Method iterateAndMerge

merge.go:61–100

()

var errNoMerge = errors.New("No need for merge")

func (op *MergeOperator) iterateAndMerge() (newVal []byte, latest uint64, err error) {
	txn := op.db.NewTransaction(false)
	defer txn.Discard()
	opt := DefaultIteratorOptions
	opt.AllVersions = true
	it := txn.NewKeyIterator(op.key, opt)
	defer it.Close()

	var numVersions int
	for it.Rewind(); it.Valid(); it.Next() {
		item := it.Item()
		numVersions++
		if numVersions == 1 {
			// This should be the newVal, considering this is the latest version.
			newVal, err = item.ValueCopy(newVal)
			if err != nil {
				return nil, 0, err
			}
			latest = item.Version()
		} else {
			if err := item.Value(func(oldVal []byte) error {
				// The merge should always be on the newVal considering it has the merge result of
				// the latest version. The value read should be the oldVal.
				newVal = op.f(oldVal, newVal)
				return nil
			}); err != nil {
				return nil, 0, err
			}
		}
		if item.DiscardEarlierVersions() {
			break
		}
	}
	if numVersions == 0 {
		return nil, latest, ErrKeyNotFound
	} else if numVersions == 1 {
		return newVal, latest, errNoMerge
	}
	return newVal, latest, nil
}

func (op *MergeOperator) compact() error {
	op.Lock()