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vendor/github.com/tsenart/tb/io/io.go

@@ -0,0 +1,35 @@
+package io
+
+import (
+	"github.com/tsenart/tb"
+	"io"
+	"time"
+)
+
+// NewThrottledWriter is an io.Writer wrapping another io.Writer with
+// byte rate throttling, flushing block bytes at a time.
+func NewThrottledWriter(rate, block int64, w io.Writer) io.Writer {
+	return &throttledWriter{rate, block, w, tb.NewBucket(rate, -1)}
+}
+
+type throttledWriter struct {
+	rate, block int64
+	w           io.Writer
+	b           *tb.Bucket
+}
+
+func (tw *throttledWriter) Write(p []byte) (n int, err error) {
+	for wr := 0; wr < len(p); {
+		var got int64
+		for got < tw.block {
+			if got += tw.b.Take(tw.block - got); got != tw.block {
+				time.Sleep(time.Duration((1e9 / tw.rate) * (tw.block - got)))
+			}
+		}
+		if n, err = tw.w.Write(p[wr : wr+int(got)]); err != nil {
+			return wr, err
+		}
+		wr += n
+	}
+	return len(p), nil
+}