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// Copyright 2021 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
//go:build !disable_events
package otel_test
import (
"bytes"
"context"
"fmt"
"io"
"testing"
sdktrace "go.opentelemetry.io/otel/sdk/trace"
"go.opentelemetry.io/otel/trace"
"golang.org/x/exp/event"
"golang.org/x/exp/event/otel"
)
func TestTrace(t *testing.T) {
// Verify that otel and event traces work well together.
// This test uses a single, fixed span tree (see makeTraceSpec).
// Each test case varies which of the individual spans are
// created directly from an otel tracer, and which are created
// using the event package.
want := "root (f (g h) p (q r))"
for i, tfunc := range []func(int) bool{
func(int) bool { return true },
func(int) bool { return false },
func(i int) bool { return i%2 == 0 },
func(i int) bool { return i%2 == 1 },
func(i int) bool { return i%3 == 0 },
func(i int) bool { return i%3 == 1 },
} {
ctx, tr, shutdown := setupOtel()
// There are 7 spans, so we create a 7-element slice.
// tfunc determines, for each index, whether it holds
// an otel tracer or nil.
tracers := make([]trace.Tracer, 7)
for i := 0; i < len(tracers); i++ {
if tfunc(i) {
tracers[i] = tr
}
}
s := makeTraceSpec(tracers)
s.apply(ctx)
got := shutdown()
if got != want {
t.Errorf("#%d: got %v, want %v", i, got, want)
}
}
}
func makeTraceSpec(tracers []trace.Tracer) *traceSpec {
return &traceSpec{
name: "root",
tracer: tracers[0],
children: []*traceSpec{
{
name: "f",
tracer: tracers[1],
children: []*traceSpec{
{name: "g", tracer: tracers[2]},
{name: "h", tracer: tracers[3]},
},
},
{
name: "p",
tracer: tracers[4],
children: []*traceSpec{
{name: "q", tracer: tracers[5]},
{name: "r", tracer: tracers[6]},
},
},
},
}
}
type traceSpec struct {
name string
tracer trace.Tracer // nil for event
children []*traceSpec
}
// apply builds spans for the traceSpec and all its children,
// If the traceSpec has a non-nil tracer, it is used to create the span.
// Otherwise, event.Trace.Start is used.
func (s *traceSpec) apply(ctx context.Context) {
if s.tracer != nil {
var span trace.Span
ctx, span = s.tracer.Start(ctx, s.name)
defer span.End()
} else {
ctx = event.Start(ctx, s.name)
defer event.End(ctx)
}
for _, c := range s.children {
c.apply(ctx)
}
}
func setupOtel() (context.Context, trace.Tracer, func() string) {
ctx := context.Background()
e := newTestExporter()
bsp := sdktrace.NewSimpleSpanProcessor(e)
stp := sdktrace.NewTracerProvider(sdktrace.WithSpanProcessor(bsp))
tracer := stp.Tracer("")
ee := event.NewExporter(otel.NewTraceHandler(tracer), nil)
ctx = event.WithExporter(ctx, ee)
return ctx, tracer, func() string { stp.Shutdown(ctx); return e.got }
}
// testExporter is an otel exporter for traces
type testExporter struct {
m map[trace.SpanID][]sdktrace.ReadOnlySpan // key is parent SpanID
got string
}
var _ sdktrace.SpanExporter = (*testExporter)(nil)
func newTestExporter() *testExporter {
return &testExporter{m: map[trace.SpanID][]sdktrace.ReadOnlySpan{}}
}
func (e *testExporter) ExportSpans(ctx context.Context, ss []sdktrace.ReadOnlySpan) error {
for _, s := range ss {
sid := s.Parent().SpanID()
e.m[sid] = append(e.m[sid], s)
}
return nil
}
func (e *testExporter) Shutdown(ctx context.Context) error {
root := e.m[trace.SpanID{}][0]
var buf bytes.Buffer
e.print(&buf, root)
e.got = buf.String()
return nil
}
func (e *testExporter) print(w io.Writer, ss sdktrace.ReadOnlySpan) {
fmt.Fprintf(w, "%s", ss.Name())
children := e.m[ss.SpanContext().SpanID()]
if len(children) > 0 {
fmt.Fprint(w, " (")
for i, ss := range children {
if i != 0 {
fmt.Fprint(w, " ")
}
e.print(w, ss)
}
fmt.Fprint(w, ")")
}
}
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