func (wr *Wrangler) reparentShardLocked(keyspace, shard string, masterElectTabletAlias topo.TabletAlias, leaveMasterReadOnly, forceReparentToCurrentMaster bool) error {
shardInfo, err := wr.ts.GetShard(keyspace, shard)
if err != nil {
return err
}
tabletMap, err := topo.GetTabletMapForShard(context.TODO(), 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
}
// tabletExternallyReparentedLocked is called with the shard lock.
// It returns if agent.refreshTablet should be called, and the error.
// Note both are set independently (can have both true and an error).
func (agent *ActionAgent) tabletExternallyReparentedLocked(ctx context.Context, externalID string, interrupted chan struct{}) (bool, error) {
// re-read the tablet record to be sure we have the latest version
tablet, err := agent.TopoServer.GetTablet(agent.TabletAlias)
if err != nil {
return false, err
}
// read the shard, make sure again the master is not already good.
shardInfo, err := agent.TopoServer.GetShard(tablet.Keyspace, tablet.Shard)
if err != nil {
return false, err
}
if shardInfo.MasterAlias == tablet.Alias {
log.Infof("TabletExternallyReparented: tablet became the master before we get the lock?")
return false, nil
}
log.Infof("TabletExternallyReparented called and we're not the master, doing the work")
// 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(ctx, agent.TopoServer, 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 false, err
}
masterElectTablet, ok := tabletMap[tablet.Alias]
if !ok {
return false, 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,
ExternalID: externalID,
}
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.
// Note after this call, we may have changed the tablet record,
// so we will always return true, so the tablet record is re-read
// by the agent.
event.DispatchUpdate(ev, "mark ourself as new master")
err = agent.updateReplicationGraphForPromotedSlave(ctx, tablet)
if err != nil {
// This suggests we can't talk to topo server. This is bad.
return true, 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()
tmc := tmclient.NewTabletManagerClient()
topotools.RestartSlavesExternal(agent.TopoServer, logger, slaveTabletMap, masterTabletMap, masterElectTablet.Alias, func(ti *topo.TabletInfo, swrd *actionnode.SlaveWasRestartedArgs) error {
return tmc.SlaveWasRestarted(ctx, ti, swrd)
})
// 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(ctx, agent.TopoServer, shardInfo); err != nil {
return true, 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(ctx, logger, agent.TopoServer, tablet.Keyspace, tablet.Shard, cells, agent.LockTimeout, interrupted); err != nil {
return true, err
}
event.DispatchUpdate(ev, "finished")
return true, 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
}