kgo: re-fix #493, supporting other buggy clients, and add a test

twmb · twmb · commit dc5283e20fb2 · 2023-07-10T13:54:18.000-06:00
diff --git a/pkg/kgo/group_balancer.go b/pkg/kgo/group_balancer.go
@@ -216,7 +216,7 @@ func NewConsumerBalancer(balance ConsumerBalancerBalance, members []kmsg.JoinGro
 			// workaround. See #493.
 			if bytes.HasPrefix(memberMeta, []byte{0, 1}) {
 				memberMeta[0] = 0
-				memberMeta[0] = 0
+				memberMeta[1] = 0
 				if err = meta.ReadFrom(memberMeta); err != nil {
 					return nil, fmt.Errorf("unable to read member metadata: %v", err)
 				}
diff --git a/pkg/kgo/group_balancer_test.go b/pkg/kgo/group_balancer_test.go
@@ -98,3 +98,18 @@ func Test_stickyAdjustCooperative(t *testing.T) {
 		t.Errorf("got plan != exp\ngot: %#v\nexp: %#v\n", inPlan, expPlan)
 	}
 }
+
+func TestNewConsumerBalancerIssue493(t *testing.T) {
+	m := kmsg.NewConsumerMemberMetadata()
+	m.Version = 0
+	m.Topics = []string{"foo"}
+	protoMeta := m.AppendTo(nil)
+	protoMeta[1] = 1
+	member := kmsg.NewJoinGroupResponseMember()
+	member.MemberID = "test"
+	member.ProtocolMetadata = protoMeta
+	_, err := NewConsumerBalancer(nil, []kmsg.JoinGroupResponseMember{member})
+	if err != nil {
+		t.Errorf("got unexpected error: %v", err)
+	}
+}

Original file line number	Diff line number	Diff line change
`@@ -216,7 +216,7 @@ func NewConsumerBalancer(balance ConsumerBalancerBalance, members []kmsg.JoinGro`
`216`	`216`	`// workaround. See #493.`
`217`	`217`	`if bytes.HasPrefix(memberMeta, []byte{0, 1}) {`
`218`	`218`	`memberMeta[0] = 0`
`219`		`- memberMeta[0] = 0`
	`219`	`+ memberMeta[1] = 0`
`220`	`220`	`if err = meta.ReadFrom(memberMeta); err != nil {`
`221`	`221`	`return nil, fmt.Errorf("unable to read member metadata: %v", err)`
`222`	`222`	`}`