From 4753adca9f925c31dce26c7617abb0f4800d780c Mon Sep 17 00:00:00 2001
From: nb-ohad <mitrani.ohad@gmail.com>
Date: Wed, 26 Jun 2024 14:59:34 +0300
Subject: [PATCH] Driver Controller: Scaffolding for concurrent reconcile

Signed-off-by: nb-ohad <mitrani.ohad@gmail.com>
---
 internal/controller/driver_controller.go | 35 ++++++++++++++++
 utils/utils.go                           | 53 ++++++++++++++++++++++++
 2 files changed, 88 insertions(+)
 create mode 100644 utils/utils.go

diff --git a/internal/controller/driver_controller.go b/internal/controller/driver_controller.go
index ff717a45..a7aeef57 100644
--- a/internal/controller/driver_controller.go
+++ b/internal/controller/driver_controller.go
@@ -18,6 +18,7 @@ package controller
 
 import (
 	"context"
+	"errors"
 	"fmt"
 	"maps"
 	"reflect"
@@ -37,6 +38,7 @@ import (
 	"sigs.k8s.io/controller-runtime/pkg/reconcile"
 
 	csiv1a1 "github.com/ceph/ceph-csi-operator/api/v1alpha1"
+	"github.com/ceph/ceph-csi-operator/utils"
 )
 
 //+kubebuilder:rbac:groups=csi.ceph.io,resources=drivers,verbs=get;list;watch;create;update;patch;delete
@@ -139,6 +141,23 @@ func (r *driverReconcile) reconcile() (ctrl.Result, error) {
 		return ctrl.Result{}, err
 	}
 
+	// Concurrently reconcile different aspects of the clusters actual state to meet
+	// the desired state defined on the driver object
+	errChan := utils.RunConcurrently(
+		r.upsertPluginDeamonSet,
+		r.upsertProvisionerDeployment,
+		r.upsertK8sCSIDriver,
+		r.upsertLivnessService,
+	)
+
+	// Check if any reconcilatin error where raised during the concurrent execution
+	// of the reconciliation steps.
+	errList := utils.ChannelToSlice(errChan)
+	if err := errors.Join(errList...); err != nil {
+		r.log.Error(err, "Reconciliation failed")
+		return ctrl.Result{}, err
+	}
+
 	return ctrl.Result{}, nil
 }
 
@@ -188,6 +207,22 @@ func (r *driverReconcile) LoadAndValidateDesiredState() error {
 	return nil
 }
 
+func (r *driverReconcile) upsertPluginDeamonSet() error {
+	return nil
+}
+
+func (r *driverReconcile) upsertProvisionerDeployment() error {
+	return nil
+}
+
+func (r *driverReconcile) upsertK8sCSIDriver() error {
+	return nil
+}
+
+func (r *driverReconcile) upsertLivnessService() error {
+	return nil
+}
+
 // mergeDriverSpecs will fill in any unset fields in dest with a copy of the same field in src
 func mergeDriverSpecs(dest, src *csiv1a1.DriverSpec) {
 	// Create a copy of the src, making sure that any value copied into dest is a not shared
diff --git a/utils/utils.go b/utils/utils.go
new file mode 100644
index 00000000..0e635eb2
--- /dev/null
+++ b/utils/utils.go
@@ -0,0 +1,53 @@
+/*
+Copyright 2024.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package utils
+
+import (
+	"sync"
+)
+
+func RunConcurrently(fnList ...func() error) chan error {
+	errors := make(chan error)
+	wg := sync.WaitGroup{}
+
+	// Run all the functions concurrently
+	for _, fn := range fnList {
+		fn := fn
+		wg.Add(1)
+		go func() {
+			defer wg.Done()
+			errors <- fn()
+		}()
+	}
+
+	// Close the output channel whenever all of the functions completed
+	go func() {
+		wg.Wait()
+		close(errors)
+	}()
+
+	// Read from the channel and aggregate into a slice
+	return errors
+}
+
+func ChannelToSlice[T any](c chan T) []T {
+	list := []T{}
+	for value := range c {
+		list = append(list, value)
+	}
+	return list
+}