package mdb

/*
type txAggregator struct {
	Stop     chan struct{}
	Done     *sync.WaitGroup
	ModChan  chan txMod
	W        *cswal.Writer
	Index    *pagefile.Index
	Snapshot *atomic.Pointer[Snapshot]
}

func (p txAggregator) Run() {
	defer p.Done.Done()
	defer p.W.Close()

	var (
		tx       *Snapshot
		mod      txMod
		rec      cswal.Record
		err      error
		toNotify = make([]chan error, 0, 1024)
	)

READ_FIRST:

	toNotify = toNotify[:0]

	select {
	case mod = <-p.ModChan:
		goto BEGIN
	case <-p.Stop:
		goto END
	}

BEGIN:

	tx = p.Snapshot.Load().begin()
	goto APPLY_MOD

CLONE:

	tx = tx.clone()
	goto APPLY_MOD

APPLY_MOD:

	if err = mod.Update(tx); err != nil {
		mod.Resp <- err
		goto ROLLBACK
	}

	toNotify = append(toNotify, mod.Resp)
	goto NEXT

ROLLBACK:

	if len(toNotify) == 0 {
		goto READ_FIRST
	}

	tx = tx.rollback()
	goto NEXT

NEXT:

	select {
	case mod = <-p.ModChan:
		goto CLONE
	default:
		goto WRITE
	}

WRITE:

	rec, err = writeChangesToWAL(tx.changes, p.Index, p.W)
	if err == nil {
		tx.seqNum = rec.SeqNum
		tx.updatedAt = rec.CreatedAt
		tx.setReadOnly()
		p.Snapshot.Store(tx)
	}

	for i := range toNotify {
		toNotify[i] <- err
	}

	goto READ_FIRST

END:
}
*/