[#12] tracing: Add gRPC middleware

Signed-off-by: Dmitrii Stepanov <d.stepanov@yadro.com>

pkg/tracing/grpc_internal.go

@@ -0,0 +1,159 @@
+package tracing
+
+import (
+	"context"
+
+	"google.golang.org/grpc"
+	"google.golang.org/grpc/metadata"
+)
+
+type grpcMetadataCarrier struct {
+	md *metadata.MD
+}
+
+func (c *grpcMetadataCarrier) Get(key string) string {
+	values := c.md.Get(key)
+	if len(values) > 0 {
+		return values[0]
+	}
+	return ""
+}
+
+func (c *grpcMetadataCarrier) Set(key string, value string) {
+	c.md.Set(key, value)
+}
+
+func (c *grpcMetadataCarrier) Keys() []string {
+	result := make([]string, 0, c.md.Len())
+	for key := range *c.md {
+		result = append(result, key)
+	}
+	return result
+}
+
+func extractGRPCTraceInfo(ctx context.Context) context.Context {
+	md, ok := metadata.FromIncomingContext(ctx)
+	if !ok {
+		return ctx
+	}
+	carrier := &grpcMetadataCarrier{
+		md: &md,
+	}
+	return Propagator.Extract(ctx, carrier)
+}
+
+func setGRPCTraceInfo(ctx context.Context) context.Context {
+	md, ok := metadata.FromOutgoingContext(ctx)
+	if !ok {
+		md = metadata.MD{}
+	}
+	carrier := &grpcMetadataCarrier{
+		md: &md,
+	}
+	Propagator.Inject(ctx, carrier)
+	return metadata.NewOutgoingContext(ctx, md)
+}
+
+type clientStream struct {
+	originalStream grpc.ClientStream
+	desc           *grpc.StreamDesc
+	finished       chan<- error
+	done           <-chan struct{}
+}
+
+func newgRPCClientStream(originalStream grpc.ClientStream, desc *grpc.StreamDesc, finished chan<- error, done <-chan struct{}) grpc.ClientStream {
+	return &clientStream{
+		originalStream: originalStream,
+		desc:           desc,
+		finished:       finished,
+		done:           done,
+	}
+}
+
+func (cs *clientStream) Header() (metadata.MD, error) {
+	md, err := cs.originalStream.Header()
+	if err != nil {
+		select {
+		case <-cs.done:
+		case cs.finished <- err:
+		}
+	}
+	return md, err
+}
+
+func (cs *clientStream) Trailer() metadata.MD {
+	return cs.originalStream.Trailer()
+}
+
+func (cs *clientStream) CloseSend() error {
+	err := cs.originalStream.CloseSend()
+	if err != nil {
+		select {
+		case <-cs.done:
+		case cs.finished <- err:
+		}
+	}
+	return err
+}
+
+func (cs *clientStream) Context() context.Context {
+	return cs.originalStream.Context()
+}
+
+func (cs *clientStream) SendMsg(m interface{}) error {
+	err := cs.originalStream.SendMsg(m)
+	if err != nil {
+		select {
+		case <-cs.done:
+		case cs.finished <- err:
+		}
+	}
+	return err
+}
+
+func (cs *clientStream) RecvMsg(m interface{}) error {
+	err := cs.originalStream.RecvMsg(m)
+	if err != nil || !cs.desc.ServerStreams {
+		select {
+		case <-cs.done:
+		case cs.finished <- err:
+		}
+	}
+	return err
+}
+
+type serverStream struct {
+	originalStream grpc.ServerStream
+	ctx            context.Context
+}
+
+func newgRPCServerStream(ctx context.Context, originalStream grpc.ServerStream) grpc.ServerStream {
+	return &serverStream{
+		originalStream: originalStream,
+		ctx:            ctx,
+	}
+}
+
+func (ss *serverStream) SetHeader(md metadata.MD) error {
+	return ss.originalStream.SendHeader(md)
+}
+
+func (ss *serverStream) SendHeader(md metadata.MD) error {
+	return ss.originalStream.SendHeader(md)
+}
+
+func (ss *serverStream) SetTrailer(md metadata.MD) {
+	ss.originalStream.SetTrailer(md)
+}
+
+func (ss *serverStream) Context() context.Context {
+	return ss.ctx
+}
+
+func (ss *serverStream) SendMsg(m interface{}) error {
+	return ss.originalStream.SendMsg(m)
+}
+
+func (ss *serverStream) RecvMsg(m interface{}) error {
+	return ss.originalStream.RecvMsg(m)
+}