copy: provide progress bar for partial blobs

Signed-off-by: Giuseppe Scrivano <gscrivan@redhat.com>

copy/copy.go

@@ -959,9 +959,35 @@ func (c *copier) newProgressPool(ctx context.Context) (*mpb.Progress, func()) {
 	}
 }
 
+// customPartialBlobCounter provides a decorator function for the partial blobs retrieval progress bar
+func customPartialBlobCounter(filler interface{}, wcc ...decor.WC) decor.Decorator {
+	producer := func(filler interface{}) decor.DecorFunc {
+		return func(s decor.Statistics) string {
+			// if the Refill value is set, reverse the bar
+			// so that it looks like ====+++++.
+			if s.Refill > 0 {
+				type revSetter interface {
+					SetReverse(bool)
+				}
+				if t, ok := filler.(revSetter); ok {
+					t.SetReverse(true)
+				}
+			}
+			if s.Total == 0 {
+				pairFmt := "%.1f / %.1f (skipped: %.1f)"
+				return fmt.Sprintf(pairFmt, decor.SizeB1024(s.Current), decor.SizeB1024(s.Total), decor.SizeB1024(s.Refill))
+			}
+			pairFmt := "%.1f / %.1f (skipped: %.1f = %.2f%%)"
+			percentage := 100.0 * float64(s.Refill) / float64(s.Total)
+			return fmt.Sprintf(pairFmt, decor.SizeB1024(s.Current), decor.SizeB1024(s.Total), decor.SizeB1024(s.Refill), percentage)
+		}
+	}
+	return decor.Any(producer(filler), wcc...)
+}
+
 // createProgressBar creates a mpb.Bar in pool.  Note that if the copier's reportWriter
 // is ioutil.Discard, the progress bar's output will be discarded
-func (c *copier) createProgressBar(pool *mpb.Progress, info types.BlobInfo, kind string, onComplete string) *mpb.Bar {
+func (c *copier) createProgressBar(pool *mpb.Progress, partial bool, info types.BlobInfo, kind string, onComplete string) *mpb.Bar {
 	// shortDigestLen is the length of the digest used for blobs.
 	const shortDigestLen = 12
 
@@ -979,15 +1005,28 @@ func (c *copier) createProgressBar(pool *mpb.Progress, info types.BlobInfo, kind
 	// Otherwise, use a spinner to indicate that something's happening.
 	var bar *mpb.Bar
 	if info.Size > 0 {
-		bar = pool.AddBar(info.Size,
-			mpb.BarFillerClearOnComplete(),
-			mpb.PrependDecorators(
-				decor.OnComplete(decor.Name(prefix), onComplete),
-			),
-			mpb.AppendDecorators(
-				decor.OnComplete(decor.CountersKibiByte("%.1f / %.1f"), ""),
-			),
-		)
+		if partial {
+			filler := mpb.NewBarFiller(mpb.DefaultBarStyle, false)
+			bar = pool.Add(info.Size,
+				filler,
+				mpb.PrependDecorators(
+					decor.OnComplete(decor.Name(prefix), onComplete),
+				),
+				mpb.AppendDecorators(
+					customPartialBlobCounter(filler),
+				),
+			)
+		} else {
+			bar = pool.AddBar(info.Size,
+				mpb.BarFillerClearOnComplete(),
+				mpb.PrependDecorators(
+					decor.OnComplete(decor.Name(prefix), onComplete),
+				),
+				mpb.AppendDecorators(
+					decor.OnComplete(decor.CountersKibiByte("%.1f / %.1f"), ""),
+				),
+			)
+		}
 	} else {
 		bar = pool.AddSpinner(info.Size,
 			mpb.SpinnerOnLeft,
@@ -1016,7 +1055,7 @@ func (c *copier) copyConfig(ctx context.Context, src types.Image) error {
 		destInfo, err := func() (types.BlobInfo, error) { // A scope for defer
 			progressPool, progressCleanup := c.newProgressPool(ctx)
 			defer progressCleanup()
-			bar := c.createProgressBar(progressPool, srcInfo, "config", "done")
+			bar := c.createProgressBar(progressPool, false, srcInfo, "config", "done")
 			destInfo, err := c.copyBlobFromStream(ctx, bytes.NewReader(configBlob), srcInfo, nil, false, true, false, bar)
 			if err != nil {
 				return types.BlobInfo{}, err
@@ -1080,7 +1119,7 @@ func (ic *imageCopier) copyLayer(ctx context.Context, srcInfo types.BlobInfo, to
 
 		if reused {
 			logrus.Debugf("Skipping blob %s (already present):", srcInfo.Digest)
-			bar := ic.c.createProgressBar(pool, srcInfo, "blob", "skipped: already exists")
+			bar := ic.c.createProgressBar(pool, false, srcInfo, "blob", "skipped: already exists")
 			bar.SetTotal(0, true)
 
 			// Throw an event that the layer has been skipped
@@ -1097,7 +1136,7 @@ func (ic *imageCopier) copyLayer(ctx context.Context, srcInfo types.BlobInfo, to
 	imgSource, okSource := ic.c.rawSource.(types.ImageSourceSeekable)
 	imgDest, okDest := ic.c.dest.(types.ImageDestinationPartial)
 	if okSource && okDest && !diffIDIsNeeded {
-		bar := ic.c.createProgressBar(pool, srcInfo, "blob", "done")
+		bar := ic.c.createProgressBar(pool, true, srcInfo, "blob", "done")
 
 		progress := make(chan int64)
 		terminate := make(chan interface{})
@@ -1139,7 +1178,7 @@ func (ic *imageCopier) copyLayer(ctx context.Context, srcInfo types.BlobInfo, to
 	}
 	defer srcStream.Close()
 
-	bar := ic.c.createProgressBar(pool, srcInfo, "blob", "done")
+	bar := ic.c.createProgressBar(pool, false, srcInfo, "blob", "done")
 
 	blobInfo, diffIDChan, err := ic.copyLayerFromStream(ctx, srcStream, types.BlobInfo{Digest: srcInfo.Digest, Size: srcBlobSize, MediaType: srcInfo.MediaType, Annotations: srcInfo.Annotations}, diffIDIsNeeded, toEncrypt, bar)
 	if err != nil {