endpoint: Add function to initialize event queue

This is useful during endpoint validation when endpoints are being
restored. When they are being restored, their event queue is not yet
initialized because they haven't been exposed to the endpoint manager.
It is important to initialize an endpoint's event queue so that events
are not missed during their restoration.

Signed-off-by: Chris Tarazi <chris@isovalent.com>

pkg/endpoint/manager.go

@@ -60,7 +60,9 @@ func (e *Endpoint) Expose(mgr endpointManager) error {
 	// its ID, and its eventqueue can be safely started. Ensure that it is only
 	// started once it is exposed to the endpointmanager so that it will be
 	// stopped when the endpoint is removed from the endpointmanager.
-	e.eventQueue = eventqueue.NewEventQueueBuffered(fmt.Sprintf("endpoint-%d", e.ID), option.Config.EndpointQueueSize)
+	if e.eventQueue == nil {
+		e.InitEventQueue()
+	}
 	e.eventQueue.Run()
 
 	mgr.AddIPv6Address(e.IPv6)
@@ -167,3 +169,17 @@ func (e *Endpoint) Unexpose(mgr endpointManager) <-chan struct{} {
 	e.removeReferences(mgr)
 	return epRemoved
 }
+
+// InitEventQueue initializes the endpoint's event queue. Note that this
+// function does not begin processing events off the queue, as that's left up
+// to the caller to call Expose in order to allow other subsystems to access
+// the endpoint. This function assumes that the endpoint ID has already been
+// allocated!
+//
+// Having this be a separate function allows us to prepare
+// the event queue while the endpoint is being validated (during restoration)
+// so that when its metadata is resolved, events can be enqueued (such as
+// visibility policy and bandwidth policy).
+func (e *Endpoint) InitEventQueue() {
+	e.eventQueue = eventqueue.NewEventQueueBuffered(fmt.Sprintf("endpoint-%d", e.ID), option.Config.EndpointQueueSize)
+}