package mpb import ( "io" "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) return n, err } type proxyWriterTo struct { proxyReader } func (x proxyWriterTo) WriteTo(w io.Writer) (int64, error) { n, err := x.ReadCloser.(io.WriterTo).WriteTo(w) x.bar.IncrInt64(n) return n, err } type ewmaProxyReader struct { io.ReadCloser bar *Bar } func (x ewmaProxyReader) Read(p []byte) (int, error) { start := time.Now() n, err := x.ReadCloser.Read(p) x.bar.EwmaIncrBy(n, time.Since(start)) return n, err } type ewmaProxyWriterTo struct { ewmaProxyReader } func (x ewmaProxyWriterTo) WriteTo(w io.Writer) (int64, error) { start := time.Now() n, err := x.ReadCloser.(io.WriterTo).WriteTo(w) x.bar.EwmaIncrInt64(n, time.Since(start)) return n, err } func newProxyReader(r io.Reader, b *Bar, hasEwma bool) io.ReadCloser { rc := toReadCloser(r) if hasEwma { epr := ewmaProxyReader{rc, b} if _, ok := r.(io.WriterTo); ok { return ewmaProxyWriterTo{epr} } return epr } pr := proxyReader{rc, b} if _, ok := r.(io.WriterTo); ok { return proxyWriterTo{pr} } return pr } func toReadCloser(r io.Reader) io.ReadCloser { if rc, ok := r.(io.ReadCloser); ok { return rc } return toNopReadCloser(r) } func toNopReadCloser(r io.Reader) io.ReadCloser { if _, ok := r.(io.WriterTo); ok { return nopReadCloserWriterTo{r} } return nopReadCloser{r} } type nopReadCloser struct { io.Reader } func (nopReadCloser) Close() error { return nil } type nopReadCloserWriterTo struct { io.Reader } func (nopReadCloserWriterTo) Close() error { return nil } func (c nopReadCloserWriterTo) WriteTo(w io.Writer) (int64, error) { return c.Reader.(io.WriterTo).WriteTo(w) }