package mdb

/*
type follower struct {
	Stop         chan struct{}
	Done         *sync.WaitGroup
	WALRootDir   string
	SeqNum       uint64 // Current max applied sequence number.
	ApplyChanges func(rec *cswal.Record) error

	seqNum uint64 // Current max applied sequence number.
}

func (f *follower) Run() {
	defer f.Done.Done()

	f.seqNum = f.SeqNum

	for {
		f.runOnce()
		select {
		case <-f.Stop:
			return
		default:
			// Something went wrong.
			time.Sleep(time.Second)
		}
	}
}

func (f *follower) runOnce() {
	it, err := cswal.NewIterator(f.WALRootDir, f.seqNum+1)
	if err != nil {
		f.logf("Failed to get WAL iterator: %v", errs.FmtDetails(err))
		return
	}
	defer it.Close()

	for {
		hasNext := it.Next(time.Second)

		select {
		case <-f.Stop:
			return
		default:
		}

		if !hasNext {
			if it.Error() != nil {
				f.logf("Iteration error: %v", errs.FmtDetails(it.Error()))
				return
			}
			continue
		}

		rec := it.Record()
		if err := f.ApplyChanges(rec); err != nil {
			f.logf("Failed to apply changes: %s", errs.FmtDetails(err))
			return
		}
		f.seqNum = rec.SeqNum
	}
}

func (f *follower) logf(pattern string, args ...interface{}) {
	log.Printf("[FOLLOWER] "+pattern, args...)
}
*/