElectTablet.Alias, si.Keyspace(), si.ShardName(), topotools.MapKeys(slaveTabletMap))
}
// Check the master-elect and slaves are in good shape when the action
// has not been forced.
if !force {
// Make sure all tablets have the right parent and reasonable positions.
event.DispatchUpdate(ev, "checking slave replication positions")
if err := wr.checkSlaveReplication(slaveTabletMap, topo.NO_TABLET); err != nil {
return err
}
// Check the master-elect is fit for duty - call out for hardware checks.
event.DispatchUpdate(ev, "checking that new master is ready to serve")
if err := wr.checkMasterElect(masterElectTablet); err != nil {
return err
}
event.DispatchUpdate(ev, "checking slave consistency")
wr.logger.Infof("check slaves %v/%v", masterElectTablet.Keyspace, masterElectTablet.Shard)
restartableSlaveTabletMap := wr.restartableTabletMap(slaveTabletMap)
err = wr.checkSlaveConsistency(restartableSlaveTabletMap, myproto.ReplicationPosition{})
if err != nil {
return err
}
} else {
event.DispatchUpdate(ev, "stopping slave replication")
wr.logger.Infof("forcing reparent to same master %v", masterElectTablet.Alias)
err := wr.breakReplication(slaveTabletMap, masterElectTablet)
if err != nil {
return err
}
}
event.DispatchUpdate(ev, "promoting new master")
rsd, err := wr.promoteSlave(masterElectTablet)
if err != nil {
// FIXME(msolomon) This suggests that the master-elect is dead.
// We need to classify certain errors as temporary and retry.
return fmt.Errorf("promote slave failed: %v %v", err, masterElectTablet.Alias)
}
// Once the slave is promoted, remove it from our maps
delete(slaveTabletMap, masterElectTablet.Alias)
delete(masterTabletMap, masterElectTablet.Alias)
event.DispatchUpdate(ev, "restarting slaves")
majorityRestart, restartSlaveErr := wr.restartSlaves(slaveTabletMap, rsd)
if !force {
for _, failedMaster := range masterTabletMap {
event.DispatchUpdate(ev, "scrapping old master")
wr.logger.Infof("scrap dead master %v", failedMaster.Alias)
// The master is dead so execute the action locally instead of
// enqueing the scrap action for an arbitrary amount of time.
if scrapErr := topotools.Scrap(wr.ts, failedMaster.Alias, false); scrapErr != nil {
wr.logger.Warningf("scrapping failed master failed: %v", scrapErr)
}
}
}
event.DispatchUpdate(ev, "rebuilding shard serving graph")
err = wr.finishReparent(si, masterElectTablet, majorityRestart, leaveMasterReadOnly)
if err != nil {
return err
}
event.DispatchUpdate(ev, "finished")
if restartSlaveErr != nil {
// This is more of a warning at this point.
return restartSlaveErr
}
return nil
}