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Avoid concurrent writes to a map in dynamicWatch #194

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Nov 24, 2021
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Avoid concurrent writes to a map in dynamicWatch #194

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11 changes: 6 additions & 5 deletions pkg/patterns/declarative/pkg/watch/dynamic.go
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Original file line number Diff line number Diff line change
Expand Up @@ -19,6 +19,7 @@ package watch
import (
"context"
"fmt"
"sync"
"time"

"k8s.io/apimachinery/pkg/api/meta"
Expand Down Expand Up @@ -56,7 +57,7 @@ type dynamicWatch struct {

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

func (dw *dynamicWatch) newDynamicClient(gvk schema.GroupVersionKind, namespace string) (dynamic.ResourceInterface, error) {
Expand All @@ -79,7 +80,7 @@ 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)
dw.lastRV = sync.Map{}

go func() {
for {
Expand Down Expand Up @@ -140,14 +141,14 @@ func (dw *dynamicWatch) watchUntilClosed(client dynamic.ResourceInterface, trigg
switch clientEvent.Type {
case watch.Deleted:
// stop lastRV growing indefinitely
delete(dw.lastRV, key)
dw.lastRV.Delete(key)
// We always send the delete notification
case watch.Added, watch.Modified:
if previousRV, found := dw.lastRV[key]; found && previousRV == rv {
if previousRV, found := dw.lastRV.Load(key); found && previousRV == rv {
// Don't send spurious invalidations
continue
}
dw.lastRV[key] = rv
dw.lastRV.Store(key, rv)
}

log.WithValues("type", clientEvent.Type).WithValues("kind", trigger.String()).WithValues("name", key.Name, "namespace", key.Namespace).Info("broadcasting event")
Expand Down