Refactor syncNetworkEndpoints

Add a waitgroup that waits for the completeness of all NEG
oeprations.

pkg/neg/syncers/transaction.go

@@ -107,6 +107,8 @@ type transactionSyncer struct {
 
 	// syncCollector collect sync related metrics
 	syncCollector metrics.SyncerMetricsCollector
+
+	wg sync.WaitGroup
 }
 
 func NewTransactionSyncer(
@@ -465,18 +467,27 @@ func (s *transactionSyncer) syncNetworkEndpoints(addEndpoints, removeEndpoints m
 	if err := syncFunc(removeEndpoints, detachOp); err != nil {
 		return err
 	}
+	go s.collectSyncResult()
 	return nil
 }
 
+// collectSyncResult collects the result of the sync and emits the metrics for sync result
+func (s *transactionSyncer) collectSyncResult() {
+	s.wg.Wait()
+	s.logger.V(3).Info("Done collecting result.")
+}
+
 // attachNetworkEndpoints creates go routine to run operations for attaching network endpoints
 func (s *transactionSyncer) attachNetworkEndpoints(zone string, networkEndpointMap map[negtypes.NetworkEndpoint]*composite.NetworkEndpoint) {
 	s.logger.V(2).Info("Attaching endpoints to NEG.", "countOfEndpointsBeingAttached", len(networkEndpointMap), "negSyncerKey", s.NegSyncerKey.String(), "zone", zone)
+	s.wg.Add(1)
 	go s.operationInternal(attachOp, zone, networkEndpointMap)
 }
 
 // detachNetworkEndpoints creates go routine to run operations for detaching network endpoints
 func (s *transactionSyncer) detachNetworkEndpoints(zone string, networkEndpointMap map[negtypes.NetworkEndpoint]*composite.NetworkEndpoint) {
 	s.logger.V(2).Info("Detaching endpoints from NEG.", "countOfEndpointsBeingDetached", len(networkEndpointMap), "negSyncerKey", s.NegSyncerKey.String(), "zone", zone)
+	s.wg.Add(1)
 	go s.operationInternal(detachOp, zone, networkEndpointMap)
 }