Merge pull request #419 from wangzlei/master

suppress Panic in Emitter

Author: wangzlei

xray/default_emitter.go

@@ -11,6 +11,7 @@ package xray
 import (
 	"encoding/json"
 	"net"
+	"runtime/debug"
 	"sync"
 
 	"github.com/aws/aws-xray-sdk-go/internal/logger"
@@ -57,6 +58,11 @@ func (de *DefaultEmitter) refresh(raddr *net.UDPAddr) (err error) {
 // Emit segment or subsegment if root segment is sampled.
 // seg has a write lock acquired by the caller.
 func (de *DefaultEmitter) Emit(seg *Segment) {
+	defer func() {
+		if r := recover(); r != nil {
+			logger.Errorf("Panic emitting segment: %s\n%s", r, string(debug.Stack()))
+		}
+	}()
 	HeaderBytes := []byte(Header)
 
 	if seg == nil || !seg.ParentSegment.Sampled {

xray/default_emitter_test.go

@@ -180,3 +180,17 @@ func BenchmarkDefaultEmitter(b *testing.B) {
 		}
 	})
 }
+
+func TestDefaultEmitterWithPanic(t *testing.T) {
+	seg := &Segment{
+		ParentSegment: nil, // cause Panic
+	}
+	emitter, err := NewDefaultEmitter(&net.UDPAddr{
+		IP:   net.IPv4(127, 0, 0, 1),
+		Port: 3000,
+	})
+	if err != nil {
+		t.Fatal(err)
+	}
+	emitter.Emit(seg)
+}