recover the panic caused by close sendCh (#50)

reporter/grpc.go

@@ -264,6 +264,12 @@ func (r *gRPCReporter) Send(spans []go2sky.ReportedSpan) {
 		r.logger.Printf("marshal segment object err %v", err)
 		return
 	}
+	defer func() {
+		// recover the panic caused by close sendCh
+		if err := recover(); err != nil {
+			r.logger.Printf("reporter segment err %v", err)
+		}
+	}()
 	segment.Segment = b
 	select {
 	case r.sendCh <- segment:

reporter/grpc_test.go

@@ -25,6 +25,7 @@ import (
 	"os"
 	"strings"
 	"testing"
+	"time"
 
 	"github.com/golang/mock/gomock"
 
@@ -85,6 +86,25 @@ func Test_e2e(t *testing.T) {
 	}
 }
 
+func TestGRPCReporter_Close(t *testing.T) {
+	serviceName, _, instance, _, reporter := createMockReporter(t)
+	reporter.sendCh = make(chan *common.UpstreamSegment, 1)
+	tracer, err := go2sky.NewTracer(serviceName, go2sky.WithReporter(reporter), go2sky.WithInstance(instance))
+	if err != nil {
+		t.Error(err)
+	}
+	tracer.WaitUntilRegister()
+	entry, _, err := tracer.CreateEntrySpan(context.Background(), "/close", func() (s string, err error) {
+		return header, nil
+	})
+	if err != nil {
+		t.Error(err)
+	}
+	reporter.Close()
+	entry.End()
+	time.Sleep(time.Second)
+}
+
 func createMockReporter(t *testing.T) (string, int32, string, int32, *gRPCReporter) {
 	ctrl := gomock.NewController(t)
 	mockRegisterClient := mock_register.NewMockRegisterClient(ctrl)