// updateShardCellsAndMaster will update the 'Cells' and possibly
// MasterAlias records for the shard, if needed.
func (wr *Wrangler) updateShardCellsAndMaster(ctx context.Context, si *topo.ShardInfo, tabletAlias *topodatapb.TabletAlias, tabletType topodatapb.TabletType, allowMasterOverride 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 == topodatapb.TabletType_MASTER && !topoproto.TabletAliasEqual(si.MasterAlias, tabletAlias) {
shardUpdateRequired = true
}
if !shardUpdateRequired {
return nil
}
// we do need to update the shard, lock it to not interfere with
// reparenting operations.
actionNode := actionnode.UpdateShard()
keyspace := si.Keyspace()
shard := si.ShardName()
lockPath, err := wr.lockShard(ctx, keyspace, shard, actionNode)
if err != nil {
return err
}
// run the update
_, err = wr.ts.UpdateShardFields(ctx, keyspace, shard, func(s *topodatapb.Shard) error {
wasUpdated := false
if !topoproto.ShardHasCell(s, tabletAlias.Cell) {
s.Cells = append(s.Cells, tabletAlias.Cell)
wasUpdated = true
}
if tabletType == topodatapb.TabletType_MASTER && !topoproto.TabletAliasEqual(s.MasterAlias, tabletAlias) {
if !topoproto.TabletAliasIsZero(s.MasterAlias) && !allowMasterOverride {
return fmt.Errorf("creating this tablet would override old master %v in shard %v/%v", topoproto.TabletAliasString(s.MasterAlias), keyspace, shard)
}
s.MasterAlias = tabletAlias
wasUpdated = true
}
if !wasUpdated {
return topo.ErrNoUpdateNeeded
}
return nil
})
return wr.unlockShard(ctx, keyspace, shard, actionNode, lockPath, err)
}
// HasCell returns true if the cell is listed in the Cells for the shard.
func (si *ShardInfo) HasCell(cell string) bool {
return topoproto.ShardHasCell(si.Shard, cell)
}