refactor: redundancy getter exhaust

pkg/replicas/getter.go

@@ -24,7 +24,13 @@ import (
 // then the probability of Swarmageddon is less than 0.000001
 // assuming the error rate of chunk retrievals stays below the level expressed
 // as depth by the publisher.
-var ErrSwarmageddon = errors.New("swarmageddon has begun")
+var (
+	ErrSwarmageddon = errors.New("swarmageddon has begun")
+	// errGetterExhausted is returned when the retry loop exhausts all levels without
+	// receiving a result or enough errors to trigger ErrSwarmageddon.
+	// This path should never be reached under normal operation.
+	errGetterExhausted = errors.New("replicas getter: exhausted all levels without result (unexpected)")
+)
 
 // getter is the private implementation of storage.Getter, an interface for
 // retrieving chunks. This getter embeds the original simple chunk getter and extends it
@@ -48,6 +54,9 @@ func NewGetter(g storage.Getter, level redundancy.Level) storage.Getter {
 
 // Get makes the getter satisfy the storage.Getter interface
 func (g *getter) Get(ctx context.Context, addr swarm.Address) (ch swarm.Chunk, err error) {
+	if g.level == redundancy.NONE {
+		return g.Getter.Get(ctx, addr)
+	}
 	ctx, cancel := context.WithCancel(ctx)
 	defer cancel()
 
@@ -77,7 +86,11 @@ func (g *getter) Get(ctx context.Context, addr swarm.Address) (ch swarm.Chunk, e
 	target := 2 // the number of replicas attempted to download in this batch
 	total := g.level.GetReplicaCount()
 
-	//
+	// The replicator feeds replica addresses in batches that double each RetryInterval
+	// (2, 2, 4, 8, 16 for PARANOID). The replicator exhausts exactly at the last iteration,
+	// which then drains a nil from `next` and becomes an indefinite wait on resultC/errc.
+	// The loop therefore always terminates via resultC (success) or Swarmageddon (all fail),
+	// never by falling through to the return below.
 	rr := newReplicator(addr, g.level)
 	next := rr.c
 	var wait <-chan time.Time // nil channel to disable case
@@ -142,5 +155,6 @@ func (g *getter) Get(ctx context.Context, addr swarm.Address) (ch swarm.Chunk, e
 		}
 	}
 
-	return nil, nil
+	// unreachable: the loop always exits via resultC or Swarmageddon (see comment above)
+	return nil, errGetterExhausted
 }

pkg/replicas/getter_test.go

@@ -194,8 +194,10 @@ func TestGetter(t *testing.T) {
 				}
 
 				t.Run("returns correct error", func(t *testing.T) {
-					if !errors.Is(err, replicas.ErrSwarmageddon) {
-						t.Fatalf("incorrect error. want Swarmageddon. got %v", err)
+					if tc.level > 0 {
+						if !errors.Is(err, replicas.ErrSwarmageddon) {
+							t.Fatalf("incorrect error. want Swarmageddon. got %v", err)
+						}
 					}
 					if !errors.Is(err, tc.failure.err) {
 						t.Fatalf("incorrect error. want it to wrap %v. got %v", tc.failure.err, err)