Method traverse

internal/surgeon/xray.go:24–77

(stack []common.Pgid, visited map[common.Pgid]struct{}, callback func(page *common.Page, stack []common.Pgid) error)

}

func (n XRay) traverse(stack []common.Pgid, visited map[common.Pgid]struct{}, callback func(page *common.Page, stack []common.Pgid) error) error {
	pgid := stack[len(stack)-1]
	if _, ok := visited[pgid]; ok {
		return fmt.Errorf("cycle detected at page %d (stack %v)", pgid, stack)
	}
	visited[pgid] = struct{}{}

	p, data, err := guts_cli.ReadPage(n.path, uint64(pgid))
	if err != nil {
		return fmt.Errorf("failed reading page (stack %v): %w", stack, err)
	}
	err = callback(p, stack)
	if err != nil {
		return fmt.Errorf("failed callback for page (stack %v): %w", stack, err)
	}
	switch p.Typ() {
	case "meta":
		{
			m := common.LoadPageMeta(data)
			r := m.RootBucket().RootPage()
			return n.traverse(append(stack, r), visited, callback)
		}
	case "branch":
		{
			for i := uint16(0); i < p.Count(); i++ {
				bpe := p.BranchPageElement(i)
				if err := n.traverse(append(stack, bpe.Pgid()), visited, callback); err != nil {
					return err
				}
			}
		}
	case "leaf":
		for i := uint16(0); i < p.Count(); i++ {
			lpe := p.LeafPageElement(i)
			if lpe.IsBucketEntry() {
				pgid := lpe.Bucket().RootPage()
				if pgid > 0 {
					if err := n.traverse(append(stack, pgid), visited, callback); err != nil {
						return err
					}
				} else {
					inlinePage := lpe.Bucket().InlinePage(lpe.Value())
					if err := callback(inlinePage, stack); err != nil {
						return fmt.Errorf("failed callback for inline page  (stack %v): %w", stack, err)
					}
				}
			}
		}
	case "freelist":
		return nil
		// Free does not have children.
	}
	return nil
}

// FindPathsToKey finds all paths from root to the page that contains the given key.
// As it traverses multiple buckets, so in theory there might be multiple keys with the given name.