// 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)
}