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Merge pull request #7 from kubescape/lru
add lru cache to deduplicate events from watches
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,69 @@ | ||
| package utils | ||
|
|
||
| import ( | ||
| "time" | ||
|
|
||
| lru "github.com/hashicorp/golang-lru/v2/expirable" | ||
| "k8s.io/apimachinery/pkg/apis/meta/v1/unstructured" | ||
| "k8s.io/apimachinery/pkg/watch" | ||
| ) | ||
|
|
||
| const ( | ||
| // Default size for the cooldown queue | ||
| DefaultQueueSize = 512 | ||
| // Default TTL for events put in the queue | ||
| DefaultTTL = 5 * time.Second | ||
| ) | ||
|
|
||
| // CooldownQueue is a queue that lets clients put events into it with a cooldown | ||
| // | ||
| // When a client puts an event into a queue, it forwards the event to its | ||
| // output channel and starts a cooldown for this event. If a client attempts to | ||
| // put the same event into the queue while the cooldown is running, the queue | ||
| // will silently drop the event. When the cooldown resets and a client puts the | ||
| // same event into the queue, it will be forwarded to the output channel | ||
| type CooldownQueue struct { | ||
| seenEvents *lru.LRU[string, bool] | ||
| // inner channel for producing events | ||
| innerChan chan watch.Event | ||
| // public channel for reading events | ||
| ResultChan <-chan watch.Event | ||
| } | ||
|
|
||
| // NewCooldownQueue returns a new Cooldown Queue | ||
| func NewCooldownQueue(size int, cooldown time.Duration) *CooldownQueue { | ||
| cache := lru.NewLRU[string, bool](size, nil, cooldown) | ||
| events := make(chan watch.Event) | ||
| return &CooldownQueue{ | ||
| seenEvents: cache, | ||
| innerChan: events, | ||
| ResultChan: events, | ||
| } | ||
| } | ||
|
|
||
| // makeEventKey creates a unique key for an event from a watcher | ||
| func makeEventKey(e watch.Event) string { | ||
| object, ok := e.Object.(*unstructured.Unstructured) | ||
| if !ok { | ||
| return "" | ||
| } | ||
| eventKey := string(e.Type) + "-" + string(object.GetUID()) | ||
| return eventKey | ||
| } | ||
|
|
||
| // Enqueue enqueues an event in the Cooldown Queue | ||
| func (q *CooldownQueue) Enqueue(e watch.Event) { | ||
| eventKey := makeEventKey(e) | ||
| _, exists := q.seenEvents.Get(eventKey) | ||
| if exists { | ||
| return | ||
| } | ||
| go func() { | ||
| q.innerChan <- e | ||
| }() | ||
| q.seenEvents.Add(eventKey, true) | ||
| } | ||
|
|
||
| func (q *CooldownQueue) Stop() { | ||
| close(q.innerChan) | ||
| } |