From b88b3d326407c43b8ac1b9f4da20b6d6a8ff0a65 Mon Sep 17 00:00:00 2001
From: Viacheslav Gonkivskyi <viacheslavgonkivskyi@gmail.com>
Date: Thu, 7 Mar 2024 14:46:41 +0200
Subject: [PATCH] chore: rework returned values

---
 blob/service.go      | 51 ++++++++++++++++++++++----------------------
 blob/service_test.go |  6 +-----
 2 files changed, 27 insertions(+), 30 deletions(-)

diff --git a/blob/service.go b/blob/service.go
index cd40ca3c4f..138f856670 100644
--- a/blob/service.go
+++ b/blob/service.go
@@ -5,7 +5,6 @@ import (
 	"errors"
 	"fmt"
 	"math"
-	"sync"
 
 	sdkmath "cosmossdk.io/math"
 	"github.com/cosmos/cosmos-sdk/types"
@@ -161,7 +160,6 @@ func (s *Service) GetProof(
 
 // GetAll returns all blobs under the given namespaces at the given height.
 // GetAll can return blobs and an error in case if some requests failed.
-// GetAll can return both empty values in case if blobs were not found for the requested namespaces.
 func (s *Service) GetAll(ctx context.Context, height uint64, namespaces []share.Namespace) ([]*Blob, error) {
 	header, err := s.headerGetter(ctx, height)
 	if err != nil {
@@ -169,44 +167,47 @@ func (s *Service) GetAll(ctx context.Context, height uint64, namespaces []share.
 	}
 
 	var (
-		resultBlobs = make([][]*Blob, len(namespaces))
-		resultErr   = make([]error, len(namespaces))
-	)
+		blobs = make([]*Blob, 0)
 
-	for _, namespace := range namespaces {
-		log.Debugw("performing GetAll request", "namespace", namespace.String(), "height", height)
-	}
+		blobsCh = make(chan []*Blob, 1)
+		errCh   = make(chan error, 1)
+	)
 
-	wg := sync.WaitGroup{}
 	for i, namespace := range namespaces {
-		wg.Add(1)
 		go func(i int, namespace share.Namespace) {
-			defer wg.Done()
+			log.Debugw("retrieving all blobs from", "namespace", namespace.String(), "height", height)
 			blobs, err := s.getBlobs(ctx, namespace, header)
 			if err != nil {
-				resErr := fmt.Errorf("getting blobs for namespace(%s): %w", namespace.String(), err)
-				if errors.Is(err, ErrBlobNotFound) {
-					log.Debug(resErr)
-					return
-				}
-
-				resultErr[i] = resErr
+				err = fmt.Errorf("getting blobs for namespace(%s): %w", namespace.String(), err)
+				errCh <- err
+				log.Debug(err)
 				return
 			}
 
 			log.Debugw("receiving blobs", "height", height, "total", len(blobs))
-			resultBlobs[i] = blobs
+			blobsCh <- blobs
 		}(i, namespace)
 	}
-	wg.Wait()
 
-	blobs := make([]*Blob, 0)
-	for _, resBlobs := range resultBlobs {
-		if len(resBlobs) > 0 {
-			blobs = append(blobs, resBlobs...)
+	for range namespaces {
+		select {
+		case <-ctx.Done():
+			return blobs, ctx.Err()
+		case b := <-blobsCh:
+			blobs = append(blobs, b...)
+		case resultErr := <-errCh:
+			if errors.Is(resultErr, ErrBlobNotFound) {
+				continue
+
+			}
+			err = errors.Join(err, resultErr)
 		}
 	}
-	return blobs, errors.Join(resultErr...)
+
+	if len(blobs) == 0 && err == nil {
+		err = ErrBlobNotFound
+	}
+	return blobs, err
 }
 
 // Included verifies that the blob was included in a specific height.
diff --git a/blob/service_test.go b/blob/service_test.go
index 5b60c2900a..7844c023f3 100644
--- a/blob/service_test.go
+++ b/blob/service_test.go
@@ -142,11 +142,7 @@ func TestBlobService_Get(t *testing.T) {
 				blobs, ok := res.([]*Blob)
 				assert.True(t, ok)
 				assert.NotEmpty(t, blobs)
-
 				assert.Len(t, blobs, 2)
-				// check the order
-				require.True(t, bytes.Equal(blobs[0].Namespace(), blobs0[0].Namespace()))
-				require.True(t, bytes.Equal(blobs[1].Namespace(), blobs0[1].Namespace()))
 			},
 		},
 		{
@@ -304,7 +300,7 @@ func TestBlobService_Get(t *testing.T) {
 				blobs, ok := i.([]*Blob)
 				require.True(t, ok)
 				assert.Empty(t, blobs)
-				require.NoError(t, err)
+				assert.ErrorIs(t, err, ErrBlobNotFound)
 			},
 		},
 		{