Added integration support for DataDog APM Tracing

vendor/gopkg.in/DataDog/dd-trace-go.v1/ddtrace/tracer/time_windows.go

@@ -0,0 +1,35 @@
+package tracer
+
+import (
+	"log"
+	"time"
+
+	"golang.org/x/sys/windows"
+)
+
+// This method is more precise than the go1.8 time.Now on Windows
+// See https://msdn.microsoft.com/en-us/library/windows/desktop/hh706895(v=vs.85).aspx
+// It is however ~10x slower and requires Windows 8+.
+func highPrecisionNow() int64 {
+	var ft windows.Filetime
+	windows.GetSystemTimePreciseAsFileTime(&ft)
+	return ft.Nanoseconds()
+}
+
+func lowPrecisionNow() int64 {
+	return time.Now().UTC().UnixNano()
+}
+
+var now func() int64
+
+// If GetSystemTimePreciseAsFileTime is not available we default to the less
+// precise implementation based on time.Now()
+func init() {
+	if err := windows.LoadGetSystemTimePreciseAsFileTime(); err != nil {
+		log.Printf("Unable to load high precison timer, defaulting to time.Now()")
+		now = lowPrecisionNow
+	} else {
+		log.Printf("Using high precision timer")
+		now = highPrecisionNow
+	}
+}