Added integration support for DataDog APM Tracing

vendor/github.com/tinylib/msgp/msgp/circular.go

@@ -0,0 +1,39 @@
+package msgp
+
+type timer interface {
+	StartTimer()
+	StopTimer()
+}
+
+// EndlessReader is an io.Reader
+// that loops over the same data
+// endlessly. It is used for benchmarking.
+type EndlessReader struct {
+	tb     timer
+	data   []byte
+	offset int
+}
+
+// NewEndlessReader returns a new endless reader
+func NewEndlessReader(b []byte, tb timer) *EndlessReader {
+	return &EndlessReader{tb: tb, data: b, offset: 0}
+}
+
+// Read implements io.Reader. In practice, it
+// always returns (len(p), nil), although it
+// fills the supplied slice while the benchmark
+// timer is stopped.
+func (c *EndlessReader) Read(p []byte) (int, error) {
+	c.tb.StopTimer()
+	var n int
+	l := len(p)
+	m := len(c.data)
+	for n < l {
+		nn := copy(p[n:], c.data[c.offset:])
+		n += nn
+		c.offset += nn
+		c.offset %= m
+	}
+	c.tb.StartTimer()
+	return n, nil
+}