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Improve watch event handling #186

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Nov 17, 2021
Merged

Improve watch event handling #186

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36 changes: 33 additions & 3 deletions pkg/patterns/declarative/pkg/watch/dynamic.go
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Original file line number Diff line number Diff line change
Expand Up @@ -23,8 +23,10 @@ import (

"k8s.io/apimachinery/pkg/api/meta"
metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
"k8s.io/apimachinery/pkg/apis/meta/v1/unstructured"
"k8s.io/apimachinery/pkg/runtime"
"k8s.io/apimachinery/pkg/runtime/schema"
"k8s.io/apimachinery/pkg/types"
"k8s.io/apimachinery/pkg/watch"
"k8s.io/client-go/dynamic"
"sigs.k8s.io/controller-runtime/pkg/client"
Expand All @@ -51,6 +53,10 @@ type dynamicWatch struct {
client dynamic.Interface
restMapper meta.RESTMapper
events chan event.GenericEvent

// lastRV caches the last reported resource version.
// This helps us avoid sending duplicate events (e.g. on a rewatch)
lastRV map[types.NamespacedName]string
}

func (dw *dynamicWatch) newDynamicClient(gvk schema.GroupVersionKind, namespace string) (dynamic.ResourceInterface, error) {
Expand All @@ -73,6 +79,8 @@ func (dw *dynamicWatch) Add(trigger schema.GroupVersionKind, options metav1.List
return fmt.Errorf("creating client for (%s): %v", trigger.String(), err)
}

dw.lastRV = make(map[types.NamespacedName]string)

go func() {
for {
dw.watchUntilClosed(client, trigger, options, filterNamespace, target)
Expand Down Expand Up @@ -116,11 +124,33 @@ func (dw *dynamicWatch) watchUntilClosed(client dynamic.ResourceInterface, trigg
defer events.Stop()

for clientEvent := range events.ResultChan() {
if clientEvent.Type == watch.Bookmark {
// not an invalidation, we ignore it
switch clientEvent.Type {
case watch.Bookmark:
// not an object change, we ignore it
continue
case watch.Error:
log.Error(fmt.Errorf("unexpected error from watch: %v", clientEvent.Object), "error during watch")
return
}
log.WithValues("type", clientEvent.Type).WithValues("kind", trigger.String()).Info("broadcasting event")

u := clientEvent.Object.(*unstructured.Unstructured)
key := types.NamespacedName{Namespace: u.GetNamespace(), Name: u.GetName()}
rv := u.GetResourceVersion()

switch clientEvent.Type {
case watch.Deleted:
// stop lastRV growing indefinitely
delete(dw.lastRV, key)
// We always send the delete notification
case watch.Added, watch.Modified:
if previousRV, found := dw.lastRV[key]; found && previousRV == rv {
// Don't send spurious invalidations
continue
}
dw.lastRV[key] = rv
}

log.WithValues("type", clientEvent.Type).WithValues("kind", trigger.String()).WithValues("name", key.Name, "namespace", key.Namespace).Info("broadcasting event")
dw.events <- event.GenericEvent{Object: clientObject{Object: clientEvent.Object, ObjectMeta: &target}}
}

Expand Down