Links in tracez should be relative

Fixes: #559

examples/grpc/helloworld_server/main.go

@@ -18,13 +18,16 @@ package main
 
 import (
 	"log"
+	"math/rand"
 	"net"
 	"net/http"
+	"time"
 
 	"go.opencensus.io/examples/exporter"
 	pb "go.opencensus.io/examples/grpc/proto"
 	"go.opencensus.io/plugin/ocgrpc"
 	"go.opencensus.io/stats/view"
+	"go.opencensus.io/trace"
 	"go.opencensus.io/zpages"
 	"golang.org/x/net/context"
 	"google.golang.org/grpc"
@@ -38,11 +41,17 @@ type server struct{}
 
 // SayHello implements helloworld.GreeterServer
 func (s *server) SayHello(ctx context.Context, in *pb.HelloRequest) (*pb.HelloReply, error) {
+	ctx, span := trace.StartSpan(ctx, "sleep")
+	time.Sleep(time.Duration(rand.Float64() * float64(time.Second)))
+	span.End()
 	return &pb.HelloReply{Message: "Hello " + in.Name}, nil
 }
 
 func main() {
-	go func() { log.Fatal(http.ListenAndServe(":8081", zpages.Handler)) }()
+	go func() {
+		http.Handle("/debug/", http.StripPrefix("/debug", zpages.Handler))
+		log.Fatal(http.ListenAndServe(":8081", nil))
+	}()
 	// Register stats and trace exporters to export
 	// the collected data.
 	view.RegisterExporter(&exporter.PrintExporter{})

stats/view/worker.go

@@ -80,8 +80,7 @@ func (v *View) Subscribe() error {
 // Once a view is subscribed, it reports data to the registered exporters.
 func Subscribe(views ...*View) error {
 	for _, v := range views {
-		err := v.canonicalize()
-		if err != nil {
+		if err := v.canonicalize(); err != nil {
 			return err
 		}
 	}

zpages/rpcz_test.go

@@ -1,4 +1,4 @@
-// Copyright 2017, OpenCensus Authors
+// Copyright 2018, OpenCensus Authors
 //
 // Licensed under the Apache License, Version 2.0 (the "License");
 // you may not use this file except in compliance with the License.
@@ -102,6 +102,9 @@ func TestRpcz(t *testing.T) {
 	time.Sleep(2 * time.Millisecond)
 	view.SetReportingPeriod(time.Second)
 
+	mu.Lock()
+	defer mu.Unlock()
+
 	if len(snaps) == 0 {
 		t.Fatal("Expected len(snaps) > 0")
 	}

zpages/tracez.go

@@ -408,14 +408,10 @@ type summaryPageRow struct {
 	Errors  int
 }
 
-func (s *summaryPageData) Len() int           { return len(s.Rows) }
-func (s *summaryPageData) Less(i, j int) bool { return s.Rows[i].Name < s.Rows[j].Name }
-func (s *summaryPageData) Swap(i, j int)      { s.Rows[i], s.Rows[j] = s.Rows[j], s.Rows[i] }
-
 func getSummaryPageData() summaryPageData {
 	data := summaryPageData{
 		Links:          true,
-		TracesEndpoint: "/tracez",
+		TracesEndpoint: "tracez",
 	}
 	internalTrace := internal.Trace.(interface {
 		ReportSpansPerMethod() map[string]internal.PerMethodSummary
@@ -443,6 +439,8 @@ func getSummaryPageData() summaryPageData {
 		}
 		data.Rows = append(data.Rows, row)
 	}
-	sort.Sort(&data)
+	sort.Slice(data.Rows, func(i, j int) bool {
+		return data.Rows[i].Name < data.Rows[j].Name
+	})
 	return data
 }