Function ProgressHandler

pkg/transferutil/progress.go:57–161

ProgressHandler returns a progress callback and a cleanup function to render transfer progress. This implementation is based on containerd's ctr command progress handler.

(ctx context.Context, out io.Writer)

// ProgressHandler returns a progress callback and a cleanup function to render transfer progress.
// This implementation is based on containerd's ctr command progress handler.
func ProgressHandler(ctx context.Context, out io.Writer) (transfer.ProgressFunc, func()) {
	ctx, cancel := context.WithCancel(ctx)
	var (
		fw       = progress.NewWriter(out)
		start    = time.Now()
		statuses = map[string]*progressNode{}
		roots    = []*progressNode{}
		pc       = make(chan transfer.Progress, 5)
		status   string
		closeC   = make(chan struct{})
	)

	progressFn := func(p transfer.Progress) {
		select {
		case pc <- p:
		case <-ctx.Done():
		}
	}

	done := func() {
		cancel()
		<-closeC
	}

	go func() {
		defer close(closeC)
		for {
			select {
			case p := <-pc:
				if p.Name == "" {
					status = p.Event
					continue
				}
				if node, ok := statuses[p.Name]; !ok {
					node = &progressNode{
						Progress: p,
						root:     true,
					}
					if len(p.Parents) == 0 {
						roots = append(roots, node)
					} else {
						var parents []string
						for _, parent := range p.Parents {
							pStatus, ok := statuses[parent]
							if ok {
								parents = append(parents, parent)
								pStatus.children = append(pStatus.children, node)
								node.root = false
							}
						}
						node.Progress.Parents = parents
						if node.root {
							roots = append(roots, node)
						}
					}
					statuses[p.Name] = node
				} else {
					if len(node.Progress.Parents) != len(p.Parents) {