Enable 'OptimizeDestinationImageAlreadyExists' feature

Signed-off-by: George Jenkins <gjenkins8@bloomberg.net>

vendor/github.com/vbauerster/mpb/v6/proxyreader.go

@@ -0,0 +1,90 @@
+package mpb
+
+import (
+	"io"
+	"io/ioutil"
+	"time"
+)
+
+type proxyReader struct {
+	io.ReadCloser
+	bar *Bar
+}
+
+func (x *proxyReader) Read(p []byte) (int, error) {
+	n, err := x.ReadCloser.Read(p)
+	x.bar.IncrBy(n)
+	if err == io.EOF {
+		go x.bar.SetTotal(0, true)
+	}
+	return n, err
+}
+
+type proxyWriterTo struct {
+	io.ReadCloser // *proxyReader
+	wt            io.WriterTo
+	bar           *Bar
+}
+
+func (x *proxyWriterTo) WriteTo(w io.Writer) (int64, error) {
+	n, err := x.wt.WriteTo(w)
+	x.bar.IncrInt64(n)
+	if err == io.EOF {
+		go x.bar.SetTotal(0, true)
+	}
+	return n, err
+}
+
+type ewmaProxyReader struct {
+	io.ReadCloser // *proxyReader
+	bar           *Bar
+	iT            time.Time
+}
+
+func (x *ewmaProxyReader) Read(p []byte) (int, error) {
+	n, err := x.ReadCloser.Read(p)
+	if n > 0 {
+		x.bar.DecoratorEwmaUpdate(time.Since(x.iT))
+		x.iT = time.Now()
+	}
+	return n, err
+}
+
+type ewmaProxyWriterTo struct {
+	io.ReadCloser             // *ewmaProxyReader
+	wt            io.WriterTo // *proxyWriterTo
+	bar           *Bar
+	iT            time.Time
+}
+
+func (x *ewmaProxyWriterTo) WriteTo(w io.Writer) (int64, error) {
+	n, err := x.wt.WriteTo(w)
+	if n > 0 {
+		x.bar.DecoratorEwmaUpdate(time.Since(x.iT))
+		x.iT = time.Now()
+	}
+	return n, err
+}
+
+func newProxyReader(r io.Reader, bar *Bar) io.ReadCloser {
+	rc := toReadCloser(r)
+	rc = &proxyReader{rc, bar}
+
+	if wt, isWriterTo := r.(io.WriterTo); bar.hasEwmaDecorators {
+		now := time.Now()
+		rc = &ewmaProxyReader{rc, bar, now}
+		if isWriterTo {
+			rc = &ewmaProxyWriterTo{rc, wt, bar, now}
+		}
+	} else if isWriterTo {
+		rc = &proxyWriterTo{rc, wt, bar}
+	}
+	return rc
+}
+
+func toReadCloser(r io.Reader) io.ReadCloser {
+	if rc, ok := r.(io.ReadCloser); ok {
+		return rc
+	}
+	return ioutil.NopCloser(r)
+}