Use map for accumulating errors

Author: ykadowak

pkg/agent/core/ngt/handler/grpc/object.go

@@ -28,7 +28,6 @@ import (
 	"github.com/vdaas/vald/internal/net/grpc/errdetails"
 	"github.com/vdaas/vald/internal/net/grpc/status"
 	"github.com/vdaas/vald/internal/observability/trace"
-	"github.com/vdaas/vald/internal/slices"
 )
 
 func (s *server) Exists(ctx context.Context, uid *payload.Object_ID) (res *payload.Object_ID, err error) {
@@ -211,8 +210,9 @@ func (s *server) StreamListObject(_ *payload.Object_List_Request, stream vald.Ob
 
 	var (
 		mu   sync.Mutex
-		emu  sync.Mutex
+		emu  sync.RWMutex
 		errs = make([]error, 0, s.ngt.Len())
+		emap = make(map[string]struct{})
 	)
 	s.ngt.ListObjectFunc(ctx, func(uuid string, _ uint32, _ int64) bool {
 		vec, ts, err := s.ngt.GetObject(uuid)
@@ -241,27 +241,34 @@ func (s *server) StreamListObject(_ *payload.Object_List_Request, stream vald.Ob
 		mu.Unlock()
 
 		if err != nil {
-			emu.Lock()
-			errs = append(errs, err)
-			emu.Unlock()
+			emu.RLock()
+			_, ok := emap[err.Error()]
+			emu.RUnlock()
+			if !ok {
+				emu.Lock()
+				errs = append(errs, err)
+				emap[err.Error()] = struct{}{}
+				emu.Unlock()
+			}
 		}
 
 		// always return true to continue streaming and let the context cancel the Range when stream closes.
 		return true
 	})
 
 	if len(errs) != 0 {
-		slices.RemoveDuplicates(errs, func(left, right error) bool {
-			return left.Error() < right.Error()
-		})
-		err = errors.Join(errs...)
-		st, msg, err := status.ParseError(err, codes.Internal, "failed to parse StreamListObject final gRPC error response")
-		if span != nil {
-			span.RecordError(err)
-			span.SetAttributes(trace.FromGRPCStatus(st.Code(), msg)...)
-			span.SetStatus(trace.StatusError, msg)
+		// Register all the gRPC codes to the span. Doing this because ParseError cannot parse joined error.
+		for _, e := range errs {
+			st, msg, err := status.ParseError(e, codes.Internal, "failed to parse StreamListObject final gRPC error response")
+			if span != nil {
+				span.RecordError(err)
+				span.SetAttributes(trace.FromGRPCStatus(st.Code(), msg)...)
+				span.SetStatus(trace.StatusError, msg)
+			}
 		}
-		return err
+
+		// now join all the errors to return
+		return errors.Join(errs...)
 	}
 	return nil
 }