From 1ee3b82d999eeb02e5def89c65e80e817e40e774 Mon Sep 17 00:00:00 2001
From: 7h3-3mp7y-m4n <emailtorash@gmail.com>
Date: Wed, 5 Jun 2024 23:45:42 +0530
Subject: [PATCH 1/2] Fix: Parallels updates subscription where possible,
 instead of recreating it

---
 pkg/reconciler/parallel/parallel.go      | 13 +++++++++++--
 pkg/reconciler/parallel/parallel_test.go | 21 ++++++++++++---------
 2 files changed, 23 insertions(+), 11 deletions(-)

diff --git a/pkg/reconciler/parallel/parallel.go b/pkg/reconciler/parallel/parallel.go
index 26f3521b03c..f7b94764451 100644
--- a/pkg/reconciler/parallel/parallel.go
+++ b/pkg/reconciler/parallel/parallel.go
@@ -22,7 +22,8 @@ import (
 
 	"go.uber.org/zap"
 	corev1 "k8s.io/api/core/v1"
-	"k8s.io/apimachinery/pkg/api/equality"
+
+	//"k8s.io/apimachinery/pkg/api/equality"
 	apierrs "k8s.io/apimachinery/pkg/api/errors"
 	"k8s.io/apimachinery/pkg/api/meta"
 	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
@@ -45,6 +46,7 @@ import (
 	messaginglisters "knative.dev/eventing/pkg/client/listers/messaging/v1"
 	ducklib "knative.dev/eventing/pkg/duck"
 	"knative.dev/eventing/pkg/reconciler/parallel/resources"
+	"knative.dev/pkg/kmp"
 )
 
 type Reconciler struct {
@@ -216,7 +218,7 @@ func (r *Reconciler) reconcileSubscription(ctx context.Context, branchNumber int
 		// TODO: Send events here, or elsewhere?
 		//r.Recorder.Eventf(p, corev1.EventTypeWarning, subscriptionCreateFailed, "Create Parallels's subscription failed: %v", err)
 		return nil, fmt.Errorf("failed to get Subscription: %s", err)
-	} else if !equality.Semantic.DeepDerivative(expected.Spec, sub.Spec) {
+	} else if immutableFieldsChanged := expected.CheckImmutableFields(ctx, sub); immutableFieldsChanged != nil {
 		// Given that spec.channel is immutable, we cannot just update the subscription. We delete
 		// it instead, and re-create it.
 		err = r.eventingClientSet.MessagingV1().Subscriptions(sub.Namespace).Delete(ctx, sub.Name, metav1.DeleteOptions{})
@@ -230,6 +232,13 @@ func (r *Reconciler) reconcileSubscription(ctx context.Context, branchNumber int
 			return nil, err
 		}
 		return newSub, nil
+	} else if equal, err := kmp.SafeEqual(sub.Spec, expected.Spec); !equal || err != nil {
+		updatedSub, err := r.eventingClientSet.MessagingV1().Subscriptions(sub.Namespace).Update(ctx, expected, metav1.UpdateOptions{})
+		if err != nil {
+			logging.FromContext(ctx).Infow("Cannot update subscription", zap.Error(err))
+			return nil, err
+		}
+		return updatedSub, nil
 	}
 	return sub, nil
 }
diff --git a/pkg/reconciler/parallel/parallel_test.go b/pkg/reconciler/parallel/parallel_test.go
index 54dbec0d76f..8a3dbee44b8 100644
--- a/pkg/reconciler/parallel/parallel_test.go
+++ b/pkg/reconciler/parallel/parallel_test.go
@@ -427,22 +427,25 @@ func TestAllBranches(t *testing.T) {
 						{Subscriber: createSubscriber(0)},
 					})))},
 			WantErr: false,
-			WantDeletes: []clientgotesting.DeleteActionImpl{{
-				ActionImpl: clientgotesting.ActionImpl{
-					Namespace: testNS,
-					Resource:  v1.SchemeGroupVersion.WithResource("subscriptions"),
+			WantUpdates: []clientgotesting.UpdateActionImpl{
+				{
+					ActionImpl: clientgotesting.ActionImpl{
+						Namespace: testNS,
+						Resource:  v1.SchemeGroupVersion.WithResource("subscriptions"),
+					},
+					Object: resources.NewSubscription(0, NewFlowsParallel(parallelName, testNS,
+						WithFlowsParallelChannelTemplateSpec(imc),
+						WithFlowsParallelBranches([]v1.ParallelBranch{
+							{Subscriber: createSubscriber(1)},
+						}))),
 				},
-				Name: resources.ParallelBranchChannelName(parallelName, 0),
-			}},
+			},
 			WantCreates: []runtime.Object{
 				createChannel(parallelName),
 				createBranchChannel(parallelName, 0),
 				resources.NewFilterSubscription(0, NewFlowsParallel(parallelName, testNS, WithFlowsParallelChannelTemplateSpec(imc), WithFlowsParallelBranches([]v1.ParallelBranch{
 					{Subscriber: createSubscriber(1)},
 				}))),
-				resources.NewSubscription(0, NewFlowsParallel(parallelName, testNS, WithFlowsParallelChannelTemplateSpec(imc), WithFlowsParallelBranches([]v1.ParallelBranch{
-					{Subscriber: createSubscriber(1)},
-				}))),
 			},
 			WantStatusUpdates: []clientgotesting.UpdateActionImpl{{
 				Object: NewFlowsParallel(parallelName, testNS,

From 5553cf3f91fc52ffebaf53b03b0b6d1ede072ec1 Mon Sep 17 00:00:00 2001
From: 7h3-3mp7y-m4n <emailtorash@gmail.com>
Date: Mon, 10 Jun 2024 16:23:07 +0530
Subject: [PATCH 2/2] Fix: removing not imported pkg

---
 pkg/reconciler/parallel/parallel.go | 2 --
 1 file changed, 2 deletions(-)

diff --git a/pkg/reconciler/parallel/parallel.go b/pkg/reconciler/parallel/parallel.go
index f7b94764451..1e6d674a6a2 100644
--- a/pkg/reconciler/parallel/parallel.go
+++ b/pkg/reconciler/parallel/parallel.go
@@ -22,8 +22,6 @@ import (
 
 	"go.uber.org/zap"
 	corev1 "k8s.io/api/core/v1"
-
-	//"k8s.io/apimachinery/pkg/api/equality"
 	apierrs "k8s.io/apimachinery/pkg/api/errors"
 	"k8s.io/apimachinery/pkg/api/meta"
 	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"