Пример #1
0
// findChecker:
// - find a rdonly instance in the keyspace / shard
// - mark it as checker
// - tag it with our worker process
func findChecker(wr *wrangler.Wrangler, cleaner *wrangler.Cleaner, cell, keyspace, shard string) (topo.TabletAlias, error) {
	endPoints, err := wr.TopoServer().GetEndPoints(cell, keyspace, shard, topo.TYPE_RDONLY)
	if err != nil {
		return topo.TabletAlias{}, fmt.Errorf("GetEndPoints(%v,%v,%v,rdonly) failed: %v", cell, keyspace, shard, err)
	}
	if len(endPoints.Entries) == 0 {
		return topo.TabletAlias{}, fmt.Errorf("No endpoint to chose from in (%v,%v/%v)", cell, keyspace, shard)
	}
	tabletAlias := topo.TabletAlias{
		Cell: cell,
		Uid:  endPoints.Entries[0].Uid,
	}

	// We add the tag before calling ChangeSlaveType, so the destination
	// vttablet reloads the worker URL when it reloads the tablet.
	ourURL := servenv.ListeningURL.String()
	log.Infof("Adding tag[worker]=%v to tablet %v", ourURL, tabletAlias)
	if err := wr.TopoServer().UpdateTabletFields(tabletAlias, func(tablet *topo.Tablet) error {
		if tablet.Tags == nil {
			tablet.Tags = make(map[string]string)
		}
		tablet.Tags["worker"] = ourURL
		return nil
	}); err != nil {
		return topo.TabletAlias{}, err
	}
	// we remove the tag *before* calling ChangeSlaveType back, so
	// we need to record this tag change after the change slave
	// type change in the cleaner.
	defer wrangler.RecordTabletTagAction(cleaner, tabletAlias, "worker", "")

	log.Infof("Changing tablet %v to 'checker'", tabletAlias)
	wr.ResetActionTimeout(30 * time.Second)
	if err := wr.ChangeType(tabletAlias, topo.TYPE_CHECKER, false /*force*/); err != nil {
		return topo.TabletAlias{}, err
	}

	// Record a clean-up action to take the tablet back to rdonly.
	// We will alter this one later on and let the tablet go back to
	// 'spare' if we have stopped replication for too long on it.
	wrangler.RecordChangeSlaveTypeAction(cleaner, tabletAlias, topo.TYPE_RDONLY)
	return tabletAlias, nil
}