Added payload size to http server integration (#1129)

* Added payload size to http server integration, logged in the LogExporter, and modified example to use LogExporter

* Fixed format problems

* Corrected comment

Author: alexamies

examples/exporter/logexporter.go

@@ -177,6 +177,14 @@ func (e *LogExporter) ExportSpan(sd *trace.SpanData) {
 	e.tLogger.Printf("Status:  %v [%v]\n", sd.Status.Message, sd.Status.Code)
 	e.tLogger.Printf("Elapsed: %v\n", sd.EndTime.Sub(sd.StartTime).Round(time.Millisecond))
 
+	spanKinds := map[int]string{
+		1: "Server",
+		2: "Client",
+	}
+	if spanKind, ok := spanKinds[sd.SpanKind]; ok {
+		e.tLogger.Printf("SpanKind: %s\n", spanKind)
+	}
+
 	if len(sd.Annotations) > 0 {
 		e.tLogger.Println()
 		e.tLogger.Println("Annotations:")
@@ -196,4 +204,21 @@ func (e *LogExporter) ExportSpan(sd *trace.SpanData) {
 			e.tLogger.Printf("%v- %v=%v\n", indent, k, v)
 		}
 	}
+
+	if len(sd.MessageEvents) > 0 {
+		eventTypes := map[trace.MessageEventType]string{
+			trace.MessageEventTypeSent: "Sent",
+			trace.MessageEventTypeRecv: "Received",
+		}
+		e.tLogger.Println()
+		e.tLogger.Println("MessageEvents:")
+		for _, item := range sd.MessageEvents {
+			if eventType, ok := eventTypes[item.EventType]; ok {
+				e.tLogger.Print(eventType)
+			}
+			e.tLogger.Printf("UncompressedByteSize: %v", item.UncompressedByteSize)
+			e.tLogger.Printf("CompressedByteSize: %v", item.CompressedByteSize)
+			e.tLogger.Println()
+		}
+	}
 }

examples/http/helloworld_server/main.go

@@ -28,6 +28,11 @@ import (
 	"go.opencensus.io/trace"
 )
 
+const (
+	metricsLogFile = "/tmp/metrics.log"
+	tracesLogFile  = "/tmp/trace.log"
+)
+
 func main() {
 	// Start z-Pages server.
 	go func() {
@@ -36,10 +41,18 @@ func main() {
 		log.Fatal(http.ListenAndServe("127.0.0.1:8081", mux))
 	}()
 
-	// Register stats and trace exporters to export the collected data.
-	exporter := &exporter.PrintExporter{}
-	view.RegisterExporter(exporter)
-	trace.RegisterExporter(exporter)
+	// Using log exporter to export metrics but you can choose any supported exporter.
+	exporter, err := exporter.NewLogExporter(exporter.Options{
+		ReportingInterval: time.Duration(10 * time.Second),
+		MetricsLogFile:    metricsLogFile,
+		TracesLogFile:     tracesLogFile,
+	})
+	if err != nil {
+		log.Fatalf("Error creating log exporter: %v", err)
+	}
+	exporter.Start()
+	defer exporter.Stop()
+	defer exporter.Close()
 
 	// Always trace for this demo. In a production application, you should
 	// configure this to a trace.ProbabilitySampler set at the desired

plugin/ochttp/server.go

@@ -124,6 +124,12 @@ func (h *Handler) startTrace(w http.ResponseWriter, r *http.Request) (*http.Requ
 		}
 	}
 	span.AddAttributes(requestAttrs(r)...)
+	if r.Body == nil {
+		// TODO: Handle cases where ContentLength is not set.
+	} else if r.ContentLength > 0 {
+		span.AddMessageReceiveEvent(0, /* TODO: messageID */
+			int64(r.ContentLength), -1)
+	}
 	return r.WithContext(ctx), span.End
 }
 
@@ -201,6 +207,9 @@ func (t *trackingResponseWriter) Header() http.Header {
 func (t *trackingResponseWriter) Write(data []byte) (int, error) {
 	n, err := t.writer.Write(data)
 	t.respSize += int64(n)
+	// Add message event for request bytes sent.
+	span := trace.FromContext(t.ctx)
+	span.AddMessageSendEvent(0 /* TODO: messageID */, int64(n), -1)
 	return n, err
 }