Merge pull request #35 from apechimp/asyncchild-race

Asyncchild race

.travis.yml

@@ -3,3 +3,5 @@ language: go
 go:
     - "1.10"
     - "1.9"
+script:
+    - "go test -v ./... -race"

trace/trace.go

@@ -144,6 +144,7 @@ type Span struct {
 	isSent       bool
 	isRoot       bool
 	children     []*Span
+	childrenLock sync.Mutex
 	ev           *libhoney.Event
 	spanID       string
 	parentID     string
@@ -234,6 +235,7 @@ func (s *Span) Send() {
 		s.AddField(k, v)
 	}
 	s.rollupLock.Unlock()
+	s.childrenLock.Lock()
 	for _, child := range s.children {
 		if !child.IsAsync() {
 			if !child.isSent {
@@ -242,6 +244,7 @@ func (s *Span) Send() {
 			}
 		}
 	}
+	s.childrenLock.Unlock()
 	// now that we're all sent, send the span and all its children.
 	s.send()
 	s.isSent = true
@@ -280,7 +283,9 @@ func (s *Span) CreateChild(ctx context.Context) (context.Context, *Span) {
 	newSpan.parentID = s.spanID
 	newSpan.trace = s.trace
 	newSpan.ev = s.trace.builder.NewEvent()
+	s.childrenLock.Lock()
 	s.children = append(s.children, newSpan)
+	s.childrenLock.Unlock()
 	ctx = PutSpanInContext(ctx, newSpan)
 	return ctx, newSpan
 }

trace/trace_test.go

@@ -3,6 +3,7 @@ package trace
 import (
 	"context"
 	"fmt"
+	"sync"
 	"testing"
 	"time"
 
@@ -217,6 +218,24 @@ func TestSpan(t *testing.T) {
 
 }
 
+func TestCreateAsyncSpanDoesNotCauseRaceInSend(t *testing.T) {
+	setupLibhoney()
+	ctx, tr := NewTrace(context.Background(), t.Name())
+	rs := tr.GetRootSpan()
+
+	wg := &sync.WaitGroup{}
+	wg.Add(2)
+	go func() {
+		rs.Send()
+		wg.Done()
+	}()
+	go func() {
+		rs.CreateAsyncChild(ctx)
+		wg.Done()
+	}()
+	wg.Wait()
+}
+
 func TestAddFieldDoesNotCauseRaceInSendHooks(t *testing.T) {
 	samplerHook := func(fields map[string]interface{}) (bool, int) {
 		for range fields {
@@ -234,11 +253,14 @@ func TestAddFieldDoesNotCauseRaceInSendHooks(t *testing.T) {
 
 	run := make(chan *Span)
 
+	wg := &sync.WaitGroup{}
+	wg.Add(1)
 	go func() {
 		for s := range run {
 			time.Sleep(time.Microsecond)
 			s.Send()
 		}
+		wg.Done()
 	}()
 
 	ctx, tr := NewTrace(context.Background(), "")
@@ -254,6 +276,8 @@ func TestAddFieldDoesNotCauseRaceInSendHooks(t *testing.T) {
 		}
 	}
 	close(run)
+	// need to wait here to avoid a race on resetting the SamplerHook
+	wg.Wait()
 }
 
 func setupLibhoney() *libhoney.MockOutput {