add async reconciler that can reconcile multiple services simultaneously

controllers/async_reconciler.go

@@ -0,0 +1,37 @@
+package controllers
+
+import (
+	"context"
+	kerrors "k8s.io/apimachinery/pkg/util/errors"
+	"sigs.k8s.io/cluster-api-provider-azure/azure"
+)
+
+type asyncReconciler struct {
+	results chan error
+}
+
+func NewAsyncReconciler() asyncReconciler {
+	return asyncReconciler{}
+}
+
+func (ar *asyncReconciler) submit(ctx context.Context, task azure.Reconciler) {
+	go func() {
+		ar.results <- task.Reconcile(ctx)
+
+	}()
+}
+
+func (ar *asyncReconciler) wait() error {
+	var errs []error
+	for r := range ar.results {
+		if r != nil {
+			errs = append(errs, r)
+		}
+	}
+
+	if len(errs) > 0 {
+		return kerrors.NewAggregate(errs)
+	}
+
+	return nil
+}